JP7052407B2 - Controls, end effectors, robots and control methods - Google Patents

Description

The present invention relates to control devices, end effectors, robots and control methods.

The electric hand described in Patent Document 1 includes a position control unit that performs position feedback control, a force control unit that performs force feedback control, a control switching unit that switches between position feedback control and force feedback control, and a finger unit. It has an actuator for driving the finger portion, a force sensor provided on the finger portion, and a contact determination unit for determining contact between the finger portion and an object.

In such an electric hand, first, the position control unit performs position feedback control based on the position detection value from the position sensor provided in the actuator to move the finger unit. Then, when the contact determination unit determines that "the finger unit has come into contact with the object", the control switching unit switches the drive control of the finger unit from the position control unit to the force control unit. Then, the force control unit performs force feedback control based on the force detection value from the force sensor, and drives the finger unit (actuator) so that the force detection value matches the set force target value.

Japanese Unexamined Patent Publication No. 2014-108466

When an electromagnetic motor is used as an actuator in such an electric hand, the gripping force of the finger portion can be controlled by controlling the current value applied to the electromagnetic motor. However, when a piezo drive motor (piezoelectric motor) is used as the actuator, unlike the case of the electromagnetic motor described above, the gripping force of the finger portion cannot be controlled by controlling the current value applied to the piezo drive motor. There was a problem.

In the control device according to the application example of the present invention, the grip portion that grips the object, the drive portion that drives the grip portion, the position detection unit that detects the position of the grip portion, and the grip portion are the object. A control device that controls an end effector having a force detection unit that detects the force received from the device.
It is characterized in that the target position of the grip portion is updated based on the output of the force detection unit, and the drive of the drive unit is controlled so that the grip portion moves to the latest target position.

It is a top view which shows the robot hand which concerns on 1st Embodiment of this invention. It is a block diagram which shows the circuit system of the robot hand of FIG. It is sectional drawing which shows the piezoelectric drive device which the robot hand of FIG. 1 has. It is sectional drawing which shows the piezoelectric module which the piezoelectric drive device of FIG. 3 has. It is a perspective view which shows the piezoelectric module of FIG. It is a top view which shows the piezoelectric actuator which the piezoelectric module of FIG. 4 has. It is a graph for demonstrating the 1st control method. It is a flowchart which shows the 1st control method. It is a graph for demonstrating the 2nd control method. It is a flowchart which shows the 2nd control method. It is a graph for demonstrating the 4th control method. It is a flowchart which shows the 4th control method. It is a flowchart which shows the 5th control method. It is a perspective view which shows the robot which concerns on 2nd Embodiment of this invention.

Hereinafter, the control device, end effector, robot, and control method of the present invention will be described in detail based on the embodiments shown in the accompanying drawings.

<First Embodiment>
FIG. 1 is a plan view showing a robot hand according to the first embodiment of the present invention. FIG. 2 is a block diagram showing a circuit system of the robot hand of FIG. FIG. 3 is a cross-sectional view showing a piezoelectric drive device included in the robot hand of FIG. FIG. 4 is a cross-sectional view showing a piezoelectric module included in the piezoelectric drive device of FIG. FIG. 5 is a perspective view showing the piezoelectric module of FIG. FIG. 6 is a plan view showing a piezoelectric actuator included in the piezoelectric module of FIG. FIG. 7 is a graph for explaining the first control method. FIG. 8 is a flowchart showing the first control method. FIG. 9 is a graph for explaining the second control method. FIG. 10 is a flowchart showing the second control method. FIG. 11 is a graph for explaining the fourth control method. FIG. 12 is a flowchart showing a fourth control method. FIG. 13 is a flowchart showing a fifth control method.

The robot hand 1 as an end effector shown in FIG. 1 is a hand that sandwiches and grips an object W from both sides. The robot hand 1 positions the pair of finger portions 23, 24 (grip portion) that grip the object W, the piezoelectric drive device 3 (drive portion) that drives the finger portions 23, 24, and the finger portions 23, 24. It has an encoder 4 (position detection unit) for detecting, a force detecting unit 5 for detecting the force received by the finger units 23 and 24 from the object W, and a control device 6. Further, as shown in FIG. 2, the control device 6 updates the target positions of the finger portions 23 and 24 based on the output of the encoder 4 and the output of the force detection unit 5, and the finger portions 23 and 24 reach the updated target positions. It has a processor 61 that controls the drive of the piezoelectric drive device 3 so as to move. According to such a robot hand 1, the object W can be gripped with an appropriate gripping force. Hereinafter, the robot hand 1 will be described in detail.

The robot hand 1 engages with the base 20, a pair of sliders 21 and 22 slidably supported with respect to the base 20, fingers 23 and 24 fixed to the sliders 21 and 22, and sliders 21 and 22. The pinion gear 26, the piezoelectric drive device 3 for rotationally driving the pinion gear 26, the encoder 4 connected to the piezoelectric drive device 3, and the force detection unit 5 for detecting the force received by the finger portions 23 and 24 from the object W. And a control device 6 for controlling the drive of the piezoelectric drive device 3.

