JP2016078196A - Double arm robot and double arm robot control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome the problem that, when each articulated arm moves to an unintended position while a robot is powered off until the robot is powered on again, it is difficult to return the articulated arm to a normal, initial position.SOLUTION: A double-arm robot control unit notifies a user of motions permitted for a plurality of articulated arms using a notification unit when a state becomes a third state where the supply of power resumes, on the basis of (i) a first difference between a first position of each articulated arm when a first state where power is supplied to a robot changes to a second state where the supply of power is stopped and a second position of each articulated arm when the second state changes to the third state where the supply of the power resumes, or (ii) a second difference between a preset third position of each articulated arm and the second position.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a multi-arm robot and its control device.

  Conventionally, a robot system using a robot having a multi-joint arm (also referred to as a “multi-joint robot”) has been used. When an articulated robot is used, it is common to prevent interference between the robot body and peripheral devices and the arm by limiting the movement range of the arm to a predetermined allowable range. For example, Patent Literature 1 discloses a technique for monitoring whether or not a robot control point (representative point of an end effector) is within an operation area, and when the robot deviates from the operation area, the power is shut off and the robot operation is prohibited. Is disclosed. In this patent document 1, when the robot deviates from the operation area for some reason, the worker activates the invalid input for invalidating the operation prohibition to make the robot operable, and the operator pendates. A technique is described in which the control point of the robot is returned to the operation area by operating the.

JP 2008-213056 A

  By the way, when the robot is transported, the articulated arm of the robot may move to an unintended position for some reason during the transport. For example, if the articulated arm moves to an unintended position, it may not always be easy to return to the normal initial position. Also, if the operation of forcibly returning to the initial position is performed, the articulated arm and the other part of the robot may interfere with each other, which may cause problems such as damage to the robot. In particular, in the case of an articulated arm having seven or more joint axes and having a redundant degree of freedom, it is often quite difficult to return from a position changed during transportation to a normal initial position. Such a problem is common not only when the robot is being transported, but also when the articulated arm of the robot moves to an unintended position between the time when the power of the robot is stopped and the time when the power is turned on again. However, in the past, since the recognition of such a problem was not sufficient, the actual situation was that the countermeasure was not fully taken.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

(1) According to one aspect of the present invention, a multi-arm robot is provided that includes a plurality of multi-joint arms, a position detector that detects the position of each multi-joint arm, a control unit, and a notification unit. . The control unit is configured to: (i) a first state of each multi-joint arm when the power supply to the multi-arm robot is changed from a first state where power is supplied to the multi-arm robot to a second state where power supply is stopped The first difference between the position 1 and the second position of each articulated arm when the supply of power from the second state is resumed to the third state, or (ii) predetermined The plurality of articulated arms when the third state where the supply of power is resumed is based on the third difference between the third position of each articulated arm and the second position. The operation that is allowed is notified using the notification unit.
According to the multi-arm robot, even when the multi-joint arm of the robot moves to an unintended position between the stop of the power supply of the robot and the restart thereof, an allowable operation is notified by the notification unit. Therefore, the robot operator can easily perform the operation of returning the articulated arm to the normal initial position in accordance with this notification.

(2) In the multi-arm robot, when the control unit is in the third state in which the supply of power is resumed, the plurality of multi-arm robots are based on the first difference or the second difference. It may be determined whether or not a return operation for driving the joint arm to return to a predetermined initial position is permitted, and the determination result is notified using the notification unit.
According to this configuration, since the return operation is not allowed when the first difference or the second difference is excessively large, the possibility of problems such as robot damage being reduced by performing the return operation is reduced. Is possible.

(3) In the multi-arm robot, the control unit is permitted for the plurality of multi-joint arms when the return operation is permitted when the power supply is resumed in the third state. The notification unit may be used to notify the operator of the multi-arm robot to select a motion candidate.
According to this configuration, the robot operator can perform the return operation by selecting from the motion candidates notified by the notification unit while observing the actual state of the multi-joint arm. It is possible to easily perform the operation of returning to the normal initial position.

(4) In the multi-arm robot, the control unit determines whether or not the return operation is permitted when the supply of power is resumed and the third state is reached. 2 is less than the first threshold, the control unit (a) when the supply of power is resumed and the third state is reached, the first difference or the second If the difference is less than the first threshold and less than or equal to the second threshold smaller than the first threshold, the return operation is allowed according to one preselected operation mode; (b) When the first difference or the second difference is less than the first threshold and exceeds the second threshold when the supply of power is resumed and enters the third state, Candidate motions that are allowed for a plurality of multi-joint arms It may alternatively be notified using the notification unit for selection by the operator.
According to this configuration, since the above (a) and (b) are executed according to the relationship between the first difference or the second difference and the first threshold value and the second threshold value, the robot operator Can execute an appropriate operation according to the magnitude of the first difference or the second difference.

