CN118882901A - Six-axis force sensor and manufacturing method thereof - Google Patents

Abstract

The embodiment of the present application discloses a six-axis force sensor and a manufacturing method thereof, wherein the six-axis force sensor comprises: a force-bearing block; a support frame, the support frame surrounds the force-bearing block, and there is a gap between the force-bearing block and the support frame; multiple groups of elastic members, the multiple groups of elastic members are arranged in the gap, and are respectively connected to the force-bearing block and the support frame, and the multiple groups of elastic members divide the gap into multiple first deformation cavities; a plurality of force-sensitive resistors, the multiple force-sensitive resistors are arranged in the elastic members to form six groups of Wheatstone bridges, which are respectively used to measure the first force, the second force, the third force, the first moment, the second moment and the third moment; each group of elastic members includes a pair of elastic beams arranged at intervals; any pair of elastic beams and the force-bearing block and the support frame enclose a second deformation cavity. According to the present application, its double elastic beam structure provides a space for the force-sensitive resistor to be arranged, realizes the self-decoupling between the measured force and moment and the non-measured force and moment, and improves the accuracy of the six-axis force sensor of the present application.

Description

Six-axis force sensor and manufacturing method thereof

Technical Field

The present application relates to the technical field of force sensors, and in particular to a six-axis force sensor and a manufacturing method thereof.

Background Art

Existing six-axis force sensors usually adopt a purely mechanical structure design, which is bulky and inconvenient to use in the micro field. General micro six-axis force sensors often have complex structures, are difficult to process, and have complex decoupling between the axial forces.

The force-sensitive resistors of piezoresistive force sensors often form a Wheatstone bridge to achieve accurate force measurement. A complete low-coupling six-axis force sensor requires six groups of Wheatstone bridges with a total of 24 force-sensitive resistors. In order to ensure the sensitivity to the measured force dimension and the low response to the forces in the remaining dimensions, each Wheatstone bridge has special requirements for the arrangement of its force-sensitive resistors. The force distribution on the single-beam structure is fixed, and only one force-sensitive resistor can be placed at the same position, which requires double-layer or double-sided doping of the beam to arrange the force-sensitive resistors in layers. This makes the process complicated, and it is difficult to ensure the consistency of the doping concentration on the upper and lower surfaces, resulting in poor consistency of the device. Therefore, how to set the elastic beam structure to meet the arrangement of the force-sensitive resistors is an urgent problem to be solved.

Summary of the invention

The embodiments of the present application provide a six-axis force sensor and a method for manufacturing the same, using a dual-beam structure to provide a space for arranging force-sensitive resistors and self-decoupling between measured forces, moments, or moments and non-measured forces and moments.

In order to solve the above technical problems, the embodiments of the present application disclose the following technical solutions:

In one aspect, a six-axis force sensor is provided, comprising:

Load bearing block;

A supporting frame, wherein the supporting frame surrounds the force-bearing block, and a gap is provided between the force-bearing block and the supporting frame;

A plurality of groups of elastic members, the plurality of groups of elastic members are arranged in the gap and are respectively connected to the force-bearing block and the support frame, the plurality of groups of elastic members divide the gap into a plurality of first deformation cavities, and the first deformation cavities are used to accommodate the deformation of the elastic members;

A plurality of force-sensitive resistors, wherein the plurality of force-sensitive resistors are arranged in the elastic member to form six groups of Wheatstone bridges, respectively used to measure a first force, a second force, a third force, a first torque, a second torque, and a third torque;

Each group of the elastic members includes a pair of elastic beams arranged at intervals; any pair of the elastic beams, the force-bearing blocks and the supporting frame enclose a second deformation cavity, and the second deformation cavity is used to accommodate the deformation of the elastic beams.

In addition to or instead of one or more of the features disclosed above, the six-axis force sensor has a first plane, in which there are intersecting and perpendicular first and second axes, one side surface of the elastic member is in the first plane, and the elastic beams in the same group of elastic members are symmetrical about the first axis or the second axis.

In addition to or as an alternative to one or more of the features disclosed above, the plurality of force-sensitive resistors are all arranged in the first plane;

A center point is provided in the first plane, and a force-sensitive resistor in the Wheatstone bridge for measuring the first force, the second force or the third force is rotationally symmetric about the center point in the first plane;

The force-sensitive resistors in the Wheatstone bridge for measuring the first torque, the second torque and the third torque are symmetrical about the first axial direction or the second axial direction in a first plane.

In addition to or as an alternative to one or more features disclosed above, the Wheatstone bridges used to measure the first force, the second force, the third force, the first moment, the second moment and the third moment are all full-arm Wheatstone bridges.

In addition to or as an alternative to one or more of the features disclosed above, the direction of the first force extends along the first axial direction, the plurality of force-sensitive resistors include a first force-sensitive resistor, a second force-sensitive resistor, a third force-sensitive resistor and a fourth force-sensitive resistor for measuring the first force, the first force-sensitive resistor and the second force-sensitive resistor are respectively arranged on a pair of the elastic beams on one side of the force-bearing block about the second axial direction, and the third force-sensitive resistor and the fourth force-sensitive resistor are respectively arranged on a pair of the elastic beams on the other side; the first force-sensitive resistor and the second force-sensitive resistor are diagonally arranged in the bridge, and the third force-sensitive resistor and the fourth force-sensitive resistor are diagonally arranged in the bridge;

The direction of the second force extends along the second axial direction, and the plurality of force-sensitive resistors also include a fifth force-sensitive resistor, a sixth force-sensitive resistor, a seventh force-sensitive resistor and an eighth force-sensitive resistor for measuring the second force, the fifth force-sensitive resistor and the eighth force-sensitive resistor are respectively arranged on a pair of the elastic beams on one side of the force-bearing block with respect to the first axial direction, and the sixth force-sensitive resistor and the seventh force-sensitive resistor are respectively arranged on a pair of the elastic beams on the other side; the fifth force-sensitive resistor and the eighth force-sensitive resistor are diagonally arranged in the bridge, and the sixth force-sensitive resistor and the seventh force-sensitive resistor are diagonally arranged in the bridge; The direction of the third force extends along a third axial direction, and the plurality of force-sensitive resistors also include a ninth force-sensitive resistor, a tenth force-sensitive resistor, an eleventh force-sensitive resistor and a twelfth force-sensitive resistor for measuring the third force, the fifth force-sensitive resistor and the tenth force-sensitive resistor are arranged on one of the elastic beams on one side of the force-bearing block about the first axial direction or the second axial direction, and the eleventh force-sensitive resistor and the twelfth force-sensitive resistor are both arranged on one of the elastic beams on the other side; the ninth force-sensitive resistor and the twelfth force-sensitive resistor are diagonally arranged in the bridge, and the tenth force-sensitive resistor and the eleventh force-sensitive resistor are diagonally arranged in the bridge.

In addition to one or more features disclosed above, or as an alternative, the direction of the first torque rotates counterclockwise around the first axis, the plurality of force-sensitive resistors include a thirteenth force-sensitive resistor, a fourteenth force-sensitive resistor, a fifteenth force-sensitive resistor and a sixteenth force-sensitive resistor for measuring the first torque, the thirteenth force-sensitive resistor and the fourteenth force-sensitive resistor are arranged on one of the elastic beams on one side of the first axis, and the fifteenth force-sensitive resistor and the sixteenth force-sensitive resistor are arranged on one of the elastic beams on the other side; the thirteenth force-sensitive resistor and the fifteenth force-sensitive resistor are arranged diagonally in the bridge, and the fourteenth force-sensitive resistor and the sixteenth force-sensitive resistor are arranged diagonally in the bridge;

The direction of the second torque rotates counterclockwise around the second axis, and the plurality of force-sensitive resistors further include a seventeenth force-sensitive resistor, an eighteenth force-sensitive resistor, a nineteenth force-sensitive resistor, and a twentieth force-sensitive resistor for measuring the second torque, the seventeenth force-sensitive resistor and the eighteenth force-sensitive resistor are arranged on one of the elastic beams on one side of the second axis, and the nineteenth force-sensitive resistor and the twentieth force-sensitive resistor are arranged on one of the elastic beams on the other side; the seventeenth force-sensitive resistor and the nineteenth force-sensitive resistor are arranged diagonally in the bridge, and the eighteenth force-sensitive resistor and the twentieth force-sensitive resistor are arranged diagonally in the bridge;

The direction of the third torque rotates counterclockwise around the third axial direction, and the plurality of force-sensitive resistors include a twenty-first force-sensitive resistor, a twenty-second force-sensitive resistor, a twenty-third force-sensitive resistor and a twenty-fourth force-sensitive resistor for measuring the third torque, the twenty-first force-sensitive resistor and the twenty-fourth force-sensitive resistor are respectively arranged on a pair of the elastic beams on one side of the first axial direction or the second axial direction, and the twenty-second force-sensitive resistor and the twenty-third force-sensitive resistor are respectively arranged on a pair of the elastic beams on the other side; the twenty-first force-sensitive resistor and the twenty-third force-sensitive resistor are diagonally arranged in the bridge, and the twenty-second force-sensitive resistor and the twenty-fourth force-sensitive resistor are diagonally arranged in the bridge.

