WO2018003631A1

WO2018003631A1 - Robot arm mechanism and rotation joint mechanism

Info

Publication number: WO2018003631A1
Application number: PCT/JP2017/022873
Authority: WO
Inventors: 尹　祐根; 啓明松田
Original assignee: ライフロボティクス株式会社
Priority date: 2016-07-01
Filing date: 2017-06-21
Publication date: 2018-01-04
Also published as: JP2019141915A; TW201801873A

Abstract

The objectives of the present invention are a robot arm mechanism and a robot joint mechanism wherein damage to cables is suppressed and nimble rotation movement is achieved. A support column part 2 provided with a rotation joint part J1 is installed in the base 1 of the robot arm mechanism. The support column part 2 has a support column lower part and a support column upper part. A motor unit 212 is housed in a tubular motor housing part 211 fixed on the support column upper part. One end of a cable 230 that includes a power supply line is fixed to a lower clamp 204 of the support column lower part, and the other end is fixed to an upper clamp 205 on the support column upper part. When the support column upper part is positioned in the center of the movement range, the upper clamp is positioned on a radius line passing through the lower clamp as viewed from above, and the cable is wrapped in a spiral shape on the outer side of the motor housing part from the lower clamp to the upper clamp.

Description

Robot arm mechanism and rotary joint mechanism

Embodiments of the present invention relate to a robot arm mechanism and a rotary joint mechanism.

The robot arm mechanism is used in various fields such as industrial robots. The inventors have developed a linear motion extension mechanism applicable to a robot arm mechanism (Patent Document 1). The linear motion expansion / contraction mechanism does not require an elbow joint and enables construction of a robot arm mechanism having no singular point. Since the robot arm mechanism is improved in safety, it can cooperate with the worker next to the worker.

The rotary joint equipped in the robot arm mechanism has a fixed part and a rotary part. A cable for supplying power and signals is spanned between the fixed part and the rotating part. The rotation of the rotating part twists the cable, bends the cable at an acute angle, and turns the cable back. It causes damage to the cable. Bending or turning of the cable hinders light rotational movement.

Japanese Patent No. 5435679

The purpose is to realize a light rotary motion while suppressing cable breakage in the robot arm mechanism and the rotary joint mechanism.

In the robot arm mechanism according to the present embodiment, a support column having a rotary joint for turning is erected on a base. A hoisting part having a rotating joint part for raising and lowering the arm part is mounted on the column part, and a wrist part having a plurality of rotating joint parts for posture change is equipped at the tip of the arm part. The column part has a column lower part and a column upper part supported by the column lower part so as to be rotatable within a predetermined movable range. A motor unit for generating power for rotating the upper part of the support is fixed in a cylindrical motor housing provided in the upper part of the support. The output shaft of the motor unit is fixed to the bottom of the base or the lower part of the column. The rotation of the output shaft causes the motor unit to rotate with the motor housing and the upper portion of the support. One end of a flexible cable including a power supply line to the motor unit is fixed to the lower clamp at the lower part of the column, and the other end of the cable is fixed to the upper clamp at the upper part of the column. The upper clamp is positioned on the plane and on the radial line that passes through the lower clamp, with the upper part of the support positioned at the center of the movable range, and the cable is spirally routed outside the motor housing from the lower clamp to the upper clamp. .

FIG. 1 is a perspective view illustrating an appearance of a robot arm mechanism including a rotary joint mechanism according to the present embodiment. FIG. 2 is a side view showing the internal structure of the robot arm mechanism of FIG. FIG. 3 is a diagram showing the configuration of the robot arm mechanism of FIG. FIG. 4 is a perspective view showing the column part of FIG. 1 with the top cover removed. FIG. 5A is a vertical cross-sectional view of the lower portion of the support column showing the state of the cable when the upper portion of the support column is located at the origin position. FIG. 5B is a vertical cross-sectional view of the lower portion of the column showing the state of the cable when the upper portion of the column is positioned at the first limit position. FIG. 5C is a vertical cross-sectional view of the lower portion of the column showing the state of the cable when the upper portion of the column is located at the second limit position. FIG. 6A is a plan view corresponding to FIG. 5A. FIG. 6B is a plan view corresponding to FIG. 5B. FIG. 6C is a plan view corresponding to FIG. 5C. FIG. 7A is a schematic perspective view corresponding to FIG. 5A. FIG. 7B is a schematic perspective view corresponding to FIG. 5B. FIG. 7C is a schematic perspective view corresponding to FIG. 5C.

