JPH01316193A - Gripper for robot - Google Patents

Abstract

PURPOSE:To grasp sufficiently a handling condition of a work by providing a tactile sensor comprising a resistance element provided on a monocrystal body substrate and a distortion generating body which makes this resistance element to generate a mechanical transformation, on a finger member. CONSTITUTION:A tactile sensor (joint) 120 having the piezoresistance efficiency that an electric resistance is changed by a mechanical transformation, has a resistance element formed on a monocrystal substrate (for example, semi-conductor), a supporting part fixed on the first section 110 with a vis 30 and an operation part fixed on the second section with a screw 131, and comprises a distortion generating body 20 which make a resistance element to generate a mechanical transformation on the basis of a displacement to the supporting part of the operation part. This tactile sensor is installed on a finger member 100 so that a displacement is generated between the supporting part and the operation part by a handling operation when a work is handled, and a handling condition between the work and the finger members 100 is detected as a change of an electric resistance value of this resistance element.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gripper for a robot, and particularly to a gripper for a robot equipped with a tactile sensor for detecting the gripping state of a workpiece.

[Conventional technology]

Industrial robots are currently used in a variety of fields, and the gripper portion of these robots that actually holds the workpiece requires motion control appropriate to the workpiece. For example, a gripper that works on glass products requires more precise control than a gripper that works on bolts and nuts.

In order to perform such precise control, it is effective to attach a tactile sensor to the gripper to adjust the gripping force, detect the presence or absence of a workpiece, the position of the workpiece, etc. Such tactile senses are generally classified into tactile senses, pressure senses, force senses, sliding senses, and the like. Microswitches, touch sensors, and the like are used as contact sensors, and strain gauges, conductive rubber, and the like are used as pressure sensors and force sensors. Further, as a slip sensor, no effective sensor has been developed at present because surface slip has no directionality.

[Problem to be solved by the invention]

However, as mentioned above, although several tactile sensors are used in conventional robot grippers, they all have problems. That is, a contact sensor such as a microswitch or a touch sensor can only detect the presence or absence of contact, and cannot detect pressure. Furthermore, pressure sensors and force sensors such as strain gauges and conductive rubber have low sensitivity and have the drawback of not being able to provide linear output. As far as the slip sensor is concerned, there is no effective sensor.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a gripper for a robot that is equipped with a highly accurate tactile sensor that can sufficiently grasp the gripping state of a workpiece.

[Means to solve the problem]

The present invention provides a gripper for a robot that includes a finger member for gripping a workpiece and a hand member movably supporting the finger member, and grips the workpiece by moving the finger member relative to the hand member. It has a piezoresistance effect in which electrical resistance changes due to mechanical deformation, and has a resistance element formed on an R11 crystal substrate, a support part and an action part, and the resistance element changes based on the displacement of the action part with respect to the support part. A tactile sensor comprising: a strain-generating body that causes mechanical deformation on the finger member; The structure is such that the gripping state between the member and the member can be detected as a change in the electrical resistance value of the resistance element.

[For production]

The tactile sensor used in the present invention is a sensor using a single crystal substrate such as a semiconductor, and a highly accurate linear output is obtained as an electrical resistance value of a resistive element in response to a force applied to the substrate. Furthermore, by arranging the resistive elements on the single crystal substrate, it becomes possible to detect forces in all axial directions and moments about all axes in a three-dimensional coordinate system.

Therefore, sufficient information regarding the grasping state of the workpiece can be obtained. Furthermore, the finger members are connected via strain-generating bodies without directly connecting the single crystal substrate. Therefore, even if a large force necessary for functioning as a robot gripper is applied, the single crystal substrate will not be damaged.

〔Example〕

Structure of Embodiment The present invention will be described below based on an illustrative embodiment. FIG. 1 is a diagram showing a gripper for a robot according to an embodiment of the present invention, in which FIG. 1(a) is a side view of the tip of the gripper, and FIG. 1(b) is a partially enlarged sectional view thereof. This gripper has two finger members 100 for gripping a workpiece, and a hand member 200 that movably supports these two finger members.

The finger member 100 is connected to the hand member 200 as shown by the broken line in the figure.
The workpiece slides against the workpiece and holds the workpiece between them. A link mechanism, a hydraulic mechanism, etc. for driving the finger member 100 are provided inside the hand member 200, but a description of these mechanisms will be omitted here.