In addition to one or more features disclosed above, or as an alternative, the eleventh force-sensitive resistor and the nineteenth force-sensitive resistor are the same force-sensitive resistor, and the twelfth force-sensitive resistor and the twentieth force-sensitive resistor are the same force-sensitive resistor.

In addition to or as an alternative to one or more of the features disclosed above, the force-sensitive resistor for measuring the first force and the second force is arranged at a position of 1/6 to 1/2 of the elastic beam close to the support frame.

In addition to or as an alternative to one or more features disclosed above, the force-sensitive resistor for measuring the third force, the first moment and the second moment is arranged at one end close to the force-bearing block and one end close to the supporting frame.

In addition to one or more of the features disclosed above, or as an alternative, the force-sensitive resistors for measuring the third moment are all arranged at one end of the elastic beam close to the force-bearing block, or the force-sensitive resistors for measuring the third moment are all arranged at one end of the elastic beam close to the support frame;

The force-sensitive resistor for measuring the third torque is arranged on the outside of an elastic beam away from another elastic beam in the same group of elastic members.

In addition to or instead of one or more of the features disclosed above, the six-axis force sensor also has a third axis that intersects and is perpendicular to the first plane, and in the third axis, the thickness of the support frame is greater than the thickness of the force block and the elastic member.

On the other hand, a six-axis force sensor manufacturing method is further disclosed. In addition to or as an alternative to one or more of the features disclosed above, the six-axis force sensor manufacturing method includes the six-axis force sensor as described in any one of the above items, and the six-axis force sensor manufacturing method includes:

Providing a silicon wafer, and forming an oxide layer on a surface of one side of the silicon wafer;

Performing patterning on the oxide layer to form a force-sensitive resistor pattern, and doping the silicon wafer at the position of the force-sensitive resistor pattern to form a force-sensitive resistor in the silicon wafer;

The oxide layer is patterned to form an ohmic contact layer pattern, and the silicon wafer at the position of the ohmic contact layer pattern is doped to form an ohmic contact layer on the surface of the silicon wafer, wherein the ohmic contact layer is connected to the force-sensitive resistor; the ohmic contact layer is etched to form a plurality of ohmic contact regions corresponding to the force-sensitive resistors; and annealing is performed to activate the force-sensitive resistor and the ohmic contact region;

Forming a wiring on a surface of one side of the silicon wafer having an ohmic contact area, wherein the wiring is connected to the force-sensitive resistor through the ohmic contact area;

Patterning and etching the surface of the silicon wafer on one side away from the wiring to form a support frame to the thickness position of the force-bearing block and the elastic member;

The surface of the silicon wafer on one side away from the wiring is patterned and etched in an area other than the supporting frame to form the force-bearing block and the elastic member.

One of the above technical solutions has the following advantages or beneficial effects: the elastic member of the present application adopts a double elastic beam structure, which provides more layout space for force-sensitive resistors compared to the single elastic beam structure in the prior art; the larger layout space can increase the distance between adjacent force-sensitive resistors, reduce the difficulty of the production process and the manufacturing cost, and avoid the Wheatstone bridge being affected by non-measured forces and torques to produce signal errors, realize the self-decoupling between the measured force and torque and the non-measured force and torque, and improve the accuracy of the six-axis force sensor of the present application. A number of force-sensitive resistors are arranged on the elastic beam to form six groups of Wheatstone bridges for measuring six-axis forces and torques respectively, and the force-sensitive resistors are all arranged in the same plane of the elastic beam. Compared with the technical solution of setting the force-sensitive resistors in different planes in the prior art, the present application greatly reduces the difficulty of the manufacturing process and the manufacturing cost, and the doping and manufacturing of the force-sensitive resistors in the same plane can ensure the consistency of the doping concentration, greatly improve the consistency of all force-sensitive resistor devices, and thus improve the accuracy of the measurement of the six-axis force sensor of the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

FIG1 is a schematic diagram of the structure of a six-axis force sensor provided according to an embodiment of the present application.

FIG2 is a schematic diagram of force direction of a six-axis force sensor provided according to an embodiment of the present application.

FIG3 is a schematic diagram of the torque direction of a six-axis force sensor provided according to an embodiment of the present application.

4 shows a schematic diagram of stress distribution of a six-axis force sensor proposed in an embodiment of the present application under the action of a first force, a second force, a third force, a first moment, a second moment and a third moment respectively.

FIG5 is a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring a first force in a six-axis force sensor provided according to an embodiment of the present application.

FIG6 is a circuit diagram of a Wheatstone bridge for measuring a first force in a six-axis force sensor provided according to an embodiment of the present application.

FIG. 7 is a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring a second force in a six-axis force sensor provided according to an embodiment of the present application.

FIG8 is a circuit diagram of a Wheatstone bridge for measuring a second force in a six-axis force sensor provided according to an embodiment of the present application.

FIG9 is a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring a third force in a six-axis force sensor provided according to an embodiment of the present application.

FIG. 10 is a circuit diagram of a Wheatstone bridge for measuring a third force in a six-axis force sensor provided according to an embodiment of the present application.

FIG11 is a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring a first torque in a six-axis force sensor provided according to an embodiment of the present application.

FIG. 12 is a circuit diagram of a Wheatstone bridge for measuring a first torque in a six-axis force sensor provided according to an embodiment of the present application.

13 is a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring a second torque in a six-axis force sensor provided according to an embodiment of the present application.

FIG. 14 is a circuit diagram of a Wheatstone bridge for measuring a second torque in a six-axis force sensor provided according to an embodiment of the present application.

FIG. 15 is a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring a third torque in a six-axis force sensor provided according to an embodiment of the present application.

FIG. 16 is a circuit diagram of a Wheatstone bridge for measuring a third torque in a six-axis force sensor provided according to an embodiment of the present application.

In the figure: 100-support frame; 200-force block; 300-elastic member; 311-first elastic beam; 312-second elastic beam; 321-third elastic beam; 322-fourth elastic beam; 331-fifth elastic beam; 332-sixth elastic beam; 341-seventh elastic beam; 342-eighth elastic beam; 400-gap; 401-first deformation cavity; 402-second deformation cavity.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and beneficial effects of this application more clear, the following further describes this application in detail in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described in this specification are only for explaining this application, not for limiting this application.

In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" refers to two or more, unless otherwise clearly and specifically defined.

In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

Referring to FIG. 1 , FIG. 1 shows a schematic diagram of the structure of a six-axis force sensor provided according to an embodiment of the present application. The six-axis force sensor provided in an embodiment of the present application includes: a force block 200, a support frame 100, a plurality of groups of elastic members 300, and a plurality of force-sensitive resistors. The support frame 100 surrounds the force block 200, and a gap 400 is provided between the force block 200 and the support frame 100; the plurality of groups of elastic members 300 are arranged in the gap and are respectively connected to the force block 200 and the support frame 100. The plurality of groups of elastic members 300 divide the gap 400 into a plurality of first deformation cavities 401, and the first deformation cavity 401 is used to accommodate the deformation of the elastic member 300; a plurality of force-sensitive resistors are arranged in the elastic member 300 to form six groups of Wheatstone bridges, which are respectively used to measure a first force, a second force, a third force, a first moment, a second moment, and a third moment;

Furthermore, each set of elastic members 300 includes a pair of elastic beams arranged at intervals; any pair of elastic beams, the force-bearing block 200 and the support frame 100 enclose a second deformation cavity 402, and the second deformation cavity 402 is used to accommodate the deformation of the elastic beams. The double elastic beam structure provides a space for the force-sensitive resistor to be arranged, realizes the self-decoupling between the measured force and moment and the non-measured force and moment, and improves the accuracy of the six-axis force sensor of the present application.

Specifically, the force-bearing block 200 is a square block structure, and the force-bearing block 200 is arranged at the geometric center of the support frame 100, and the geometric center of the force-bearing block 200 coincides with the geometric center of the support frame 100. The square side of the force-bearing block 200 is arranged parallel to the square side of the support frame 100, and the distance from any square side of the force-bearing block 200 to the corresponding square side of the support frame 100 is equal.