Hereinafter, the rotary joint mechanism according to the present embodiment will be described with reference to the drawings. The rotary joint mechanism according to the present embodiment can be used as a single mechanism (joint). In the following description, a robot arm mechanism in which one rotary joint part of the plurality of joint parts is configured by the rotary joint mechanism according to the present embodiment will be described as an example. As the robot arm mechanism, a vertical articulated robot arm mechanism provided with a linear motion expansion / contraction mechanism will be described here, but other types of robot arm mechanisms may be used. In the following description, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

FIG. 1 is a perspective view showing an appearance of a robot arm mechanism including a rotary joint mechanism according to the present embodiment. FIG. 2 is a side view showing the internal structure of the robot arm mechanism of FIG. The robot arm mechanism includes a base 1, a support column (swivel unit) 2, an undulating unit 4, an arm unit 5, and a wrist unit 6. The column part 2, the undulating part 4, the arm part 5 and the wrist part 6 are arranged in order from the base 1. The plurality of joint portions J1, J2, J3, J4, J5, and J6 are arranged in order from the base 1. A column 1 having a cylindrical body is typically installed vertically on the base 1. The support column 2 accommodates a first joint J1 as a turning rotary joint. The first joint portion J1 includes a rotation axis RA1. The rotation axis RA1 is parallel to the vertical direction. The column part 2 includes a column lower part 2-1 and a column upper part 2-2. The column lower part 2-1 includes a cylindrical lower frame 31. The column upper part 2-2 includes a cylindrical upper cover 32. A cylindrical upper frame 22 is provided inside the upper cover 32. One end of the lower column 2-1 is connected to the base 1. The other end of the column lower part 2-1 is connected to the fixed part of the first joint part J1. One end of the column upper part 2-2 is connected to the rotating part of the first joint part J1. The undulating portion 4 is placed on the other end of the upper column 2-2. As the first joint portion J1 rotates, the column upper portion 2-2 rotates about the rotation axis RA1 with respect to the column lower portion 2-1, so that the undulating portion 4 rotates together with the arm portion 5 horizontally. First and

second frame rows

51 and 52 of a third joint portion J3 as a linear motion expansion / contraction mechanism to be described later are housed in the hollow interior of the column portion 2 forming a cylindrical body.

The undulating part 4 is installed on the upper part of the column part 2. The undulating portion 4 has a second joint portion J2 as a undulating rotary joint portion. The rotation axis RA2 of the second joint portion J2 is perpendicular to the rotation axis RA1. The undulating part 4 has a pair of side frames 23 as a fixing part (support part) of the second joint part J2. The pair of side frames 23 is connected to the column upper part 2-2. The pair of side frames 23 is covered with a bowl-shaped cover 33. The pair of side frames 23 supports a cylindrical body 24 as a rotating portion of the second joint portion J2 that also serves as a motor housing. A delivery mechanism 25 is attached to the peripheral surface of the cylindrical body 24. The delivery mechanism 25 holds a drive gear 56, a guide roller 57, and a roller unit 58. As the cylindrical body 24 rotates, the delivery mechanism 25 rotates, and the arm portion 5 supported by the delivery mechanism 25 undulates up and down. The delivery mechanism 25 is covered with a cylindrical cover 34. The gap between the bowl-shaped cover 33 and the cylindrical cover 34 is covered with a U-shaped bellows cover 14 having a U-shaped cross section. The U-shaped bellows cover 14 expands and contracts following the up-and-down movement of the second joint portion J2.

