JPH0276697A - Robot controlling device - Google Patents

Abstract

PURPOSE:To make proper control of a robot by furnishing a control part to perceive accurately the position of each joint on the basis of signal from a pulse encodereven when the supply voltage has momentarily stopped or abnormally dropped. CONSTITUTION:Each servo motor 11 is driven by a control part 3 on the basis of command and the output value of a corresponding counter 6 and stopped in conformity to No.1 abnormality signal, and the output value of each counter 6 at this time is written in a memory. On the basis of No.2 abnormality signal the control part 3 also checks whether writing-in of each counter output value into memory 4 has occurred, and if yes, a robot body 20 will not make return motion to the point of origin after the voltage of a DC power supply 1 is normalized, and if no, it makes the return motion after normalization. Further the function of the control part 3 itself is stopped on the basis of No.3 abnormality signal, and after the voltage is normalized, the output value of each counter 6 written in the memory 4 is read.

Description

[Detailed description of the invention] [Industrial application field]

The present invention is a device that drives each joint of a robot body based on a command by a servo motor equipped with a pulse encoder attached thereto, and in particular, even when the power supply voltage momentarily fails or abnormally drops, the position of each joint is controlled by pulses. The present invention relates to a robot control device that is accurately recognized based on signals from an encoder.

[Conventional technology]

In conventional robot control devices, the position of each joint of the robot body is generally recognized (detected) based on counting of pulse signals from a pulse encoder attached to a servo motor. In order to ensure accurate operation of the robot device, the origin positions of the joints are confirmed by the return-to-origin operation of the robot body at system startup or other necessary times.

[Problem to be solved by the invention]

As described above, in the conventional technology, in order to ensure accurate operation of the robot device, it is necessary to confirm the origin position of the joint by the origin return operation of the robot body at system startup or other necessary times. This return-to-origin operation becomes a very complicated procedure, especially when the robot device becomes complicated, and becomes a cause of hindering system operation rate, safety, and reliability. Furthermore, if the power supply voltage suddenly stops or drops abnormally and the robot continues to operate without being aware of this,
The origin deviation, that is, the joint position deviation, remains until the next return-to-origin operation is performed. This is a serious problem because it not only leads to the production of a large number of defective products, but also leads to secondary accidents. The object of this invention is to solve the problems of the conventional technology, and to enable a robot that can accurately recognize the position of each joint based on signals from the pulse encoder even when the power supply voltage is momentarily interrupted or abnormally dropped. The purpose is to provide a control device.

[Means to solve the problem]

In order to solve this problem, a robot control device according to the present invention is a device that drives each joint of a robot body based on a command by a servo motor attached thereto, and includes an internal power source for the device that is powered from a commercial power source. a counter that counts pulse signals from a pulse encoder attached to each of the servo motors; and a first abnormal signal when the output voltage of the DC power supply drops below a first predetermined value. and outputs a second abnormal signal when the output voltage of the DC power supply drops to a second predetermined value lower than the first predetermined value, and outputs a second abnormal signal when the output voltage of the DC power supply drops to the second predetermined value,
a voltage monitoring section that outputs a third abnormal signal when the voltage drops below a third predetermined value lower than the predetermined value; and a voltage monitoring section that outputs a third abnormal signal when the voltage falls below a third predetermined value that is lower than the predetermined value; While driving the motor, after stopping each of the servo motors by the first abnormal signal, the output value of each of the counters at that time is written, and the readable and written data does not indicate that power is supplied from the DC power supply. The output values of each counter are written in a storage unit that is held independently, and the second abnormality signal is used to check whether or not each counter output value has been written to the storage unit, and if “yes”, the robot main body is does not perform a return-to-origin operation, and if "no" causes the robot main body to perform a return-to-origin operation after the voltage of the DC power supply section is normalized, and further stops its own function in response to the third abnormality signal;
and a control unit that reads out the output values of the counters written in the storage unit after the voltage of the DC power supply unit is normalized.

