JP2025131433A - Sensor - Google Patents

Abstract

To provide a sensor that can suppress the variation in detection accuracy.SOLUTION: A proximity sensor 1 as a sensor includes a sheet member 2, and a detection substrate 3 that detects an object H that approaches the sheet member 2. The sheet member 2 includes a detection electrode 11 with conductivity, an active guard electrode 12 with conductivity that is electrically connected to the detection electrode 11 so as to have the same potential as the detection electrode 11, a guard electrode 13 with conductivity that is grounded, a first insulating film 21 that is formed of an insulator, in which a front surface adheres to a back surface of the detection electrode 11 and a back surface adheres to a front surface of the active guard electrode 12, and a second insulating film 22 that is formed of the insulator, in which a front surface adheres to a back surface of the active guard electrode 12 and a back surface adheres to a front surface of the guard electrode 13. The detection substrate 3 detects the change in electrostatic capacitance generated between the detection electrode 11 and the object H.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sensor.

Patent Document 1 discloses a proximity sensor that includes a cloth made by overlapping a conductive first cloth and an insulating second cloth, and a capacitance sensor IC electrically connected to the first cloth. The proximity sensor detects the proximity of an object by detecting changes in capacitance that occur between the first cloth and the object approaching.

Japanese Patent Application Laid-Open No. 2021-135169

The above-mentioned proximity sensor has the disadvantage that it is affected by the capacitance that occurs between the first fabric and anything other than the nearby object, resulting in variations in the accuracy of detecting nearby objects.

The present invention was made in light of the above situation, and aims to provide a sensor that can reduce variation in detection accuracy.

In order to achieve the above object, the sensor according to the present invention comprises:
A sheet member;
a detection unit that detects an object approaching the sheet member,
The sheet member is
a first fabric having electrical conductivity;
a second fabric that is conductive and electrically connected to the first fabric so as to have the same potential as the first fabric;
a third fabric that is electrically conductive and grounded;
a first insulating film made of an insulator, the front surface of which is in close contact with the rear surface of the first fabric and the rear surface of which is in close contact with the front surface of the second fabric;
a second insulating film made of an insulator, the surface of which is in close contact with the back surface of the second fabric and the surface of which is in close contact with the front surface of the third fabric;
The detection unit detects a change in capacitance occurring between the first cloth and the object.

The sensor according to the present invention can reduce variations in detection accuracy.

1 is a schematic diagram illustrating a configuration of a proximity sensor according to an embodiment of the present invention. 2 is a schematic diagram showing a state in which a part of the sheet member in FIG. 1 is folded back. FIG. 1A is a diagram showing a part of a stacked detection electrode, an active guard electrode, and a guard electrode, while FIGS. 1B and 1C are diagrams showing the detection electrode, the active guard electrode, and the guard electrode connected to a detection substrate. 1A is a schematic diagram showing an electric field formed by a sheet member when no object is nearby, and FIG. 1B is a schematic diagram showing an electric field formed by a sheet member when an object is nearby. 1A and 1B are schematic diagrams showing the electric field formed by a sheet member not including an active guard electrode when no object is nearby, respectively, and the electric field formed by a sheet member not including an active guard electrode when an object is nearby. FIG. 10 is a diagram showing the difference in area of each layer of a sheet member. 10 is a flowchart of a filtering process. 10 is a graph showing the relationship between the absolute value of the difference and the detection value. 1A and 1B are perspective views showing a human-collaborative robot. FIG. 1 is a perspective view showing a vertical articulated robot. FIG. 1 is a perspective view showing a SCARA robot. FIG. 1 is a perspective view showing a mobile robot. 10A and 10B are perspective views showing an example in which a sensor is used in a cover of an end effector of an articulated robot.

Embodiments of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or equivalent parts are designated by the same reference numerals. Note that in the following embodiments, the terms "have," "include," and "contain" also include the meanings of "consisting of" and "consisting of."

As shown in FIG. 1, the proximity sensor 1 according to this embodiment covers the object to be protected G and detects an object H approaching the object to be protected G. The proximity sensor 1 includes a sheet member 2 and a detection board 3 as a detection unit. The sheet member 2 and the detection board 3 are electrically connected.

[Sheet member]
The sheet member 2 is a sheet-like member. The sheet member 2 includes a detection electrode 11 as a first fabric, an active guard electrode 12 as a second fabric, and a guard electrode 13 as a third fabric. The detection electrode 11, the active guard electrode 12, and the guard electrode 13 are conductive. The sheet member 2 further includes a first insulating film 21 and a second insulating film 22. The first insulating film 21 and the second insulating film 22 are made of an insulator. In FIG. 1 , only a portion of the detection electrode 11, the active guard electrode 12, the guard electrode 13, the first insulating film 21, and the second insulating film 22 are shown in order to illustrate the configuration of the sheet member 2.

[Detection electrode, active guard electrode and guard electrode]
The detection electrode 11, the active guard electrode 12, and the guard electrode 13 are formed from yarns made by drawing fibrous materials in parallel or twisted yarns. The detection electrode 11, the active guard electrode 12, and the guard electrode 13 are formed by bonding or intertwining conductive yarns. The detection electrode 11, the active guard electrode 12, and the guard electrode 13 may be woven or knitted fabrics made from conductive yarns. The detection electrode 11, the active guard electrode 12, and the guard electrode 13 may also be nonwoven fabrics (including felt).

The threads that make up the detection electrode 11, active guard electrode 12, and guard electrode 13 can be made of fibrous resin plated with metal. More specifically, the threads that make up the detection electrode 11, active guard electrode 12, and guard electrode 13 can be made of, for example, nylon plated with silver. The threads that make up the detection electrode 11, active guard electrode 12, and guard electrode 13 can also be made of conductive fibers (for example, fibrous metal). These threads are regularly or irregularly bonded or entangled to conduct electricity with each other and form a single sheet of electrode cloth.