As shown in FIG. 1(b), the finger member 100 is composed of three parts: a first joint 110, a joint 120, and a second joint 130. First joint portion 110 and second joint portion 130
is made of a rigid body such as metal. The indirect 120 is
It is a tactile sensor whose main components are a single crystal substrate 10 and a strain body 20, and a portion around the strain body 20 (support portion).
is attached to the first joint part 110 by screws 30, and the second joint part 130 is attached to the central part (action part) by a threaded part 131. A thin flexible portion is formed between the supporting portion around the flexure body 20 and the central acting portion, and when a force is applied between the first joint portion 110 and the second joint portion 130, , this flexible part bends, and a displacement occurs between the support part and the action part. This displacement causes distortion in the single crystal substrate 10. A resistance element is formed on this single crystal substrate 10, and the electrical resistance of this resistance element changes due to strain. In the end, the force applied between the first node 110 and the second node 130 can be detected as a change in the electrical resistance of the resistance element on the single crystal substrate 10. Electric signals are extracted from the single crystal substrate 10 to the outside via electrodes 13 for external wiring.

Structure of Tactile Sensor Next, details of the structure of the tactile sensor used as the joint 120 in the above embodiment will be explained.

Figure 2 (a) is a side sectional view of this tactile sensor, and Figure 2 (b) is a side sectional view of this tactile sensor.
) is a top view. Here, it is assumed that the X-axis, Y-axis, and Z-axis are defined in the direction of the figure. FIG. 2(a) corresponds to a cross-sectional view of the sensor shown in FIG. 2(b) taken along the X-axis.

In this sensor, a total of 12 resistance elements R are formed on a silicon single crystal substrate 10. Resistance elements Rxl to RX4 are arranged on the X-axis and used to detect force in the X-axis direction, resistance elements Ryl-Ry4 are arranged on the Y-axis and used to detect force in the Y-axis direction, and resistance elements Rzl to Rz4 are arranged on the Y-axis and used to detect force in the Y-axis direction. is X
It is arranged on the axis parallel to and near this axis and used to detect force in the Z-axis direction.

The specific structure of each resistive element R and its manufacturing method will be described in detail later, but these resistive elements R are elements having a piezoresistive effect whose electrical resistance changes by mechanical deformation.

This single crystal substrate 10 is bonded to a strain-generating body 20. In the example shown in FIG. 2, the strain-generating body 2o has a surrounding support part 21
A flexible portion 22 whose wall thickness is reduced to provide flexibility;
It is composed of an action part 23 that protrudes from the center. Strain body 2
Kovar (an alloy of iron, cobalt, and nickel) is used as the material for 0. Since Kovar has almost the same coefficient of thermal expansion as the silicon single crystal substrate 10, it has the advantage that even if it is bonded to the single crystal substrate 10, thermal stress caused by temperature changes is extremely small. Strain body 20
The material and shape are not limited to those described above, and the embodiment shown here is only an optimal embodiment. In addition,
This strain-generating body 2o is provided with a mounting hole 24, through which it is fixed with screws.

Each resistance element is wired as shown in FIG. That is, the resistance elements Rxl to Rx4 are assembled into a bridge circuit as shown in FIG. 3(a), the resistance elements Ryl to Ry4 are assembled into a bridge circuit as shown in FIG. 3(b), and the resistance elements Rzl to Rz4 are assembled into a bridge circuit as shown in FIG. are assembled into a bridge as shown in FIG. 3(c). A predetermined voltage or current is supplied to each bridge circuit from a power supply 50, and each bridge voltage is measured by a voltmeter 50.
1 to 53. In order to perform such wiring for each resistance element R, as shown in FIG. 13 are connected with the bonding wire 12. Electrode 13 is in wiring hole 2
5 to the outside.

Principle of a tactile sensor In FIG. 2(a), when a force is applied to the point of action S at the tip of the action part 23, a stress strain is generated in the construction material 20 in accordance with the applied force. As described above, since the flexible portion 22 is thin and flexible, displacement occurs between the action portion 23 and the support portion 21, and each resistance element R is mechanically deformed. This deformation changes the electrical resistance of each resistance element R, and the applied force is eventually detected as a change in each bridge voltage shown in FIG.

