JP7131323B2 - Control device - Google Patents

Description

The present invention relates to a robot controller having a manipulator that grips an object to be gripped.

2. Description of the Related Art In recent years, various researches and developments have been made on control methods for robots having manipulators that grip objects to be gripped. Position control, impedance control, which is a type of force control, and compliance control, which is a simplified form of impedance control, are generally known as such control methods. Japanese Patent Laid-Open No. 2002-200001 discloses a technique for dynamically changing compliance control parameters to soften the impact.

JP 2011-104740 A

However, with the technology disclosed in Patent Document 1, misrecognition occurs due to the inability to distinguish between external forces and other forces (self-weight and inertia force when accelerating), and it is possible that the grasped object cannot be approached with high accuracy. have a nature. On the other hand, if the robot is controlled by position control, it is possible to accurately approach the object to be grasped, but even if excessive force (impact) is applied to the manipulator, it cannot be controlled to soften the impact. As a result, there is a possibility that the manipulator will destroy the obstacle that receives the impact, or that the manipulator will be damaged by the impact.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and provides a control device capable of softening the impact when it is applied to the manipulator and accurately approaching the object to be grasped. The purpose is to

A control device according to the present invention is a control device for a robot having a manipulator that grips an object to be gripped, wherein the control mode for controlling the robot is a first control mode that controls by position control and a control mode that controls by impedance control. first, the first control mode is set to cause the robot to start gripping the object to be gripped, and an impact detection unit detects an impact exerted on the manipulator. When an impact is detected, the control mode is switched to the second control mode and the robot is operated to avoid the impact in the direction of softening the impact. , and causes the robot to attempt to grip the gripping object again.

First, by starting the gripping operation of the gripping target in the first control mode, it is possible to accurately approach the gripping target when there are no obstacles around the gripping target. Further, by switching to the second control mode when an impact is applied to the manipulator, the impact applied to the manipulator can be softened. Furthermore, by switching to the first control mode after the avoidance in the direction of softening the impact is completed, it is possible to accurately approach the grasped object in a second attempt to grasp the grasped object.

Further, when a predetermined position of the manipulator is separated from the grasped object by a predetermined distance or more, grasping of the grasped object in the first control mode may be attempted again. When switching to the first control mode and attempting to grip the gripping object again in a state where the manipulator is close to the gripping object, there is a high possibility that the manipulator will collide with the impacted obstacle again and receive an impact. By reattempting to grip the gripping object when the gripping object is separated from the gripping object by a predetermined distance or more, the success rate of the second attempt can be increased.

Furthermore, coordinate information of a predetermined position of the manipulator at the time of impact may be stored, and the coordinate information may be taken into account when attempting to grip the gripping object again after avoidance is completed. . In this way, the success rate of the current grasping attempt can be increased by utilizing the information obtained in the previous grasping attempt.

ADVANTAGE OF THE INVENTION According to this invention, when an impact is applied to a manipulator, an impact can be softened, and an approach to an object to be grasped can be accurately performed.

1 is an external perspective view of a robot to which a control device according to this embodiment is applied; FIG. It is a block diagram which shows the control structure of a robot. 4 is a flowchart for explaining a flow of processing for controlling an operation of a robot to grip an object to be gripped in a control device; FIG. 4 is a schematic diagram showing an example of processing in step S103 of FIG. 3; FIG. FIG. 4 is a schematic diagram showing an example of processing for determining whether or not avoidance has been completed in step S104 of FIG. 3 ; It is a schematic diagram which shows the example which comprised the control apparatus separately from the robot.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described through embodiments of the invention, but the invention according to the scope of claims is not limited to the following embodiments. Moreover, not all the configurations described in the embodiments are essential as means for solving the problems. For clarity of explanation, the following descriptions and drawings are omitted and simplified as appropriate. In each drawing, the same elements are denoted by the same reference numerals, and redundant description is omitted as necessary.

First, the configuration of a robot to which the control device according to this embodiment is applied will be described.
FIG. 1 is an external perspective view of a robot 100 to which a control device according to this embodiment is applied. In the figure, the xy plane is the running plane of the robot 100, and the z-axis plus direction indicates the zenith direction. As shown in FIG. 1, the robot 100 is roughly composed of a carriage 110 as a moving mechanism for moving on a running surface, a main body 120, and a manipulator 230 as a gripping mechanism. Manipulator 230 includes a robot arm 130 and a robot hand 140 .