The detection electrode 11, active guard electrode 12, and guard electrode 13 are soft and thin enough to be foldable. The detection electrode 11, active guard electrode 12, and guard electrode 13 can be folded back without leaving any gaps. The detection electrode 11, active guard electrode 12, and guard electrode 13 are able to fold back when the yarn bends, deforming the gaps between the yarns.

[First insulating film and second insulating film]
The first insulating film 21 and the second insulating film 22 are made of a soft material that is flexible and stretchable. The first insulating film 21 and the second insulating film 22 are thin film-like members that can be folded back without leaving a gap (so that the surfaces before and after the folding point contact each other). The first insulating film 21 and the second insulating film 22 are made of an insulating material that is flexible and foldable, i.e., can be folded back without leaving a gap. The first insulating film 21 and the second insulating film 22 are made to have a uniform thickness.

The first insulating film 21 and the second insulating film 22 can be film-like members made of resin, rubber, or other elastomers. Using these materials can impart waterproofing to the sheet member 2, preventing the penetration of water and other substances between the electrodes. In this embodiment, the first insulating film 21 and the second insulating film 22 are insulating cloths made by bonding or intertwining insulating threads. The threads making up the first insulating film 21 and the second insulating film 22 are made of resin, for example, nylon. These threads are bonded or intertwined with each other in a regular or irregular manner to form a single piece of insulating cloth. The first insulating film 21 and the second insulating film 22 can be folded back when the threads bend and the gaps between the threads deform.

In FIG. 1, the film thicknesses of the first insulating film 21 and the second insulating film 22 are shown as being the same as the film thicknesses of the detection electrode 11, the active guard electrode 12, and the guard electrode 13. However, this is not limited to this. The film thicknesses of the first insulating film 21 and the second insulating film 22 do not need to be the same as the film thicknesses of the detection electrode 11, the active guard electrode 12, and the guard electrode 13.

As shown in FIG. 1, the upper surface of the sheet member 2 facing the object H is referred to as the front surface, and the lower surface facing the object to be protected G is referred to as the back surface. The upper surfaces of the detection electrode 11, active guard electrode 12, guard electrode 13, first insulating film 21, and second insulating film 22 in FIG. 1 are referred to as the front surface, and the lower surfaces thereof are referred to as the back surfaces. The front surface of the detection electrode 11 constitutes the front surface of the sheet member 2, and the back surface of the guard electrode 13 constitutes the back surface of the sheet member 2. The sheet member 2 is formed by laminating the detection electrode 11, first insulating film 21, active guard electrode 12, second insulating film 22, and guard electrode 13 in this order from top to bottom in FIG. 1. The front surface of the first insulating film 21 is in close contact with the back surface of the detection electrode 11, and the front surface of the active guard electrode 12 is in close contact with the back surface of the first insulating film 21. The front surface of the second insulating film 22 is in close contact with the back surface of the active guard electrode 12, and the front surface of the guard electrode 13 is in close contact with the back surface of the second insulating film 22.

In this embodiment, the first insulating film 21 and the second insulating film 22 are adhered to the detection electrode 11, the active guard electrode 12, and the guard electrode 13 with an adhesive. An insulating adhesive may be used, or a conductive adhesive may be used as long as insulation between the detection electrode 11, the active guard electrode 12, and the guard electrode 13 is maintained. Preferably, the adhesive is a hot-melt adhesive that melts and adheres when heated, but other types of adhesives may also be used. Furthermore, double-sided tape may also be used instead of an adhesive.

The detection electrode 11, active guard electrode 12, and guard electrode 13 may be sewn to the first insulating film 21 or the second insulating film 22. In this case, the detection electrode 11, first insulating film 21, active guard electrode 12, second insulating film 22, and guard electrode 13 must be sewn together closely so that no gaps are left between the opposing surfaces, even when the sheet member 2 is folded.

As shown in FIG. 2 , the sheet member 2 is configured to be foldable. Being foldable means being configured to be foldable. As in the present embodiment, the sheet member 2 may be configured to be foldable without leaving any gaps, or it may be configured to leave gaps when folded. In other words, the sheet member 2 has sufficient flexibility and thickness to be foldable. The detection electrodes 11, active guard electrodes 12, and guard electrodes 13 are bonded to the first insulating film 21 and second insulating film 22 with an adhesive. Therefore, even when the sheet member 2 is folded, the adhesion between the detection electrodes 11, active guard electrodes 12, and guard electrodes 13 and the first insulating film 21 and second insulating film 22 is maintained. This is because the detection electrodes 11, active guard electrodes 12, and guard electrodes 13 are configured by bonding or intertwining threads, and the first insulating film 21 and second insulating film 22 are configured from an elastic material. With this configuration, when a portion of the sheet member 2 is folded back, the gaps between the threads in the folded back portion deform, allowing the sheet member 2 to deform without generating internal stress.

