JPS6368906A - Controller for industrial robot - Google Patents

Abstract

PURPOSE:To perform acceleration smoothly without any defect in operation by controlling a current control value by a torque controller which limits an acceleration torque value with the outputs of an acceleration torque arithmetic unit and a central arithmetic processor. CONSTITUTION:The acceleration torque arithmetic unit 17 reads a speed pattern out of a speed pattern controller and calculates and outputs acceleration torque based upon it to the torque controller 16. Consequently, the output of the controller 16 is so controlled that the limit value of a current to a servomotor 4 is a maximum permissible current value. Then, when torque needs to be limited, the current is limited to a preprogrammed value under the command of the central arithmetic unit 1. This unit supplies such a current that there is no deficiency in acceleration torque to the servomotor even during operation such as insertion.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a control device for an industrial robot.

(Prior Art) FIG. 2 shows a block diagram of a control device for an industrial robot. The central processing unit 1 of the control device reads out a preprogrammed robot operation program and position information from the storage device 2 and outputs it to the speed pattern control device W3. The speed pattern control device 3 outputs a position command value an for each sampling time Δ associated with a predetermined speed pattern as shown in FIG. On the other hand, the rotational position of the servo motor 4 attached to the robot body is detected by a rotational position detector 5 and counted by a pulse counter 6 as position pulses. The deviation ΔEn=an−bn between the output bn from the pulse counter 6 for every Δ and the position command value an is input to the position deviation counter 7 and integrated.

The output from the position deviation counter 7 corresponding to this integrated value E=ΣΔB drives the servo motor 4 through the D/A converter 8 and the power amplifier 9, so that the integrated position deviation value E=O. controlled.

In this case, the rotation of the servo motor 4 is prevented for some reason, the positional deviation integrated value E increases, the positional deviation counter 7 overflows, and processing is performed such as stopping the robot as an abnormal state. However, in this case, the maximum torque is applied to the servo motor before an abnormality is detected, damaging the robot's gripping mechanism (hereinafter referred to as the hand) and the object being gripped, causing the production line to stop. For example, when the robot 20 is used to grip a part 21 with the hand 22 and insert it into the hole 24 of the target workpiece 23 as shown in Part 4, if the center positions of the hand 22 and the hole 24 are misaligned, the part 21 cannot be inserted. As a result, an overcurrent flows to the vertical axis drive servo motor, and the component 21 and the target work 23 are damaged.

To prevent this, the control device has the following functions. As described above, in FIG. 2, the current limiting device 10 is connected to the power amplifier 9 to prevent overcurrent to the servo motor 4, and normally the current limiting reference REF is input to the current limiting device 10 through the switching device 12. has been done. The output voltage of the DC constant voltage power supply 11 is set so that the current limit value becomes the maximum allowable current of the servo motor 4. When performing the above-mentioned insertion operation, the output voltage of the current limit setting device 13 is set to a current limit value that will not damage the hand 22, the component 21, and the workpiece 23, and the central calculation is performed during the insertion operation. The switching device 12 is switched by the output of the processing device 1, and the output of the current limit setting device 13 is changed to the current limit setting device 10.
Enter. In this state, the vertical axis of the robot 20 is driven. This prevents the hand 225 parts 21 and the workpiece 23 from being damaged. Further, when the insertion operation is obstructed and the positional deviation integrated value E of the positional deviation Carantuff exceeds the setting value of the setting device 14, the comparator 15 detects this and outputs an interrupt signal to the central processing unit 1.

As a result, the central processing unit 1 stops the operation of the robot and executes a pre-stored abnormality handling program.

(Problem to be solved by the invention) Conventional devices had the following problems.

■ If the strength of the hand or parts to be protected is relatively low and the current limit value is set low, the torque will be insufficient when accelerating the insertion operation, making it impossible to operate.

(2) If there are more than one type of parts or target workpieces to be inserted, but they have different strengths, it is necessary to variously change the current setting value, but it is difficult to do this automatically.

41 The present invention solves the above problems, changes the current limit value according to the strength of each part and workpiece even if the parts and workpieces to be protected change, and also generates the necessary torque when accelerating the insertion operation. The purpose is to provide a control device for industrial robots.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a storage device in which predetermined operation program information and position information are stored, and a central device for reading out the information stored in this storage device. an arithmetic processing unit; a speed pattern control device that is connected to the central processing unit and outputs position information of a point to be moved at predetermined time intervals based on predetermined speed pattern information; Rotational position information detection means for detecting;
positional deviation detection means for detecting and integrating the deviation between the position information of the point to be moved and the rotational position information of the drive motor; and a power supply means for driving the drive motor according to the output of the position deviation detection means. , a current control device that controls the output current of the power supply means, and when the position deviation detection means integrates a deviation of a predetermined value or more, outputs an interrupt signal that causes the central processing unit to execute an abnormality handling program. an acceleration torque calculation device that calculates acceleration torque according to the speed pattern from the speed pattern control device; and a comparison means for receiving the output of the acceleration torque calculation device and the central calculation The present invention is characterized in that it includes a torque control device that limits the value of acceleration torque based on the output of the processing device, and the torque control device controls the current limit value of the current limit device.