The third joint portion J3 is provided by a linear motion expansion / contraction mechanism. The linear motion expansion / contraction mechanism has a structure newly developed by the inventors, and is clearly distinguished from a so-called conventional linear motion joint in terms of a movable range. Although the arm portion 5 of the third joint portion J3 is freely bendable, the bending is limited when the arm portion 5 is fed forward along the central axis (extension / contraction center axis RA3) from the base feed mechanism 25 of the arm portion 5, and linear rigidity is obtained. Is secured. When the arm part 5 is pulled back, the bending is recovered. The arm unit 5 includes a first frame row 51 and a second frame row 52. The first frame row 51 is composed of a plurality of first frames 53 that are connected to be freely bent. The first frame 53 is formed in a substantially flat plate shape. The first frame 53 is connected to be bent at a hinge portion at an end portion. The second frame row 52 includes a plurality of second frames 54. The second frame 54 is configured as a grooved body having a U-shaped cross section or a cylindrical body having a rectangular shape. The second frame 54 is connected to bendable at the hinge portion at the end of the bottom plate. The bending of the second frame row 52 is limited at a position where the end surfaces of the side plates of the second frame 54 come into contact with each other. At that position, the second frame row 52 is linearly arranged. The first first frame 53 of the first frame sequence 51 and the second second frame 54 of the second frame sequence 52 are connected by a combined frame 55. For example, the combined frame 55 has a shape obtained by combining the first frame 53 and the second frame 54.

The first and

second frame rows

51 and 52 are pressed and joined to each other by the roller 59 when passing through the roller unit 58 of the feed mechanism 25. By joining, the first and

second frame rows

51 and 52 exhibit linear rigidity and constitute a columnar arm portion 5. A drive gear 56 is disposed behind the roller unit 58 together with the guide roller 57. The drive gear 56 is connected to a motor unit (not shown). A linear gear is formed along the connecting direction in the center of the inner surface of the first frame 53, that is, the width center of the surface joined to the second frame 54. When the plurality of first frames 53 are arranged in a straight line, adjacent linear gears are connected in a straight line to form a long linear gear. The drive gear 56 is meshed with the linear gear of the first frame 53 pressed by the guide roller 57. The linear gear connected in a straight line forms a rack and pinion mechanism together with the drive gear 56. When the drive gear 56 rotates forward, the first and

second frame rows

51 and 52 are fed forward from the roller unit 58. When the drive gear 56 rotates in the reverse direction, the first and

second frame rows

51 and 52 are pulled back to the rear of the roller unit 58. The pulled back first and

second frame rows

51 and 52 are separated from each other between the roller unit 58 and the drive gear 56. The separated first and

second frame rows

51 and 52 are returned to a bendable state. The first and

second frame rows

51, 52 that have returned to the bendable state are both bent in the same direction (inner side), and are stored vertically in the column portion 2. At this time, the first frame row 51 is stored in a state of being substantially aligned with the second frame row 52 substantially in parallel.

The wrist part 6 is attached to the tip of the arm part 5. The wrist 6 is equipped with fourth to sixth joints J4 to J6. The fourth to sixth joints J4 to J6 are each provided with three orthogonal rotation axes RA4 to RA6. The fourth joint portion J4 is a rotary joint centered on a fourth rotation axis RA4 that substantially coincides with the expansion / contraction center axis RA3, and the end effector swings by the rotation of the fourth joint portion J4. The fifth joint J5 is a rotary joint centered on a fifth rotation axis RA5 arranged perpendicular to the fourth rotation axis RA4, and the end effector tilts back and forth by the rotation of the fifth joint J5. The sixth joint portion J6 is a rotational joint centered on a sixth rotational axis RA6 that is disposed perpendicular to the fourth rotational axis RA4 and the fifth rotational axis RA5, and ends by the rotation of the sixth joint portion J6. The effector rotates about the axis.