FIG. 4 shows the relationship between stress strain and change in electrical resistance of the resistance element R. Here, for convenience of explanation, the single crystal substrate 10
A case will be considered in which only the acting portion 23 of the strain body 20 is illustrated, and four resistance elements R1 to R4 are formed from left to right in the figure. First, as shown in FIG. 4(a), when no force is applied to the point of application S, no stress strain is applied to the single crystal substrate 10, and the resistance changes of all resistance elements are 0. However, when a downward force F1 is applied, the single crystal substrate 10 is mechanically deformed as shown in the figure. Now, if the conductivity type of the resistor element is P type, by this deformation, the resistor element R1
and R4 expand to increase their resistance (denoted by + symbols), and resistive elements R2 and R3 contract to decrease their resistance (-
(I will show it with a symbol). Furthermore, when a force F2 in the right direction is applied, the single crystal substrate 10 is mechanically deformed as shown in the figure (actually, the single crystal substrate 10 is
Force F2 acts as a moment force). This deformation causes resistive elements R1 and R3 to stretch and increase their resistance, and resistive elements R2 and R4 to contract and decrease their resistance.

Note that since each resistance element R is a resistance element whose elongated direction is the horizontal direction of the figure, when a force is applied in a direction perpendicular to the plane of the figure, the change in resistance value of each resistance element can be ignored. In this way, this sensor uses the fact that the resistance change characteristics of the resistance element differ depending on the direction of applied force to independently detect forces in each direction.

Operation of the tactile sensor The operation of the tactile sensor described above will be explained below with reference to FIGS. 5 to 7. Figure 5 shows the stress applied to each resistance element when force is applied in the X-axis direction, Figure 6 shows the stress applied in the X-axis direction, and Figure 7 shows the stress applied to each resistance element when force is applied in the Z-axis direction.
+ indicates the direction of expansion, - indicates the direction of contraction, and 0 indicates no change)
are shown respectively. In each figure, (a) shows a cross-section of the sensor shown in Fig. 2 taken along the X-axis, (b) shows a cross-section taken along the Y-axis, and the element Rz parallel to the X-axis.
A cross section taken along the line 1 to Rz4 is shown as (C).

First, arrow Fx (
If we consider the case where a force is applied in the X-axis direction (in the direction perpendicular to the plane of the paper in FIG. 5(b)), stresses of the polarities shown are generated. The polarity of this stress can be easily understood from the explanation of FIG. In each resistance element R, a resistance change occurs in response to this stress.

For example, the resistance of the resistance wire Rxl decreases (-), the resistance of the resistance element Rx2 increases (10), and the resistance of the resistance element Ry1 does not change (0). Furthermore, when forces are applied in the Y-axis and Z-axis directions as indicated by arrows Fy and Fz in FIGS. 6 and 7, respectively, stresses as shown are generated.

Ultimately, the relationship between the applied force and the change in each resistance element is summarized in a table as shown in Table 1.

If we take into account that each resistance element R constitutes a bridge as shown in Figure 3, the relationship between the applied force and the presence or absence of changes in each voltmeter 51 to 53 is as shown in Table 2. .

Table 2> Resistance elements Rzl-Rz4 undergo almost the same stress changes as resistance elements Rx1-Rx4, but as shown in Fig. 3, the bridge configuration has holes in both, so voltmeters 51 and 53 have different stress changes. Please be careful when responding. In the end, voltmeter 5
1.52.53 will respond to forces in the X, Y, and Z axes, respectively.

Although Table 2 shows only the presence or absence of change, the polarity of the change is controlled by the direction of the applied force, and the amount of change is controlled by the magnitude of the applied force.

Structure of a tactile sensor that can detect six components The tactile sensor described above did not clearly distinguish between force and moment in each axial direction, but the tactile sensor described here detects forces acting in each axial direction. and the moment acting around each axis can be detected separately. That is 6
Detection of components is possible. Hereinafter, this sensor will be referred to as a six-component sensor.

FIG. 8 is a top view of this six-component sensor, and FIG. 9 is a sectional view of the device shown in FIG. 8 taken along section line A--A. In this embodiment, 16 resistance element groups R1 to R18 are formed on the surface of the strain body 210. Strain body 210
is made of a silicon single crystal substrate, and the resistance element groups R1 to R
1B is a set of a plurality of resistance elements, and each resistance element is formed by diffusing impurities on this single crystal substrate. The resistance element thus formed exhibits a piezoresistance effect, and has the property that its electrical resistance changes with mechanical deformation.