[For use]

Each servo motor is driven by the control unit based on the output value of the corresponding counter and the command, and the first
It is stopped based on the abnormal signal, and the output value of each counter at that time is written into the storage section. In addition, the control unit
Based on the second abnormal signal, it is checked whether each counter output value has been written to the storage section. If "Yes", the robot body will not return to the origin after the voltage of the DC power supply section is normalized; After the voltage of the DC power supply unit becomes normal, the robot body performs a return-to-origin operation, and the function of the control unit itself is stopped based on the third abnormal signal, and after the voltage of the DC power supply unit becomes normal, the output values of each counter written in the memory unit are Read out.

【Example】

Embodiments of the robot control device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. In FIG. 1, the robot device schematically includes a robot control device 10 and a robot body 20. Regarding the robot control device 10, 1 is a DC power supply circuit, which is an internal power supply for the robot control device 10 connected to a commercial power source 8. Reference numeral 2 denotes a voltage monitoring circuit, which monitors abnormal drops in the output voltage of the DC power supply circuit and takes measures as described below. Reference numeral 3 indicates a control circuit, which is a main part of the robot control device 10. Reference numeral 4 indicates a battery. 5 is a drive circuit, which drives a servo motor 11 of the robot body 20, which will be described later, according to the output of the control circuit 3. 6 is a counter, which is a pulse encoder of the robot body 20, which will be described later. Pulse signals from 12 are differentially counted. 7 is a switch inserted between the commercial power supply 8 and the DC power supply circuit 1. The robot body 20 includes a joint 13 and a switch provided for the joint 13. A set of a servo motor 11 and a pulse encoder 12 attached to the servo motor 11 are representatively shown. Note that the number of positive and reverse pulse signals output from the pulse encoder I2 is differentially counted. By doing so, changes in the rotation angle (position) of the servo motor 11 and thus the joint 13 are recognized.Now, the control circuit 3 is supplied with power from the DC power supply circuit 1, and responds to commands from a setting device (not shown). A control signal is output to the drive circuit 5 based on the output value of the counter 6, and the position of the joint 13 is controlled according to the command K.Furthermore, when the commercial power supply 8 is out of power, the output voltage of the DC power supply circuit 1 is Since the voltage drops with a certain time constant, the voltage value in the process of dropping is detected by the voltage monitoring circuit 2, and three types of abnormal signals, which will be described in detail later, are outputted.This abnormal signal causes the control circuit 3 to The position of the joint 13 is maintained and predetermined processing such as storing its value is performed.
This will be explained with reference to the flowchart shown in the figure. Note that the numerical symbols attached to the circuit names and the like in the following explanation are those in FIG. 1. In step S1, the presence or absence of the first abnormality signal A1 from the voltage monitoring circuit 2 is determined, and if NO, the process goes straight to step S2, and if YES, the process moves to step S2. First abnormal signal A
I is output when the output voltage of the DC power supply circuit 1 becomes equal to or less than the first predetermined value ■1. Similarly, when the output voltage becomes equal to or less than the second predetermined value V2, which is lower than the first predetermined value ■1, the second predetermined value
When the output voltage of the abnormal signal A2 becomes equal to or less than the third predetermined value ■3 which is lower than the second predetermined value ■2, the third abnormal signal A3 is output. In step S2, the servo motor M is stopped, and in step S3, the output value D of the counter 6 (position data of the joint 13) at that time is written into the memory 4. Next, in step S4, when the output voltage of the DC power supply circuit 1 is normalized, the presence or absence of the normalization signal N output from the voltage monitoring circuit 2 is determined. If YES, the value is read out from the memory 4 in step S21, and the servo motor M is activated in step S22 to perform positioning based on the value. In other words, the servo motor is returned to the position before the voltage drop. Now, in step S4, when there is no normalization signal N, it is further determined in step S5 whether or not there is a second abnormality signal A2. If NO, the process returns to step S4, and if YES, the process proceeds to step S6. At step S6, it is determined that the previous value has been written to the memory 4 as l+! Approved, Y
If ES, state E is set in step S7, and if NO, state F is set in step S23. These states E and F determine whether or not a return-to-origin operation should be performed when the power supply voltage returns to normal later. Next, in step S8, the presence or absence of the normalization signal N is determined. If NO, the process proceeds to step S9; if YES, the value is read out in step S25; then, in step S26, the servo motor M is started, and positioning is performed based on the value. is performed and returns to its original state. In step S9, the presence or absence of the third abnormal signal A3 is determined;
If No, proceed to step S8; if YES, proceed to step S.
IO respectively. In step 310, control circuit C is stopped. This means that if the output voltage of the DC power supply circuit 1 falls below the third predetermined value ■3, the normal operation of the control circuit C is no longer guaranteed, so the function must be stopped before that happens to at least prevent malfunctions. do. Next, if there is a normalization signal N in step Sll, it is determined in step 312 whether the state is E or not. -Y E S, the control circuit C is activated in step S13, and then the previous step S25. It returns to its original state through S26. When the state is not E in step S12 (when the state is F),
and Y in the determination of the presence or absence of the normalization signal N in step 324.
In the case of ES, in step S27, treatment G, that is, a return-to-origin operation is performed, and then the original state is returned. In addition, step S
When the answer is No in 24, the process moves to the previous stage of step S9. As described above, in this robot control device 10, when the power supply voltage suddenly stops or abnormally drops, the measures to be taken will differ depending on the degree, but once the voltage returns to normal, it will automatically return to its original state. Moreover, the return-to-origin operation of the servo motor 11 can be suppressed to the minimum necessary, that is, only in the extremely rare case where the axis position of the servo motor 11 at the time of voltage drop is not written in the memory 4.