The sliders 21 and 22 are supported by the base 20 via the slide guide 25, respectively, and can slide in the same direction with respect to the base 20. Further, a rack gear 211 is formed on the surface of the slider 21 facing the slider 22, and a rack gear 221 is formed on the surface of the slider 22 facing the slider 21. Further, a pinion gear 26 is provided between the sliders 21 and 22, and the pinion gear 26 meshes with the rack gears 211 and 221. Therefore, when the pinion gear 26 is rotated by the drive of the piezoelectric drive device 3, the sliders 21 and 22 move in opposite directions to each other, and the fingers 23 and 24 approach and separate from each other accordingly. By approaching and separating the finger portions 23 and 24 in this way, the object W can be gripped by the finger portions 23 and 24, and the gripped object W can be released.

Further, the finger portions 23 and 24 have elasticity, respectively. Therefore, when the object W is gripped, it is elastically deformed by the force received from the object W. Since the finger portions 23 and 24 have elasticity, the impact at the time of contact between the object W and the finger portions 23 and 24 can be softened. Therefore, damage to the object W and the fingers 23 and 24 can be effectively suppressed. Further, it is possible to prevent an excessive force from being applied to the object W due to the deformation of the finger portions 23 and 24, and it is possible to prevent the object W from being damaged. Further, as will be described later, it becomes easy to obtain the relationship between the separation distance d of the sliders 21 and 22 and the gripping force f, and the gripping force f can be accurately controlled by the control device 6.

However, for example, when the object W has elasticity, the finger portions 23 and 24 do not have to have elasticity, respectively. That is, it may be so hard that it does not substantially deform when the object W is gripped. Even in such a case, the elasticity of the object W can be used to accurately control the gripping force f as in the present embodiment, and the impact at the time of contact with the object W can be summed up. You can also get rid of it.

As shown in FIG. 3, the piezoelectric drive device 3 includes a base 31, a rotor 32 that can rotate with respect to the base 31, a driven portion 33 provided on the rotor 32, and a driven portion 33 fixed to the base 31. It has a plurality of piezoelectric modules 34 pressed against. In such a piezoelectric drive device 3, the rotor 32 rotates around the central axis J with respect to the base 31 by driving (vibrating) each piezoelectric module 34. On the other hand, when the drive of the piezoelectric module 34 is stopped, the piezoelectric module 34 is pressed against the driven portion 33, so that the rotor 32 is fixed to the base 31 by the frictional force between them. ..

As shown in FIGS. 4 and 5, each piezoelectric module 34 has a laminate 350 in which a plurality of piezoelectric actuators 35 are laminated, and an urging portion 36 that urges the laminate 350 toward the driven portion 33. Have. Further, as shown in FIG. 6, each piezoelectric actuator 35 vibrates with a vibrating portion 351 and a support portion 352 that supports the vibrating portion 351 and a pair of connecting portions 353 that connect the vibrating portion 351 and the support portion 352. It is provided at the tip end portion of the portion 351 and has a transmission portion 354 for transmitting the driving force of the vibrating portion 351 to the driven portion 33.

The vibrating section 351 is provided with five piezoelectric elements 351a, 351b, 351c, 351d, and 351e, and by applying a predetermined drive signal to each of these piezoelectric elements 351a to 351e, the vibrating section 351 vibrates (transmits). The portion 354 makes an elliptical motion), and the rotor 32 rotates (forward rotation / reverse rotation) with respect to the base 31.

Although not shown, each of the piezoelectric elements 351a to 351e has a configuration in which a piezoelectric body is sandwiched between a pair of electrodes. Further, the piezoelectric body is common to the piezoelectric elements 351a to 351e. Further, one of the electrodes is also shared by the piezoelectric elements 351a to 351e, and is connected to, for example, a GND. The other electrode is individually formed by the piezoelectric elements 351a to 351e. That is, the other electrode forms five vibration regions (parts that function as piezoelectric elements) in one piezoelectric body. Therefore, by individually applying a drive signal to the other electrode, the piezoelectric elements 351a to 351e can be driven independently. However, the configuration of the piezoelectric elements piezoelectric elements 351a to 351e is not limited to this, and for example, the piezoelectric body and one of the electrodes may be individually formed by the piezoelectric elements 351a to 351e. That is, a plurality of piezoelectric bodies may be provided.

Although the piezoelectric drive device 3 has been described above, the piezoelectric drive device 3 is not particularly limited as long as it utilizes the deformation of the piezoelectric element. For example, the piezoelectric drive device 3 is a rotary type piezoelectric drive device in which the rotor 32 rotates with respect to the base 31, but is not limited to this, and is slidable with respect to the base 31 instead of the rotor 32, for example. A slide-type piezoelectric drive device may be provided in which a slider is provided and the slider slides with respect to the base 31.