(5) In the multi-arm robot, the control unit calculates the accumulated difference by accumulating the first difference or the second difference every time the supply of power is resumed. When a predetermined allowable value is exceeded, a warning may be notified using the notification unit.
If the accumulated difference is excessively large, there is a possibility that some trouble has occurred in the mechanism of the articulated arm, so the robot operator receives a warning that the accumulated difference has exceeded the allowable value. It is possible to take measures against defects.

  The present invention can be realized in various forms. For example, in addition to a multi-arm robot, the present invention is realized in various forms such as a control method and control apparatus for a multi-arm robot, and a robot system having a multi-arm robot. be able to.

The perspective view which looked at the multi-arm robot from the front. The perspective view which looked at the double-arm robot from the back. The figure which looked at the state at the time of conveyance of a double arm robot from the front. Explanatory drawing which shows the mechanism of the multi-axis of a multi-arm robot. The block diagram which shows the relationship between the various detectors and control part of a multi-arm robot. The flowchart which shows the control action of the double-arm robot after conveyance. Explanatory drawing which shows an example of movement amount (DELTA) Xi of the axis | shaft Ji, and threshold value Ta, Tb.

  FIG. 1 is a perspective view of a multi-arm robot 1 according to an embodiment of the present invention as seen from the front, and FIG. 2 is a perspective view as seen from the back. The multi-arm robot 1 includes a robot body 10, an articulated arm 11, a touch panel monitor 12, a transfer handle 14, an electronic camera 15, a signal lamp 16, a power switch 17, an external I / F unit 18, and the like. A lifting handle 19.

  The robot body 10 includes a shoulder portion 10A, a trunk portion 10B, a leg portion 10C, an upper frame 10Ba, and a lower frame 10Ca. Articulated arms 11 (also referred to as “manipulators”) are provided in the vicinity of the upper ends of both side surfaces of the shoulder portion 10A. In the following, for convenience of explanation, the upper side in FIGS. 1 and 2 is referred to as “upper” or “upper”, and the lower side is referred to as “lower” or “lower”. Also, the front side in FIG. 1 is referred to as “front side” or “front side”, and the front side in FIG. 2 is referred to as “rear side” or “rear side”.

  The multi-joint arm 11 has a configuration in which a plurality of arm members 11a are connected by joint portions. The mechanism of the articulated arm 11 will be described later. The multi-joint arm 11 is provided with a hand eye camera 11b for photographing a workpiece or the like placed on a work table.

  Various end effectors can be connected to the wrist portion (also referred to as “end effector mounting portion”) of the articulated arm 11. In the example of FIGS. 1 and 2, a hand 11c that holds a workpiece or a tool is connected as an end effector. The position of the end point of the multi-joint arm 11 (the target of end point control of the multi-arm robot 1) is the tip position of the hand 11c.

  An electronic camera 15 and a signal lamp 16 are provided on the head protruding upward from the shoulder 10A. For example, the electronic camera 15 can capture an image of a work table or a workpiece. Further, the electronic camera 15 may be used as a position detector that detects the position of the articulated arm 11 or an attitude detector that detects the attitude of the articulated arm 11. The signal lamp 16 includes, for example, LEDs that respectively emit red light, yellow light, and blue light. These LEDs are appropriately selected according to the current state of the multi-arm robot 1 and emit light.

  A bumper 13 is provided in front of the body portion 10B. The bumper 13 is a member for keeping the horizontal distance between the multi-arm robot 1 and the work table constant by contacting the work table in order to accurately perform the manufacturing work.

  A touch panel monitor 12 having a monitor visible from the back side of the multi-arm robot 1 is disposed on the back side of the body 10B. The touch panel monitor 12 is fixed to the conveyance handle 14. The touch panel monitor 12 is used as a notification unit that displays, for example, the current operation state of the multi-arm robot 1, notification of whether or not the return operation after conveyance is permitted, and notification of the types of permitted operations. Is done. The touch panel monitor 12 has a touch panel function and can be used as an operation unit for setting operations and inputting commands for the multi-arm robot 1. However, the touch panel function may be omitted. A lifting handle 19 is further provided on the back surface of the body portion 10B. When the elevating handle 19 is rotated, the shoulder portion 10A moves in the vertical direction with respect to the trunk portion 10B.

  The trunk portion 10B is provided on the lower frame 10Ca inside the leg portion 10C. A control unit (described later) for controlling the multi-arm robot 1 is installed inside the lower frame 10Ca. The lower frame 10Ca and the upper frame 10Ba are integrally formed. The lower frame 10Ca is provided with a rotation shaft (not shown), and this rotation shaft can move in the upper frame 10Ba in the vertical direction. A shoulder 10A is provided at the upper end of the rotating shaft, and the rotating shaft moves up and down in accordance with the operation of the lifting handle 19.

  On the back surface of the leg portion 10C, a power switch 17 and an external I / F unit 18 that is an external connection terminal for connecting the control unit and an external PC or the like are provided. The power switch 17 includes a power-on switch 17 a for turning on the power of the double-arm robot 1 and a power-off switch 17 b for cutting off the power of the double-arm robot 1. The operation of these switches 17a and 17b starts (restarts) and stops the power supply of the main power supply to the multi-arm robot 1. “Power supply from the power supply” is also simply referred to as “power supply”. The power source of the double-arm robot 1 is normally an external power source, but a large-capacity battery may be provided as a power source inside the double-arm robot 1.

  A transport handle 14 is further provided on the back surface of the leg portion 10C. The transfer handle 14 is a portion that is held by an operator when the multi-arm robot 1 is transferred. A plurality of casters and adjustment feet (both not shown) are installed at intervals in the horizontal direction at the bottom of the leg 10C. Using these mechanisms, after the operator transports the multi-arm robot 1, the multi-arm robot 1 can be fixed at a desired installation position. The caster may have a brake mechanism (not shown). Thereby, for example, on a downhill, it is possible to transport the multi-arm robot 1 more safely by using a brake. The method of braking is not particularly limited, but operability is good if a brake lever (not shown) is provided on the transport handle 14 and the brake is applied by gripping the brake lever.

  FIG. 3 is a diagram of an example of the state of the multi-arm robot 1 when it is transported as viewed from the front. At the time of conveyance, the two multi-joint arms 11 are each folded to the back side, and the wrist is set to face rearward. Further, an end effector is not attached to the wrist. As described above, in general, a compact posture is usually set when the robot is transported. Further, at the time of transportation, the position of each axis is fixed by a brake provided on each axis so that the axis of the robot does not rotate. As this brake, for example, an electromagnetic brake is used. As the electromagnetic brake, a non-excitation brake that can be turned on when the power is turned off can be used.

  FIG. 4 is an explanatory view showing a mechanism of a plurality of axes provided in the multi-arm robot 1. A rotation axis J0 is provided between the shoulder portion 10A and the trunk portion 10B. Each of the two multi-joint arms 11 is provided with seven joint axes J1 to J7. Actuators (not shown) for operating these rotary shafts J0 and joint shafts J1 to J7 are provided for operating them. In addition, the rotational axes J0 and the seven joint axes J1 to J7 of the multi-joint arm 11 are provided with position detectors PS0 and PS1 to PS7 for detecting respective rotational angles (“positions” of the respective axes). As the position detectors PS0 to PS7, an encoder, a potentiometer, a resolver, or the like can be used. The position detection signals output from the position detectors PS0 to PS7 are used for position feedback control and speed feedback control of the multi-arm robot 1. When the joint is a rotary joint, the “position” of the joint axis is a rotation angle, and when the joint is a linear motion joint, the “position” of the joint axis is a position on a straight line. In the example of FIG. 4, since the joint axes J0 to J7 are all rotary joints, their positions are detected as rotation angles.

  A force sensor FS is provided on the wrist portion of the articulated arm 11. The force sensor FS is a sensor that detects a reaction force and a moment with respect to the force exerted on the workpiece by the hand 11c (FIG. 1). As the force sensor FS, for example, a six-axis force sensor that can simultaneously detect six components of a force component in the translational three-axis direction and a moment component around the three rotation axes can be used. The force sensor FS is not limited to a 6-axis sensor, and may be a 3-axis sensor, for example.

  FIG. 5 is a block diagram showing the relationship between various detectors provided in the multi-arm robot 1 and the control unit. The position detectors PS0 to PS7 of each axis, the force sensor FS, and the electronic camera 15 are connected to the control unit 100, respectively. In FIG. 5, only one arm is representatively illustrated as the position detectors PS1 to PS7 of the multi-joint arm 11, but actually these positions are related to each of the two multi-joint arms 11. There are detectors PS1 to PS7. The control unit 100 executes control of the multi-arm robot 1 using output signals from the position detectors PS0 to PS7 and the force sensor FS and images captured by the electronic camera 15. Further, the control unit 100 displays various notifications and warnings on the touch panel monitor 12 as necessary. The position detectors PS0 to PS7 are connected to a battery BT installed inside the double-arm robot 1. Therefore, these position detectors PS0 to PS7 can detect the positions of the respective axes even when the power of the multi-arm robot 1 is not supplied (for example, during conveyance).

  FIG. 6 is a flowchart showing a robot control operation when power supply is started after the robot is transported. When the transfer and installation of the multi-arm robot 1 is completed and the supply of power to the multi-arm robot 1 is started, first, in step S100, the control unit 100 detects the position of the joint axes J1 to J7 of the multi-joint arm 11. A position detection signal that is an output signal of PS1 to PS7 is acquired. As described with reference to FIG. 5, power is supplied from the battery BT to the position detectors PS1 to PS7, and the position of each axis can be detected even when the power is turned off during conveyance or installation. Therefore, even if an unexpected movement (position change) occurs in the joint axes J1 to J7 from the set state during conveyance (FIG. 3), the control unit 100 calculates the movement amount in step S100. Is possible. In addition, in order to be able to calculate the movement amount of each joint axis J1-J7 in step S100, the control part 100 stores the position of each joint axis J1-J7 in the setting state at the time of conveyance in a non-volatile memory. It is preferable to keep it. In the process described below, the position of the rotation axis J0 (FIG. 4) between the trunk portion 10B and the shoulder portion 10A is not used, but the position of the rotation axis J0 is also the rotation axis J1 to J1 of the articulated arm 11. You may use similarly to J7.

  In step S110, the control unit 100 compares the relationship between the movement amounts ΔXi of the seven joint axes J1 to J7 of the multi-joint arm 11 and the predetermined threshold values Ta and Tb, and in accordance with the comparison result, step S200, One of the processes of S300 and S400 is executed.

  FIG. 7 is an explanatory diagram showing an example of the movement amount ΔXi of a certain joint axis Ji and its threshold values Ta and Tb. Here, the subscript i indicates the numbers 1 to 7 of the joint axes J1 to J7 of the multi-joint arm 11. In this example, the normal movable range of the joint axis is set to a range of −ΔXmax to + ΔXmax with the origin (point of ΔX = 0) as the center. However, the minimum value −ΔXmax and the maximum value + ΔXmax may be different. Here, the origin is the position of the joint axis Ji in the set state during conveyance. The first threshold Ta and the second threshold Tb are set as follows.

<First threshold Ta>
If the movement amount ΔXi during the transfer is equal to or greater than the first threshold value Ta, the first threshold Ta is overloaded to the multi-arm robot 1 during the transfer, and the movement considered to have a high possibility of failure. A value indicating the quantity. Further, if the movement amount ΔXi during the conveyance is equal to or greater than the first threshold value Ta, if the joint axes J1 to J7 of the multi-arm robot 1 are controlled to return to the setting state at the time of the conveyance, some trouble or breakage is caused. It is a value that may be generated. As will be described later, when the movement amount ΔXi during conveyance is equal to or greater than the first threshold Ta, a return operation for operating the multi-joint arm 11 to return the multi-joint arm 11 to the initial position (predetermined initial position) is performed. It is forbidden. On the other hand, when the movement amount ΔXi in the middle of the conveyance is less than the first threshold value Ta, a return operation for operating the articulated arm 11 so as to return the articulated arm 11 to the initial position (predetermined initial position) is allowed. . Various operation modes can be used as the return operation.

<Second threshold Tb>
The second threshold value Tb is a value smaller than the first threshold value Ta, and if the movement amount ΔXi during conveyance is equal to or less than the second threshold value Tb, the joint axes J1 to J7 of the multi-arm robot 1 are conveyed. Even if it is operated so as to return to the set state, it is a value considered that there is no possibility of causing the malfunction or damage to the multi-arm robot 1. As will be described later, when the movement amount ΔXi during conveyance is equal to or smaller than the second threshold value Tb, the return operation is executed according to one operation mode selected in advance. On the other hand, when the movement amount ΔXi during conveyance exceeds the second threshold value Tb, the touch panel monitor 12 notifies the user (operator) of a candidate operation mode that is permitted as a return operation.

  The threshold values Ta and Tb for each joint axis Ji are individually set to values suitable for each joint axis Ji. Further, the comparison between the movement amount ΔXi of each joint axis Ji and the threshold values Ta and Tb is performed using their absolute values. However, in the following description, for the sake of convenience of explanation, it is assumed that the movement amount ΔXi is compared with the threshold values Ta and Tb.

  When the movement amount ΔXi of at least one joint axis Ji among the joint axes J1 to J7 of the multijoint arm 11 is greater than or equal to the first threshold Ta, the multijoint arm 11 is returned to the initial position. The return operation for operating is prohibited, and step S400 is executed. Here, the “initial position” means a position in the set posture (FIG. 3) during conveyance. In step S400, the control unit 100 notifies the user of an alarm indicating that the soft return operation is impossible. In this notification, it is desirable to notify the user which axis has a problem. This notification is performed, for example, by displaying the notification on the monitor 12. The same applies to other notifications to be described later. Here, the “soft return operation” means an operation for returning the double-arm robot 1 to the initial position when the user inputs a command on the control software of the double-arm robot 1. When an alarm indicating that the soft return operation is impossible is notified, the user cannot cause the multi-arm robot 1 to perform an operation at the installation site of the double-arm robot 1. In this case, for example, a maintenance support company (or a maintenance worker) of the multi-arm robot 1 is contacted and a maintenance work for returning the multi-arm robot 1 to an operable state is requested. In the maintenance work, a confirmation work including whether or not the double-arm robot 1 is free from defects and damages is performed. As described with reference to FIG. 3, during transportation, each shaft is braked by a brake provided on each shaft, but release of this brake is allowed during maintenance work. As a result, in the maintenance work, the maintenance worker can move the articulated arm 11 by hand.

  When the movement amount ΔXi of all the joint axes J1 to J7 of the multi-joint arm 11 is less than the first threshold Ta, a return operation for operating the multi-joint arm 11 to return the multi-joint arm 11 to the initial position is allowed. Then, the process of steps S200 to S220 or the process of steps S300 to S360 is executed. That is, in the present embodiment, when the return operation is permitted, one of the processes in steps S200 to S220 and the processes in steps S300 to S360 is performed according to the comparison result between the movement amount ΔXi and the second threshold value Tb. Performed selectively.

  When the movement amount ΔXi of all the joint axes J1 to J7 of the multi-joint arm 11 is equal to or less than the second threshold value Tb, steps S200 to S220 are executed. In step S200, the control unit 100 notifies the user that a return operation is possible. The “returning operation” means an operation for returning the positions of the axes J0 to J7 to the initial positions in the original transport posture. In step S210, an operation of moving the positions of the axes J0 to J7 using impedance control to the initial position in the original transport posture is executed. As described above, the force sensor FS (FIG. 4) is provided on the wrist portion of the articulated arm 11. In the impedance control, when the user (operator) moves the articulated arm 11 while holding the wrist of the articulated arm 11 by hand, the force detected by the force sensor FS is controlled so as not to become excessively large. The articulated arm 11 can be slowly returned to the initial position. Instead of moving the articulated arm 11 in the impedance control state, the double arm robot 1 itself returns the articulated arm 11 to the initial position by updating the command of the double arm robot 1 in the impedance control state. Is also possible. In step S220, the control unit 100 operates the axes J0 to J7 so as to move from the initial position in the original transport posture to the position in the initial posture for normal operation. The initial posture of the normal operation is a preset posture, and the position of each axis in this posture is stored in a nonvolatile memory in the control unit 100. The posture shown in FIGS. 1 and 2 is close to the initial posture of normal operation. In the operation of step S220, it is not necessary for the user to touch the multi-joint arm 11 or the wrist of the multi-arm robot 1, and the control unit 100 is automatically executed by driving the actuators of the axes J0 to J7. . However, step S220 may be omitted.

  On the other hand, when the movement amount ΔXi of the joint axes J1 to J7 of the multi-joint arm 11 does not satisfy the above-described conditions for shifting to step S200 and step S400, steps S300 to S360 are executed. That is, when the movement amount ΔXi of all the joint axes J1 to J7 of the multi-joint arm 11 is less than the first threshold value Ta, and the movement amount ΔXi of at least one joint axis Ji exceeds the second threshold value Tb. Steps S300 to S360 are executed. In step S300, the control unit 100 displays an alarm on the touch panel monitor 12 to notify the user that a soft return operation is possible. In this notification, it is desirable to notify the user which axis has a problem. In this state, it is allowed to release the brakes of the respective axes. In step S310, after the user cancels the alarm on the touch panel monitor 12, the user selects one of a plurality of operation mode options, and one of the operations of steps S320, S330, and S340 is performed according to the selection. Perform recovery operation by mode.

  In step S320, an operation of moving to the initial position in the original transport posture by impedance control is performed. This operation is the same as step S210 described above. In step S330, the brake of the axis designated by the user is released. The designation of the axis is performed on the touch panel monitor 12, for example. At this time, it is preferable that the user interface on the touch panel monitor 12 is configured so that an axis targeted for brake release can be selectively designated from all the axes J0 to J7 of the multi-arm robot 1. After releasing the brake of the designated axis, the user may move the joint of the axis to near the initial position in the original transport posture by moving the joint. In step S340, the multi-arm robot 1 is caused to move the articulated arm 11 (or its wrist) away from the torso 10B of the multi-arm robot 1 in accordance with a user instruction or selection. The reason why the articulated arm 11 is moved away from the trunk portion 10B is that when the articulated arm 11 is excessively close to the trunk portion 10B, if the returning operation to return to the initial position in the original transport posture is performed, the articulated arm This is because there is a possibility that 11 and the body portion 10B interfere with each other. After steps S330 and S340, a return operation for moving to the initial position in the original transport posture is performed by impedance control in step S350. However, step S350 may be omitted when the operation returns to sufficiently close to the initial position by the operations of steps S330 and S340. In this way, when returning to the initial position (or a position close thereto) in the original transport posture in steps S320 to S350, in step S360, the control unit 100 moves to the initial posture for normal operation from each initial position. The axes J0 to J7 are operated. This process is the same as step S220 described above. Note that step S360 may be omitted similarly to step S220.

  Note that in steps S210 and S320 of FIG. 6, the axis may be moved to the original transport posture using position control instead of impedance control. From the viewpoint of preventing contact between the robot body and peripheral devices and the arm, impedance control is more preferable than position control. However, with respect to the time required for movement, position control is preferable in that it is shortened.

  According to the processing procedure of FIG. 6, when the power is turned on after the multi-arm robot 1 is transported, the operation allowed for the multi-arm robot 1 according to the movement amount ΔXi of each axis between the stop and restart of the power. Is determined and notified to the user, so that the user can select an appropriate action. That is, the user moves the multi-arm robot 1 to the initial position in the original transport posture while selecting the appropriate motion according to the magnitude of the movement amount ΔXi. Can do. Further, when the movement amount ΔXi of the axis Ji of the articulated arm 11 is equal to or greater than the first threshold value Ta, there is a possibility that an excessive load is applied in the middle of the conveyance. Since the operation is prohibited, it is possible to reduce the possibility of causing problems and damage to the multi-arm robot 1.

Note that in steps S210 and S320 to S350 in FIG. 6, one or more of the following conditions may be set for the operation when returning to the initial position (or a position close thereto) of the original transport posture. preferable.
<Condition 1>
The operable range of each joint axis Ji of the multi-joint arm 11 is set wider than the normal operating range −ΔXmax to + ΔXmax. The reason for setting such condition 1 is that even if the axis Ji of the articulated arm 11 has moved out of the normal operating range, it can return to the normal operating range. Because.
<Condition 2>
The overload detection threshold in the torque calculation of the actuator of each joint axis Ji is reduced. The overload detection threshold value is a value that is controlled so as to prohibit the operation of the joint axis when the calculated torque value of each joint axis Ji exceeds the threshold value. If the overload detection threshold is reduced, the torque applied to each joint axis Ji when the multi-joint arm 11 is moved to return to the initial position is limited to a smaller value than usual. Even when the multi-arm robot 1 itself comes into contact with the robot, it is possible to minimize damage and problems caused by the robot.
<Condition 3>
Increase the overload detection threshold of the force sensor FS. This overload detection threshold is a value that is controlled so as to prohibit the operation of the multi-joint arm 11 when the load detected by the force sensor FS exceeds this threshold. If the overload detection threshold of the force sensor FS is increased, the articulated arm 11 can be operated more freely in the impedance control, and it is easier to return to the initial position.

  In addition, it is not necessary to set all the conditions 1 to 3 described above, and only some of them may be set. Further, regarding the settings of these conditions 1 to 3, different settings may be used in steps S210, S320, S330, S340, and S350.

  In the example of FIG. 6, the difference ΔXi between the position of the articulated arm 11 of the multi-arm robot 1 at the start of power supply after the transport of the multi-arm robot 1 and the position at the initial position (the position of the set posture at the time of transport). In the example described above, the user is notified of the motion allowed for the multi-arm robot 1 in accordance with the difference ΔXi. However, the process as shown in FIG. 6 can be similarly applied to a case where the multi-arm robot 1 is not transported and is restarted after the power supply is once shut off. That is, the processing of FIG. 6 can also be applied to processing when the supply of power to the multi-arm robot 1 is stopped and then restarted. Even when the multi-arm robot 1 is not transported, if the difference ΔXi between the arm positions of the multi-arm robot 1 when the power supply is stopped and then restarted is large, the multi-arm robot 1 is operated as it is. Since some trouble may occur, it is preferable to perform a process similar to FIG. However, in this case, the “original transport posture” in steps S210, S23, and S350 is read as “posture when power supply is stopped”.

  Instead of calculating the difference ΔXi (first difference) between the position when the power supply of the multi-joint arm 11 is stopped and the position when the power supply is resumed, the preset initial position and the power supply are resumed. A difference ΔXi (second difference) from the position of may be calculated and used for the determination of FIG. In this case as well, the operation allowed for the multi-arm robot 1 is determined according to the magnitude of the difference ΔXi (second difference) between the predetermined initial position and the position at the time when the supply of power is resumed. If notified, the user can select an appropriate action. Each time the supply of power is resumed, the first difference or the second difference is accumulated to calculate the accumulated difference. When the accumulated difference exceeds a predetermined allowable value, the control unit 100 A warning may be notified using the monitor 12. When the accumulated difference is excessively large, there is a possibility that some trouble has occurred in the mechanism of the articulated arm 11. The user of the multi-arm robot 1 can take countermeasures by receiving a warning that the accumulated difference exceeds the allowable value. In addition, as the cumulative difference of the first difference or the second difference, a cumulative value obtained by adding both the first difference and the second difference may be used, or only the first difference is added. An accumulated value or an accumulated value obtained by adding only the second difference may be used.

  According to the above-described embodiment, the position of each articulated arm 11 when power supply to the multi-arm robot 1 is stopped, and the position of each articulated arm 11 when power supply is resumed from this state. Or (ii) a predetermined initial position of the multi-joint arm 11 and a position of each multi-joint arm 11 when the supply of power to the multi-arm robot 1 is resumed. Since the motion allowed for the articulated arm 11 is notified based on the second difference ΔXi, the user causes the multi-arm robot 1 to perform an appropriate motion corresponding to the difference ΔXi in the movement amount. Is possible.

・ Modification:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

・ Modification 1:
In the above embodiment, encoders, potentiometers, resolvers, and the like are used as position detectors PS0 to PS7 that detect the position and posture of the multi-joint arm 11 of the multi-arm robot 1, but instead, for example, a camera is used. The position and posture of the multi-joint arm 11 of the multi-arm robot 1 may be used.

Modification 2
In the above-described embodiment, the touch panel monitor 12 is used as the notification unit, but any other notification unit can be used. For example, a monitor that displays an image, a speaker that generates sound, a light source such as an LED, and the like may be used as the notification unit.

・ Modification 3:
In the above embodiment, when the position movement amount ΔXi is relatively small (steps S210, S320, and S350 in FIG. 6), the articulated arm 11 is moved to the initial position (that is, the predetermined initial position) using impedance control. However, other operation modes of position control and hybrid control may be used instead of impedance control. However, it is preferable that these steps are set in advance so that one operation mode selected in advance is used. In this way, it is possible to operate the multi-arm robot 1 so as to return the articulated arm 11 to a predetermined initial position without causing any trouble by using a certain operation mode.

-Modification 4:
In step S110 of FIG. 6, using the movement amounts ΔXi of all joint axes of the multi-arm robot 1, whether or not the return operation is allowed and what operation is allowed when the return operation is allowed. However, instead of this, such a determination may be performed using the movement amount ΔXi of one or more joint axes selected in advance as a representative joint axis.

Modification 5:
Various modifications other than those described above are possible for the processing of FIG. For example, the return operation by the processing of steps S200 to S220 may be omitted, and some of the return operations by the processing of steps S300 to S360 may be omitted.

  In the process of FIG. 6, when the movement amount ΔXi is less than the first threshold Ta and the return operation is allowed, the movement amount ΔXi is further compared with the second threshold Tb. The comparison with the threshold value Tb may not be performed. In this case, for example, the user can select an arbitrary operation from among a part or all of the return operation by the process of steps S200 to S220 and the return operation by the process of steps S300 to S360. In addition, it is preferable to notify the user.

Modification 6:
In the above embodiment, a robot having a seven-axis multi-joint arm has been described. However, the number of joints of the multi-joint arm is not limited to seven, and any number of two or more can be employed. However, since the multi-joint arm having seven or more joints has redundancy in the degree of freedom, the return operation is more complicated and difficult when the movement amount at the time of restarting the power supply is large. Therefore, the effect of the present invention is remarkable when applied to a robot having a multi-joint arm having seven or more joint axes.

  The embodiments of the present invention have been described above based on some examples. However, the above-described embodiments of the present invention are for facilitating the understanding of the present invention and limit the present invention. It is not a thing. The present invention can be changed and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Multi-arm robot 10 ... Robot main body 10A ... Shoulder part 10B ... Trunk part 10C ... Leg part 10Ba ... Upper frame 10Ca ... Lower frame 11 ... Articulated arm 11a ... Arm member 11b ... Hand eye camera 11c ... Hand 12 ... Touch panel monitor DESCRIPTION OF SYMBOLS 13 ... Bumper 14 ... Conveying handle 15 ... Electronic camera 16 ... Signal lamp 17 ... Power switch 17a ... Power on switch 17b ... Power off switch 18 ... External I / F part 19 ... Lifting handle 100 ... Control part

Claims (6)

Multiple articulated arms,
A position detector for detecting the position of each articulated arm;
A control unit;
A notification unit;
With
The controller is
(I) a first position of each multi-joint arm in a second state in which power supply to the multi-arm robot is stopped from a first state in which power is supplied to the multi-arm robot; A first difference from a second position of each articulated arm when the third state is reached when power supply is resumed from the second state;
Or
(Ii) Based on a predetermined third position of each articulated arm and a second difference between the second position,
A multi-arm robot that uses the notification unit to notify an operation permitted for the plurality of articulated arms when the power supply is resumed in the third state. The multi-arm robot according to claim 1,
The controller is predetermined by driving the plurality of articulated arms based on the first difference or the second difference when the third state where the supply of power is resumed is reached. A multi-arm robot that determines whether or not a return operation to return to the initial position is permitted and notifies the result of the determination using the notification unit. The double-arm robot according to claim 2,
When the return operation is permitted when the control unit is in the third state in which the supply of power is resumed, the control unit determines a motion candidate permitted for the plurality of multi-joint arms. A multi-arm robot that uses the notification unit to notify the operator to select. The double-arm robot according to claim 3,
The control unit determines whether the return operation is permitted when the supply of power is resumed and the state is the third state. The first difference or the second difference is less than a first threshold value. Judgment by whether or not,
The controller is
(A) When the supply of power is resumed and the third state is reached, the first difference or the second difference is less than the first threshold and smaller than the first threshold. If the threshold value is less than or equal to 2, the return operation is allowed according to one preselected operation mode,
(B) When the first difference or the second difference is less than the first threshold and exceeds the second threshold when the supply of power is resumed and the third state is reached. Is a multi-arm robot that uses the notification unit to notify the operator of the multi-arm robot of the motion candidates allowed for the plurality of articulated arms. The multi-arm robot according to any one of claims 1 to 4,
The controller is
Each time the supply of power is resumed, the cumulative difference is calculated by accumulating the first difference or the second difference,
A multi-arm robot that notifies a warning using the notification unit when the cumulative difference exceeds a predetermined allowable value. A control device for a multi-arm robot having a plurality of multi-joint arms and a position detector for detecting the position of each multi-joint arm, the control device comprising:
(I) a first position of each multi-joint arm in a second state in which power supply to the multi-arm robot is stopped from a first state in which power is supplied to the multi-arm robot; A first difference from a second position of each articulated arm when the third state is reached when power supply is resumed from the second state;
Or
(Ii) Based on a predetermined third position of each articulated arm and a second difference between the second position,
A control apparatus for a multi-arm robot, which uses a notification unit to notify an operation permitted for the plurality of articulated arms when the power supply is resumed in the third state.

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