The end effector (hand effector) is attached to an adapter 7 provided at the lower part of the rotating part of the sixth joint part J6 of the wrist part 6. The end effector is a part having a function of directly acting on a work target (work) by the robot, and various tools such as a gripping part, a vacuum suction part, a nut fastener, a welding gun, and a spray gun exist. The end effector is moved to an arbitrary position by the first, second, and third joint portions J1, J2, and J3, and is disposed in an arbitrary posture by the fourth, fifth, and sixth joint portions J4, J5, and J6. In particular, the length of the expansion / contraction distance of the arm portion 5 of the third joint portion J3 enables the end effector to reach a wide range of objects from the proximity position of the base 1 to the remote position. The third joint portion J3 is a characteristic point that is different from the conventional linear motion joint in the linear expansion / contraction operation realized by the linear motion expansion / contraction mechanism constituting the third joint portion J3 and the length of the expansion / contraction distance.

Fig. 3 shows the configuration of the rotary joint mechanism in graphical symbols. In the rotary joint mechanism, three degrees of freedom of position are realized by the first joint portion J1, the second joint portion J2, and the third joint portion J3 that constitute the root three axes. In addition, three posture degrees of freedom are realized by the fourth joint portion J4, the fifth joint portion J5, and the sixth joint portion J6 constituting the wrist three axes. As shown in FIG. 3, the rotation axis RA1 of the first joint portion J1 is provided in the vertical direction. The rotation axis RA2 of the second joint portion J2 is provided in the horizontal direction. The second joint portion J2 is offset with respect to the first joint portion J1 with respect to the two directions of the rotation axis RA1 and an axis orthogonal to the rotation axis RA1. The rotation axis RA2 of the second joint portion J2 does not intersect the rotation axis RA1 of the first joint portion J1. The movement axis RA3 of the third joint portion J3 is provided in a direction perpendicular to the rotation axis RA2. The third joint portion J2 is offset with respect to the second joint portion J2 with respect to two directions of the rotation axis RA1 and an axis orthogonal to the rotation axis RA1. The rotation axis RA3 of the third joint portion J3 does not intersect the rotation axis RA2 of the second joint portion J2. One rotary joint part of the base three axes of the plurality of joint parts J1-J6 is replaced with a linear motion expansion / contraction joint part J3, and the second joint part J2 is offset in two directions with respect to the first joint part J1, By offsetting the third joint portion J3 in two directions with respect to the second joint portion J2, the robot arm mechanism eliminates the singularity posture structurally.

FIG. 4 is a perspective view showing the support column 2 with the upper cover 32 removed. FIG. 5A is a vertical cross-sectional view of the lower portion of the column. A cylindrical lower frame 31 is erected on the base 1. An annular rotating pedestal 201 is fixed to the upper part of the lower frame 31. The rotating pedestal 201 forms a fixing part of the first joint part J1. An annular turntable 202 is rotatably supported on the turntable 201 via a bearing or the like. A cylindrical upper frame 22 of a column upper part 2-2 is fixed to the upper surface of the turntable 202. A bottomed cylindrical motor case 211 is fixed downward on the lower surface of the turntable 202. A cable 230 is routed in the gap between the lower frame 31 and the motor case 211.

The motor unit 212 is accommodated in the motor case 211. The motor unit 212 includes, for example, an electric motor and a gear box. The motor unit 212 is aligned with the motor case 211 so that the central axis of the motor case 211 and the drive shaft 213 coincide with each other, and the motor unit 212 is fixed to the motor case 211 with a spiral or the like at that position. The bottom center of the motor case 211 is opened, and the drive shaft 213 projects from the opening. The tip of the drive shaft 213 is fixed to the base 1 with screws. With this structure, when the drive shaft 213 of the motor unit 212 rotates, the motor unit 212 rotates together with the motor case 211 and the turntable 202. As the turntable 202 rotates, the column upper part 2-2 fixed to the turntable 202 rotates.