Furthermore, the six-axis force sensor has a first plane, in which a first axial direction X and a second axial direction Y intersect and are perpendicular to each other. A side surface of the elastic member 300 is in the first plane, and a pair of elastic beams in the same group of elastic members 300 are symmetrical about the first axial direction X or the second axial direction Y.

Specifically, the elastic beam includes a first elastic beam 311 and a second elastic beam 312 arranged on one side of the force-bearing block 200 with respect to the first axial direction X, and a fifth elastic beam 331 and a sixth elastic beam 332 on the other side, and also includes a third elastic beam 321 and a fourth elastic beam 322 arranged on one side of the force-bearing block 200 with respect to the second axial direction Y, and a seventh elastic beam 341 and an eighth elastic beam 342 on the other side.

Furthermore, several force-sensitive resistors are arranged in a first plane; a center point is provided in the first plane, and the force-sensitive resistors in a Wheatstone bridge for measuring the first force, the second force or the third force are rotationally symmetric about the center point in the first plane; the force-sensitive resistors in a Wheatstone bridge for measuring the first torque, the second torque and the third torque are symmetric about the first axial direction X or the second axial direction Y in the first plane.

Specifically, the force-bearing block 200 has a center point O in the first plane, and the center point O coincides with the geometric center of the force-bearing block 200; four groups of elastic members 300 are arranged in the gap 400, and connect the support frame 100 and the force-bearing block 200. The four groups of elastic members 300 are arranged on the periphery of the force-bearing block 200, and the four groups of elastic members 300 are rotationally symmetrical about the center point O. The four groups of elastic members 300 are respectively arranged on both sides of the force-bearing block 200 about the first axial direction X, and on both sides of the force-bearing block 200 about the second axial direction Y. The extension direction of the elastic members 300 arranged on both sides of the force-bearing block 200 about the first axial direction X extends along the second axial direction Y, and the extension direction of the elastic members 300 arranged on both sides of the force-bearing block 200 about the second axial direction Y extends along the first axial direction X, and the extension directions of adjacent elastic members 300 are perpendicular to each other. Each group of elastic members 300 includes a pair of elastic beams arranged at intervals, and the elastic beams in each group of elastic members 300 are symmetrical about the first axial direction X or the second axial direction Y. The extension direction of the elastic beam disposed on one side of the first axial direction X or the second axial direction Y of the force-bearing block 200 is collinear with the extension direction of the elastic beam on the other side.

Several force-sensitive resistors are arranged on the elastic beam to form six groups of Wheatstone bridges for measuring six-axis forces and moments respectively. The force-sensitive resistors are all arranged in the first plane of the elastic beam. Compared with the technical solution of arranging the force-sensitive resistors in different planes in the prior art, the present application greatly reduces the difficulty and cost of the manufacturing process. In addition, the force-sensitive resistors are manufactured by doping in the same plane, which can ensure the consistency of the doping concentration, greatly improving the consistency of all force-sensitive resistor devices, thereby improving the measurement accuracy of the six-axis force sensor of the present application.

Furthermore, the six-axis force sensor also has a third axial direction Z that intersects and is perpendicular to the first plane. The height of the support frame 100 in the third axial direction Z (i.e., its thickness direction) is greater than the height of the force block 200 and the elastic member 300 in the third axial direction Z, that is, the height of the gap 400 in the third axial direction Z is greater than the height of the force block 200 and the elastic member 300 in the third axial direction Z, thereby providing a movable space for the displacement of the force block 200 and the elastic member 300.

As shown in FIG2 and FIG3, six groups of Wheatstone bridges are used to measure the first force FX, the second force FY, the third force FZ, the first moment MX, the second moment MY and the third moment MZ, respectively. The direction of the first force FX extends along the first axial direction X, the direction of the second force FY extends along the second axial direction Y, and the direction of the third force FZ extends along the third axial direction Z. According to the right-hand screw rule of the moment, the direction of the first moment MX rotates counterclockwise around the first axial direction X, the direction of the second moment MY rotates counterclockwise around the second axial direction Y, and the direction of the third moment MZ rotates counterclockwise around the third axial direction Z.

Referring to FIG4 , a, b, c, d, e, and f in FIG4 respectively show schematic diagrams of stress distribution of a six-axis force sensor proposed in accordance with an embodiment of the present application under the action of a first force FX, a second force FY, a third force FZ, a first moment MX, a second moment MY, and a third moment MZ. In the figure, green represents stress-free distribution or low stress distribution, red represents a positive result value of the stress in the first axial X direction minus the stress in the second axial Y direction, and blue represents a negative result value of the stress in the first axial X direction minus the stress in the second axial Y direction. The darker the red or blue color, the greater the absolute value of the result value, that is, the greater the stress value of the elastic beam.

As shown in FIG1 , the force-sensitive resistors in the present application are all arranged at positions where the elastic beam has greater stress under the action of force or torque to form a full-arm Wheatstone bridge. Compared with a single-arm Wheatstone bridge or a double-arm Wheatstone bridge in which only some of the force-sensitive resistors are arranged at positions with greater stress, and the remaining force-sensitive resistors are arranged at positions with no stress distribution or low stress distribution, the full-arm Wheatstone bridge of the present application has higher sensitivity and accuracy. Because the number of force-sensitive resistors required to be arranged in a full-arm Wheatstone bridge is greater than that of a single-arm Wheatstone bridge or a double-arm Wheatstone bridge, the dual elastic beam structure of the present application provides space for the force-sensitive resistors of the full-arm Wheatstone bridge to be arranged.

Continuing to refer to FIG. 4 , when the six-axis force sensor is subjected to the first force FX, the second force FY, the first moment MX, and the second moment MY, the stress distribution of the two elastic beams in the same group of elastic members 300 corresponding to the force (i.e., the elastic beams in the elastic member 300 with the largest deformation) is symmetrical about the first axial direction X or the second axial direction Y, and the stress distribution of the two elastic beams in the same line of the two groups of elastic members 300 corresponding to the force is opposite about the first axial direction X or the second axial direction Y (i.e., the stress magnitude is equal and the direction is opposite). When the six-axis force sensor is subjected to the third force FZ, the stress distribution on all elastic beams is the same. When the six-axis force sensor is subjected to the third moment MZ, the stress distribution of the two elastic beams in the same group of elastic members 300 is opposite, and the elastic members 300 arranged on both sides of the force block 200 about the first axial direction X are symmetrical about the rotation axis of the center point; the elastic members 300 arranged on both sides of the force block 200 about the second axial direction Y are symmetrical about the rotation axis of the center point.

As shown in Figures 2 and 5, the elastic beam has a length _L1 , a width _L2 and a height _L3 . For the length _L1 of the elastic beam, the longer the length _L1 of the elastic beam is, the smaller the stress gradient on the elastic beam is under the same force, and the easier it is to place the force-sensitive resistor. However, the increase in the length _L1 of the elastic beam will lead to an increase in the size of the sensor chip. Therefore, considering the above factors comprehensively, when the force-sensitive resistor is subjected to the first force FX, the difference between the stress values at both ends of the force-sensitive resistor along the first axial direction X that measures the first force FX is divided by the average stress on the first axial direction X, and the value is less than 0.002, so it is more reasonable to set the length _L1 of the elastic beam.

For the elastic beam width _L2 , the smaller the elastic beam width _L2 is, the smaller the elastic beam's ability to resist deformation is, and the higher the sensitivity of the force-sensitive resistor is; but if the elastic beam width _L2 is too narrow, the stress gradient of the force-sensitive resistor measuring the third moment MZ will change too much when the third moment MZ acts. Therefore, when the force-sensitive resistor measuring the third moment MZ is subjected to the third moment MZ, the overall stress value difference of each point is within 20%, and it is more reasonable to set the elastic beam width _L2 size; in addition, the elastic beam width _L2 is also limited by the influence of the force-sensitive resistor electrical signal transmission wire. The elastic beam width _L2 must ensure the normal arrangement of the force-sensitive resistor electrical signal transmission wire to avoid cross-influence. Under the condition of ensuring the normal arrangement of the force-sensitive resistor electrical signal transmission wire and the stress distribution of the force-sensitive resistor measuring the third moment MZ, the narrower the elastic beam width _L2 is, the better.

For the elastic beam height L ₃ , when the measurement range is met, the smaller the elastic beam height L ₃ is, the higher the sensitivity is.