The strain body 210 has a fixed part 2 formed in an annular shape around the periphery.
11, four bridge parts 212 to 215, and an action part 216 to which these four bridge parts 212 to 215 are combined. The fixed part 211 is fixed to the outside, and a force or moment to be detected is applied to a point of action P at the center of the action part 216. Since the fixed part 211 is fixed to the outside, when a force or moment is applied to the point of application P, stress strain corresponding to this force or moment is generated in the bridge parts 212 to 215, and the resistance element groups R1 to R16
A change in electrical resistance occurs. This device detects force and moment based on this change in electrical resistance. In this embodiment, each resistance element has the same size, shape, and material, and all have the same resistance value. Further, the rate of change in resistance based on stress strain is also all the same.

Now, as shown in FIGS. 8 and 9, the operating portion 216
Assume that the point of action P at the center of is the origin of the XYZ three-dimensional coordinate system, and the three axes x, y, and z are defined as shown in the figure.

In other words, in Fig. 8, the right side of the figure is the X-axis pressure direction, and the lower side is the Y-axis pressure direction.
The axial pressure direction is defined as the Z-axis pressure direction, and the downward direction perpendicular to the plane of the paper is defined as the Z-axis pressure direction. Effecting bodies 221 and 222 are attached above and below the acting part 216, and all forces and moments acting on the point of application P are applied via these acting bodies 221 and 222.

Here, regarding the point of application P, the force applied in the X-axis direction is FX
, the force applied in the Y-axis direction is FY, and the force applied in the Z-axis direction is FY.
Let MX be the moment applied around the zSX axis, MZ be the moment applied around the Y axis, MZ be the moment applied around the Z axis, then the answers and moments are defined in the directions shown by the arrows in FIG. That is, the force FX applied in the X-axis direction becomes a force that moves both the effecting bodies 221 and 222 to the right in the figure, and the force FY applied in the Y-axis direction causes both the effecting bodies 221 and 222 to move upward perpendicularly to the plane of the figure. The force FZ applied in the Z-axis direction becomes a force that moves both the effecting bodies 221 and 222 downward in the figure. In addition, the moment MX around the X axis is the acting body 22
1 upward perpendicularly to the plane of the paper, and the moment M around the Y axis to the moment that moves the effecting body 222 downward perpendicularly to the plane of the paper.
Y is a moment that moves the acting body 221 to the left in the figure and the acting body 222 to the right in the figure, and the moment MZ around the Z axis is such that both the acting bodies 221 and 222 are moved clockwise when viewed from above the device. It will be a great moment.

The 16 resistance element groups R1-RIB are arranged in symmetrical positions as shown in FIG. That is, R1-R4 is in the bridge portion 212, and R5-R8 is in the bridge portion 213.
However, the bridge portion 214 is provided with R9 to R12, and the bridge portion 215 is provided with R13 to R1G. Regarding each bridge part, a pair of resistance element groups are provided near the fixed part 211 and a pair of resistance element groups are provided near the action part 216, and each pair of resistance element groups is provided on both sides of the X-axis or Y-axis. There is.

Using 16 resistance element groups like this, Figure 10(a)
Six types of bridges as shown in ~(r) are formed. A power supply 230 is connected to each bridge, and FX, FY, FZ.

MX, MY, MZt, 1m proportional voltage VFX, VFY
.

Voltmeters 241 to 246 that output VFZ, VMX, VMY, and VMZ as bridge voltages are connected.

The symbol of each resistor element shown in this bridge circuit diagram means one resistor element in the group of resistor elements, and even if the resistor elements have the same symbol, These are assumed to mean different resistance elements belonging to the same resistance element group. For example, R1 is
), but actually two resistance elements are placed at the position R1 in FIG. 8, and different resistance elements are used in different bridges.

Hereinafter, for convenience of explanation, resistance element group Rx (x-1 to 16)
The same symbol Rx will also be used to indicate one resistance element belonging to .

Operation of the six-component sensor The operation of the above-described device will now be described. When the resistive elements are arranged as shown in FIG. 8, the forces and moments F X, F Y, F Z, MX, MY are generated at the point of action P.

When MZ is applied, each resistance element R1-RIB is
The electrical resistance changes as shown in the table shown in FIG. 1 (assuming that each resistance element is made of a P-type semiconductor). Here “0”
"" indicates no change, "10" indicates an increase in electrical resistance, and "-" indicates a decrease in electrical resistance.

Here, we will explain the reason for the results shown in Figure 11 in the 12th section.
This will be briefly explained with reference to FIGS.