The truck portion 110 supports two drive wheels 111 and one caster 112, each of which is in contact with the running surface, in a cylindrical housing. The two driving wheels 111 are arranged so that their rotation axes are aligned with each other. Each driving wheel 111 is independently rotationally driven by a motor (not shown). The caster 112 is a driven wheel, and is provided so that a turning shaft extending vertically from the truck portion 110 is separated from the rotation axis of the wheel and supports the wheel, and follows the moving direction of the truck portion 110. do. For example, if the two driving wheels 111 are rotated in the same direction at the same rotational speed, the robot 100 goes straight, and if it is rotated in the opposite direction at the same rotational speed, the robot 100 passes through the center of the two driving wheels 111 of the carriage 110. Rotate around a vertical axis.

The main body 120 supports the robot arm 130 and has a display panel 123 forming part of the user interface. The display panel 123 is, for example, a liquid crystal panel, and displays the character's face and presents information about the robot 100 . The display panel 123 has a touch panel on its display surface, and can receive an instruction input from the user.

The main body 120 has an environmental camera 121 at a position where it can overlook the forward environmental space including the operating range of the robot arm 130 and the robot hand 140 . The environmental camera 121 includes an imaging device such as a CMOS image sensor and an image data generation unit, and outputs image data generated by imaging the environmental space in front. A control unit 190 is also provided in the body portion 120 . The control unit 190 includes a control section, memory, etc., which will be described later.

A robot arm 130 supported by the body portion 120 has a plurality of links, for example, two links as shown in the figure, and joint portions 131 (wrist joints, elbow joints, shoulder joints, etc.) rotatably connecting the links. ) can take various postures by driving the actuators provided in. Each joint 131 is provided with a reduction mechanism. A robot hand 140 is connected to the tip of the robot arm 130 , and the entire robot hand 140 can rotate around a pivot axis parallel to the extending direction of the tip link of the robot arm 130 by driving the actuator.

A robot hand 140 at the tip of the robot arm 130 is provided with a hand camera 141 . The hand camera 141 includes an imaging device such as a CMOS image sensor and an image data generator, and outputs image data generated by imaging the space in front of the robot hand 140 . The robot hand 140 has a first finger 140a and a second finger 140b driven by an actuator provided at the tip. The first finger 140a and the second finger 140b move toward each other, as indicated by the dotted arrows, to grasp the object by pinching it.

FIG. 2 is a block diagram showing the control configuration of the robot 100. As shown in FIG. A control device 200 according to this embodiment is incorporated in the robot 100 . That is, the control device 200 is, for example, a CPU, and is stored in the control unit 190 (see FIG. 1) of the main body 120. FIG. The drive wheel unit 210 includes a drive circuit and a motor for driving the drive wheels 111 (see FIG. 1), and is provided on the truck portion 110 (see FIG. 1).

The robot arm 130 included in the manipulator 230 includes, in addition to the structure described using FIG. It has a sensor 134 and a force sensor 133 that detects the operating force (torque) of each joint 131 . Actuator 132 is, for example, a servo motor. The rotation sensor 134 is, for example, an encoder. The force sensor 133 is, for example, a torque sensor that detects torque of each joint 131 . The robot hand 140 included in the manipulator 230 has an actuator 142 that drives the first finger 140 a and the second finger 140 b (see FIG. 1), and a force sensor 143 that detects the operating force of the robot hand 140 .

The sensor unit 220 includes various sensors for detecting obstacles during movement and for detecting contact from the outside, and is distributed between the carriage 110 and the main body 120 (see FIG. 1). By sending a control signal to the sensor unit 220, the control device 200 drives various sensors and acquires their outputs. Sensor unit 220 includes an impact detection section 221 that detects an impact exerted on manipulator 230 .