【Effect of the invention】

According to this invention, there are the following superior effects compared to the conventional technology. (1) Even if the power supply voltage stops momentarily or drops abnormally,
The position of each joint is accurately recognized, and based on this, accurate robot control is possible. Even if the joint positions are not stored for some reason, the joint positions will be recognized by returning the robot body to its origin after the voltage is normalized, and accurate movement will be guaranteed. (2) Since the encoder attached to the servo motor is an incremental type, it is simpler than an absolute type, and costs can be further reduced. (3) Since it is possible to reduce the number of times the return-to-origin operation is required, it is possible to improve the operating rate, safety, and reliability of the system, especially when the robot device is complex.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment according to the present invention, and FIG. 2 is a flowchart showing the operation of this embodiment. Code explanation: DC power supply circuit, 2: Voltage monitoring circuit, 3: Control circuit,
4: Memory, 5: Drive circuit, 6: Counter, 7: Switch, 8: Commercial power supply, 10: Robot controller, 11: Servo motor, 12: Pulse encoder, 13: Joint, 2
0: Robot body. %1 Kinuta

Claims (1)

[Claims] 1) In a device that drives each joint of a robot body based on a command by a servo motor attached thereto, a DC power supply unit as an internal power source for the device supplied with power from a commercial power source; attached to each of the servo motors. a counter that counts pulse signals from a pulse encoder; outputs a first abnormal signal when the output voltage of the DC power supply drops below a first predetermined value; outputting a second abnormal signal when the voltage drops below a second predetermined value that is lower than the predetermined value; a voltage monitoring unit that outputs an abnormality signal; a voltage monitoring unit that is supplied with power from the DC power supply unit and drives each of the servo motors based on the output value of each of the counters and the command; After stopping, the output values of each of the counters at that time are written to a storage unit that is writable and readable and in which the written data is retained regardless of the power supply from the DC power supply, and the second abnormality is detected. Check whether the output values of each of the counters have been written to the storage section according to the signal, and if "yes", the robot main body will not return to the origin after the voltage of the DC power supply section is normalized, and if "no", the DC After the voltage of the power supply section is normalized, the robot main body is caused to perform a return-to-origin operation, and further, its own functions are stopped by the third abnormality signal, and after the voltage of the DC power supply section is normalized, the robot body is caused to write in the storage section. a control unit that reads the output value of the counter;
A robot control device comprising: