JP2017087341A - Robot system and teaching device for robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot system and a teaching device for a robot capable of easily performing direct teaching even when the weight of a robot arm is increased.SOLUTION: A robot system 100 includes teaching means (teaching button 30) to which a movement point of a robot arm 12 is taught by moving the robot arm 12 by a hand of a teacher and which provides a controller 20 with the teaching data. A balance weight 40 for cancelling the weight of the robot arm 12 acting on a movement system of the robot arm 12 is additionally included in the movement system of the robot arm 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a robot system and a robot teaching apparatus.

  In a conventional robot system, there is direct teaching that teaches a moving point of a robot arm by moving a robot arm, which is freed by turning off motor excitation, by a teacher's hand.

  In this direct teaching, the teacher can easily move the robot arm. However, if the motor is free when the tool or workpiece is heavy or the robot arm is under its own weight, the robot arm falls due to gravity, and thus cannot be put into practical use.

  Therefore, as described in Patent Document 1, as a conventional robot system, a robot arm that supports a tool or a workpiece against gravity, a sensor that detects torque applied to a motor shaft of a motor that moves the robot arm, A torque signal input unit that captures the sensor output as a torque value, and a control unit that causes the torque value input to the torque signal input unit to follow the command torque value. There is a configuration in which a counter torque is applied to the motor shaft to achieve a balance.

Japanese Patent Laid-Open No. 5-192885

However, the robot system described in Patent Document 1 has the following problems.
(1) The torque command value during direct teaching is set to the required torque to hold the robot arm at the position immediately before switching to direct teaching against the weight of the robot arm. An operation for adding and subtracting a minute torque for moving the arm is always required, and the drive control of the motor becomes complicated.

  (2) The greater the weight of the robot arm, the larger the torque control unit that drives the motor, so the motor response to small torque input values decreases, and the teacher responds to the minute torque that moved the robot arm. The drive control of the power motor becomes difficult.

  (3) The motor must always output the necessary torque to counter the weight of the robot arm during normal operation (non-direct teaching) and direct teaching. Therefore, the lift capacity of the robot arm by the motor is reduced to a value obtained by subtracting the necessary torque to counter the weight of the robot arm from the allowable torque of the motor (the maximum torque that can be used when the motor is operated).

  (4) The robot arm may fall when the motor becomes uncontrollable or loses the brake function.

  An object of the present invention is to provide a robot system and a robot teaching apparatus that can easily and directly teach even when the robot arm is heavy.

  The invention according to claim 1 is a robot system comprising: a robot including an actuator; a robot arm moved by the actuator; and a controller that controls the movement of the robot arm by driving the actuator. By moving the robot arm by the teacher's hand, the moving point of the robot arm is taught, the teaching means for supplying the teaching data to the controller, and the weight of the robot arm acting on the moving system of the robot arm. Is added to the movement system of the robot arm.

  The invention according to claim 2 is the invention according to claim 1, wherein the balance weight is further added to a driving force transmission system for a robot arm by an actuator.

  The invention according to claim 3 has a robot arm that is moved by an actuator, the movement point of the robot arm is taught by moving the robot arm by a teacher's hand, and the teaching data is transmitted to the robot arm. In the robot teaching apparatus used for movement control, a balance weight that cancels the weight of the robot arm acting on the movement system of the robot arm is added to the movement system of the robot arm.

  According to a fourth aspect of the invention, in the third aspect of the invention, the balance weight is further added to a driving force transmission system for a robot arm by an actuator.

(Claims 1 and 3)
(a) A balance weight that offsets the weight of the robot arm (including the weight of the hand and end effector) is added to the movement system of the robot arm (the system that moves together with the movement of the robot arm). Therefore, during direct teaching, it is not necessary to drive and control an actuator such as a motor or to perform a brake operation, and the robot arm can be easily moved to an arbitrary position by a teacher's hand regardless of the weight of the robot arm. And you can stop even if you let go.

  (b) At the time of direct teaching, it is not necessary to drive and control an actuator such as a motor according to the above (a), and it is only necessary to read position information of the actuator such as a motor as teaching data.

  (c) Even if the weight of the robot arm increases, the teacher can move the robot arm with direct teaching by reducing the movement resistance such as sliding resistance generated in the movement system of the actuator such as a motor sufficiently. Direct teaching with a minute force of a teacher's hand is possible without reducing the response of an actuator such as a motor to a force.

  (d) When an actuator such as a motor controls the movement of the robot arm during normal operation, it is not necessary to output a necessary torque against the weight of the robot arm. Therefore, the lifting capacity of the robot arm by the actuator such as a motor can be maximized to the allowable torque of the actuator such as the motor (maximum torque that can be used when operating the actuator such as the motor). The robot arm can be moved and controlled by an actuator such as a small capacity motor.

  (e) Even if an actuator such as a motor becomes uncontrollable during normal operation or loses the brake function, the weight of the robot arm is offset by the balance weight, and the robot arm cannot fall.

(Claims 2 and 4)
(f) The balance weight can be added to a driving force transmission system (a system for transmitting the driving force of the motor to the robot arm) for the robot arm by the motor.

FIG. 1 is a schematic diagram showing a robot system. FIG. 2 is a schematic diagram showing a modification of the robot system.

  A robot system 100 shown in FIG. 1 includes a robot 10 and a controller 20, and performs a part machining operation and a transfer operation.

  The robot 10 includes a motor 11 and a robot arm 12 that is moved by the motor 11. The robot 10 includes, for example, a driving vehicle 13A fixed to the output shaft of the motor 11, a driven vehicle 13B disposed away from the driving vehicle 13A, and a transmission belt 13C wound around the driving vehicle 13A and the driven vehicle 13B. And a driving force transmission system 13 for the robot arm 12, and a base portion 12 </ b> A of the robot arm 12 is connected to an intermediate portion of a transmission belt 13 </ b> C constituting the driving force transmission system 13.

  In the robot 10, an end effector such as a hand for gripping a tool or a workpiece or a camera used for visual inspection is attached to a flange 12 </ b> B that is a tip portion of the robot arm 12.

  The robot 10 has a rotation angle detection sensor 11 </ b> A and can output a motor rotation position signal of the motor 11. As the rotation angle detection sensor 11A, for example, an encoder connected to the output shaft of the motor 11 can be employed.

  The controller 20 includes a motor drive control unit 21 that drives and controls the motor 11 to control the movement of the robot arm 12, and receives a motor rotation position signal output from the rotation angle detection sensor 11 </ b> A of the motor 11. The unit 22 is provided. The controller 20 includes a memory 23 in which various control programs for automatically controlling the robot arm 12 of the robot 10 are recorded, including a control program used for direct teaching described later.

  The controller 20 includes a robot operation unit 24 as an accessory. When an operator selects an operation program of the robot 10 recorded in the memory 23 using the robot operation unit 24 during normal operation of the robot 10, the robot arm specified by the memory 23 in the operation program is selected. A motor rotation position command to be given to the motor 11 corresponding to each of the 12 movement points is set in the motor drive control unit 21. Thereby, the motor drive control unit 21 feedback-controls the rotation angle position of the motor 11 so that the motor rotation position signal transferred from the motor rotation position detection unit 22 follows the motor rotation position command.

  Hereinafter, direct teaching of the robot arm 12 in the robot 10 will be described.

  The robot system 100 includes a teaching button 30 as a teaching means attached to the controller 20, and the weight of the robot arm 12 (robot) acting on the moving system of the robot arm 12 (the system that moves with the movement of the robot arm 12). A balance weight 40 on which the weight of the arm 12 is added to the weight of the robot arm 12 plus the weight of the hand and end effector attached to the flange 12B of the robot arm 12 is added to the moving system of the robot arm 12.

  Specifically, the balance weight 40 is added to the transmission belt 13 </ b> C constituting the driving force transmission system 13 for the robot arm 12 by the motor 11. However, the balance weight 40 is not limited to the one directly added to the driving force transmission system 13 of the motor 11 from the motor 11 to the robot arm 12, but is wound around the pulley 14 as shown in FIG. It may be connected to the other end of the wire 15 connected to the base 12A of the robot arm 12 or the like. The other end of the wire 15 to which the balance weight 40 is connected constitutes a system that moves with the movement of the robot arm 12 (a movement system of the robot arm 12).

  However, in the robot system 100, when the operator who is a teacher selects the direct teaching program recorded in the memory 23 using the teaching button 30 when the robot 10 is directly teaching, the motor 11 Is turned off (brake is released) and the robot arm 12 is moved along a predetermined path by the teacher's hand. Each time 30 is turned on, one or more continuous movement points of the robot arm 12 are continuously taught as teaching data. That is, when the ON signal of the teaching button 30 is transmitted to the motor drive control unit 21 of the controller 20, the motor drive control 21 is used as a motor rotation position signal of the motor 11 corresponding to the moving point of the robot arm 12 at that time. Then, the motor rotation position signal transferred from the motor rotation position detection unit 22 is captured and recorded in the memory 23 as teaching data. When a series of movement processes along the above-mentioned predetermined movement path of the robot arm 12 is completed and teaching data for all the movement points of the robot arm 12 is fetched, the teaching data is updated for the normal operation of the robot 10. Thus, the movement point of the robot arm 12 in the operation program is defined. As a result, the direct teaching program is terminated by an operation performed by the teacher on the robot operation unit 24.