As shown in FIG. 2, the control device 6 has a processor 61, a memory 62 communicably connected to the processor 61, and an external interface 63. Each part of the control device 6 is communicably connected via various buses. The processor 61 executes various programs and the like stored in the memory 62. Various programs that can be executed by the processor 61 are stored (stored) in the memory 62. Further, the memory 62 can store various data received by the external interface 63. The memory 62 includes, for example, a volatile memory such as a RAM (Random Access Memory) and a non-volatile memory such as a ROM (Read Only Memory).

Hereinafter, a method of controlling the drive of the piezoelectric drive device 3 by the control device 6 will be described. The processor 61 included in the control device 6 updates the target positions of the sliders 21 and 22 (separation distance d of the sliders 21 and 22) based on the output of the encoder 4 and the output of the force detection unit 5, and sets the target position to the latest. The drive of the piezoelectric drive device 3 is controlled so that the sliders 21 and 22 move. According to such a control method, the gripping force f that grips the object W can be controlled accurately (the gripping force f can be maintained almost constant), and the gripping force f is too large to control the object. It is possible to prevent the W from being damaged or the object W from falling (disengaging) from the robot hand 1 because the gripping force f is too small. In particular, in this embodiment, the piezoelectric drive device 3 is used as the drive unit. It is difficult to control the gripping force f to be constant in the piezoelectric drive device 3, but according to such a control method, the gripping force f can be accurately controlled even when the piezoelectric drive device 3 is used as the drive unit. Can be done.

The separation distance d between the sliders 21 and 22 is, in other words, the base end portion of the finger portion 23 (the portion that is connected to the slider portion and is not substantially displaced by elastic deformation) and the finger portion 24. It can also be said to be a separation distance d from the base end portion (a portion that is connected to the slider 22 and is not substantially displaced by elastic deformation). Further, the separation distance d of the sliders 21 and 22 can also be said to be the separation distance d of the finger portions 23 and 24 when elastic deformation does not occur.

First, the first control method of the piezoelectric drive device 3 by the processor 61 will be described with reference to FIGS. 7 and 8. In the graph shown in FIG. 7, the horizontal axis is the separation distance d, and the vertical axis is the gripping force f by the sliders 21, 22 and the fingers 23, 24 (the force received by the fingers 23, 24 from the object W). Further, the region indicated by the "non-contact region" in the figure is a region in which the fingers 23 and 24 are not in contact with the object W and the gripping force f is substantially zero. On the other hand, the region indicated by the "contact region" in the figure is a region where the finger portions 23 and 24 are in contact with the object W and a gripping force f is generated. The gripping force f generated in the contact region increases as the separation distance d decreases.

First, the processor 61 drives the piezoelectric drive device 3 to set the separation distance d sufficiently open from the object W (initial state). Next, the object W is positioned between the fingers 23 and 24. Next, the processor 61 sets the first target position m1 of the sliders 21 and 22 (fingers 23 and 24) so that the separation distance d becomes smaller than the width (length in the gripping direction) of the object. , The drive of the piezoelectric drive device 3 is controlled so that the sliders 21 and 22 are at the first target position m1. The first target position m1 is sent from, for example, a host computer connected to the processor 61 according to the shape of the object W. When the sliders 21 and 22 are closed so as to be at the first target position m1, the fingers 23 and 24 come into contact with the object W on the way (before reaching the first target position m1). As a result, a gripping force f is generated. The gripping force f is detected by the force detecting unit 5 as a force received by the finger units 23 and 24 from the object W, and the detection result (output) by the force detecting unit 5 is fed back to the processor 61.

When the gripping force f detected from the force detecting unit 5 becomes the preset minimum gripping force f1, the processor 61 determines the target positions (separation distance d) of the sliders 21 and 22 such that the gripping force f becomes the target value f2. ) Is created as the second target position m2. The target value f2 is sent from, for example, the host computer. In the following, for convenience of explanation, the state in which the minimum gripping force f1 is generated is also referred to as a “minimum gripping force state”.

The method of creating the second target position m2 is not particularly limited. For example, the relationship between the separation distance d and the gripping force f in the contact region is obtained, and the positions (separation distance d2) of the sliders 21 and 22 whose gripping force f is the target value f2 are obtained based on the obtained relationship. May be set as the second target position m2. Specifically, since the fingers 23 and 24 have elasticity, the gripping force f increases as the separation distance d decreases in the contact region, and the separation distance d and the gripping force f have a substantially linear relationship. Further, the inclination (hereinafter, also referred to as “estimated inclination”) substantially coincides with the elastic modulus E of the fingers 23 and 24. Therefore, when the separation distance d in the minimum gripping force state is d1, the target value of the gripping force f is f2, and the separation distance d when the target value f2 is generated is d2, these are expressed in the following equation (1). Satisfy the relationship.