A connector 203 is provided at the lower back of the lower column 2-1. The connector 203 is connected via a relay cable 220 to a cable 230 that bundles power supply lines and signal lines to the motor units of the plurality of joint portions J1-J6.

The upper end of the cable 230 is fixed to the upper surface of the turntable 202 with the upper clamp 205. A position where the upper end of the cable 230 is fixed to the upper clamp 205 is referred to as an upper mounting position. The lower end of the cable 230 is fixed to the upper surface of the substrate 1 by the lower clamp 204. A position where the lower end of the cable 230 is fixed to the lower clamp 204 is referred to as a lower mounting position. The cable 230 is routed from the lower clamp 204 to the upper clamp 205 above it while being wound around the outer periphery of the motor case 211 in one direction and spirally. The handling of the cable 230 according to the present embodiment does not occur when the cable 230 is folded in the reverse direction in the middle or when the upper clamp 205 or the lower clamp 204 is folded back to the opposite side. Thereby, the twist of the cable 230 is suppressed to the minimum, and the cable 230 is not bent in the middle or at an acute angle. Therefore, damage to the cable 230 is suppressed, and a light rotational motion is realized. Hereinafter, the handling of the cable 230 according to the present embodiment will be described in detail.

FIG. 5A, FIG. 6A, and FIG. 7A show the state of the cable when the column upper part 2-2 is located at the center of the movable range. It is assumed that the movable range of the column upper part 2-2 relative to the column lower part 2-1 is limited to “± 180 degrees (360 degrees)” by a stopper mechanism or software air. The robot arm mechanism is assembled so that the arm unit 5 faces the front when the upper column 2-2 is positioned at the center of its movable range, that is, at zero degrees. The central position of the movable range is called the origin position. One limit position of the movable range is referred to as a first limit position, and the limit position on the opposite side of the movable range is referred to as a second limit position.

As shown in FIG. 5A, FIG. 6A, and FIG. 7A, the upper clamp 205 is disposed at a position on the turntable 201 that approaches the lower clamp 204 again at the origin position. The situation is that when viewed in a plane, the upper clamp 205 is located on a radial line from the center of rotation C through the lower clamp 204. The cable 230 is obtained by adding a slight margin, for example, 30 degrees to the total angle (540 degrees, 1.5 laps) of 360 degrees around the outer circumference of the motor case 211 and a half of the movable range, here 180 degrees. It has a length necessary to draw a spiral trajectory that rises from the lower clamp 204 to the upper clamp 205 while circling by an angle. The cable 230 is shorter than the total angle of 360 degrees and the movable range, here, the length necessary to draw a spiral trajectory of 720 degrees. The cable 230 is wound from the lower clamp 204 to the upper clamp 205, for example, in the forward direction (clockwise in FIG. 6A). The cable 230 may be wound in the reverse direction (counterclockwise in FIG. 6A).

FIG. 5B, FIG. 6B, and FIG. 7B show the state of the cable 230 when the upper column 2-2 rotates to the first limit position. The cable 230 is wound around the outer side of the motor case 211 from the lower clamp 204 to the upper clamp 205 in a relatively tightened state in a spiral shape within a range of 1.5 laps. In the process in which the column upper part 2-2 rotates in the forward direction from the origin position to the first limit position, the cable 230 is wound around the motor case 211 little by little while the spiral radius is gradually reduced. During this time, the winding direction of the cable 230 is maintained in the forward direction. Therefore, the cable 230 does not fold to the opposite side in the middle, and does not fold back to the opposite side by the upper clamp 205 or the lower clamp 204, and the cable 230 is hardly twisted or bent at an acute angle. Absent.