Therefore, according to the present Example, there exist the following effects.
(a) A balance weight 40 that offsets the weight of the robot arm 12 (including the weight of the hand and the end effector) is added to the movement system of the robot arm 12 (a system that moves as the robot arm 12 moves). Therefore, during direct teaching, it is not necessary to drive and control the motor 11 or to operate the brake, and the robot arm 12 can be easily moved to an arbitrary position by a teacher's hand regardless of the weight of the robot arm 12. And you can stop even if you let go.

  (b) At the time of direct teaching, it is not necessary to drive and control the motor 11 according to the above (a), and it is only necessary to read the position information of the motor 11 as teaching data.

  (c) Even if the weight of the robot arm 12 is increased, by reducing the movement resistance such as the sliding resistance generated in the moving system of the motor 11 sufficiently, the teacher can move the robot arm 12 along with direct teaching. The direct teaching by the minute force of the teacher's hand is possible without reducing the response of the motor 11 to the force.

  (d) The motor 11 does not need to output a necessary torque to counter the weight of the robot arm 12 when the robot arm 12 is controlled to move during normal operation. Therefore, the lifting capacity of the robot arm 12 by the motor 11 can be fully utilized up to the allowable torque of the motor 11 (maximum torque that can be used when the motor 11 is operated). The robot arm 12 can be moved and controlled by a small capacity motor 11.

  (e) Even if the motor 11 becomes uncontrollable during normal operation or loses the brake function, the weight of the robot arm 12 is offset by the balance weight 40, and the robot arm 12 cannot fall. .

  In the present invention, an articulated robot having a plurality of motors having a plurality of axes and corresponding to each axis, and a plurality of robot arms moved by each motor, and driving control of the plurality of motors. Thus, the present invention can be applied to a robot system having a controller for controlling the movement of each robot arm. In such an articulated robot teaching device, each motor is de-energized (brake is released) to make it free, and a robot arm located at the forefront to which a hand or an end effector is attached is placed by a teacher's hand. By moving, the moving point of each robot arm is taught, and teaching means for supplying the teaching data to the controller is provided. Each balance weight that cancels the weight of the robot arm acting on the movement system of each robot arm is added to the movement system of each robot arm (including a driving force transmission system for each robot arm by a motor). Become a thing.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. For example, as the teaching button 30 as the teaching means, a foot switch, a limit switch, a proximity switch, an optical switch, and the like can be adopted in addition to a hand switch. The display button 30 can also be replaced with a timer that can capture the motor rotation position signal of the motor 11 as display data at regular intervals. These teaching means can be incorporated in the controller 20.

  The actuator that moves the robot arm of the robot to which the present invention is applied is not limited to a rotary motor, may be a linear motor, is not limited to an electric motor, may be a hydraulic drive motor, is not limited to a motor, and is a fluid pressure cylinder or the like. It may be composed of

  According to the present invention, it is possible to provide a robot system and a robot teaching apparatus that can easily perform direct teaching even when the weight of the robot arm is large.

DESCRIPTION OF SYMBOLS 10 Robot 11 Motor 11A Rotation angle detection sensor 12 Robot arm 13 Driving force transmission system 20 Controller 21 Motor control part 22 Rotation position detection part 23 Memory 30 Teaching button (teaching means)
40 Balance weight 100 Robot system

Claims (4)

A robot comprising an actuator and a robot arm moved by the actuator;
In a robot system having a controller that controls the movement of the robot arm by driving the actuator,
By moving the robot arm by the teacher's hand, the moving point of the robot arm is taught, and teaching means for supplying the teaching data to the controller is provided.
A robot system comprising a balance weight for canceling the weight of the robot arm acting on the robot arm moving system, added to the robot arm moving system.   The robot system according to claim 1, wherein the balance weight is added to a driving force transmission system for a robot arm by an actuator. Having a robot arm moved by an actuator;
In the robot teaching apparatus, the moving point of the robot arm is taught by moving the robot arm by a teacher's hand, and the teaching data is used for controlling the movement of the robot arm.
A robot teaching apparatus, wherein a balance weight that cancels the weight of the robot arm acting on the robot arm moving system is added to the robot arm moving system.   The robot teaching apparatus according to claim 3, wherein the balance weight is added to a driving force transmission system for a robot arm by an actuator.

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