Here, the elastic modulus E and the minimum gripping force f1 in the equation (1) are known values (for example, a value stored in the memory 62 or the like, a value sent from the host computer), and the separation distance d1 is the minimum. It can be detected based on the output from the encoder 4 in the gripping force state. Therefore, by substituting the target value f2 into the equation (1), the separation distance d2 that becomes the target value f2 can be obtained. The processor 61 sets the positions of the sliders 21 and 22 having the separation distance d2 obtained from the equation (1) as the second target position m2. The processor 61 updates the target position from the first target position m1 to the second target position m2, and sets the second target position m2 as the latest target position. Then, the processor 61 controls the drive of the piezoelectric drive device 3 so that the sliders 21 and 22 are at the second target position m2 (latest target position). Then, the sliders 21 and 22 move to the second target position m2, and when the gripping force f reaches the target value f2, the driving of the piezoelectric drive device 3 is stopped. As a result, the object W can be gripped at the target value f2.

According to the first control method as described above, since the gripping force f can be set to the target value f2, the gripping force f is too large to damage the object W, or the gripping force f is too small to be the target. It is possible to prevent the object W from falling (leaving) from the robot hand 1.

Next, a second control method of the piezoelectric drive device 3 by the processor 61 will be described with reference to FIGS. 9 and 10. If the object W is sufficiently rigid with respect to the fingers 23 and 24, there is almost no deviation in the separation distance d2 at which the gripping force f obtained from the equation (1) becomes the target value f2, but the object W is If it is soft, the separation distance d2 obtained from the equation (1) may deviate. That is, if the object W is soft, the gripping force f does not reach the target value f2 even if the sliders 21 and 22 are moved so as to have a separation distance d2. That is, as shown in FIG. 9, the actual inclination in the contact region becomes smaller than the estimated inclination. This is because a part of the gripping force f is canceled due to the deformation of the object W. Therefore, the processor 61 creates a third target position m3 when the actual gripping force f is smaller than the target value f2 even though the sliders 21 and 22 are moved so as to have the separation distance d2. do.

The method for creating the third target position m3 is not particularly limited. For example, when the gripping force generated at the separation distance d2 is f2', the actual inclination α in the contact region is obtained from the following equation (2). Further, when the target value of the gripping force f is f2 and the separation distance d of the sliders 21 and 22 when the target value f2 is generated is d3, these satisfy the relationship of the following equation (3).

Here, since the actual inclination α, the minimum gripping force f1 and the separation distance d1 in the equation (3) are known values, when the target value f2 is substituted into the equation (3), the target value f2 is obtained. The value of the separation distance d3 of is obtained. The processor 61 sets the positions of the sliders 21 and 22 having the separation distance d3 obtained from the equation (3) as the third target position m3. The processor 61 updates the target position from the second target position m2 to the third target position m3, and sets the third target position m3 as the latest target position. Then, the processor 61 controls the drive of the piezoelectric drive device 3 so that the sliders 21 and 22 are at the third target position m3 (latest target position). Then, the sliders 21 and 22 move to the third target position m3, and when the gripping force f reaches the target value f2, the driving of the piezoelectric drive device 3 is stopped. With the above control, the object W can be gripped at the target value f2.

If the gripping force f does not reach the target value f2 even in the state of the separation distance d3, a new target position (fourth target position m4, fifth target) is created in the same manner as in the creation of the third target position m3. The position m5) may be created and updated as the latest target position. In this way, by continuously updating the target position until the gripping force f reaches the target value f2, the object W is gripped more reliably at the target value f2 without being affected by the hardness of the object W. be able to.

Next, a third control method of the piezoelectric drive device 3 by the processor 61 will be described. For example, when the object W is an object that undergoes creep deformation in which the amount of deformation increases with the passage of time, even if the gripping force f reaches the target value f2, the gripping force f decreases with the passage of time. In this case, the processor 61 keeps the gripping force f maintaining the target value f2 even after the gripping force f reaches the target value f2 (so that the gripping force f does not deviate significantly from the target value f2). The target position is continuously updated, and the drive of the piezoelectric drive device 3 is controlled so as to reach the updated target position. The new target position can be created, for example, by the method of creating the third target position m3 described above. Further, the timing of updating to a new target position is not particularly limited, and may be updated at predetermined time intervals, for example, and the difference between the target value f2 and the actual gripping force f becomes a predetermined value or more. It may be time.

Next, a fourth control method of the piezoelectric drive device 3 by the processor 61 will be described with reference to FIGS. 11 and 12. First, the processor 61 drives the piezoelectric drive device 3 to set the sliders 21 and 22 in the initial state. Next, the processor 61 estimates that the estimated inclination rises from the initial state, and at that time, the target position (separation distance d) of the sliders 21 and 22 such that the gripping force f becomes the target value f2 is set as the first target position. Create as m1. Next, the processor 61 sets the first target position m1 as the target position, and the sliders 21 and 22 (fingers 23 and 24) become the first target position m1 (latest target position). Control the drive of. When the sliders 21 and 22 reach the first target position m1, the processor 61 estimates that the estimated inclination rises from the first target position m1, and at that time, the slider 21 such that the gripping force f becomes the target value f2. , 22 target positions (separation distance d) are created as the second target position m2. Next, the processor 61 controls the drive of the piezoelectric drive device 3 so that the second target position m2 is set as the target position and the sliders 21 and 22 are set to the second target position m2 (latest target position). When the sliders 21 and 22 reach the second target position m2, the processor 61 estimates that the estimated inclination rises from the second target position m2, and at that time, the slider 21 such that the gripping force f becomes the target value f2. , 22 target positions (separation distance d) are created as the third target position m3. Next, the processor 61 controls the drive of the piezoelectric drive device 3 so that the third target position m3 is set as the target position and the sliders 21 and 22 are set to the third target position m3 (latest target position). In FIG. 11, the gripping force f reaches the target value f2 before the sliders 21 and 22 reach the third target position m3 (at the separation distance d2). When the gripping force f reaches the target value f2, the processor 61 stops driving the piezoelectric drive device 3 at that time. With the above control, the object W can be gripped at the target value f2.

If the gripping force f reaches the target value f2 before the sliders 21 and 22 reach the second target position m2, the processor 61 stops driving the piezoelectric drive device 3 at that time, and is described above. The third target position m3 such as the above is not created. Further, if the gripping force f does not reach the target value f2 even if the sliders 21 and 22 reach the third target position m3, the processor 61 will perform the fourth until the gripping force f reaches the target value f2. The target position m4, the fifth target position m5, and so on, and the target position is continuously updated.

In this way, the sliders 21 and 22 move to the latest target position by continuously updating the target position created by estimating that the estimated inclination rises from the current position until the gripping force f reaches the target value f2. The distance can be kept short. By keeping the moving distances of the sliders 21 and 22 short, the driving time of the piezoelectric driving device 3 is also shortened, and as a result, the speed of the piezoelectric driving device 3 is limited. Therefore, for example, overshoot (a phenomenon in which the sliders 21 and 22 do not stop at the target position and go too far) can be effectively suppressed. Thereby, the separation distance d of the sliders 21 and 22 can be controlled with high accuracy. Further, when overshoot occurs, it is necessary to rotate the piezoelectric drive device 3 in the reverse direction to increase the separation distance d, but the piezoelectric drive device 3 is good at switching from forward rotation to reverse rotation due to its structure. Instead, there will be a time lag. Therefore, by suppressing the overshoot, the robot hand 1 can be driven more quickly.

In the first to fourth control methods described above, the processor 61 updates the target position so that the gripping force f becomes the target value f2. That is, it is a control that gives priority to the target value f2. Separately from this, for example, as in the fifth control method shown in FIG. 13, in the first control method, the first target position m1 may be prioritized. For example, the processor 61 creates a second target position m2 in the same manner as in the first control method, and has a separation distance d0 and a second target position m2 of the sliders 21 and 22 defined by the first target position m1. Compare with the separation distance d2 defined in. Then, if d0 <d2, the processor 61 updates the second target position m2 as the latest target position, and controls the drive of the piezoelectric drive device 3 so that the second target position m2 is reached. On the contrary, if d0 ≧ d2, the processor 61 does not update the second target position m2 as the latest target position, but becomes the first target position m1 which is the immediately preceding target position. Control the drive of 3. In this case, the gripping force f becomes smaller than the target value f2.

According to such a control method, the instruction (first target position m1) from the post computer (upper control unit) connected to the processor 61 is prioritized, so that the system as a whole can be controlled more safely. Become.

The control method of the robot hand 1, the control device 6 of the robot hand 1, and the robot hand 1 has been described above. As described above, the control device 6 of the robot hand 1 is a piezoelectric drive device 3 (drive) that drives the finger portions 23 and 24 (grip portions) that grip the object W, and the sliders 21 and 22 and the finger portions 23 and 24. Robot hand 1 (end), including an encoder 4 (position detection unit) that detects the positions of the sliders 21 and 22, and a force detection unit 5 that detects the force that the fingers 23 and 24 receive from the object W. It is a control device that controls the effector). Then, the control device 6 updates the target positions of the sliders 21 and 22 based on the output of the encoder 4 and the output of the force detection unit 5, and the piezoelectric drive device so that the sliders 21 and 22 move to the latest target positions. Control the drive of 3. In particular, in the present embodiment, the control device 6 updates the target positions of the sliders 21 and 22 based on the output of the encoder 4 and the output of the force detection unit 5, and the sliders 21 and 22 move to the latest target positions. As described above, the processor 61 for controlling the drive of the piezoelectric drive device 3 is provided.

According to such a control device 6, the gripping force f for gripping the object W can be accurately controlled (the gripping force f can be maintained substantially constant), and the gripping force f is too large for the target. It is possible to prevent the object W from being damaged or the object W from falling (disengaging) from the robot hand 1 because the gripping force f is too small. Further, since the target position is determined, for example, the timing for stopping the driving of the piezoelectric drive device 3 can be known. Therefore, for example, the piezoelectric drive device 3 can be driven at the maximum speed to the limit, and the time required to move the fingers 23 and 24 to the target position can be shortened.

Further, as described above, the drive unit is the piezoelectric drive device 3. In the piezoelectric drive device 3, it is difficult to control the gripping force f to be constant, but according to the control device 6 as described above, the gripping force f can be accurately controlled even if the piezoelectric drive device 3 is used as the drive unit. can do. That is, the control device 6 can accurately control the gripping force f without being affected by the configuration of the drive unit. In the present embodiment, the piezoelectric drive device 3 (piezoelectric motor) is used as the drive unit, but the present invention is not limited to this, and for example, an electromagnetic motor may be used.

Further, as described above, the control device 6 updates the target position so that the force (grip force f) received by the finger portions 23 and 24 from the object W becomes the target value f2. As a result, the object W can be gripped at the target value f2.

Further, as described above, the control device 6 does not update the target position until the finger portions 23 and 24 come into contact with the object W as in the first to third control methods. As a result, the number of times the target position is updated can be reduced, and the driving speed of the robot hand 1 can be increased.

Further, as described above, the finger portions 23 and 24 have elasticity and are elastically deformed by the force received from the object W. As a result, the impact at the time of contact between the object W and the fingers 23 and 24 can be softened. Therefore, damage to the object W and the fingers 23 and 24 can be effectively suppressed. Further, it is possible to prevent an excessive force from being applied to the object W due to the deformation of the finger portions 23 and 24, and it is possible to prevent the object W from being damaged. Further, as described above, the relationship between the separation distance d of the sliders 21 and 22 and the gripping force f can be easily obtained, and the gripping force f can be accurately controlled by the control device 6.

Further, as described above, in the control device 6, the separation distance d (moving distance) of the sliders 21 and 22 and the force received by the fingers 23 and 24 from the object W based on the elastic modulus E of the fingers 23 and 24. Find the relationship with and update the target position based on that relationship. As a result, the gripping force f can be controlled accurately by the control device 6, and the object W can be gripped more reliably with the target value f2.

Further, as described above, the robot hand 1 (end effector) is a piezoelectric drive device 3 that drives the finger portions 23 and 24 (grip portions) that grip the object W, and the sliders 21 and 22 and the finger portions 23 and 24. (Drive unit), encoder 4 (position detection unit) that detects the positions of the sliders 21 and 22, force detection unit 5 that detects the force that the finger units 23 and 24 receive from the object W, and the output and output of the encoder 4. A control device 6 that updates the target positions of the sliders 21 and 22 based on the output of the force detection unit 5 and controls the drive of the piezoelectric drive device 3 so that the sliders 21 and 22 move to the latest target positions. Have. As a result, the effect of the control device 6 described above can be exhibited. That is, the gripping force f that grips the object W can be controlled accurately (the gripping force f can be maintained almost constant), and the gripping force f is too large to damage the object W or grip the object W. It is possible to prevent the object W from falling (disengaging) from the robot hand 1 because the force f is too small.

Further, as described above, the control method of the robot hand 1 (end effector) is a piezoelectric method for driving the fingers 23 and 24 (grip portions) that grip the object W, and the sliders 21 and 22 and the fingers 23 and 24. It has a drive device 3 (drive unit), an encoder 4 (position detection unit) that detects the positions of the sliders 21 and 22, and a force detection unit 5 that detects the force that the finger units 23 and 24 receive from the object W. This is a control method for controlling the robot hand 1. Then, in such a control method, the target positions of the sliders 21 and 22 are updated based on the output of the encoder 4 and the output of the force detection unit 5, so that the finger portions 23 and 24 move to the latest target positions. The drive of the piezoelectric drive device 3 is controlled. According to such a control method, the gripping force f that grips the object W can be controlled accurately (the gripping force f can be maintained almost constant), and the gripping force f is too large to control the object. It is possible to prevent the W from being damaged or the object W from falling (disengaging) from the robot hand 1 because the gripping force f is too small.

<Second Embodiment>
FIG. 14 is a perspective view showing a robot according to a second embodiment of the present invention.