Figures 12 to 17 are diagrams showing changes in stress strain and electrical resistance that occur in the bridge when force or moment FX, FY, FZ, MX, MY, MZ is applied to the point of application P. Each figure (a) is a top view of the bridge, and each figure (a) is a top view of the bridge section.
b) is a front sectional view, and each figure (C) is a side sectional view. For example, FIG. 12 shows the state when the force FX in the X-axis direction is applied at the point of action pH. The force FX causes the bridge portion 214 to expand and the bridge portion 215 to contract. Therefore, the resistance element (R9-R12) in the bridge portion 214
(in the case of a P-type semiconductor), the resistance elements (R13 to R16) in the bridge portion 215 contract and reduce the electrical resistance. The resistance elements in the bridge portions 212 and 213 expand or contract depending on the placement position. In the end, it is easy to understand that the results shown in the first column of the table in FIG. 11 are obtained. Hereinafter, by referring to FIGS. 13 to 17, it will be understood that the results in columns 2 to 6 of the table in FIG. 11 can be obtained.

Now, considering that a bridge as shown in FIG. 10 is constituted by each of the resistive elements R1 to R16, FX, FY, and FZ applied to the point of action P.

MX, MY, MZ and the detection voltages V FX, V FY, V FZ, VMX, VMY appearing on the voltmeters 241 to 246
, and the relationship with VMZ is as shown in the table shown in FIG. Here, "0" indicates that no voltage change occurs, and "V"
indicates that a voltage change occurs depending on the applied force or moment. The polarity of the voltage change will depend on the direction of the applied force or moment, and the magnitude of the voltage change will depend on the magnitude of the applied force or moment.

Obtaining the table shown in Figure 18 is easy if we consider that in the circuit diagram of Figure 10, if the products of the resistance values of the resistor elements on opposite sides of the bridge are equal to each other, there is no voltage change. I can understand.

For example, when force FX is applied, each resistance element
A change in electrical resistance occurs as shown in the first column of the table in the figure. Now, referring to FIG. 10(a), R9°RIO, R11,
The resistance value of both R12 increases, R13゜R14, R1
5. The resistance value of both RIO decreases. Therefore, a large difference occurs in the product of the resistance values of the resistance elements on the opposite sides, and a voltage change "v" is detected. On the other hand, Fig. 10 (
In the bridge circuits b) to (r), no change occurs in the bridge voltage.

For example, in the circuit of FIG. 10(b), R1 is "-"
In this case, R2 becomes "10", and the resistance changes are canceled out for each branch. In this way, the effect of force FX only affects VFX, and force FX can be detected independently by measuring VFX.

As mentioned above, in the table of FIG. 18, only the diagonal component is "V
”, and all other values are “O”, indicating that each detected value can be directly obtained as a voltmeter reading without performing any calculations.

By configuring the bridge as described above,
The effects of resistance changes due to factors other than stress can be canceled out. For example, the electrical resistance of each resistance element changes depending on the temperature, but since all the resistance elements making up the bridge change almost equally, the effects of this temperature change are canceled out.

Therefore, this bridge configuration allows for more accurate measurements.

Instead of the tactile sensor shown in FIG.
By using the component sensor to obtain detection data for the six components, more detailed information about the gripping state of the workpiece can be obtained. In this case, Fig. 1(b)
In this case, the fixing part 210 of the six-component sensor is attached to the joint part 110.
, and the action part 216 of the six-axis component sensor is connected to the joint part 130.
You can either connect this or do the exact opposite.

Manufacturing of a resistive element having a piezoresistance effect Next, an example of a method for manufacturing a resistive element used in the above-mentioned sensor will be briefly described. This resistance element has a piezoresistance effect and is formed on a semiconductor substrate by a semiconductor planar process. First, as shown in FIG. 19(a), an N-type silicon substrate 401 is thermally oxidized, and a silicon oxide layer 40 is formed on the surface.
form 2. Subsequently, as shown in FIG. 4B, the silicon oxide layer 402 is etched by photolithography to form an opening 403. Subsequently, as shown in FIG. 4C, boron is thermally diffused from this opening 403 to form a P-type diffusion region 404.