As shown in FIG. 5 and FIG. 6, FIG. 5 and FIG. 6 respectively show a distribution diagram and a circuit diagram of force-sensitive resistors in a Wheatstone bridge for measuring a first force FX in a six-axis force sensor provided according to an embodiment of the present application. The Wheatstone bridge for measuring the first force FX is a first force FX bridge, and the first force FX bridge includes a first force-sensitive resistor FXR1, a second force-sensitive resistor FXR2, a third force-sensitive resistor FXR3, and a fourth force-sensitive resistor FXR4. Among them, the first force-sensitive resistor FXR1 and the second force-sensitive resistor FXR2 are respectively arranged on the eighth elastic beam 342 and the seventh elastic beam 341, and the third force-sensitive resistor FXR3 and the fourth force-sensitive resistor FXR4 are respectively arranged on the fourth elastic beam 322 and the third elastic beam 321. In conjunction with the stress distribution diagram of the six-axis force sensor of this embodiment at a in Figure 4 when the first force FX is applied to the first axial direction X, the force block 200 is displaced along the first axial direction X by the first force FX, the seventh elastic beam 341 and the eighth elastic beam 342 are subjected to stress in the first axial direction X as the force block 200 is displaced, the third elastic beam 321 and the fourth elastic beam 322 are subjected to stress in the second direction Y as the force block 200 is displaced, the first force-sensitive resistor FXR1, the second force-sensitive resistor FXR2, the third force-sensitive resistor FXR3 and the fourth force-sensitive resistor FXR4 are all arranged at positions where the stress of the elastic beams is relatively large, the first force-sensitive resistor FXR1 and the second force-sensitive resistor FXR2 are subjected to stress in the first axial direction X and their resistance values become larger (equivalent to the resistors being stretched), and the third force-sensitive resistor FXR3 and the fourth force-sensitive resistor FXR4 are subjected to stress in the second axial direction Y and their resistance values become smaller (equivalent to the resistors being widened). The first force-sensitive resistor FXR1 and the third force-sensitive resistor FXR3 are rotationally symmetrical about the center point at 180°, and the second force-sensitive resistor FXR2 and the fourth force-sensitive resistor FXR4 are rotationally symmetrical about the center point at 180°. As shown in FIG6 , the first force-sensitive resistor FXR1 and the second force-sensitive resistor FXR2 are diagonally arranged in the bridge, and the third force-sensitive resistor FXR3 and the fourth force-sensitive resistor FXR4 are diagonally arranged in the bridge.

Furthermore, the first force-sensitive resistor FXR1, the second force-sensitive resistor FXR2, the third force-sensitive resistor FXR3 and the fourth force-sensitive resistor FXR4 can be set at the 1/6~1/2 position of the elastic beam close to the support frame 100, for example, 1/6, 1/5, 1/4, 1/3, 1/2, so that the first to fourth force-sensitive resistors can be set at the position where the stress of the elastic beam is relatively large, thereby improving the measurement sensitivity of the first force FX, and providing arrangement space for the arrangement of force-sensitive resistors of other Wheatstone bridges. The resistance value changes of the first force-sensitive resistor FXR1, the second force-sensitive resistor FXR2, the third force-sensitive resistor FXR3 and the fourth force-sensitive resistor FXR4 in the first force FX bridge under the action of six-axis force and the output of the Wheatstone bridge signal are shown in the following Table 1 (where "+Δ" and "-Δ" respectively indicate that the resistance value of the force-sensitive resistor increases or decreases by the same value Δ, and "+Δ" and "-Δ" have the same meaning in all tables below):

Table 1

Because the full-arm Wheatstone bridge needs to meet the signal output conditions that the change trends of the diagonal force-sensitive resistors in the bridge are in the same direction (both increase, or both decrease) and the change values are equal, and the change trends of the force-sensitive resistors on the same side are opposite (one increases, the other decreases) and the change values are equal, the first force FX bridge under the action of the first force FX meets the above signal output conditions and outputs a signal, and under the action of the second force FY, the third force FZ, the first moment MX, the second moment MY and the third moment MZ, the first force FX bridge does not meet the signal output conditions and has no signal output, which avoids the first force FX bridge being affected by non-measured forces and moments to generate signal errors, realizes self-decoupling between measured forces and moments and non-measured forces and moments, and improves the accuracy of the six-axis force sensor of the present application.

As shown in FIG. 7 and FIG. 8, FIG. 7 and FIG. 8 respectively show a distribution diagram and a circuit diagram of force-sensitive resistors in a Wheatstone bridge for measuring a second force FY in a six-axis force sensor provided according to an embodiment of the present application. The Wheatstone bridge for measuring the second force FY is a second force FY bridge, and the second force FY bridge includes a fifth force-sensitive resistor FYR1, a sixth force-sensitive resistor FYR2, a seventh force-sensitive resistor FYR3, and an eighth force-sensitive resistor FYR4. Among them, the fifth force-sensitive resistor FYR1 and the eighth force-sensitive resistor FYR4 are respectively arranged on the first elastic beam 311 and the second elastic beam 312, and the sixth force-sensitive resistor FYR2 and the seventh force-sensitive resistor FYR3 are respectively arranged on the sixth elastic beam 332 and the fifth elastic beam 331. Combined with the stress distribution diagram of the six-axis force sensor at b in Figure 4 when it is subjected to the second force FY in the second axial direction Y, the force block 200 is displaced along the second axial direction Y by the second force FY, the fifth elastic beam 331 and the sixth elastic beam 332 are subjected to stress in the second axial direction Y as the force block 200 is displaced, the first elastic beam 311 and the second elastic beam 312 are subjected to stress in the first axial direction X as the force block 200 is displaced, the fifth force-sensitive resistor FYR1, the sixth force-sensitive resistor FYR2, the seventh force-sensitive resistor FYR3 and the eighth force-sensitive resistor FYR4 are all arranged at positions where the stress of the elastic beams is relatively large, the sixth force-sensitive resistor FYR2 and the seventh force-sensitive resistor FYR3 are subjected to stress in the second axial direction Y and their resistance values become larger (equivalent to the resistors being stretched), and the fifth force-sensitive resistor FYR1 and the eighth force-sensitive resistor FYR4 are subjected to stress in the first axial direction X and their resistance values become smaller (equivalent to the resistors being widened). The fifth force-sensitive resistor FYR1 and the seventh force-sensitive resistor FYR3 are 180° rotationally symmetrical about the center point, and the eighth force-sensitive resistor FYR4 and the sixth force-sensitive resistor FYR2 are 180° rotationally symmetrical about the center point. As shown in FIG8 , the fifth force-sensitive resistor FYR1 and the eighth force-sensitive resistor FYR4 are diagonally arranged in the bridge, and the sixth force-sensitive resistor FYR2 and the seventh force-sensitive resistor FYR3 are diagonally arranged in the bridge.

Furthermore, the fifth force-sensitive resistor FYR1, the sixth force-sensitive resistor FYR2, the seventh force-sensitive resistor FYR3, and the eighth force-sensitive resistor FYR4 can be set at the 1/6~1/2 position of the elastic beam close to the support frame 100, for example, 1/6, 1/5, 1/4, 1/3, 1/2. This can not only set the fifth to eighth force-sensitive resistors at positions where the stress of the elastic beam is larger to improve the measurement sensitivity of the second force FY, but also provide layout space for the force-sensitive resistors of other Wheatstone bridges.

The resistance value changes of the fifth force-sensitive resistor FYR1, the sixth force-sensitive resistor FYR2, the seventh force-sensitive resistor FYR3, and the eighth force-sensitive resistor FYR4 in the second force FY bridge under the action of the six-axis force and the output of the Wheatstone bridge are shown in Table 2 below:

Table 2

Under the action of the second force FY, the second force FY bridge meets the above-mentioned signal output conditions and outputs a signal. Under the action of the first force FX, the third force FZ, the first moment MX, the second moment MY and the third moment MZ, the second force FY bridge does not meet the signal output conditions and has no signal output. This avoids the second force FY bridge being affected by non-measured forces and moments to generate signal errors, achieves self-decoupling between measured forces and moments and non-measured forces and moments, and improves the accuracy of the six-axis force sensor of the present application.