5C, FIG. 6C, and FIG. 7C show the state of the cable 230 when the column upper part 2-2 rotates in the reverse direction from the origin position to the second limit position. Since the cable 230 has a length of more than 1.5 turns, the cable 230 is routed around the outside of the motor case 211 in a range of 0.5 turns from the lower clamp 204 to the upper clamp 205 in a gently curved state. There is a height difference between the lower clamp 204 and the upper clamp 205, and the gap between the lower frame 31 and the motor case 211 is sufficiently wide. Therefore, the cable 230 is not bent at an intermediate portion, and the cable 230 is not bent. Is not folded back to the opposite side, and is not folded back to the opposite side by the upper clamp 205 or the lower clamp 204, and fits in the gap between the lower frame 31 and the motor case 211 in a gently curved state.

According to the handling of the cable 230 of the rotary joint mechanism according to this embodiment, the winding direction of the cable 230 is kept constant even if the forward and reverse directions of the first joint portion J1 rotate in the direction, and the cable 230 is in the middle It does not fold to the opposite side, nor does it fold back to the opposite side with the upper clamp 205 or the lower clamp 204. Therefore, the breakage of the cable is suppressed and the light rotational movement is not hindered.

Note that the cable routing according to the present embodiment can also be applied to the case where a flexible tube connected to the end effector attached to the adapter 7 is routed. A typical tube is an air tube that connects an external vacuum device to the suction portion of the end effector attached to the adapter 7.

The length of the cable 230 is not less than 360 degrees around the motor case 211 and an angle that is a half of the movable range plus a slight margin, and is the length necessary to go around the range of less than 720 degrees. Have When the flexibility of the cable 230 is very high, it is allowed that the length of the cable 230 is a length necessary to go around a range exceeding 720 degrees.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

J1 ... 1st rotation joint part, 1 ... Base, 2 ... Column part, 2-1 ... Column lower part, 2-2 ... Column upper part, 22 ... Upper frame, 31 ... Lower cover, 201 ... Rotating base, 202 ... Rotation Body 203, connector 204, lower clamp, 205 upper clamp, 211 cylindrical body, 212 motor unit, 213 output shaft, 220 cable, 230 cable bundle.

Claims

A strut portion having a rotary joint portion for turning is erected on the base, and a undulation portion having a rotary joint portion for raising and lowering the arm portion is mounted on the strut portion, and at the tip of the arm portion In a robot arm mechanism equipped with a wrist portion having a plurality of rotary joint portions for posture change,
The column part includes a column lower part and a column upper part supported by the column lower part rotatably within a predetermined movable range,
A motor unit that generates power for rotating the upper part of the support is fixed in a cylindrical motor housing provided at the upper part of the support, and an output shaft of the motor unit is fixed to the base or the bottom of the lower part of the support. The rotation of the output shaft causes the motor unit to rotate along with the motor housing portion and the upper portion of the column,
One end of a flexible cable including a power supply line to the motor unit is fixed to the lower clamp at the lower part of the column, and the other end of the cable is fixed to the upper clamp at the upper part of the column.
The upper clamp is positioned on a plane and on a radial line passing through the lower clamp in a state where the upper portion of the support column is located at the center of the movable range, and the cable extends from the lower clamp to the upper clamp. Robot arm mechanism that can be wound around in a spiral.
The cable has a length that wraps around the outside of the motor housing portion in a range exceeding an angle obtained by adding a half of the movable range to 360 degrees from the first clamp to the second clamp. The robot arm mechanism according to claim 1.
The robot arm mechanism according to claim 2, wherein the cable has a length that goes around the outside of the motor housing portion in a range of less than 720 degrees from the first clamp to the second clamp.
In a rotary joint mechanism having a fixed part and a rotary part supported by the fixed part so as to be rotatable within a predetermined movable range,
One end of a flexible cable including a feeder line is fixed to the first clamp on the fixed portion, and the other end of the cable is fixed to the second clamp on the rotating portion,
In a state where the rotating part is positioned at the center of the movable range, the second clamp is positioned on a plane and on a radial line passing through the first clamp, and the cable is 360 to the second clamp from the first clamp to the second clamp. A rotary joint mechanism that is rotated in a spiral manner within a range of less than 720 degrees exceeding an angle obtained by adding 1/2 of the movable range to a degree.