[Detection board]
As shown in FIG. 1 , the detection electrode 11, the active guard electrode 12, and the guard electrode 13 are each electrically connected to the detection substrate 3. FIG. 3A shows a portion of the detection electrode 11, the active guard electrode 12, and the guard electrode 13 that constitute the sheet member 2, with the first insulating film 21 and the second insulating film 22 removed. As shown in FIG. 3A , the detection electrode 11, the active guard electrode 12, and the guard electrode 13 each include an extension portion 11a, 12a, and 13a extending from the outer edge. A through hole 2a is formed at the tip of the extension portion 11a, 12a, and 13a. As shown in FIG. 3B and FIG. 3C , a cross-sectional view taken along line IIIC-IIIC in FIG. 3B , a bolt 5 is inserted into the through hole, and the bolt 5 is fastened to a nut 6, thereby connecting each connection terminal 3a of the detection substrate 3 disposed below the case 7 to the extension portion 11a, 12a, and 13a, respectively. As a result, the detection electrode 11, the active guard electrode 12, and the guard electrode 13 are electrically connected to the detection board 3. In this manner, the detection electrode 11, the active guard electrode 12, and the guard electrode 13 that constitute the sheet member 2 can be connected to the detection board 3 by the extensions 11a, 12a, and 13a that are parts of the sheet member 2. This eliminates the need for cables that connect the detection electrode 11, the active guard electrode 12, and the guard electrode 13 to the detection board 3. In FIG. 3C , the first insulating film 21 and the second insulating film 22 are shown as a single insulating layer 23 that contains the detection electrode 11, the active guard electrode 12, and the guard electrode 13.

Returning to Figure 1, the detection board 3 detects the approach of an object H to the protection target G based on changes in the electrostatic capacitance of the sheet member 2. In the detection board 3, the active guard electrode 12 is electrically connected to the detection electrode 11 so that it has the same potential as the detection electrode 11. In this embodiment, the potential of the active guard electrode 12 is buffered from the potential of the detection electrode 11. Furthermore, the guard electrode 13 is grounded via the detection board 3.

The detection board 3 is equipped with a detection circuit 4 that detects the capacitance of the sheet member 2. The detection electrode 11 and active guard electrode 12 are connected to the detection circuit 4. When an object H approaches the detection electrode 11, the gap between the detection electrode 11 and the object H narrows, increasing the capacitance and changing the phase and frequency of the voltage input from the detection electrode 11 to the detection circuit 4. The detection circuit 4 converts this change in voltage phase and frequency into a change in capacitance, and detects the approach of the object H when the change in capacitance exceeds a threshold. In Figure 1, a human hand is shown as the approaching object H. However, the approaching object H is not limited to a human hand.

[Detection principle of nearby objects]
4A, when the object H is not close to the sheet member 2, a capacitor is formed between the detection electrode 11 and the ground. At this time, the detection electrode 11 and the active guard electrode 12 have the same potential, so no capacitance is generated between the detection electrode 11 and the active guard electrode 12. As a result, the capacitance detected by the detection circuit 4 is the capacitance C1 generated between the detection electrode 11 and the ground.

As shown in Figure 4 (B), when an object H approaches the detection electrode 11, a capacitance is generated between the detection electrode 11 and the object H. The capacitance C1 generated between the detection electrode 11 and the object H is much larger than the capacitance C1 generated between the detection electrode 11 and the ground, so the capacitance detected by the detection circuit 4 changes significantly. This change allows the detection circuit 4 to detect that the object H is approaching the detection electrode 11.

As shown in Figures 5(A) and 5(B), consider a hypothetical case where the sheet member 2 does not include an active guard electrode 12, but instead includes only the detection electrode 11 and guard electrode 13 with the first insulating film 21 between them. In this case, in addition to the capacitance C1 generated between the detection electrode 11 and the ground, a capacitance C2 also generates between the detection electrode 11 and the guard electrode 13. In this case, because the latter electrode is closer to the former electrode than the latter, the latter capacitance C2 becomes more dominant than the former capacitance C1. Therefore, the component of the capacitance C2 between the detection electrode 11 and the guard electrode 13 becomes noise when detecting the proximity of an object H, and the capacitance C2 generated between the detection electrode 11 and the guard electrode 13 varies significantly depending on the electrical coupling relationship between the protected object G and the sheet member 2. Therefore, in a hypothetical sheet member 2 that does not include an active guard electrode 12 and includes only the detection electrode 11 and guard electrode 13 with the first insulating film 21 between them, the detection accuracy of the capacitance detected by the detection electrode 11 varies.

In the sheet member 2 according to this embodiment, as shown in FIG. 3(A), an active guard electrode 12 having the same potential as the detection electrode 11 is sandwiched between the detection electrode 11 and the guard electrode 13, preventing the generation of capacitance C2 between the detection electrode 11 and the active guard electrode 12. This allows the capacitance detected by the detection circuit 4 to be determined as being due to capacitance C1 generated between the detection electrode 11 and the ground or between the detection electrode 11 and the object H. Therefore, with the sheet member 2 according to this embodiment, variation in the detection accuracy of the approach of object H can be reduced.

The active guard electrode 12 functions as an electrode that reduces the electrical influence on the detection electrode 11. In this way, even if, for example, the sheet member 2 is folded and partially wrinkled, the first insulating film 21 and the second insulating film 22 are compressed, and the distance between the electrodes changes, the detection circuit 4 is not affected and can accurately detect the approach of the object H.

As shown in FIG. 6 , the detection electrode 11, active guard electrode 12, guard electrode 13, first insulating film 21, and second insulating film 22 are different in size. The surface area S21 of the first insulating film 21 and the surface area S22 of the second insulating film 22 are larger than the fabric surface area S11 of the detection electrode 11, the fabric surface area S12 of the active guard electrode 12, and the fabric surface area S13 of the guard electrode 13. When viewed from the stacking direction of the sheet member 2, the detection electrode 11, active guard electrode 12, and guard electrode 13 are enclosed within the first insulating film 21 and second insulating film 22. In this way, the first insulating film 21 and second insulating film 22 can prevent short-circuiting between the detection electrode 11, active guard electrode 12, and guard electrode 13. Since the detection electrode 11, active guard electrode 12, and guard electrode 13 are no longer short-circuited, malfunctions and failures of the detection circuit 4 can be suppressed. The reduction of capacitance C2, which is a noise component in the capacitance detected by the detection circuit 4, is brought about by the active guard electrode 12. In order for the electric field lines emitted from the detection electrode 11 to reach the guard electrode 13, they must bypass the active guard electrode 12, which suppresses the generation of capacitance C2.

The active guard electrode 12 is also intended to prevent the generation of electrostatic capacitance between the detection electrode 11 and the active guard electrode 12. Therefore, the detection electrode 11 and the active guard electrode 12 are formed so that the area S12 of the cloth surface of the active guard electrode 12 is larger than the area S11 of the cloth surface of the detection electrode 11 and the area S13 of the cloth surface of the guard electrode 13. Furthermore, the guard electrode 13 is provided so that the protected object G does not affect the electrostatic capacitance generated in the detection electrode 11. Therefore, the detection electrode 11 and the guard electrode 13 are formed so that the area S13 of the cloth surface of the guard electrode 13 is larger than the area S11 of the cloth surface of the detection electrode 11.

[Filtering process]
The detection circuit 4 performs a filtering process on the detection value that detects the approach of the object H. This filtering process will be described. The detection circuit 4 includes a filtering means that performs a filtering process that performs a correction calculation based on the detection value for each sampling that corresponds to the electrical signal obtained from the sheet member 2 at a predetermined sampling interval, and outputs an output value of the calculation result. The detection circuit 4 detects the approach of the object H based on the output value output from the filtering means.

In the following, the detection value sampled at each detection timing is designated X _n (n is a natural number such as 1, 2, 3, ...). The detection circuit 4 has a counter that counts the natural number n. The filtering means of the detection circuit 4 designates the most recently sampled detection value as the current detection value X _n , the value output from the filtering means after undergoing filtering processing one sampling ago as the previous output value X' _n-1 , and the output value filtered in accordance with the current detection value X _n as the current output value X' _n .

As shown in FIG. 7, in the filtering process, first, the filtering means of the detection circuit 4 initializes the counter value n to 0 (step S1), and sets the detection value X _n (here, X ₀ ) and the output value X′ _n (here, X′ ₀ ) to initial values (e.g., 0) (step S2).

Next, the filtering means waits until the detection timing arrives (Step S3; No). When the detection timing arrives (Step S3; Yes), the filtering means increments the counter value n by 1 (Step S4) and obtains the current detection value _Xn (Step S5).

Next, the filtering means determines whether the current detection value _Xn is greater than the previous output value X'n _-1 that was filtered and output one sampling ago (step S6). If _Xn >X'n-1 (step S6; Yes), the filtering means calculates the absolute value _Dn of the difference obtained by subtracting the previous output value _{X'n -1} from the current detection value Xn (step S7). On the other hand, if _Xn >X'n _{- 1} is not true (step S6; No), the filtering means determines whether the current detection value _Xn is smaller than the previous output value X'n _-1 (step S8). If _Xn <X'n _-1 (step S8; Yes), the filtering means calculates the absolute value _Dn of the difference obtained by subtracting the previous output value X'n _-1 from the current detection _value Xn (step S9).

(When X _n =X' _n-1 )
On the other hand, if X _n <X' _n-1 is not true (step S8; No), X _n = X' _n-1 , so the filtering means sets C _n = D _n (= 0) (step S15), adds C _n (= 0) to the previous output value X' _n-1 to calculate the current output value X' _n (step S16), and outputs the current output value X' _n (step S20). That is, in this case, the current output value X' _n will be the same as the previous output value X' _n-1 .

(Determination of Numerical Range)
8, in this embodiment, the numerical range of 0 to T is divided into three numerical ranges A1, A2, and A3: 0 to d1, d1 to d2, and d2 to T, and the correction method is changed depending on which numerical range the absolute value of the difference _Dn falls into. Therefore, after calculating the absolute value of the difference _Dn (steps S7 and S9), the filtering means performs a determination process to determine in which of the three numerical ranges A1, A2, and A3 the absolute value of the difference _Dn falls (steps S10A to S10C, steps S11A to S11D, steps S13A to 13C, and steps S14A to S14D).

The graph shown in FIG. 8 plots the absolute value D _n (|X _n -X' _n-1 |) of the difference between the current detection value X _n and the previous output value X' n _-1 on the horizontal axis, and the absolute value D _n corresponding to this absolute value D _n is plotted on the vertical axis. This is to clarify the relationship between the absolute value D _n of the difference and the numerical ranges A1, A2, and A3. The absolute value D _n corresponding to the absolute value D _n of the difference represents a linear function and is shown by a dashed dotted line. Furthermore, the graph shown in FIG. 8 plots the absolute value C _n (|X' _n -X' _n-1 |) of the difference C _n between the current output value X' _n and the previous output value X' _n-1 on the vertical axis, corresponding to the absolute value D n of the difference shown on the horizontal axis. The absolute value of this difference C _n is shown by a bold line. As shown in FIG. 8, the correction to the current output value X' _n differs depending on the absolute value D _n of the difference. The filtering means divides the numerical range on the horizontal axis from 0 to less than the threshold T into three numerical ranges A1, A2, and A3, and corrects the current output value _X'n as follows depending on which of the numerical ranges A1, A2, and A3 the absolute value of the difference _Dn falls into. Note that the number of divisions into the numerical ranges is not limited to three and may be any number.
(A) When the absolute value D _n of the difference is included in the numerical range A1: the filtering means outputs the same value as the previous output value X' _n-1 as the current output value X' _n .
(B) When the absolute value of the difference _Dn is included in the numerical range A2, the filtering means outputs the current output value _X'n , which is closer to the current detected value Xn by a certain intermediate value _d1 . The intermediate value d1 is the value of the absolute value of the difference _Dn at the boundary between the numerical range A1 and the numerical range A2.
(C) When the absolute value of the difference _Dn is within the numerical range A3: the filtering means outputs as the current output value _X'n a value indicating that the difference between the current detection value _Xn and the absolute value of the difference Dn becomes smaller as the absolute value of the difference _Dn approaches the threshold value T. Specifically, the current output value _X'n is calculated as the value obtained by subtracting the absolute value of the difference _Dn from the threshold T, which is the value obtained by subtracting the absolute value of the difference _Dn from the _threshold T. The flow of the process for determining the current output value _X'n will be described below.

(When X _n >X' _n-1 )
Returning to Fig. 7, after executing step S7, if _Dn ≦ d1 (step S10A; Yes), the filtering means uses the graph shown in Fig. 8 to set _Cn corresponding to the absolute value of the difference _Dn to 0 (step S11A). Also, if d1 < _Dn < d2 (step S10B; Yes), the filtering means uses the graph shown in Fig. 8 to calculate Dn _- d1 and substitutes it for _Cn (step S11B). Also, if d2 ≦ _Dn ≦ T (step S10C; Yes), the filtering means uses the graph shown in Fig. 8 to calculate _Dn - (T - _Dn ) and substitutes it for _Cn (step S11C). If d2 ≦ _Dn ≦ T is not true (step S10C; No), the filtering means substitutes the absolute value of the difference _Dn for _Cn (step S11D).

(When X _n <X′ _n−1 )
After executing step S9, if D _n ≦d1 (step S13A; Yes), the filtering means uses the graph shown in FIG. 8 to set C _n corresponding to the absolute value D _n of the difference to 0 (step S14A). Also, if d1<D _n <d2 (step S13B; Yes), the filtering means uses the graph shown in FIG. 8 to calculate d1−D _n and substitutes it for C _n (step S14B). Also, if d2≦D _n ≦T (step S13C; Yes), the filtering means uses the graph shown in FIG. 8 to calculate (T−D _n )−D _n and substitutes it for C _n (step S14C). If d2≦D _n ≦T is not satisfied (step S13C; No), the filtering means uses the graph shown in FIG. 8 to calculate −D _n and substitutes it for C _n (step S14D).

After steps S11A to S11D and steps S14A to S14D are completed, the filtering means adds _Cn to the previous output value X'n _-1 , which was output after filtering processing one sampling before, to update the current output value _X'n as the latest output value (step S16).The filtering means outputs the updated current output value _X'n as the current output value after filtering (step S20).

After outputting the current output value _X'n (step S20), the filtering means waits for the detection timing (step S3; No). Thereafter, when the detection timing arrives (step S3; Yes), the filtering means executes steps S4 to S20, increments n by 1, and if the absolute value _Dn of the difference is smaller than the threshold T, finds the next output value _X'n in the above-described filtering process flow.

As described above, the filtering means detects the capacitance C1 of the sheet member 2 at predetermined sampling intervals. If the absolute value _Dn of the difference between the current detection value _Xn and the previous output value X'n _-1 is greater than 0 and smaller than the threshold value T, the filtering means performs a filtering process to output, as the current output value _X'n , a value closer to the previous output value X'n _-1 than the current detection value _Xn .

The filtering means also performs filtering processing that exhibits a relationship in which the current output value X' _{n approaches the current detected value X' n as} the absolute value D _n of the difference approaches the threshold value T from 0. Specifically, when the absolute value D _n of the difference is within at least a part of the numerical range A1 (a numerical range greater than 0 and smaller than d1) of the numerical ranges A1, A2, A3 greater than 0 and smaller than the threshold value T, the filtering means outputs the same value as the previous output value X' _n-1 as the current output value X' _n . When the absolute value D _n of the difference is within at least a part of the numerical range A2 (a numerical range equal to or greater than d1 and smaller than d2) of the numerical ranges A1, A2, A3 greater than 0 and smaller than the threshold value T, the filtering means outputs a value that is closer to the previous output value X' _n-1 from the current detected value X _n by a certain intermediate value d1 as the current output value X' _n . Furthermore, when the absolute value _Dn of the difference is in at least a part of the numerical range A3 (a numerical range equal to or greater than d2 and smaller than the threshold value T) among the numerical ranges A1, A2, A3 greater than 0 and smaller than the threshold value T, the filtering means outputs as the current output value _X'n a value whose difference from the current detected value _Xn becomes smaller as the absolute value _Dn of the difference approaches the threshold value T.

However, the current output value _X'n is not limited to the above. The numerical range in which the absolute value of the difference _Dn is smaller than the threshold value T may be divided into two numerical ranges: one in which the correction value _Cn increases as the absolute value of the difference _Dn increases, and another in which the correction value Cn decreases as the absolute value of the difference Dn increases, or the entire range may be defined as the numerical range A1. How the current output value X'n is corrected so as to approach the previous output value _{X'n -1} can be adjusted as appropriate.

[Example of use]
The sheet member 2 has the detection electrodes 11 on the outside and the guard electrodes 13 facing the protection target G (with the guard electrodes 13 on the inside), and functions as a cover that covers at least a part of the protection target G. For example, as shown in Figures 9(A) and 9(B), 10 and 11, the sheet member 2 can be used as a cover for an articulated robot.

As shown in Figure 9 (A), the sheet member 2 according to this embodiment can be used as a cover for the human-collaborative robot 30. The human-collaborative robot 30 is a robot designed to be able to work together with humans while sharing the same space, without the need for safety fences. Because it shares the same space as humans, the sheet member 2 can be used as a cover for the human-collaborative robot 30 to avoid contact with humans, allowing it to detect proximity to a human.

In Figure 9(A), the sheet member 2 is assumed to be transparent. As shown in Figure 9(A), the collaborative robot 30 comprises a base unit 30a, multiple joint units 30b to 30e, arm units 31a to 31d, and a hand unit (end effector) 32. The base unit 30a and joint units 30a to 30e each have a built-in motor, and when driven by the motor, the position and posture of the connected arm units 31a to 31d (first arm, second arm) and the hand unit 32 at the tip can be changed. In summary, the human-collaborative robot 30 is a robot arm having a base unit 30a, arm units 31a to 31d, a joint unit 30b connecting arm unit 31a and arm unit 31b, a joint unit 30c connecting arm unit 31b and arm unit 31c, a joint unit 30d connecting arm unit 31c and arm unit 31d, and a hand unit 32 connected to arm unit 31d via joint unit 30e.

As shown in Figure 9 (B), the sheet member 2 covers the entire human-collaborative robot 30 except for the hand unit 32. The sheet member 2 has a through-hole 2a through which the hand unit 32 passes and protrudes, allowing the hand unit 32 to perform tasks. The sheet member 2 is sized to allow a certain amount of room for the human-collaborative robot 30. Even when the human-collaborative robot 30 deforms, the sheet member 2 deforms to match the human-collaborative robot 30. Even during this deformation, the active guard electrode 12 functions as an electrode with the same potential as the detection electrode 11, guarding the detection electrode 11 from the protected object G. Therefore, unless another object H (see Figure 1, e.g., a person) approaches, the capacitance detected by the detection circuit 4 does not change significantly. However, when the object H approaches, the capacitance detected by the detection circuit 4 changes significantly. This allows the detection circuit 4 to detect the approach of the object H.

The sheet member 2 can also be used as a cover for the vertical articulated robot 33 shown in FIG. 10 and the SCARA robot 35 shown in FIG. 11. In both FIGS. 10 and 11, the cover (sheet member 2) is illustrated as being transparent. As shown in FIG. 10, the vertical articulated robot 33 has a base 33a, arms 33b and 33c, and a hand 34. Joints with built-in motors are provided between the base 33a and arm 33b, between arm 33b and arm 33c, and between arm 33c and hand 34. As shown in FIG. 11, the SCARA robot 35 has a base 35a, arms 35b and 35c, and a hand 36. Joints with built-in motors are provided between the base 35a and arm 35b, between arm 35b and arm 35c, and between arm 35c and hand 36.

As shown in Figures 10 and 11, the sheet member 2 is sized to allow ample space for the vertical articulated robot 33 and the SCARA robot 35, and covers the vertical articulated robot 33 and the SCARA robot 35 with their respective hand units 34, 36 protruding outward through the through-holes 2a. Therefore, even when the joints of the vertical articulated robot 33 and the SCARA robot 35 rotate, the sheet member 2 deforms to fit the shape of the robot. Even during this deformation, the capacitance detected by the detection circuit 4 does not change significantly unless another object H (see Figure 1, for example, a person) is present nearby.

The sheet member 2 can also be used as a cover for a mobile robot 37 as shown in Figure 12. The mobile robot 37 comprises a robot body 37a and wheels 37b for movement. The robot body 37a is provided with a drive unit that rotates the wheels 37b, and the robot moves by driving the wheels 37b. The mobile robot 37 has functions suited to its use, such as monitoring the surroundings, cleaning the floor, or serving food. The sheet member 2 is attached to at least a portion of the robot body 37a, for example, to the side. The detection circuit 4 can detect the approach of an object H (see Figure 1) to the robot body 37a based on the change in detected capacitance.

As shown in Figures 13(A) and 13(B), the sheet member 2 may protect a portion of the articulated robot 40 as the protected object G. Of the arm unit 41 and hand unit 42 that make up the articulated robot 40, the sheet member 2 protects the hand unit 42 as the protected object G. The sheet member 2 is sewn into a cylindrical shape and wrapped around the side of the hand unit 42 so that the suction portion or finger portion that holds the workpiece is exposed. The sheet member 2 may also be formed into a cylindrical shape using Velcro (registered trademark). The hand unit 42 has the largest range of motion of all the parts of the articulated robot 40 and is prone to interference with other objects. In addition, it is not equipped with a safety device (contact detection device, proximity detection device). Attaching the sheet member 2 to the hand unit 42 can reduce the risk of contact with a person, for example.

In the above embodiment, the sheet member 2 is constructed by attaching the detection electrode 11, active guard electrode 12, and guard electrode 13, which are made of conductive thread, and the first insulating film 21 and second insulating film 22, which are made of insulating thread, to an adhesive material. However, this is not limited to this. The sheet member 2 may also be formed by knitting or weaving a combination of conductive and insulating threads, so that a layer of insulating thread is formed between two layers of conductive thread.

Also, if the object G to be protected is large, multiple sheet members 2 may be joined together to form an overall cover. In this case, a detection circuit 4 is connected to each sheet member 2. In this case, the sheet members 2 may be joined together with adhesive or by sewing them together.

[summary]
(1) As described above in detail, the proximity sensor 1 according to this embodiment includes a sheet member 2 and a detection substrate 3 that detects an object H approaching the sheet member 2. The sheet member 2 includes a conductive detection electrode 11, a conductive active guard electrode 12 that is electrically connected to the detection electrode 11 so as to have the same potential as the detection electrode 11, and a conductive grounded guard electrode 13. The sheet member 2 further includes a first insulating film 21 made of an insulator and having a front surface in close contact with the rear surface of the detection electrode 11 and a rear surface in close contact with the front surface of the active guard electrode 12, and a second insulating film 22 made of an insulator and having a front surface in close contact with the rear surface of the active guard electrode 12 and a rear surface in close contact with the front surface of the guard electrode 13. The detection substrate 3 detects changes in capacitance occurring between the detection electrode 11 and the object H. Because the detection electrode 11 and the active guard electrode 12 are at the same potential, no capacitance occurs between them. Therefore, the capacitance detected by the detection electrode 11 can be narrowed down to the capacitance between the detection electrode 11 and the object H, thereby suppressing variations in detection accuracy.