In combination with FIG. 9 and FIG. 10, FIG. 9 and FIG. 10 respectively show a distribution diagram and a circuit diagram of force-sensitive resistors in a Wheatstone bridge for measuring the third force FZ in a six-axis force sensor provided according to an embodiment of the present application. The Wheatstone bridge for measuring the third force FZ is a third force FZ bridge, and the third force FZ bridge includes a ninth force-sensitive resistor FZR1, a tenth force-sensitive resistor FZR2, an eleventh force-sensitive resistor FZR3, and a twelfth force-sensitive resistor FZR4. Among them, the ninth force-sensitive resistor FZR1 and the tenth force-sensitive resistor FZR2 are respectively arranged at the two ends of the seventh elastic beam 341, and the eleventh force-sensitive resistor FZR3 and the twelfth force-sensitive resistor FZR4 are respectively arranged at the two ends of the third elastic beam 321. Combined with the stress distribution diagram of the six-axis force sensor at c in Figure 4 when it is subjected to the third force FZ in the third axial direction Z, the ninth force-sensitive resistor FZR1, the tenth force-sensitive resistor FZR2, the eleventh force-sensitive resistor FZR3, and the twelfth force-sensitive resistor FZR4 are all arranged at positions where the stress of the elastic beam is relatively large, and the force block 200 is displaced along the third axial direction Z under the action of the third force FZ, and both ends of the third elastic beam 321 and the seventh elastic beam 341 are bent. As can be seen from Figure 4c, the ends of the third elastic beam 321 and the seventh elastic beam 341 close to the force-bearing block 200 are subjected to stress in the first axial X direction. Therefore, the tenth force-sensitive resistor FZR2 arranged at the end of the seventh elastic beam 341 close to the force-bearing block 200 and the eleventh force-sensitive resistor FZR3 arranged at the end of the third elastic beam 321 close to the force-bearing block 200 are subjected to stress in the first axial X direction and their resistance values become larger (equivalent to the resistor being stretched), and the ends of the third elastic beam 321 and the seventh elastic beam 341 close to the supporting frame 100 are subjected to stress in the second axial Y direction. Therefore, the ninth force-sensitive resistor FZR1 arranged at the end of the seventh elastic beam 341 close to the supporting frame 100 and the twelfth force-sensitive resistor FZR4 arranged at the end of the third elastic beam 321 close to the supporting frame 100 are subjected to stress in the second axial Y direction and their resistance values become smaller (equivalent to the resistor being widened) due to the stress in the second axial Y direction. The ninth force-sensitive resistor FZR1 and the twelfth force-sensitive resistor FZR4 are 180° rotationally symmetrical about the center point, and the tenth force-sensitive resistor FZR2 and the eleventh force-sensitive resistor FZR3 are 180° rotationally symmetrical about the center point. As shown in FIG10 , the ninth force-sensitive resistor FZR1 and the twelfth force-sensitive resistor FZR4 are diagonally arranged in the bridge, and the tenth force-sensitive resistor FZR2 and the eleventh force-sensitive resistor FZR3 are diagonally arranged in the bridge.

The resistance value changes of the ninth force-sensitive resistor FZR1, the tenth force-sensitive resistor FZR2, the eleventh force-sensitive resistor FZR3, and the twelfth force-sensitive resistor FZR4 in the third force FZ bridge under the action of the six-axis force and the Wheatstone bridge signal output are shown in Table 3 below:

Table 3

Under the action of the third force FZ, the third force FZ bridge meets the above-mentioned signal output conditions and outputs a signal. Under the action of the first force FX, the second force FY, the first moment MX, the second moment MY and the third moment MZ, the third force FZ bridge does not meet the signal output conditions and has no signal output. This avoids the third force FZ bridge being affected by non-measured forces and moments to produce signal errors, achieves self-decoupling between measured forces and moments and non-measured forces and moments, and improves the accuracy of the six-axis force sensor of the present application.

It should be noted that, in the present embodiment, the ninth force-sensitive resistor FZR1, the tenth force-sensitive resistor FZR2, the eleventh force-sensitive resistor FZR3, and the twelfth force-sensitive resistor FZR4 of the third force FZ bridge are arranged on the third elastic beam 321 and the seventh elastic beam 341. In another embodiment, the ninth force-sensitive resistor FZR1, the tenth force-sensitive resistor FZR2, the eleventh force-sensitive resistor FZR3, and the twelfth force-sensitive resistor FZR4 can also be arranged on the fourth elastic beam 322 and the eighth elastic beam 342, or on the first elastic beam 311 and the fifth elastic beam 331 according to actual needs, and the ninth force-sensitive resistor FZR1, the tenth force-sensitive resistor FZR2, the eleventh force-sensitive resistor FZR3, and the twelfth force-sensitive resistor FZR4 are arranged on elastic beams that are opposite and non-collinear with respect to the first axial direction X or the second axial direction Y, which are not specifically limited here. The ninth force-sensitive resistor FZR1, the tenth force-sensitive resistor FZR2, the eleventh force-sensitive resistor FZR3 and the twelfth force-sensitive resistor FZR4 are arranged on elastic beams that are opposite and non-collinear with respect to the first axial direction X or the second axial direction Y to avoid signal errors caused by the third force FZ bridge under the action of non-measured forces and moments.

Referring to Figures 11 and 12, Figures 11 and 12 respectively show a distribution schematic diagram and a circuit schematic diagram of force-sensitive resistors in a Wheatstone bridge for measuring a first torque MX in a six-axis force sensor provided according to an embodiment of the present application. The Wheatstone bridge for measuring the first torque MX is a first torque MX bridge, and the first torque MX bridge includes a thirteenth force-sensitive resistor MXR1, a fourteenth force-sensitive resistor MXR2, a fifteenth force-sensitive resistor MXR3, and a sixteenth force-sensitive resistor MXR4. Among them, the thirteenth force-sensitive resistor MXR1 and the fourteenth force-sensitive resistor MXR2 are respectively arranged at the two ends of the first elastic beam 311, the fifteenth force-sensitive resistor MXR3 and the sixteenth force-sensitive resistor MXR4 are respectively arranged at the two ends of the sixth elastic beam 332, the thirteenth force-sensitive resistor MXR1 and the fourteenth force-sensitive resistor MXR2 are both arranged at the midline position of the first elastic beam 311, the fifteenth force-sensitive resistor MXR3 and the sixteenth force-sensitive resistor MXR4 are both arranged at the midline position of the sixth elastic beam 332. Because the axes of the first elastic beam 311 and the sixth elastic beam 332 are collinear, the thirteenth force-sensitive resistor MXR1, the fourteenth force-sensitive resistor MXR2, the fifteenth force-sensitive resistor MXR3 and the sixteenth force-sensitive resistor MXR4 are collinearly arranged. Combined with the stress distribution diagram of the six-axis force sensor at d in Figure 4 when it is subjected to the first moment MX around the first axial direction X, the thirteenth force-sensitive resistor MXR1, the fourteenth force-sensitive resistor MXR2, the fifteenth force-sensitive resistor MXR3, and the sixteenth force-sensitive resistor MXR4 are all arranged at the positions where the stress of the elastic beam is relatively large, and the force block 200 rotates around the first axial direction X under the action of the first moment MX, and both ends of the first elastic beam 311 and the sixth elastic beam 332 are bent. The end of the first elastic beam 311 close to the force block 200 and the end of the sixth elastic beam 332 close to the supporting frame 100 are subjected to stress in the second axial Y direction. Therefore, the fourteenth force-sensitive resistor MXR2 arranged at the end of the first elastic beam 311 close to the force block 200 and the sixteenth force-sensitive resistor MXR4 arranged at the end of the sixth elastic beam 332 close to the supporting frame 100 increase their resistance values due to the stress in the second axial Y direction. The end of the first elastic beam 311 close to the supporting frame 100 and the end of the sixth elastic beam 332 close to the force block 200 are subjected to stress in the first axial X direction. Therefore, the thirteenth force-sensitive resistor MXR1 arranged at the end of the first elastic beam 311 close to the supporting frame 100 and the fifteenth force-sensitive resistor MXR3 arranged at the end of the sixth elastic beam 332 close to the force block 200 decrease their resistance values due to the stress in the first axial X direction. The thirteenth force-sensitive resistor MXR1 and the sixteenth force-sensitive resistor MXR4 are symmetrically arranged about the first axial direction X, and the fourteenth force-sensitive resistor MXR2 and the fifteenth force-sensitive resistor MXR3 are symmetrically arranged about the first axial direction X. As shown in FIG12 , the thirteenth force-sensitive resistor MXR1 and the fifteenth force-sensitive resistor MXR3 are diagonally arranged in the bridge, and the fourteenth force-sensitive resistor MXR2 and the sixteenth force-sensitive resistor MXR4 are diagonally arranged in the bridge.

The resistance value changes of the thirteenth force-sensitive resistor MXR1, the fourteenth force-sensitive resistor MXR2, the fifteenth force-sensitive resistor MXR3, and the sixteenth force-sensitive resistor MXR4 in the first torque MX bridge under the action of six-axis force and the output of the Wheatstone bridge signal are shown in Table 4 below:

Table 4

The first torque MX bridge under the action of the first torque MX meets the above-mentioned signal output conditions and outputs a signal. Under the action of the first force FX, the second force FY, the third force FZ, the second moment MY and the third moment MZ, the first torque MX bridge does not meet the signal output conditions and has no signal output, thereby avoiding the first torque MX bridge from being affected by non-measured forces and moments and generating signal errors, realizing self-decoupling between measured forces and moments and non-measured forces and moments, and improving the accuracy of the six-axis force sensor of the present application.