Note that in this thermal diffusion step, a silicon oxide layer 405 is formed in the opening 403. Next, the same figure (d)
As shown in FIG. 3, silicon nitride is deposited by CVD to form a silicon nitride layer 406 as a protective layer. As shown in FIG. 4(e), this silicon nitride layer 40
After contact holes are formed in the silicon oxide layer 405 and the silicon oxide layer 405 by photolithography, an aluminum wiring layer 407 is formed by vapor deposition, as shown in FIG. Finally, this aluminum wiring layer 407 is patterned by photolithography to obtain a structure as shown in FIG. 4(g).

In addition, the above-mentioned manufacturing process is shown as an example,
In short, the sensor used in the present invention can be realized using any resistive element that has a piezoresistance effect.

Operation as a robot gripper The structure and operation of the tactile sensor used in the robot gripper according to the present invention have been described in detail above. Next, the operation of the robot gripper equipped with this tactile sensor will be described. FIG. 20 is a diagram showing a state in which a workpiece 500 is gripped by this robot gripper. As described above, the two finger members 100 are movably supported by the hand member 200, and the two finger members 100 hold the workpiece 500 from both sides as shown in the figure.
00 can be included. In this example, the workpiece 500 comes into contact with the two finger members 100 at contact points PL and P2. In order to hold the workpiece 500, forces will be present at the contact points PI and P2.

That is, the force generated at the contact point P1 applies a force to the point of application S1, and the force generated at the contact point P2 applies a force to the point of application S2.
Force will be added to. As mentioned above, the indirect 120 is
It constitutes a tactile sensor and includes a strain body 20. When force is applied to the point of application, the flexible strain body 20 bends,
The direction and magnitude of the applied force will be extracted as an electrical signal. The tactile sensor using the single crystal substrate 10 can obtain a very sensitive linear output, and based on this output signal, an accurate value of the contact pressure against the workpiece 500 can be determined. As described above, the tactile sensor has the function of detecting the force acting on the contact point for each three-dimensional component, and therefore can also obtain information about the surface direction of the workpiece at the contact point.

Here, the physical quantity detected by the tactile sensor is actually moment force. Now, in the schematic diagram as shown in FIG. 21, the workpiece 500 is at the position 500a and
(Actually, the workpiece 500 is held between two finger members, but for convenience of explanation,
We will consider only one of them). In any case, assuming that the second joint portion 130 always presses down the workpiece 500 with a constant force F, the moment force detected by the indirect (tactile sensor) 120 is M(a) with respect to the workpiece 500a. ) -K life F J , and for the workpiece 500b, M(b) '-K -F -(g-6g). Here K is a constant. Therefore, even if the workpiece 500, which was supposed to be held at a distance g with force F, slides by a distance Δg, the sliding distance Δg can be calculated by calculation based on the above two equations. It can be done. This function is nothing but the ability to measure the sensation of slippage, which could not be measured with conventional sensors.

Further, by indirectly using the above-mentioned six component sensors, it is possible to determine the amount of slippage even if the force pressing down the workpiece 500 changes. That is, the workpiece 50
0a is held down with force F1, and the workpiece 500b
If the force F2 is applied to the force F2, then M(a) - will have -F 1・g M(b) - will have -F2・ (g - 6g), but in the case of a 6-component sensor, M(a ), M(b
).

Since Fl and F2 can be detected separately, the slipped distance Δg can also be calculated based on the above two equations.

FIG. 22 is a diagram showing an embodiment in which the finger member 100 is composed of a large number of joints. Similar to the previous embodiment, two finger members 100 are supported by a hand member 200.

A first joint 110 is rotatably attached to the hand member 200, a joint 120 is connected to the first joint 110, and a second joint 130 is connected to the joint 120.

This second joint portion 130 is further rotatably connected to a drive joint portion 140. This driving joint section 140 further includes a first
The joint portion 110 is rotatably attached, and the finger member 100 is constructed by repeating each of the above-mentioned members.

The drive joint section 140 is provided with, for example, a link mechanism or a hydraulic mechanism, and the first joint section 1 connected to both sides thereof.
10 and the second joint portion 130 can be adjusted.

With a gripper having such a structure, a gripping motion closer to that of a human finger is possible, and the force applied to each joint can be detected by the plurality of joints 120.

Another Embodiment FIG. 23(a) is a diagram showing a gripper for a robot according to another embodiment of the present invention, in which FIG. 23(a) is a side view of the tip of the gripper, and FIG. FIG. 3 is a partially enlarged sectional view.