(2) In the proximity sensor 1 according to this embodiment, the detection electrode 11, active guard electrode 12, and guard electrode 13 each have an extension 11a, 12a, and 13a that extend from the outer edge and connect to the detection board 3. The detection board 3 detects the proximity of the object H based on the electrical signal transmitted via the extension 11a, 12a, and 13a. This eliminates the need for a cable connecting the sheet member 2 and the detection board 3.

(3) In the proximity sensor 1 according to this embodiment, the film surface areas of the first insulating film 21 and the second insulating film 22 are larger than the cloth surface areas of the detection electrode 11, the active guard electrode 12, and the guard electrode 13. The cloth surface area of the active guard electrode 12 is larger than the cloth surface areas of the detection electrode 11 and the guard electrode 13. Furthermore, the cloth surface area of the guard electrode 13 is equal to or larger than the cloth surface area of the detection electrode 11. This prevents the detection electrode 11, the active guard electrode 12, and the guard electrode 13 from shorting out. Preventing shorting out of the detection electrode 11, the active guard electrode 12, and the guard electrode 13 can suppress malfunctions and failures of the detection circuit 4. In this way, the capacitance detected by the detection electrode 11 can be narrowed down to the capacitance between the detection electrode 11 and the object H, thereby suppressing variations in detection accuracy.

(4) In the proximity sensor 1 according to this embodiment, the detection board 3 (detection circuit 4) includes filtering means that performs filtering processing based on the detection value _Xn for each sampling corresponding to the electrical signal obtained from the sheet member 2 at a predetermined sampling interval and outputs an output value of the calculation result, and detects the proximity of the object H based on the output value _X'n output from the filtering means, and when the absolute value _Dn of the difference between the current detection value _Xn and the previous output value X'n _-1 is greater than 0 and less than the threshold value T, the filtering means performs filtering processing to output, as the current output value _X'n , a value closer to the previous output value X'n _{-1 than} the current detection value Xn. This makes it possible to reduce minute noise contained in the detection value _Xn .

(5) In the proximity sensor 1 according to this embodiment, the filtering means performs filtering processing that indicates a relationship in which the current output value X' _n approaches the current detection value X' _n as the absolute value D _n of the difference approaches the threshold value T from 0. In this way, even if the current output value X' _n fluctuates around the threshold value T, the current output value X' _n can be made to fluctuate smoothly.

(6) In the proximity sensor 1 according to the present embodiment, when the absolute value _Dn of the difference is in at least a part of the numerical range A1 among the numerical ranges A1, A2, and A3 that are greater than 0 and less than the threshold value T, the filtering means outputs the same value as the previous output value X'n _-1 as the current output value _X'n . This allows minute changes in the detection value _Xn to be regarded as noise components and made insensitive, thereby reducing minute noise contained in the detection value _Xn .

(7) In proximity sensor 1 according to the present embodiment, when the absolute value _Dn of the difference is in at least a part of the numerical range A2 among the numerical ranges A1, A2, and A3 that are greater than 0 and less than the threshold value T, the filtering means outputs as the current output value X'n a value that is closer to the previous output value X'n _{-1 from the} current detection value Xn by a certain intermediate value d1. This allows minute changes in detection value _Xn to be regarded as noise components and set to a certain small value, thereby reducing minute noise contained in detection value _Xn .

(8) In the proximity sensor 1 according to the present embodiment, when the absolute value of the difference _Dn is in at least a part of the numerical range A3 among the numerical ranges A1, A2, and A3 that are greater than 0 and less than the threshold value T, the filtering means _outputs as the current output value _X'n a value that indicates a relationship in which the difference from the current detection value Xn approaches ₀ as the absolute value of the difference _Dn approaches the threshold value T. This allows minute changes in the detection value Xn to be regarded as noise components and reduced, thereby making it possible to suppress minute noise contained in the detection value _Xn .

(9) In the proximity sensor 1 according to this embodiment, at least one of the detection electrode 11, the active guard electrode 12, and the guard electrode 13 is adhered to the first insulating film 21 and the second insulating film 22. In this way, the sheet member 2 can be deformed while the detection electrode 11, the active guard electrode 12, and the guard electrode 13 are kept in close contact with the first insulating film 21 and the second insulating film 22.

(10) In the proximity sensor 1 according to this embodiment, at least one of the detection electrode 11, the active guard electrode 12, and the guard electrode 13 is sewn to the first insulating film 21 and the second insulating film 22. By sewing these together, the sheet member 2 can be used even in environments where the use of adhesives is undesirable.

(11) In the sheet member 2 according to this embodiment, the guard electrode 13 faces the object to be protected G (with the guard electrode 13 facing inward), and functions as a cover that covers at least a portion of the object to be protected G. In other words, the sheet member 2 can be used as a cover that protects the object to be protected G.

(12) As shown in Figures 9(A), 9(B), 10, and 11, the sheet member 2 covers a robot arm having a first arm, a second arm, and a joint connecting the first arm and the second arm as the object to be protected G. The proximity sensor 1 can also respond to deformation of the object to be protected G.

