Sensor

Abstract

A proximity sensor (1) serving as a sensor comprises: a sheet member (2); and a detection board (3) that detects an object (H) approaching the sheet member (2). The sheet member (2) comprises: an electrically conductive detection electrode (11); an electrically 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); an electrically conductive and grounded guard electrode (13); a first insulating film (21) that is made of an insulator, has a front surface in close contact with a rear surface of the detection electrode (11), and has a back surface in close contact with a front surface of the active guard electrode (12); and a second insulating film (22) that is made of an insulator, has a front surface in close contact with a back surface of the active guard electrode (12), and has a back surface in close contact with a front surface of the guard electrode (13). The detection substrate (3) detects a change in capacitance generated between the detection electrode (11) and the object (H).

Description

Sensor

[0001] The present invention relates to a sensor.

[0002] Patent Document 1 discloses a proximity sensor that includes a cloth formed 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 a change in capacitance that occurs between the first cloth and the object approaching the first cloth.

[0003] Japanese Patent Application Laid-Open No. 2021-135169

[0004] The above-mentioned proximity sensor has the disadvantage that the accuracy of detecting a nearby object varies due to the effect of capacitance generated between the first fabric and something other than the nearby object.

[0005] The present invention has been made in light of the above-mentioned circumstances, and has an object to provide a sensor that can suppress variations in detection accuracy.

[0006] In order to achieve the above object, the sensor of the present invention comprises a sheet member and a detection unit that detects an object in the vicinity of the sheet member, wherein the sheet member comprises: a first cloth that is conductive; a second cloth that is conductive and electrically connected to the first cloth so as to have the same potential as the first cloth; a third cloth that is conductive and grounded; a first insulating film that is made of an insulator and has its front surface in close contact with the back surface of the first cloth and its back surface in close contact with the front surface of the second cloth; and a second insulating film that is made of an insulator and has its front surface in close contact with the back surface of the second cloth and its back surface in close contact with the front surface of the third cloth, and the detection unit detects a change in capacitance that occurs between the first cloth and the object.

[0007] According to the sensor of the present invention, it is possible to suppress variations in detection accuracy.

[0008] 3B is a schematic diagram showing the configuration of a proximity sensor according to an embodiment of the present invention. FIG. 3C is a schematic diagram showing a state in which a portion of the sheet member of FIG. 1 is folded back. FIG. 3D is a diagram showing portions of stacked detection electrodes, active guard electrodes, and guard electrodes. FIG. 3E is a diagram showing a state in which the detection electrodes, active guard electrodes, and guard electrodes are connected to a detection substrate. FIG. 3F is a cross-sectional view taken along line IIIC-IIIC of FIG. 3B. FIG. 3C is a schematic diagram showing an electric field formed by a sheet member when an object is not in proximity. FIG. 3D is a schematic diagram showing an electric field formed by a sheet member when an object is in proximity. FIG. 3E is a schematic diagram showing an electric field formed by a sheet member without an active guard electrode when an object is not in proximity. FIG. 3F is a schematic diagram showing an electric field formed by a sheet member without an active guard electrode when an object is in proximity. FIG. 3F is a diagram showing a difference in the area size of each layer of a sheet member. FIG. 3F is a flowchart of filtering processing. FIG. 3G is a graph showing the relationship between the absolute value of the difference and the detection value. FIG. 3H is a perspective view showing a first example of a human-collaborative robot. FIG. 3I is a perspective view showing a third example of a human-collaborative robot. FIG. 3I is a perspective view showing a vertical articulated robot. FIG. 3I is a perspective view showing a SCARA robot. FIG. 3I is a perspective view showing a mobile robot. FIG. 3I is a perspective view showing a first example in which a sensor is used in a cover of an end effector of an articulated robot. FIG. 10 is a perspective view showing a second example in which a sensor is used in the cover of an end effector of an articulated robot.

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or equivalent parts are denoted by the same reference numerals. In the following embodiments, the terms "have," "include," or "contain" also mean "consist of" or "consist of."

[0010] 1, a proximity sensor 1 according to this embodiment covers a protection target G and detects an object H approaching the protection target 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.

[0011] [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.

[0012] [Detection Electrode, Active Guard Electrode, and Guard Electrode] The detection electrode 11, active guard electrode 12, and guard electrode 13 are formed from yarns made by drawing fibrous materials in parallel or twisted yarns. The detection electrode 11, active guard electrode 12, and guard electrode 13 are formed by bonding or intertwining conductive yarns. The detection electrode 11, active guard electrode 12, and guard electrode 13 may be woven or knitted fabrics made from conductive yarns. The detection electrode 11, active guard electrode 12, and guard electrode 13 may also be nonwoven fabrics (including felt).

[0013] The threads constituting the detection electrode 11, the active guard electrode 12, and the guard electrode 13 may be made of fibrous resin plated with a metal. More specifically, the threads constituting the detection electrode 11, the active guard electrode 12, and the guard electrode 13 may be made of, for example, nylon plated with silver. The threads constituting the detection electrode 11, the active guard electrode 12, and the guard electrode 13 may 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.

[0014] The detection electrode 11, the active guard electrode 12, and the guard electrode 13 are soft and thin enough to be foldable. The detection electrode 11, the active guard electrode 12, and the guard electrode 13 can be folded back without leaving any gaps. The detection electrode 11, the active guard electrode 12, and the guard electrode 13 can be folded back by bending the yarn and deforming the gaps between the yarns.

[0015] [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.

[0016] The first insulating film 21 and the second insulating film 22 may be film-like members made of resin, rubber, or other elastomers. Using these materials can impart waterproofing to the sheet member 2, preventing 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 formed by bonding or intertwining insulating threads. The threads forming 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 are capable of folding back as the threads bend and the gaps between the threads deform.

[0017] 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 limiting. 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.

[0018] 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 protection target 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 configured 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.

[0019] In this embodiment, the first insulating film 21 and the second insulating film 22 are bonded to the detection electrode 11, the active guard electrode 12, and the guard electrode 13 with an adhesive. An adhesive having insulating properties may be used, or an adhesive having conductivity 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, a hot-melt adhesive that melts and bonds with heat is used as the adhesive, but other types of adhesives may also be used. Also, the adhesive is not limited to adhesive, and double-sided tape may be used.

[0020] The detection electrode 11, the active guard electrode 12, and the guard electrode 13 may be sewn to the first insulating film 21 or the second insulating film 22. In this case, even when the sheet member 2 is folded, the detection electrode 11, the first insulating film 21, the active guard electrode 12, the second insulating film 22, and the guard electrode 13 need to be sewn together closely so that no gaps are formed between the opposing surfaces.

[0021] 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 may be configured to leave gaps when folded. In other words, the sheet member 2 has flexibility and thickness that allows it to be foldable. The detection electrodes 11, the active guard electrodes 12, and the guard electrodes 13 are bonded to the first insulating film 21 and the second insulating film 22 with an adhesive. Therefore, even when the sheet member 2 is folded, the detection electrodes 11, the active guard electrodes 12, and the guard electrodes 13 are kept in close contact with the first insulating film 21 and the second insulating film 22. This is because the detection electrodes 11, the active guard electrodes 12, and the guard electrodes 13 are configured by bonding or intertwining threads, and the first insulating film 21 and the second insulating film 22 are configured from an elastic material. With this configuration, when a part of the sheet member 2 is folded back, the gaps between the threads in the folded back part deform, so that the sheet member 2 can deform without generating internal stress.

[0022] [Detection Board] As shown in FIG. 1 , the detection electrode 11, the active guard electrode 12, and the guard electrode 13 are electrically connected to the detection board 3. In FIG. 3A , portions of the detection electrode 11, the active guard electrode 12, and the guard electrode 13 constituting the sheet member 2 are shown without the first insulating film 21 and the second insulating film 22. 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 FIGS. 3B and 3C , a bolt 5 is inserted into the through-hole and fastened to a nut 6, thereby connecting each connection terminal 3a of the detection board 3 disposed at the bottom of the case 7 to the extension portion 11a, 12a, and 13a. 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 way, the detection electrodes 11, active guard electrodes 12, and guard electrodes 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 electrodes 11, active guard electrodes 12, and guard electrodes 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 electrodes 11, active guard electrodes 12, and guard electrodes 13.

[0023] 1 , the detection board 3 detects the approach of an object H to the protection target G based on a change 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 as to have 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.

[0024] The detection board 3 includes a detection circuit 4 that detects the capacitance of the sheet member 2. The detection electrode 11 and the 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 the phase and frequency of the voltage into a change in capacitance, and detects the approach of the object H when the change in capacitance exceeds a threshold. In FIG. 1 , a human hand is shown as the approaching object H. However, the approaching object H is not limited to a human hand.

[0025] 4A, when the object H is not in proximity 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.

[0026] 4B , 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 enables the detection circuit 4 to detect that the object H is approaching the detection electrode 11.

[0027] 5A and 5B , consider a hypothetical case where the sheet member 2 does not include the active guard electrode 12, but includes only the detection electrode 11 and the guard electrode 13 with the first insulating film 21 between them. In this case, in addition to the capacitance C1 between the detection electrode 11 and the ground, a capacitance C2 also occurs between the detection electrode 11 and the guard electrode 13. In this case, because the latter electrode is spaced closer than the former electrode, 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 between the detection electrode 11 and the guard electrode 13 varies significantly depending on the electrical coupling relationship between the protection target G and the sheet member 2. Therefore, in a hypothetical sheet member 2 that does not include the active guard electrode 12 and includes only the detection electrode 11 and the guard electrode 13 with the first insulating film 21 between them, the detection accuracy of the capacitance detected by the detection electrode 11 varies.

[0028] 3A , in the sheet member 2 according to this embodiment, 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, thereby 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, in the sheet member 2 according to this embodiment, variation in the detection accuracy of the approach of the object H can be suppressed.

[0029] The active guard electrode 12 functions as an electrode that reduces the electrical influence on the detection electrode 11. In this way, even if 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 can accurately detect the approach of the object H without being affected by this.

[0030] As shown in FIG. 6 , the detecting electrode 11, the active guard electrode 12, the guard electrode 13, the first insulating film 21, and the second insulating film 22 are different in size. The film surface area S21 of the first insulating film 21 and the film surface area S22 of the second insulating film 22 are larger than the cloth surface area S11 of the detecting electrode 11, the cloth surface area S12 of the active guard electrode 12, and the cloth surface area S13 of the guard electrode 13. When viewed from the stacking direction of the sheet member 2, the detecting electrode 11, the active guard electrode 12, and the guard electrode 13 are enclosed by the first insulating film 21 and the second insulating film 22. In this manner, the first insulating film 21 and the second insulating film 22 can prevent the detecting electrode 11, the active guard electrode 12, and the guard electrode 13 from shorting out. Since the detecting electrode 11, the active guard electrode 12, and the guard electrode 13 are not shorted out, 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 makes it possible to suppress the generation of capacitance C2.

[0031] The active guard electrode 12 is provided 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.

[0032] [Filtering Process] The detection circuit 4 performs 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 filtering means that performs filtering process by performing correction calculation based on the detection value 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. The detection circuit 4 detects the approach of the object H based on the output value output from the filtering means.

[0033] Hereinafter, the detection value sampled at each detection timing is expressed as 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 also filters the most recently sampled detection value into the current detection value X ｎ The value output from the filtering means after the filtering process one sampling before is the previous output value X' ｎ－１ Let the current detected value be X ｎ The output value that is filtered according to the current output value X' ｎ Let's say.

[0034] 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 ｎ (Here, X ０ ) and output value X' ｎ (Here, X' ０ ) is set to an initial value (for example, 0) (step S2).

[0035] Next, the filtering means waits until the detection timing comes (Step S3; No). When the detection timing comes (Step S3; Yes), the filtering means increments the counter value n by 1 (Step S4) and calculates the current detection value X ｎ is acquired (step S5).

[0036] Next, the filtering means calculates the current detected value X ｎ is the previous output value X' that was output after being filtered one sampling ago. ｎ－１(Step S6). ｎ >X' ｎ－１ (Step S6: Yes), the filtering means ｎ to the previous output value X' ｎ－１ The absolute value of the difference D ｎ (Step S7). ｎ >X' ｎ－１ If not (step S6; No), the filtering means ｎ is the previous output value X' ｎ－１ It is determined whether the value is smaller than X (step S8). ｎ <X' ｎ－１ If so (step S8; Yes), the filtering means ｎ to the previous output value X' ｎ－１ The absolute value of the difference D ｎ is calculated (step S9).

[0037] (X ｎ = X' ｎ－１ On the other hand, X ｎ <X' ｎ－１ If not (step S8; No), X ｎ = X' ｎ－１ Therefore, the filtering means is C ｎ =D ｎ (=0) (step S15), and the previous output value X' ｎ－１ To C ｎ (=0) is added to obtain the current output value X' ｎ (Step S16), and the current output value X' ｎ (Step S20). In other words, in this case, the current output value X' ｎ is the previous output value X' ｎ－１ will be the same value as

[0038] (Determination of Numerical Range) As shown in FIG. 8, in this embodiment, the numerical range of 0 to T is divided into three numerical ranges A1, A2, and A3 of 0 to d1, d1 to d2, and d2 to T, and the absolute value of the difference D ｎ The correction method is changed depending on the range of values ​​that the absolute value of the difference D ｎAfter calculating (steps S7 and S9), the filtering means calculates the absolute value of the difference D ｎ A determination process is performed to determine whether the value is in any one of three numerical ranges A1, A2, and A3 (steps S10A to S10C, steps S11A to S11D, steps S13A to S13C, and steps S14A to S14D).

[0039] The graph shown in FIG. 8 shows the current detected value X ｎ and the previous output value X' ｎ－１ The absolute value of the difference D ｎ (|X ｎ -X' ｎ－１ |) is shown on the horizontal axis, and the absolute value of this difference D ｎ Corresponding to the absolute value of the difference D ｎ is shown on the vertical axis. This is the absolute value of the difference D ｎ The absolute value of the difference D ｎ The absolute value of the difference D ｎ represents a linear function, and is indicated by a dashed line. The graph shown in FIG. 8 also shows the absolute value of the difference D ｎ The vertical axis corresponds to the current output value X'. ｎ and the previous output value X' ｎ－１ Difference C ｎ The absolute value of (|X' ｎ -X' ｎ－１ |) is shown. ｎ The absolute value of the current output value X' is shown by a bold line. ｎ The correction to the absolute value of the difference D ｎ The filtering means divides the range of values ​​from 0 to less than the threshold T on the horizontal axis into three ranges A1, A2, and A3, and calculates the absolute value D of the difference. ｎ The current output value X' is determined depending on which of the numerical ranges A1, A2, and A3 the value falls within. ｎ is corrected as follows. The number of divisions into the numerical range is not limited to three and may be any number. (A) Absolute value of difference D ｎ is included in the numerical range A1: the filtering means ｎ－１ The same value as the current output value X' ｎ(B) Absolute value of the difference D ｎ is included in the numerical range A2: the filtering means ｎ The current output value X' is a value approaching the ｎ The intermediate value d1 is the absolute value D of the difference at the boundary between the numerical range A1 and the numerical range A2. ｎ (C) Absolute value of the difference D ｎ is included in the numerical range A3: the filtering means ｎ As the threshold T approaches, the current detected value X ｎ The value indicating the relationship in which the difference between ｎ Specifically, the absolute value of the difference D from the threshold T is output. ｎ The detected value X this time is the value obtained by subtracting ｎ to the previous output value X' ｎー１ The value that approaches this output value X' ｎ Hereinafter, the current output value X' is calculated as follows. ｎ The flow of the process for determining the value will be described below.

[0040] (X ｎ >X' ｎ－１ Returning to FIG. 7, after executing step S7, ｎ If d1 or less (step S10A; Yes), the filtering means calculates the absolute value of the difference D ｎ C corresponding to ｎ is set to 0 (step S11A). ｎ If d<d2 (step S10B; Yes), the filtering means uses the graph shown in FIG. ｎ Calculate -d1 and get C ｎ (Step S11B). ｎ If T<T (step S10C; Yes), the filtering means uses the graph shown in FIG. ｎ - (T-D ｎ ) and calculate C ｎ (Step S11C). ｎ If T is not satisfied (step S10C; No), the filtering meansｎ C ｎ (Step S11D).

[0041] (X ｎ <X' ｎ－１ After step S9 is executed, ｎ If d1 or less (step S13A; Yes), the filtering means calculates the absolute value of the difference D ｎ C corresponding to ｎ is set to 0 (step S14A). ｎ If d<d2 (step S13B; Yes), the filtering means calculates d1-D using the graph shown in FIG. ｎ Calculate C ｎ (Step S14B). ｎ If ≦T (step S13C; Yes), the filtering means uses the graph shown in FIG. 8 to calculate (T−D ｎ )-D ｎ Calculate C ｎ (Step S14C). ｎ If it is not ≦T (step S13C; No), the filtering means uses the graph shown in FIG. ｎ C ｎ (step S14D).

[0042] After steps S11A to S11D and steps S14A to S14D are completed, the filtering means outputs the previous output value X' that was output after the filtering process one sampling ago. ｎ－１ To C ｎ Add this to get the current output value X' ｎ The filtering means updates the current output value X' as the latest output value (step S16). ｎ is output as the output value after this filtering (step S20).

[0043] Current output value X' ｎAfter outputting (step S20), the filtering means waits for the detection timing (step S3; No). After that, when the detection timing arrives (step S3; Yes), the filtering means executes steps S4 to S20, increments n by 1, and calculates the absolute value D ｎ is smaller than the threshold T, the next output value X' ｎ Ask for.

[0044] As described above, the filtering means detects the capacitance C1 of the sheet member 2 at a predetermined sampling interval. ｎ and the previous output value X' ｎー１ The absolute value of the difference D ｎ is greater than 0 and smaller than the threshold T, the current detected value X ｎ The previous output value X' ｎ－１ The value closest to the current output value X' ｎ The filtering process is performed to output the result as

[0045] The filtering means also calculates the absolute value of the difference D ｎ As the value of the output X' approaches the threshold T from 0, ｎ is the current detected value X ｎ Specifically, the absolute value of the difference D ｎ is in at least a part of the numerical range A1 (a numerical range greater than 0 and smaller than d1) among the numerical ranges A1, A2, and A3 greater than 0 and smaller than the threshold value T, the filtering means ｎ－１ The same value as the current output value X' ｎ The filtering means outputs the absolute value of the difference D ｎ is in at least a part of the numerical range A2 (a numerical range equal to or greater than d1 and smaller than d2) among the numerical ranges A1, A2, and A3 which are greater than 0 and smaller than the threshold value T, the current detected value X ｎ The previous output value X' is calculated by a certain intermediate value d1. ｎ－１ The value that approaches this output value X' ｎ Furthermore, the filtering means outputs the absolute value of the difference D ｎis in at least a part of the numerical range A3 (a numerical range equal to or greater than d2 and smaller than the threshold T) among the numerical ranges A1, A2, and A3 that are greater than 0 and smaller than the threshold T, the absolute value of the difference D ｎ As the threshold T approaches, the current detected value X ｎ The value that minimizes the difference between this and the output value X' ｎ Output as

[0046] However, the current output value X' ｎ is not limited to the above. ｎ The range of values ​​where the difference is smaller than the threshold T is defined as the absolute value of the difference D ｎ As the correction value C ｎ Alternatively, the entire range may be set as the numerical range A1. ｎー１ The current output value X' ｎ How to correct this can be adjusted as appropriate.

[0047] [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 9A and 9B, 10 and 11, the sheet member 2 can be used as a cover for an articulated robot.

[0048] As shown in Fig. 9A, the sheet member 2 according to this embodiment can be used as a cover for a 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 isolation by a fence for safety. Since the robot 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, and thus enable the robot to detect proximity to a human.

[0049] 9A, the sheet member 2 is transparent. As shown in FIG. 9A, the human-collaborative robot 30 includes a base 30a, a plurality of joints 30b to 30e, arms 31a to 31d, and a hand (end effector) 32. The base 30a and the joints 30b to 30e each have a built-in motor, and when the motor is driven, the position and posture of the connected arms 31a to 31d (first arms, second arms) and the hand 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 a joint unit 30e.

[0050] As shown in FIG. 9B , 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 penetrates 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 accommodate 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 FIG. 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.

[0051] The sheet member 2 can also be used as a cover for a vertical articulated robot 33 shown in FIG. 10 and a 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 33 a, arms 33 b and 33 c, and a hand 34. Joints incorporating motors are provided between the base 33 a and the arm 33 b, between the arm 33 b and the arm 33 c, and between the arm 33 c and the hand 34. As shown in FIG. 11 , the SCARA robot 35 has a base 35 a, arms 35 b and 35 c, and a hand 36. Joints incorporating motors are provided between the base 35 a and the arm 35 b, between the arm 35 b and the arm 35 c, and between the arm 35 c and the hand 36.

[0052] 10 and 11 , the sheet member 2 is sized to have a sufficient margin 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 to the outside 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 FIG. 1 , for example, a person) is brought close.

[0053] The sheet member 2 can also be used as a cover for a mobile robot 37 as shown in FIG. 12. The mobile robot 37 includes 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 intended 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 FIG. 1) to the robot body 37a based on a change in the detected capacitance.

[0054] As shown in FIGS. 13A and 13B , the sheet member 2 may protect a portion of the articulated robot 40 as the protection target G. The sheet member 2 protects the hand 42 of the arm 41 and hand 42 that constitute the articulated robot 40. The sheet member 2 is sewn into a cylindrical shape and wrapped around the side of the hand 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 42 has the largest range of motion among the parts of the articulated robot 40, is prone to interference with other objects, and is not equipped with a safety device (contact detection device, proximity detection device). Attaching the sheet member 2 to the hand 42 can reduce the risk of contact with a person, for example.

[0055] In the above embodiment, the sheet member 2 is configured by attaching the detection electrode 11, the active guard electrode 12, and the guard electrode 13, which are made of conductive threads, and the first insulating film 21 and the second insulating film 22, which are made of insulating threads, to an adhesive material. However, this is not limited to this. The sheet member 2 may be configured by knitting or weaving a combination of conductive threads and insulating threads, so that a layer of insulating thread is formed between two layers of conductive threads.

[0056] Furthermore, when the object G to be protected is large, the entire cover may be formed by connecting multiple sheet members 2. In this case, the detection circuit 4 is connected to each sheet member 2. In this case, the sheet members 2 may be connected to each other with adhesive or by sewing.

[0057] [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 guard electrode 13 that is grounded. 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.

[0058] (2) In the proximity sensor 1 according to this embodiment, the detection electrode 11, the active guard electrode 12, and the guard electrode 13 each include an extension 11a, 12a, and 13a that extends from the outer edge and connects to the detection board 3. The detection board 3 detects the proximity of the object H based on an 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.

[0059] (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 a short circuit among 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.

[0060] (4) In the proximity sensor 1 according to this embodiment, the detection board 3 (detection circuit 4) detects a detection value X for each sampling corresponding to an electrical signal obtained from the sheet member 2 at a predetermined sampling interval. ｎ a filtering means for performing a filtering process based on the output value X' and outputting an output value of the calculation result; ｎ The proximity of the object H is detected based on the current detection value X ｎ and the previous output value X' ｎ－１ The absolute value of the difference D ｎ is greater than 0 and smaller than the threshold T, the current detected value X ｎ The previous output value X' ｎ－１ The value closest to the current output value X' ｎ This results in a filtering process that outputs the detected value X ｎ It is possible to reduce minute noise contained in the

[0061] (5) In the proximity sensor 1 according to the present embodiment, the filtering means is configured to filter the absolute value D ｎ As the value of the output X' approaches the threshold T from 0, ｎ is the current detected value X ｎ In this way, the current output value X'ｎ Even if the output value X′ fluctuates around the threshold value T, ｎ can be smoothly varied.

[0062] (6) In the proximity sensor 1 according to the present embodiment, the filtering means is configured to filter the absolute value of the difference D ｎ 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 previous output value X' ｎ－１ The same value as the current output value X' ｎ As a result, the detected value X ｎ Since minute changes in can be regarded as noise components and ignored, the detected value X ｎ It is possible to reduce minute noise contained in the

[0063] (7) In the proximity sensor 1 according to the present embodiment, the filtering means is configured to filter the absolute value D ｎ 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 current detected value X ｎ The previous output value X' is calculated by a certain intermediate value d1. ｎ－１ The value that approaches this output value X' ｎ As a result, the detected value X ｎ The minute change in the detected value X can be regarded as a noise component and can be set to a constant small value. ｎ It is possible to reduce minute noise contained in the

[0064] (8) In the proximity sensor 1 according to the present embodiment, the filtering means is configured to filter the absolute value D ｎ 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 absolute value of the difference D ｎ As the threshold T approaches, the current detected value X ｎ The value indicating the relationship in which the difference approaches 0 is the current output value X'. ｎ As a result, the detected value X ｎSince the minute change in the detected value X can be regarded as a noise component and the change can be reduced, ｎ It is possible to suppress minute noise contained in the

[0065] (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 manner, 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.

[0066] (10) In the proximity sensor 1 according to the present 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 an environment where the use of adhesives is undesirable.

[0067] (11) In the sheet member 2 according to the present 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 part 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.