In this gripper, the hand member 200 has two finger members 1
The finger member 150 is supported in the same way as in the above embodiment, but a tactile sensor 160 is formed on the workpiece surface of the finger member 150. The structure of the tactile sensor 160 is similar to that of the tactile sensor used as the joint 120 in the above-described embodiment, and the periphery of the construction body 20 is connected to the finger member 150 by screws 30.
Fixed. Note that wiring between the single crystal substrate 10 and the outside is performed by a flexible printed circuit board 60. A contact plate 170 is fixed to the central tip of the tactile sensor 160 by a screw portion 171.

As shown in FIG. 24, the finger member 150 is
0 a = c and the drive joint part 180 that connects these
It is also possible to make the motion closer to that of a human finger. By arranging the tactile sensors in this way, the contact pressure of each part can be detected as an electrical signal. Furthermore, similar to the above-described embodiments, it is also possible to detect the sensation of slippage. That is, as shown in FIG. 25(a), if the workpiece 500 is at the position 500a, contact is made with the contact plate 170 at the contact point P1, so that the single crystal substrate 10 of the tactile sensor 160 is A moment force M1 such as is detected. On the other hand, as shown in FIG. 25(b), if the workpiece 500 is at the position 500b, contact is made with the contact plate 170 at the contact point P2, so that the tactile sensor 160 is The crystal substrate 10 has a moment force M as shown in the figure.
2 will be detected. Therefore, if the workpiece 500 slips from 500a to 500b, this can be recognized from the change in the detected value.

Detection of slippage when acceleration is acting When acceleration is acting, it becomes possible to detect slippage by using a three-dimensional acceleration sensor in combination. This principle will be explained with reference to FIG. 26. Now, consider a case where a workpiece 500 of quality ff1m is being held as shown in the figure. Here, in order to simplify the model, the center of gravity G of the workpiece 500 is
It is assumed that the contact point P and the contact point P are both on the central axis of the tactile sensor 160. It is assumed that the contact plate 170 is pressing the workpiece 500 with a force F. In this case, the contact point P
The vertical force Fv acting on is Fv-mg/2, and the horizontal force Fh is Fh-F. Here, g is gravitational acceleration.

Now, let us consider a case where this entire system is mounted on a vehicle and is further subjected to vertical acceleration α. In this case, if the force acting on the contact point P is expressed with a dash, it becomes Fv' mm (g+α)/2 Fh' −F. Here, if further slipping occurs in the vertical direction, the force acting on the contact point P is expressed by adding two dashes, Fv”
, Fh"°, Fh"-Fh' -F, but Fv"≠Fv'. Since the force acting on the contact point P can be detected by the tactile sensor 160, Fv"≠Fv'. If it can be recognized that there is a slip, it is possible to judge whether there is a slip even under acceleration conditions.

Any three-dimensional acceleration sensor may be used to detect the acting acceleration α. In the example shown in Figure 26,
An acceleration sensor 600 is used.

This acceleration sensor 600 has substantially the same configuration as the tactile sensor described above. That is, the single-crystal substrate 10 is formed on the strain-generating body 20, and the strain generated in the strain-generating body 20 can be detected as a change in electrical resistance on the single-crystal substrate 10. However, at the tip of the central action part of the strain body 20, there is a weight body
7.0 is connected, and the supporting portion around the strain-generating body 20 is fixed to the gripper main body 700 by the support base 80.

Further, the top is covered with a lid 90 for protection.

When acceleration acts, force acts on the weight body 70, so
This can be detected as a change in the electrical resistance of the resistance element on the single crystal substrate 10.

〔Effect of the invention〕

As described above, according to the present invention, a tactile sensor comprising a resistance element provided on a single crystal substrate and a strain body that causes mechanical deformation of the resistance element is attached to a gripper for a robot. Highly accurate control that can fully grasp the gripping state of the workpiece becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the structure of a gripper for a robot according to an embodiment of the present invention, FIG. 2 is a diagram showing a tactile sensor used in the gripper shown in FIG. 1, and FIG. 3 is a diagram showing the tactile sensor shown in FIG. 2. 4 to 7 are diagrams showing the operating principle of the tactile sensor shown in FIG. 2, and FIG. 8 is a top view of the 6-component sensor.
FIG. 9 is a cross-sectional view of the device shown in FIG. 8 taken along cutting line A-A;
Fig. 10 is a circuit diagram of six bridges formed using each resistance element of the device shown in Fig. 8, Fig. 11 is a chart showing changes in each resistance element of the device shown in Fig. 8, and Fig. 12 is a FIG. 8 is a diagram showing the state when a force in the X-axis direction is applied to the device shown in FIG. 8. FIG. 13 is a diagram showing the state when a force in the Y-axis direction is applied to the device shown in FIG. 8. The figure shows the state when a force in the Z-axis direction is applied to the device shown in Figure 8, and Figure 15.
16 is a diagram showing a state when a moment around the X-axis is applied to the device shown in FIG. 8, and FIG. 16 is a diagram showing a state when a moment around the Y-axis is applied to the device shown in FIG. 8. Fig. 17 is a diagram showing the state when a moment about two axes is applied to the device shown in Fig. 8, and Fig. 18 is a chart showing the relationship between the force to be detected and the detected voltage in the device shown in Fig. 8. , FIG. 19 is a diagram showing an example of a method for manufacturing a single crystal substrate constituting the tactile sensor shown in FIG. 2, FIGS.
2 is a diagram showing a modified example of the gripper shown in FIG.
24 shows a modification of the gripper shown in FIG. 23, and FIG. 25 shows the operation of the gripper shown in FIG. 23. The explanatory diagram, FIG. 26, is an explanatory diagram of the operation when acceleration acts on the gripper shown in FIG. 23. DESCRIPTION OF SYMBOLS 10... Single crystal substrate, 11... Bonding pad, 12... Bonding wire, 13... Electrode for external wiring, 20... Strain body, 21... Support part, 22
...Flexible part, 23...Action part, 24...Mounting hole,
25... Wiring hole, 30... Screw, 50... Power supply,
60... Flexible printed circuit board, 70... Weight body, 80... Support stand, 90... Lid, 100... Finger member, 110... First node, 120... Indirect , 13
0...Second knot portion, 131...Threaded portion, 140...
Drive joint part, 160... Touch sensor, 170... Contact plate, 180... Drive joint part, 200... Hand member, 201... Strain body, 211... Fixing part, 212
~215...Crosslinking part, 216...Action part, 221.
222... Effecting body, 230... Power source, 241-2
46... Voltmeter, 401... Silicon substrate, 402
... silicon oxide layer, 403 ... opening, 404.
... P-type diffusion region, 405 ... silicon oxide layer, 40
6... Silicon nitride layer, 407... Aluminum wiring layer, 500... Work, 600... Acceleration sensor, 7o. ...Gripper body, S...point of action, R...resistance element. Applicant's agent Hiroshi Shimura0O (b) Figure 1 Ca > Figure 2 Figure 3 Figure 5 (α) (ψ (C) (d) (e) (f) Figure 10 Figure 11 Figure 1z Figure 1:!1 Figure <b) Figure 15 (b) Figure 16 Figure 17 Figure f8 (C, Figure too 130 120 ) 102001
riO Figure 21/'9:) (α] Figure 23 Imperial Decree 2q Figure

Claims (1)

[Scope of Claims] 1. Comprising a finger member for grasping a workpiece and a hand member movably supporting the finger member, the workpiece can be grasped by moving the finger member relative to the hand member. A gripper for a robot that has a piezoresistance effect in which electrical resistance changes due to mechanical deformation, and includes a resistance element formed on a single crystal substrate, a support part and an action part, and the support part of the action part a flexure element that mechanically deforms the resistance element based on the displacement with respect to the part; and a tactile sensor comprising: a strain-generating body that causes mechanical deformation in the resistance element based on the displacement with respect to the part; A gripper for a robot, characterized in that the gripper is provided on the finger member such that the resistor element is arranged so that the gripping state between the workpiece and the finger member can be detected as a change in the electrical resistance value of the resistor element. 2. The finger member is composed of a plurality of joints, and in order to connect the joints to each other, the support part of the tactile sensor is connected to one joint, and the action part is connected to the other joint, respectively. The gripper for a robot according to claim 1, wherein the gripper is used as an indirect part. 3. The gripper for a robot according to claim 1, wherein the support part of the tactile sensor is fixed to the work supporting surface of the finger member, and the action part of the tactile sensor is configured to abut the work. 4. The tactile sensor is capable of detecting force and moment in a three-dimensional coordinate system expressed by the three axes of XYZ, and at least about each axis to detect force in each axis direction and moment about each axis. 4. The gripper for a robot according to claim 1, wherein four resistance elements are provided, each of which forms a bridge.