It should be noted that, in the present embodiment, the thirteenth force-sensitive resistor MXR1, the fourteenth force-sensitive resistor MXR2, the fifteenth force-sensitive resistor MXR3, and the sixteenth force-sensitive resistor MXR4 of the first torque MX bridge are arranged on the first elastic beam 311 and the sixth elastic beam 332. In other embodiments, the thirteenth force-sensitive resistor MXR1, the fourteenth force-sensitive resistor MXR2, the fifteenth force-sensitive resistor MXR3, and the sixteenth force-sensitive resistor MXR4 are arranged on the second elastic beam 312 and the fifth elastic beam 331 which are opposite and collinear, and are not specifically limited here.

In combination with Figures 13 and 14, Figures 13 and 14 respectively show a distribution schematic diagram and a circuit schematic diagram of force-sensitive resistors in a Wheatstone bridge for measuring the second torque MY in a six-axis force sensor provided according to an embodiment of the present application. The Wheatstone bridge for measuring the second torque MY is a second torque MY bridge, and the second torque MY bridge includes a seventeenth force-sensitive resistor MYR1, an eighteenth force-sensitive resistor MYR2, a nineteenth force-sensitive resistor MYR3, and a twentieth force-sensitive resistor MYR4. Among them, the seventeenth force-sensitive resistor MYR1 and the eighteenth force-sensitive resistor MYR2 are respectively arranged at the two ends of the eighth elastic beam 342, the nineteenth force-sensitive resistor MYR3 and the twentieth force-sensitive resistor MYR4 are respectively arranged at the two ends of the third elastic beam 321, the seventeenth force-sensitive resistor MYR1 and the eighteenth force-sensitive resistor MYR2 are both arranged at the midline position of the eighth elastic beam 342, the nineteenth force-sensitive resistor MYR3 and the twentieth force-sensitive resistor MYR4 are both arranged at the midline position of the third elastic beam 321. Because the axes of the third elastic beam 321 and the eighth elastic beam 342 are collinear, the seventeenth force-sensitive resistor MYR1, the eighteenth force-sensitive resistor MYR2, the nineteenth force-sensitive resistor MYR3 and the twentieth force-sensitive resistor MYR4 are collinearly arranged. Combined with the stress distribution diagram of the six-axis force sensor at e in Figure 4 when it is subjected to the second moment MY around the second axial direction Y, the seventeenth force-sensitive resistor MYR1, the eighteenth force-sensitive resistor MYR2, the nineteenth force-sensitive resistor MYR3, and the twentieth force-sensitive resistor MYR4 are all arranged at the positions where the stress of the elastic beam is relatively large, and the force block 200 rotates around the second axial direction Y under the action of the second moment MY, and both ends of the third elastic beam 321 and the eighth elastic beam 342 are bent. The end of the eighth elastic beam 342 close to the force-bearing block 200 and the end of the third elastic beam 321 close to the supporting frame 100 are subjected to stress in the first axial X direction. Therefore, the eighteenth force-sensitive resistor MYR2 arranged at the end of the eighth elastic beam 342 close to the force-bearing block 200 and the twentieth force-sensitive resistor MYR4 arranged at the end of the third elastic beam 321 close to the supporting frame 100 increase their resistance values due to the stress in the first axial X direction. The end of the eighth elastic beam 342 close to the supporting frame 100 and the end of the third elastic beam 321 close to the force-bearing block 200 are subjected to stress in the second axial Y direction. Therefore, the seventeenth force-sensitive resistor MYR1 arranged at the end of the eighth elastic beam 342 close to the supporting frame 100 and the nineteenth force-sensitive resistor MYR3 arranged at the end of the third elastic beam 321 close to the force-bearing block 200 decrease their resistance values due to the stress in the second axial Y direction. The seventeenth force-sensitive resistor MYR1 and the twentieth force-sensitive resistor MYR4 are symmetrically arranged about the second axial direction Y, and the eighteenth force-sensitive resistor MYR2 and the nineteenth force-sensitive resistor MYR3 are symmetrically arranged about the second axial direction Y. As shown in FIG. 14 , the seventeenth force-sensitive resistor MYR1 and the nineteenth force-sensitive resistor MYR3 are diagonally arranged in the bridge, and the eighteenth force-sensitive resistor MYR2 and the twentieth force-sensitive resistor MYR4 are diagonally arranged in the bridge.

The resistance value changes of the seventeenth force-sensitive resistor MYR1, the eighteenth force-sensitive resistor MYR2, the nineteenth force-sensitive resistor MYR3, and the twentieth force-sensitive resistor MYR4 in the second torque MY bridge under the action of six-axis force and the output of the Wheatstone bridge signal are shown in Table 5 below:

Table 5

The second torque MY bridge under the action of the second torque MY meets the above-mentioned signal output conditions and outputs a signal. Under the action of the first force FX, the second force FY, the third force FZ, the first moment MX and the third moment MZ, the second torque MY bridge does not meet the signal output conditions and has no signal output. This avoids the second torque MY bridge being affected by non-measured forces and moments to produce signal errors, realizes self-decoupling between measured forces and moments and non-measured forces and moments, and improves the accuracy of the six-axis force sensor of the present application.

Further, referring to Fig. 4e, 4c, Fig. 9 and Fig. 13, since the end of the third elastic beam 321 close to the force block 200 is subjected to greater stress under the third force FZ and the second moment MY, the nineteenth force-sensitive resistor MYR3 and the eleventh force-sensitive resistor FZR3 can share the same force-sensitive resistor, and at the same time, since the end of the third elastic beam 321 close to the support frame 100 generates greater stress under the third force FZ and the second moment MY, the twentieth force-sensitive resistor MYR4 and the twelfth force-sensitive resistor FZR4 can share the same force-sensitive resistor. The Wheatstone bridge used to measure different axial forces can share the same force-sensitive resistor, which further provides space for arranging the force-sensitive resistors of each axis to realize the arrangement of the full-arm Wheatstone bridge.

In combination with Figures 15 and 16, Figures 15 and 16 respectively show a distribution schematic diagram and a circuit schematic diagram of force-sensitive resistors in a Wheatstone bridge for measuring the third torque MZ in a six-axis force sensor provided according to an embodiment of the present application. The Wheatstone bridge for measuring the third torque MZ is a third torque MZ bridge, and the third torque MZ bridge includes a twenty-first force-sensitive resistor MZR1, a twenty-second force-sensitive resistor MZR2, a twenty-third force-sensitive resistor MZR3, and a twenty-fourth force-sensitive resistor MZR4. Among them, the twenty-first force-sensitive resistor MZR1 is arranged at the end of the first elastic beam 311 close to the force block 200, and the twenty-first force-sensitive resistor MZR1 is arranged at the edge position of the first elastic beam 311 away from the second elastic beam 312; the twenty-second force-sensitive resistor MZR2 is arranged at the end of the sixth elastic beam 332 close to the force block 200, and the twenty-second force-sensitive resistor MZR2 is arranged at the edge position of the sixth elastic beam 332 away from the fifth elastic beam 331; the twenty-third force-sensitive resistor MZR3 is arranged at the end of the fifth elastic beam 331 close to the force block 200, and the twenty-third force-sensitive resistor MZR3 is arranged at the edge position of the fifth elastic beam 331 away from the sixth elastic beam 332; the twenty-fourth force-sensitive resistor MZR4 is arranged at the position of the second elastic beam 312 close to the force block 200, and the twenty-fourth force-sensitive resistor MZR4 is arranged at the edge position of the second elastic beam 312 away from the first elastic beam 311. Combined with the stress distribution diagram of the six-axis force sensor at f in FIG4 under the action of the third moment MZ around the third axis Z, the twenty-first force-sensitive resistor MZR1, the twenty-second force-sensitive resistor MZR2, the twenty-third force-sensitive resistor MZR3, and the twenty-fourth force-sensitive resistor MZR4 are all arranged at the position where the stress of the elastic beam is relatively large, and the force-bearing block 200 rotates around the third axis Z under the action of the third moment MZ, and all elastic beams are bent. As can be seen from FIG4f, the twenty-first force-sensitive resistor MZR1 is subjected to stress in the second axis Y direction, so the resistance value of the twenty-first force-sensitive resistor MZR1 increases, and the twenty-fourth force-sensitive resistor MZR4 is subjected to stress in the first axis X direction, so the resistance value of the twenty-fourth force-sensitive resistor MZR4 decreases; the twenty-second force-sensitive resistor MZR2 is subjected to stress in the first axis X direction, so the resistance value of the twenty-second force-sensitive resistor MZR2 decreases, and the twenty-third force-sensitive resistor MZR3 is subjected to stress in the second axis Y direction, so the resistance value of the twenty-third force-sensitive resistor MZR3 increases. The twenty-first force-sensitive resistor MZR1 and the twenty-second force-sensitive resistor MZR2 are symmetrically arranged about the first axial direction X, and the twenty-third force-sensitive resistor MZR3 and the twenty-fourth force-sensitive resistor MZR4 are symmetrically arranged about the first axial direction X. As shown in FIG16 , the twenty-first force-sensitive resistor MZR1 and the twenty-third force-sensitive resistor MZR3 are diagonally arranged in the bridge, and the twenty-second force-sensitive resistor MZR2 and the twenty-fourth force-sensitive resistor MZR4 are diagonally arranged in the bridge.