[0068] 9A, 9B, 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 a protected object G. The proximity sensor 1 can also respond to deformation of the protected object G.

[0069] 13A and 13B , 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 during robot operation.

[0070] (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 protected object 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 capacitance of the sheet member 2.

[0071] (15) The human-collaborative robot 30 according to this embodiment may include robot arms (30b to 30e, 31a to 31d, 32) having an arm portion 31a, an arm portion 31b, and a joint portion 30b connecting the arm portion 31a and the arm portion 31b; a sheet member 2 that covers the robot arms (30b to 30e, 31a to 31d, 32) as objects to be protected; and a detection circuit 4 that detects the approach of an object H to the robot arms (30b to 30e, 31a to 31d, 32) based on a change in the capacitance of the sheet member 2.

[0072] (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 a robot, and the system can be applied to any protection target G, including moving objects such as vehicles and drones, and stationary objects.

[0073] This invention allows various embodiments and modifications without departing from the broad spirit and scope of this invention. Furthermore, the above-described embodiments are intended to explain this invention and do not limit the scope of this invention. That is, the scope of this 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 considered to be within the scope of this invention.

[0074] In addition, this application claims priority based on Japanese Patent Application No. 2024-29178 filed on February 28, 2024, and the entire specification, claims, and drawings of Japanese Patent Application No. 2024-29178 are incorporated herein by reference.

[0075] The present invention can be applied to detecting nearby objects.

[0076] 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

1. A sensor comprising: a sheet member; and a detection unit that detects an object approaching the sheet member, wherein the sheet member comprises: a first cloth that is conductive; a second cloth that is conductive and electrically connected to the first cloth so as to have the same potential as the first cloth; a third cloth that is conductive and grounded; a first insulating film made of an insulator, the surface of which is in close contact with the back surface of the first cloth and the back surface of the second cloth; and a second insulating film made of an insulator, the surface of which is in close contact with the back surface of the second cloth and the back surface of the third cloth, wherein the detection unit is a sensor that detects changes in electrostatic capacitance occurring between the first cloth and the object.

2. The sensor according to claim 1, wherein the first cloth, the second cloth and the third cloth each have an extension portion that extends from an outer edge and connects to the detection unit, and the detection unit detects the proximity of the object based on an electrical signal transmitted via the extension portion.

3. A sensor as described in claim 1 or 2, wherein the area of ​​the film surfaces of the first insulating film and the second insulating film is larger than the area 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 area of ​​the cloth surfaces of the first cloth and the third cloth, and the area of ​​the cloth surface of the third cloth is equal to or larger than the area of ​​the cloth surface of the first cloth.

4. A sensor as claimed in any one of claims 1 to 3, wherein the detection unit comprises filtering means for performing filtering processing based on detection values ​​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, and detects the proximity of the object based on the output value output from the filtering means, and the filtering means performs filtering processing such that, when the absolute value of the difference between the current detection value and the previous output value is greater than 0 and less than a threshold value, a value closer to the previous output value than the current detection value is output as the current output value.

5. The sensor according to claim 4, wherein the filtering means performs filtering processing that indicates a relationship in which the current output value approaches the current detected value as the absolute value of the difference approaches the threshold value from 0.

6. The sensor according to claim 4 or 5, wherein the filtering means outputs the same value as the previous output value as the current output value when the absolute value of the difference is within at least a part of a numerical range greater than 0 and less than the threshold value.

7. A sensor as claimed in claim 4 or 5, wherein the filtering means outputs, as the current output value, a value that is closer to the previous output value by a certain intermediate value from the current detected value when the absolute value of the difference is within at least a part of a numerical range that is greater than 0 and less than the threshold value.

8. A sensor as claimed in claim 4 or 5, wherein the filtering means outputs, as the current output 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, when the absolute value of the difference is in at least a part of a numerical range greater than 0 and less than the threshold value.

9. The sensor according to any one of claims 1 to 8, wherein at least one of the first cloth, the second cloth, and the third cloth is adhered to the insulating film.

10. A sensor according to any one of claims 1 to 8, wherein at least one of the first cloth, the second cloth and the third cloth is sewn to the insulating film.

11. A sensor according to any one of claims 1 to 10, wherein 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.

12. The sensor according to any one of claims 1 to 11, wherein the sheet member covers an end effector of a robot as a protective object.

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