The robot 1000 shown in FIG. 14 can perform operations such as supplying, removing, transporting, and assembling precision equipment and parts constituting the precision equipment. The robot 1000 is a 6-axis robot, and has a base 1010 fixed to the floor or ceiling, an arm 1020 rotatably connected to the base 1010, an arm 1030 rotatably connected to the arm 1020, and an arm 1030. An arm 1040 rotatably connected to the arm 1040, an arm 1050 rotatably connected to the arm 1040, an arm 1060 rotatably connected to the arm 1050, and a rotatably connected arm 1060. It has an arm 1070 and a control device 1080 that controls the drive of these arms 1020, 1030, 1040, 1050, 1060, and 1070.

Further, the arm 1070 is provided with a hand connection portion, and the hand connection portion is equipped with an end effector 1090 corresponding to the work to be executed by the robot 1000. The robot hand 1 described above can be used as the end effector 1090.

As described above, the robot 1000 has the robot hand 1. That is, the robot 1000 detects the positions of the finger portions 23, 24 (grip portion) that grip the object W, the piezoelectric drive device 3 (drive portion) that drives the finger portions 23, 24, and the finger portions 23, 24. Based on the encoder 4 (position detection unit), the force detection unit 5 that detects the force that the finger units 23 and 24 receive from the object W, and the output of the encoder 4 and the output of the force detection unit 5, the finger unit 23, It has a control device 6 that updates the target position of 24 and controls the drive of the piezoelectric drive device 3 so that the fingers 23 and 24 move to the latest target position. As a result, the effect of the control device 6 described above can be exhibited. That is, the gripping force f that grips the object W can be controlled accurately (the gripping force f can be maintained almost constant), and the gripping force f is too large to damage the object W or grip the object W. It is possible to prevent the object W from falling (disengaging) from the robot hand 1 because the force f is too small.

The configuration of the robot 1000 is not limited to the configuration of the present embodiment, and may be, for example, a horizontal articulated robot (SCARA robot) or a dual-arm robot.

The control device, end effector, robot, and control method of the present invention have been described above based on the illustrated embodiment, but the present invention is not limited to this, and the configurations of each part have the same functions. It can be replaced with any configuration that has. Further, any other constituents may be added to the present invention. Moreover, you may combine each embodiment as appropriate.

1 ... Robot hand, 20 ... Base, 21, 22 ... Slider, 211, 221 ... Rack gear, 23, 24 ... Finger, 25 ... Slide guide, 26 ... Pinion gear, 3 ... Piezoelectric drive, 31 ... Base, 32 ... Rotor, 33 ... Driven part, 34 ... Piezoelectric module, 35 ... Piezoelectric actuator, 350 ... Laminate, 351 ... Vibration part, 351a, 351b, 351c, 351d, 351e ... Piezoelectric element, 352 ... Support part, 353 ... Connection part , 354 ... transmission unit, 36 ... urging unit, 4 ... encoder, 5 ... force detector, 6 ... control device, 61 ... processor, 62 ... memory, 63 ... external interface, 1000 ... robot, 1010 ... base, 1020, 1030, 1040, 1050, 1060, 1070 ... Arm, 1080 ... Control device, 1090 ... End effector, J ... Central axis, W ... Object, d, d1, d2, d3 ... Separation distance, f, f2'... Gripping force , F1 ... Minimum gripping force, f2 ... Target value, m1 ... First target position, m2 ... Second target position, m3 ... Third target position

Claims (9)