The resistance value changes of the twenty-first force-sensitive resistor MZR1, the twenty-second force-sensitive resistor MZR2, the twenty-third force-sensitive resistor MZR3, and the twenty-fourth force-sensitive resistor MZR4 in the third torque MZ bridge under the action of the six-axis force and the Wheatstone bridge signal output are shown in Table 6 below:

Table 6

The third torque MZ bridge under the action of the third torque MZ meets the above-mentioned signal output conditions and outputs a signal. Under the action of the first force FX, the second force FY, the third force FZ, the first moment MX and the second moment MY, the third torque MZ bridge does not meet the signal output conditions and has no signal output. This avoids the third torque MZ bridge being affected by non-measured forces and moments to produce signal errors, achieves self-decoupling between measured forces and moments and non-measured forces and moments, and improves the accuracy of the six-axis force sensor of the present application.

To summarize, the elastic member 300 of the present application adopts a double elastic beam structure. Compared with the single elastic beam structure in the prior art, the double elastic beam structure provides a space for arranging the force-sensitive resistors of the six-axis full-arm Wheatstone bridge, thereby avoiding the Wheatstone bridge from being affected by non-measured forces and moments and generating signal errors, and realizing self-decoupling between measured forces and moments and non-measured forces and moments, thereby improving the accuracy of the six-axis force sensor of the present application.

It should be noted that the force-sensitive resistor arrangement design of the present application is that only for the measured force and torque, the corresponding Wheatstone bridge will generate a signal output, while the other five-axis forces and torques do not change the force-sensitive resistor used by the Wheatstone bridge, or the resistance value changes generated are offset by the Wheatstone bridge, the bridge does not lose balance, and the output signal can be ignored. That is, the Wheatstone bridge only generates an output signal under the action of the corresponding force and torque, and under the action of other forces and torques, the current Wheatstone bridge is not affected or the output signal can be ignored, thus meeting the requirements of simultaneously and independently detecting six-axis forces and torques.

It should also be noted that the force-sensitive resistors in this embodiment are not all set at the positions where the stress is the largest under the force or torque they are used to measure. The setting of the force-sensitive resistors needs to be measured. The force-sensitive resistors in all Wheatstone bridges are set at larger and separated positions to avoid the difficulty of the manufacturing process and the increase in manufacturing costs caused by the force-sensitive resistors being too close. At the same time, it can also avoid measurement errors caused by the coupling between measured forces and torques and non-measured forces and torques.

It should also be noted that the six groups of Wheatstone bridges in this embodiment are all full-arm Wheatstone bridges. In other embodiments, the six groups of Wheatstone bridges may be partially single-arm Wheatstone bridges or double-arm Wheatstone bridges. Compared with the six groups of full-arm Wheatstone bridges in this embodiment, fewer force-sensitive resistors need to be set, and more positions can be arranged for force-sensitive resistors, which can better achieve self-decoupling between measured force and torque and non-measured force and torque, which is not specifically limited here.

The present application further provides a method for manufacturing a six-axis force sensor, the method comprising:

S10, providing a silicon wafer, and forming an oxide layer on a surface of one side of the silicon wafer;

S20, patterning the oxide layer to form a force-sensitive resistor pattern, and doping the silicon wafer at the position of the force-sensitive resistor pattern to form a force-sensitive resistor in the silicon wafer;

S30, patterning the oxide layer to form an ohmic contact layer pattern, doping the silicon wafer at the position of the ohmic contact layer pattern to form an ohmic contact layer on the surface of the silicon wafer, wherein the ohmic contact layer is connected to the force-sensitive resistor; etching the ohmic contact layer to form a plurality of ohmic contact regions corresponding to the force-sensitive resistors; annealing to activate the force-sensitive resistor and the ohmic contact region;

S40, forming a wiring on a surface of one side of the silicon wafer having the ohmic contact area, wherein the wiring is connected to the force-sensitive resistor through the ohmic contact area;

S50, patterning and etching the surface of the silicon wafer on one side away from the wiring to form a support frame 100 to the thickness position of the force-bearing block 200 and the elastic member 300;

S60, patterning and etching the area other than the support frame 100 on the surface of the silicon wafer on the side away from the wiring to form a force-bearing block 200 and an elastic member 300.

Steps S10 to S600 will be described in detail below.

In step S10, a silicon wafer is provided. The silicon wafer is a double-polished silicon wafer with an N-type crystal surface. A thin oxide layer is formed on the surface of the silicon wafer by thermal oxidation. The oxide layer is used to scatter ions during subsequent ion implantation to reduce channel effects.

In step S20, the oxide layer is patterned using a photoresist as a mask to form a force-sensitive resistor pattern. After patterning, the silicon wafer at the position of the force-sensitive resistor pattern is doped by ion implantation to form a force-sensitive resistor in the silicon wafer.

In step S30, the oxide layer is patterned using a photoresist as a mask to form an ohmic contact layer pattern, and the silicon wafer at the location of the ohmic contact layer pattern is doped by ion implantation to form an ohmic contact layer on the surface of the silicon wafer for interconnecting the force sensitive resistor and the wiring.

Using photoresist as a mask, a number of ohmic contact area patterns are formed in the ohmic contact layer, and the ohmic contact layer is etched open by reactive ion etching (RIE) to form a number of ohmic contact areas corresponding to the force-sensitive resistors.

A dielectric layer is formed on the surface of the silicon wafer by plasma enhanced chemical vapor deposition (PECVD). The dielectric layer includes silicon oxide and/or silicon nitride. The dielectric layer serves as a passivation layer on the surface of the silicon wafer and is annealed in a nitrogen atmosphere at 1150°C for 30 minutes to activate the implanted ions.

In step S40, a metal layer is formed by sputtering or evaporation, a portion of the metal layer is removed by corrosion or stripping, the remaining metal layer forms a wiring, the wiring is annealed and alloyed, and the wiring is connected to the force-sensitive resistor through the ohmic contact area.

A layer of silicon nitride is formed on the surface of the silicon wafer where the wiring is arranged by plasma enhanced chemical vapor deposition (PECVD), and the silicon nitride layer is used to protect the wiring.

In step S50, the surface of the silicon wafer facing away from the wiring is patterned with a photoresist, and the silicon wafer is etched by a deep silicon etching process (Bosch process) to form a support frame 100 and etch to the thickness of the force block 200 and the elastic member 300.

In step S60, the surface of one side of the silicon wafer where the wiring is arranged is patterned with a photoresist, and the silicon wafer is etched by a deep silicon etching process (Bosch process) to form a force-bearing block 200 and an elastic member 300 and to suspend them.

By setting a number of force-sensitive resistors on an elastic beam to form six groups of Wheatstone bridges for measuring six-axis forces and moments respectively, the force-sensitive resistors are all set in the same plane of the elastic beam. Compared with the technical solution of setting the force-sensitive resistors in different planes in the prior art, the present application greatly reduces the difficulty and cost of the manufacturing process. In addition, by doping and manufacturing the force-sensitive resistors in the same plane, it can ensure consistent doping concentration, greatly improving the consistency of all force-sensitive resistor devices, thereby improving the measurement accuracy of the six-axis force sensor of the present application.