(Function) With this configuration, acceleration torque can be appropriately applied without causing malfunction, and work can be performed smoothly.

Furthermore, it is possible to easily change the current limit value in accordance with differences in the strength of the target workpieces.

(Example) An embodiment of the present invention will be described with reference to FIG.

Components that are the same as those in FIG. 2 are denoted by the same reference numerals, and explanations thereof will be omitted below. In FIG. 1, an acceleration torque calculation device 17 reads out a speed pattern from a speed pattern control device, calculates an accompanying acceleration torque, and outputs it to a torque control device 16. For example, if the speed pattern is a trapezoidal pattern as shown in FIG. 3, the acceleration torque will be a pattern as shown in the same figure. The torque control device 16 outputs a current limit value according to the output of the acceleration torque calculation device 17 during robot acceleration operation.

Thereby, the output of the torque control device 16 is controlled so that the current limit value to the servo motor 4 becomes the maximum allowable current value. When torque limitation is necessary, for example in the case of an insertion operation as shown in FIG. 4, the current is limited to a preprogrammed value in accordance with a command from the central processing unit 1.

For example, in FIG. 4, the robot is first moved to the position shown by the solid line, and the hand 22 is moved with the current limit value lowered.
is lowered and the part 21 is inserted into the hole 24. At this time, the expected minimum distance between the insertion operation start point and the target workpiece Xm1n
must be larger than the amount of movement S in the robot acceleration region shown in FIG.

If the relative positions of the hole 24 and the component 21 are misaligned as shown in FIG. hand 22, part 21, workpiece 23.
damage is prevented. Furthermore, if the robot movement is disturbed, the count value of the position deviation counter 7 increases, and the comparator 15 increases.
detects an abnormality and sends an interrupt signal to the central processing unit 1. The function of interrupting the robot operation and executing the abnormality handling program is the same as before.

According to this embodiment, it is possible to supply current to the servo motor without causing insufficient acceleration torque even during operations such as insertion.

〔Effect of the invention〕

As explained above, according to the present invention, (1) the necessary current can be supplied to the servo motor during acceleration, so that smooth acceleration can be achieved without causing malfunction. Furthermore, the count value of the position deviation counter increases due to insufficient acceleration torque, and an abnormal state can be detected by the evacuation control function.

■ The current limit value can be easily changed by programming, so even when working with multiple parts or workpieces with different strengths, you can set an appropriate current limit value and prevent damage.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram according to an embodiment of the present invention, and FIG.
FIG. 3 is a block diagram of a conventional configuration, FIG. 3 is a diagram showing the relationship between speed and torque of a servo motor for driving a robot, and FIG. 4 is a diagram for explaining the robot insertion operation. 1... Central processing unit 2... Storage device 3
... Speed pattern control device 4 ... Servo motor 5 ... Rotation position detector 7 ... Position deviation counter 9 ... Power amplifier 10 ... Current limiting device 15 ... Comparator 16 ... Torque control device 17 ... Acceleration torque calculation device 20 ... Robot 21 ... Parts 22 ... Hand 23 ... Target workpiece 24 ... Hole agent Patent attorney Nori Chika Ken Yudo Mitsumata Kobun Figure 4

Claims (1)

[Claims] A storage device in which predetermined operating program information and position information are stored; a central processing unit that reads out information stored in the storage device; and a predetermined processing unit connected to the central processing unit. a speed pattern control device that outputs positional information of a point to be moved every predetermined time based on the speed pattern information of; a rotational position information detection means that detects rotational position information of a drive motor as a control target;
positional deviation detection means for detecting and integrating the deviation between the positional information of the point to be moved and the rotational positional information of the drive motor; and a power supply means for driving the drive motor in accordance with the output of the positional deviation detection means; A current limiting device that limits the output current of the power supply means and the position deviation detection means output an interrupt signal that causes the central processing unit to execute an abnormality handling program when the deviation is greater than or equal to a predetermined value. A control device for an industrial robot, comprising: an acceleration torque calculation device that calculates acceleration torque according to a speed pattern from the speed pattern control device; 1. A control device for an industrial robot, comprising: a torque control device that limits the value of acceleration torque based on the output of a processing device; and the torque control device controls a current limit value of the current limit device.