The impact detection unit 221 detects an impact exerted on the manipulator 230 using the force sensor 133 of the robot arm 130 and the force sensor 143 of the robot hand 140 . Here, the impact being applied to manipulator 230 means a state in which a force equal to or greater than a predetermined threshold is being applied to manipulator 230 . Note that the impact detection unit 221 may be of any type as long as it can detect impact applied to the manipulator 230 . For example, the impact detection unit 221 may detect impact from waveform changes in current values of the actuator 132 of the robot arm 130 and the actuator 142 of the robot hand 140 . Moreover, the impact detection unit 221 may detect impact by a touch sensor installed at a predetermined position of the manipulator 230 . Here, the touch sensor is a pressure-sensitive sensor that turns ON when pressure equal to or higher than a predetermined pressure is received.

The environmental camera 121 is used to observe the forward environmental space including the operating range of the robot arm 130 and the robot hand 140 as described above, and performs imaging according to imaging instructions from the control device 200 . The environmental camera 121 delivers the generated image data to the control device 200 . The hand camera 141 is used to observe the space in front of the robot hand 140 as described above, and performs imaging according to imaging instructions from the control device 200 . Hand camera 141 delivers the generated image data to control device 200 .

The memory 240 is a nonvolatile storage medium such as a solid state drive. The memory 240 stores a robot control program for controlling the robot 100 as well as various parameter values, functions, lookup tables, etc. used for control.

The control device 200 controls the operation of gripping a gripping target in the robot 100 . That is, the control device 200 performs various calculations for grasping the grasped object, and transmits drive signals to the manipulator 230 and the driving wheel unit 210 based on the calculation results. The control device 200 has two control modes, a first control mode for controlling by position control and a second control mode for controlling by impedance control, as control modes for controlling the operation of gripping an object to be gripped in the robot 100. there is A force applied to the manipulator 230 is detected by the impact detector 221 .

In the first control mode, the manipulator 230 can be accurately approached to the position of the object to be grasped. However, in the first control mode, if the manipulator 230 is impacted by an obstacle or the like while approaching the grasped object, the manipulator 230 cannot be avoided so as to soften the impact. On the other hand, in the second control mode, when manipulator 230 receives an impact, manipulator 230 can be avoided so as to soften the impact. However, in the second control mode, the manipulator 230 cannot accurately approach the position of the object to be grasped. Therefore, in the control device 200 according to the present embodiment, the robot 100 controls the gripping operation of the gripping object by appropriately switching between the first control mode and the second control mode.

Next, the flow of processing in which the robot 100 grips an object to be gripped in the control device 200 will be described.
FIG. 3 is a flowchart for explaining the flow of processing in the control device 200 for controlling the action of the robot 100 gripping an object to be gripped. As shown in FIG. 3, first, the control mode is set to the first control mode, and the gripping operation of the gripping object is started (step S101).

After step S101, it is determined whether or not the impact detector 221 has detected an impact (step S102). If it is determined in step S102 that the impact detection unit 221 has detected an impact, the control mode is switched to the second control mode, and the robot 100 is operated to avoid the impact in a direction that softens the impact (step S103).

After step S103, it is determined whether or not the avoidance in the direction of softening the impact has been completed (step S104). If it is determined in step S104 that the avoidance in the direction of softening the impact has been completed, the control mode of the robot 100 is switched to the first control mode, and gripping of the gripping object is attempted again (step S105). Coordinate information of a predetermined position of the manipulator 230 at the time of detecting the impact in gripping the previous gripping object is stored in the memory 240 (see FIG. 2). Coordinate information may be taken into consideration. Here, the predetermined position of the manipulator 230 is the tip of the manipulator 230, for example. In this way, the success rate of the current grasping attempt can be increased by utilizing the information obtained in the previous grasping attempt.

If the impact detection unit 221 determines in step S102 that an impact has not been detected, it is determined whether or not the gripping object has been successfully gripped (step S106). If it is determined in step S106 that the gripping object has not been successfully gripped, the process returns to step S102. If it is determined in step S106 that the gripping object has been successfully gripped, the process ends.

Next, the avoidance processing in step S103 of FIG. 3 will be specifically described. FIG. 4 is a schematic diagram showing an example of the processing in step S103 of FIG. As shown in the upper part of FIG. 4, it is assumed that the robot hand 140 of the manipulator 230 tries to grip a cup W1 as an object to be gripped and bumps into a shelf W2 as an obstacle. At this time, the impact detector 221 (see FIG. 2) detects that the manipulator 230 is impacted. An attempt to bring the manipulator 230 closer to the cup W1 would increase the impact. Therefore, the control device 200 (see FIG. 2) switches the control mode to the second control mode, and operates the robot 100 so as to avoid in the direction D1 that softens the impact, as shown in the lower part of FIG.