(13) As shown in Figures 13(A) and 13(B), in the proximity sensor 1 according to this embodiment, the sheet member 2 covers the hand unit 42 of the articulated robot 40 as the object to be protected G. Because the hand unit 42 is a part that is likely to come into contact with other objects H, covering this part with the sheet member 2 can increase safety when operating the robot.

(14) The mobile robot 37 according to this embodiment may include a robot body 37a of the mobile robot 37, a sheet member 2 that covers at least a portion of the robot body 37a as a protection target G, and a detection board 3 that detects the approach of an object H to the robot body 37a based on a change in the electrostatic capacitance of the sheet member 2.

(15) The human-collaborative robot 30 according to this embodiment can include robot arms (30a-30e, 31a-31d, 32) having arm portions 31a, 31b, and a joint portion 30b connecting arm portions 31a and 31b; a sheet member 2 that covers the robot arms (30a-30e, 31a-31d, 32) as protective objects; and a detection circuit 4 that detects the approach of an object H to the robot arms (30a-30e, 31a-31d, 32) based on a change in the capacitance of the sheet member 2.

(16) The proximity detection system according to this embodiment includes a protection target G, a sheet member 2 that covers at least a portion of the protection target G, and a detection board 3 that detects the proximity of an object H to the protection target G based on a change in the electrostatic capacitance of the sheet member 2. In this way, the protection target G is not limited to robots, and the system can be applied to any protection target G, including moving objects such as vehicles and drones, and stationary objects.

This invention allows for various embodiments and modifications without departing from the broad spirit and scope of the invention. Furthermore, the above-described embodiments are intended to explain the invention and do not limit the scope of the invention. In other words, the scope of the invention is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and the meaning of the invention equivalent thereto are deemed to be within the scope of the invention.

This invention can be applied to detecting nearby objects.

1 proximity sensor (sensor), 2 sheet member, 2a through hole, 3 detection board (detection unit), 3a connection terminal, 4 detection circuit, 5 bolt, 6 nut, 7 case, 11 detection electrode (first fabric), 11a extension, 12 active guard electrode (second fabric), 12a extension, 13 guard electrode (third fabric), 13a extension, 21 first insulating film, 22 second insulating film, 23 insulating layer, 30 human collaborative robot, 30a base portion, 30b, 30c, 30d, 30e joint portion, 31a, 31b, 31c, 31d arm portion (first arm, second arm), 32 hand portion, 33 vertical articulated robot, 33a base portion, 33b, 33c arm portion, 34 hand portion, 35 SCARA robot, 35a base portion, 35b, 35c arm portion, 36 Hand unit, 37 Mobile robot, 37a Robot body, 37b Wheel, 40 Articulated robot, 41 Arm unit, 42 Hand unit, G Protected object, H Object

Claims (12)

A sheet member;
a detection unit that detects an object approaching the sheet member,
The sheet member is
a first fabric having electrical conductivity;
a second fabric that is conductive and electrically connected to the first fabric so as to have the same potential as the first fabric;
a third fabric that is electrically conductive and grounded;
a first insulating film made of an insulator, the front surface of which is in close contact with the rear surface of the first fabric and the rear surface of which is in close contact with the front surface of the second fabric;
a second insulating film made of an insulator, the surface of which is in close contact with the back surface of the second fabric and the surface of which is in close contact with the front surface of the third fabric;
The detection unit is a sensor that detects a change in capacitance occurring between the first cloth and the object. the first cloth, the second cloth, and the third cloth each include an extension portion extending from an outer edge and connected to the detection portion,
the detection unit detects the proximity of the object based on an electrical signal transmitted via the extension unit.
The sensor of claim 1 . the areas of the film surfaces of the first insulating film and the second insulating film are larger than the areas of the cloth surfaces of the first cloth, the second cloth, and the third cloth;
The area of the cloth surface of the second cloth is larger than the areas of the cloth surfaces of the first cloth and the third cloth,
The area of the cloth surface of the third cloth is equal to or greater than the area of the cloth surface of the first cloth.
The sensor of claim 1 . The detection unit
a filtering means for performing filtering processing based on a detection value for each sampling corresponding to an electrical signal obtained from the sheet member at a predetermined sampling interval and outputting an output value of the calculation result;
detecting the proximity of the object based on the output value output from the filtering means;
The filtering means
If the absolute value of the difference between the current detection value and the previous output value is greater than 0 and smaller than the threshold, a filtering process is performed to output a value closer to the previous output value than the current detection value as the current output value.
A sensor according to any one of claims 1 to 3. The filtering means
performing a filtering process that indicates a relationship in which the current output value approaches the current detection value as the absolute value of the difference approaches the threshold value from 0;
The sensor of claim 4. The filtering means
If the absolute value of the difference is within at least a part of a range of values greater than 0 and less than the threshold value, the same value as the previous output value is output as the current output value.
The sensor of claim 4. The filtering means
When the absolute value of the difference is within at least a part of a range of values greater than 0 and less than the threshold value, a value that is closer to the previous output value by a certain intermediate value from the current detection value is output as the current output value.
The sensor of claim 4. The filtering means
When the absolute value of the difference is in at least a part of a range of values greater than 0 and less than the threshold value, a value indicating a relationship in which the difference from the current detection value approaches 0 as the absolute value of the difference approaches the threshold value is output as the current output value.
The sensor of claim 4. At least one of the first cloth, the second cloth, and the third cloth is adhered to the insulating film.
The sensor of claim 1 . At least one of the first cloth, the second cloth, and the third cloth is sewn to the insulating film.
The sensor of claim 1 . the sheet member covers, as a protected object, a robot arm having a first arm, a second arm, and a joint portion connecting the first arm and the second arm;
The sensor of claim 1 . The sheet member covers the end effector of the robot as a protective object.
The sensor of claim 1 .