The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims (12)

1. A six-axis force sensor, comprising: Load bearing block; A supporting frame, wherein the supporting frame surrounds the force-bearing block, and a gap is provided between the force-bearing block and the supporting frame; A plurality of groups of elastic members, the plurality of groups of elastic members are arranged in the gap and are respectively connected to the force-bearing block and the support frame, the plurality of groups of elastic members divide the gap into a plurality of first deformation cavities, and the first deformation cavities are used to accommodate the deformation of the elastic members; A plurality of force-sensitive resistors, wherein the plurality of force-sensitive resistors are arranged in the elastic member to form six groups of Wheatstone bridges, respectively used to measure a first force, a second force, a third force, a first torque, a second torque, and a third torque; Each group of the elastic members includes a pair of elastic beams arranged at intervals; any pair of the elastic beams, the force-bearing blocks and the supporting frame enclose a second deformation cavity, and the second deformation cavity is used to accommodate the deformation of the elastic beams. 2. The six-axis force sensor as described in claim 1 is characterized in that the six-axis force sensor has a first plane, and has a first axial direction and a second axial direction that intersect and are perpendicular to each other in the first plane, a side surface of the elastic member is in the first plane, and the elastic beams in the same group of the elastic members are symmetrical about the first axial direction or the second axial direction. 3. The six-axis force sensor according to claim 2, wherein the plurality of force-sensitive resistors are all arranged in the first plane; A center point is provided in the first plane, and a force-sensitive resistor in the Wheatstone bridge for measuring the first force, the second force or the third force is rotationally symmetric about the center point in the first plane; The force-sensitive resistors in the Wheatstone bridge for measuring the first torque, the second torque and the third torque are symmetrical about the first axial direction or the second axial direction in a first plane. 4. The six-axis force sensor according to any one of claims 1 to 3, characterized in that the Wheatstone bridges used to measure the first force, the second force, the third force, the first moment, the second moment and the third moment are all full-arm Wheatstone bridges. 5. The six-axis force sensor according to claim 2, characterized in that the direction of the first force extends along the first axial direction, the plurality of force-sensitive resistors include a first force-sensitive resistor, a second force-sensitive resistor, a third force-sensitive resistor and a fourth force-sensitive resistor for measuring the first force, the first force-sensitive resistor and the second force-sensitive resistor are respectively arranged on a pair of the elastic beams on one side of the force-bearing block about the second axial direction, and the third force-sensitive resistor and the fourth force-sensitive resistor are respectively arranged on a pair of the elastic beams on the other side; the first force-sensitive resistor and the second force-sensitive resistor are diagonally arranged in the bridge, and the third force-sensitive resistor and the fourth force-sensitive resistor are diagonally arranged in the bridge; The direction of the second force extends along the second axial direction, and the plurality of force-sensitive resistors further include a fifth force-sensitive resistor, a sixth force-sensitive resistor, a seventh force-sensitive resistor and an eighth force-sensitive resistor for measuring the second force, the fifth force-sensitive resistor and the eighth force-sensitive resistor are respectively arranged on a pair of the elastic beams on one side of the force-bearing block with respect to the first axial direction, and the sixth force-sensitive resistor and the seventh force-sensitive resistor are respectively arranged on a pair of the elastic beams on the other side; the fifth force-sensitive resistor and the eighth force-sensitive resistor are diagonally arranged in the bridge, and the sixth force-sensitive resistor and the seventh force-sensitive resistor are diagonally arranged in the bridge; The direction of the third force extends along a third axial direction, and the plurality of force-sensitive resistors also include a ninth force-sensitive resistor, a tenth force-sensitive resistor, an eleventh force-sensitive resistor and a twelfth force-sensitive resistor for measuring the third force, the ninth force-sensitive resistor and the tenth force-sensitive resistor are arranged on one of the elastic beams on one side of the force-bearing block about the first axial direction or the second axial direction, and the eleventh force-sensitive resistor and the twelfth force-sensitive resistor are both arranged on one of the elastic beams on the other side; the ninth force-sensitive resistor and the twelfth force-sensitive resistor are diagonally arranged in the bridge, and the tenth force-sensitive resistor and the eleventh force-sensitive resistor are diagonally arranged in the bridge. 6. The six-axis force sensor according to claim 5, characterized in that the direction of the first torque rotates counterclockwise around the first axis, the plurality of force-sensitive resistors include a thirteenth force-sensitive resistor, a fourteenth force-sensitive resistor, a fifteenth force-sensitive resistor and a sixteenth force-sensitive resistor for measuring the first torque, the thirteenth force-sensitive resistor and the fourteenth force-sensitive resistor are arranged on one of the elastic beams on one side of the first axis, and the fifteenth force-sensitive resistor and the sixteenth force-sensitive resistor are arranged on one of the elastic beams on the other side; the thirteenth force-sensitive resistor and the fifteenth force-sensitive resistor are arranged diagonally in the bridge, and the fourteenth force-sensitive resistor and the sixteenth force-sensitive resistor are arranged diagonally in the bridge; The direction of the second torque rotates counterclockwise around the second axis, and the plurality of force-sensitive resistors further include a seventeenth force-sensitive resistor, an eighteenth force-sensitive resistor, a nineteenth force-sensitive resistor, and a twentieth force-sensitive resistor for measuring the second torque, the seventeenth force-sensitive resistor and the eighteenth force-sensitive resistor are arranged on one of the elastic beams on one side of the second axis, and the nineteenth force-sensitive resistor and the twentieth force-sensitive resistor are arranged on one of the elastic beams on the other side; the seventeenth force-sensitive resistor and the nineteenth force-sensitive resistor are arranged diagonally in the bridge, and the eighteenth force-sensitive resistor and the twentieth force-sensitive resistor are arranged diagonally in the bridge; The direction of the third torque rotates counterclockwise around the third axial direction, and the plurality of force-sensitive resistors include a twenty-first force-sensitive resistor, a twenty-second force-sensitive resistor, a twenty-third force-sensitive resistor and a twenty-fourth force-sensitive resistor for measuring the third torque, the twenty-first force-sensitive resistor and the twenty-fourth force-sensitive resistor are respectively arranged on a pair of the elastic beams on one side of the first axial direction or the second axial direction, and the twenty-second force-sensitive resistor and the twenty-third force-sensitive resistor are respectively arranged on a pair of the elastic beams on the other side; the twenty-first force-sensitive resistor and the twenty-third force-sensitive resistor are diagonally arranged in the bridge, and the twenty-second force-sensitive resistor and the twenty-fourth force-sensitive resistor are diagonally arranged in the bridge. 7. The six-axis force sensor as described in claim 6 is characterized in that the eleventh force-sensitive resistor and the nineteenth force-sensitive resistor are the same force-sensitive resistor, and the twelfth force-sensitive resistor and the twentieth force-sensitive resistor are the same force-sensitive resistor. 8. The six-axis force sensor as described in claim 5 is characterized in that the force-sensitive resistor for measuring the first force and the second force is arranged at a position of 1/6 to 1/2 of the elastic beam close to the supporting frame. 9. The six-axis force sensor as described in claim 6 is characterized in that the force-sensitive resistor used to measure the third force, the first moment and the second moment is arranged at one end close to the force-bearing block and one end close to the supporting frame. 10. The six-axis force sensor according to claim 1, characterized in that the force-sensitive resistors for measuring the third moment are all arranged at one end of the elastic beam close to the force-bearing block, or the force-sensitive resistors for measuring the third moment are all arranged at one end of the elastic beam close to the supporting frame; The force-sensitive resistor for measuring the third torque is arranged on the outside of an elastic beam away from another elastic beam in the same group of elastic members. 11. The six-axis force sensor as described in claim 2 is characterized in that the six-axis force sensor also has a third axial direction intersecting with and perpendicular to the first plane, and in the third axial direction, the thickness of the support frame is greater than the thickness of the force block and the elastic member. 12. A method for manufacturing a six-axis force sensor, characterized in that it is used to manufacture the six-axis force sensor according to any one of claims 1 to 11, and the six-axis force sensor manufacturing method comprises: Providing a silicon wafer, and forming an oxide layer on a surface of one side of the silicon wafer; Patterning the oxide layer to form a force-sensitive resistor pattern, and doping the silicon wafer at the position of the force-sensitive resistor pattern to form a force-sensitive resistor in the silicon wafer; The oxide layer is patterned to form an ohmic contact layer pattern, and the silicon wafer at the position of the ohmic contact layer pattern is doped to form an ohmic contact layer on the surface of the silicon wafer, wherein the ohmic contact layer is connected to the force-sensitive resistor; the ohmic contact layer is etched to form a plurality of ohmic contact regions corresponding to the force-sensitive resistors; and annealing is performed to activate the force-sensitive resistor and the ohmic contact region; Forming a wiring on a surface of one side of the silicon wafer having an ohmic contact area, wherein the wiring is connected to the force-sensitive resistor through the ohmic contact area; Patterning and etching the surface of the silicon wafer on one side away from the wiring to form a support frame to the thickness position of the force-bearing block and the elastic member; The surface of the silicon wafer on one side away from the wiring is patterned and etched in an area other than the supporting frame to form the force-bearing block and the elastic member.