Next, the process of determining whether or not avoidance has been completed in step S104 of FIG. 3 will be specifically described. FIG. 5 is a schematic diagram showing an example of the process of determining whether the avoidance in step S104 of FIG. 3 is completed. As shown in FIG. 5, the control device 200 (see FIG. 2) enters the first control mode when the predetermined position P1 of the manipulator 230 is separated from the cup W1, which is the object to be grasped, by a predetermined distance L1 or more. It switches and attempts to grip the gripping object again. Here, the predetermined position of the manipulator 230 is the tip of the manipulator 230, for example.

It should be noted that it may be determined that the avoidance is completed when the impact detection unit 221 no longer detects impact. Sometimes it is preferable to determine that avoidance has been completed. This is because when the manipulator 230 is close to the object to be grasped and the control mode is switched to the first control mode to attempt to grasp the object to be grasped again, the robot collides with the impacted obstacle (here, the shelf W2) again. This is because there is a high possibility of receiving a shock. By reattempting to grip the gripping object when the gripping object is separated from the gripping object by a predetermined distance or more, the success rate of the second attempt can be increased.

As described above, in the control device 200 according to the present embodiment, the robot 100 is controlled in the first control mode until the impact detection unit 221 detects an impact, and when the impact detection unit 221 detects an impact, the impedance control is performed. Dodge in the direction to soften the impact by switching. Then, after the avoidance is completed, the control mode is switched to the first control mode, and gripping of the gripping object is attempted again. First, by starting the gripping operation of the gripping target in the first control mode, it is possible to accurately approach the gripping target when there are no obstacles around the gripping target. Moreover, when the manipulator 230 is subjected to an impact, the impact can be softened by switching to the second control mode. Furthermore, by switching to the first control mode after the avoidance in the direction of softening the impact is completed, it is possible to accurately approach the grasped object in a second attempt to grasp the grasped object.

It should be noted that the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the scope of the invention. In the above embodiment, the configuration in which the control device is incorporated in the robot has been described, but the control device may be configured separately from the robot.

FIG. 6 is a schematic diagram showing an example in which the control device 200 is configured separately from the robot 100. As shown in FIG. As shown in FIG. 6, a control signal from control device 200 is transmitted to robot 100 via system server 500 connected to the Internet 600 . Robot 100 and control device 200 are connected to Internet 600 via wireless router 700 . Here, the network connecting the system server 500 is not limited to the Internet, and may be another network such as an intranet.

100 Robot 110 Carriage 111 Drive wheel 112 Caster 120 Body 121 Environmental camera 123 Display panel 130 Robot arm 131 Joint 132 Actuator 133 Force sensor 134 Rotation sensor 140 Robot hand 140a First finger 140b Second finger 141 Hand camera 142 Actuator 143 Force sensor 190 Control unit 200 Control device 210 Driving wheel unit 220 Sensor unit 221 Impact detector 230 Manipulator 240 Memory 500 System server 600 Internet 700 Wireless router

Claims (2)

A control device for a robot having a manipulator that grips an object to be gripped,
As control modes for controlling the robot, a first control mode for controlling by position control and a second control mode for controlling by impedance control are provided,
First, when the robot is set to the first control mode and the gripping operation of the gripping object is started by the robot, and an impact is detected by the impact detection unit for detecting impact exerted on the manipulator, the second control mode is set. by switching to the control mode of , causing the robot to evade in a direction that softens the impact, and storing the coordinate information of the predetermined position of the manipulator when receiving the impact;
After the avoidance in the direction of softening the impact is completed, the gripping of the gripping object is performed by switching to the first control mode and controlling the position of the manipulator based on the stored coordinate information. Try again , controller. 2. The control device according to claim 1, wherein when the predetermined position of the manipulator is separated from the gripped object by a predetermined distance or more, gripping of the gripped object in the first control mode is attempted again.

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