A grip portion having a pair of finger portions to grip an object, a drive unit for driving the grip portion, a position detection unit for detecting the position of the grip portion, and a force received by the grip portion from the object. It is a control method for controlling an end effector having a force detecting unit for detecting.
The grip portion has elasticity and is elastically deformed by the force received from the object.
The drive of the drive unit is controlled based on the output of the position detection unit and the output of the force detection unit.
In the control of driving the drive unit, the target position of the grip portion is set to a first target position where the separation distance of the pair of finger portions is smaller than the length in the grip direction of the object, and the first target position is set. When the drive of the drive unit is controlled so that the grip portion moves to the target position of the above, and the minimum grip force is detected by the force detection unit before the grip portion moves to the first target position, Based on the elastic coefficient of the grip portion, the first relationship between the moving distance of the grip portion and the force that the grip portion receives from the object is obtained, and based on the first relationship, the grip portion is said to be the same. A second target position corresponding to the target force of the force received from the object is obtained, the target position of the grip portion is updated to the second target position , and the grip portion moves to the second target position. A control method comprising controlling the drive of the drive unit. In the control of driving the drive unit, when the force detected by the force detection unit when the grip unit moves to the second target position is smaller than the target force, the minimum grip force and the minimum grip force are used. The position of the grip portion when the minimum grip force is detected by the force detection unit, the force detected by the force detection unit when the grip portion moves to the second target position, and the first. Based on the target position of 2, the second relationship between the moving distance of the grip portion and the force received by the grip portion from the object is obtained, and the target force corresponds to the target force based on the second relationship. A claim that obtains a third target position, updates the target position of the grip portion to the third target position, and controls the drive of the drive portion so that the grip portion moves to the third target position. The control method according to 1. In the control of driving the drive unit, after the grip portion has moved to the second target position, the minimum grip force and the minimum grip force are detected by the force detection unit at predetermined time intervals. Based on the position of the grip portion at the time, the force currently detected by the force detection unit, and the current position of the grip portion, the moving distance of the grip portion and the grip portion receive from the object. The second relationship with the force is obtained, the third target position corresponding to the target force is obtained based on the latest second relationship, and the target position of the grip portion is set to the latest third target position. The control method according to claim 1 , wherein the drive of the drive unit is controlled so that the grip portion moves to the latest third target position . In the control of driving the drive unit, after the grip portion moves to the second target position, every time the difference between the force detected by the force detection unit and the target force becomes a predetermined value or more. The minimum gripping force, the position of the gripping portion when the minimum gripping force is detected by the force detecting portion, the force currently detected by the force detecting portion, and the current position of the gripping portion. Based on this, a second relationship between the moving distance of the grip portion and the force that the grip portion receives from the object is obtained, and based on the latest second relationship, a third target corresponding to the target force is obtained. A claim that obtains a position, updates the target position of the grip portion to the latest third target position, and controls the drive of the drive portion so that the grip portion moves to the latest third target position. The control method according to 1. The control method according to any one of claims 1 to 4 , wherein the drive unit is a piezoelectric drive device. The control method according to any one of claims 1 to 5 , wherein the target position is not updated until the grip portion comes into contact with the object. A grip portion having a pair of finger portions to grip an object, a drive unit for driving the grip portion, a position detection unit for detecting the position of the grip portion, and a force received by the grip portion from the object. A control device that controls an end effector having a force detection unit for detection.
The grip portion has elasticity and is elastically deformed by the force received from the object.
The drive of the drive unit is controlled based on the output of the position detection unit and the output of the force detection unit .
In the control of driving the drive unit, the target position of the grip portion is set to a first target position where the separation distance of the pair of finger portions is smaller than the length in the grip direction of the object, and the first target position is set. When the drive of the drive unit is controlled so that the grip portion moves to the target position of the above, and the minimum grip force is detected by the force detection unit before the grip portion moves to the first target position, Based on the elastic coefficient of the grip portion, the relationship between the moving distance of the grip portion and the force received by the grip portion from the object is obtained, and based on the relationship, the force received by the grip portion from the object is obtained. A second target position corresponding to the target force is obtained, the target position of the grip portion is updated to the second target position , and the drive unit is driven so that the grip portion moves to the second target position. A control device characterized by controlling. A grip portion that has a pair of fingers and grips an object,
The drive unit that drives the grip unit and
A position detection unit that detects the position of the grip portion and
A force detecting unit that detects the force that the gripping unit receives from the object,
It has a control device for controlling the drive of the drive unit based on the output of the position detection unit and the output of the force detection unit.
The grip portion has elasticity and is elastically deformed by the force received from the object.
In the control of driving the drive unit, the control device sets the target position of the grip portion to a first target position where the separation distance of the pair of finger portions is smaller than the length in the grip direction of the object. Then, the drive of the drive unit is controlled so that the grip portion moves to the first target position, and the minimum grip force is controlled by the force detection unit before the grip portion moves to the first target position. When is detected, the relationship between the moving distance of the grip portion and the force that the grip portion receives from the object is obtained based on the elastic coefficient of the grip portion, and based on the relationship, the grip portion is the target. A second target position corresponding to the target force of the force received from the object is obtained, the target position of the grip portion is updated to the second target position , and the grip portion moves to the second target position. An end effector characterized by controlling the drive of the drive unit. A grip portion that has a pair of fingers and grips an object,
The drive unit that drives the grip unit and
A position detection unit that detects the position of the grip portion and
A force detection unit that detects the force that the grip portion receives from the object,
It has a control device for controlling the drive of the drive unit based on the output of the position detection unit and the output of the force detection unit.
The grip portion has elasticity and is elastically deformed by the force received from the object.
In the control of driving the drive unit, the control device sets the target position of the grip portion to a first target position where the separation distance of the pair of finger portions is smaller than the length in the grip direction of the object. Then, the drive of the drive unit is controlled so that the grip portion moves to the first target position, and the minimum grip force is controlled by the force detection unit before the grip portion moves to the first target position. When is detected, the relationship between the moving distance of the grip portion and the force that the grip portion receives from the object is obtained based on the elastic coefficient of the grip portion, and based on the relationship, the grip portion is the target. A second target position corresponding to the target force of the force received from the object is obtained, the target position of the grip portion is updated to the second target position , and the grip portion moves to the second target position. A robot characterized by controlling the drive of the drive unit.

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