JP2856253B2 - Robot brake control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motor control device for a robot, and particularly to a brake control device in the motor control device.

B. Summary of the Invention The present invention controls a brake control unit based on a positioning control unit command that controls a rotation position of a motor that drives a mechanism unit such as an arm that is an operation unit of a robot, and performs brake control of the motor. In such a robot controller, a high-performance, highly-reliable controller is detected by detecting the number of rotations of the motor and effectively operating the dynamic brake and the holding brake of the brake unit based on the detection signal. obtain.

C. Prior art Fig. 5 shows one of the motor control units in the robot controller.
The configuration of the axis is shown. In FIG. 5, 1 is a positioning control unit for controlling the position of a mechanical unit such as a robot arm, 2 is a servo amplifier which is a motor rotation drive unit, 3 is a rotary drive by a servo amplifier 2, and a mechanical unit such as a robot arm. Direct current (DC) servo motor as a power source to drive and operate the
Reference numeral 4 denotes a brake control circuit for stopping and controlling the rotation of the servomotor 3; 5, a pulse generator (hereinafter simply referred to as PG) as a position detector for detecting the rotational position of the servomotor 3; 6, a choke coil; It is.

The positioning control unit 1 receives a position detection signal from the PG 5 as an input, inputs a servo start command S2 signal and a speed command signal S1 to the servo amplifier 2, and outputs a brake control circuit 4
Input the brake release command signal S5. Servo amplifier 2
Receives the position detection signal from the PG 5, starts the servo motor 3, and inputs the servo abnormality signal S 3 to the positioning control unit 1. The brake control circuit 4 receives a brake release command signal S5 from the positioning control unit, inputs a brake abnormality signal S4 to the positioning control unit 1, and controls the brake 7.

The transfer signals between the positioning control unit 1, the servo amplifier 2, and the brake control circuit 4 are interlocked at the timing shown in FIG. FIG. 6A shows the brake release command signal S5, and FIG.
6 (C) shows a brake abnormality signal S4, FIG. 6 (D) shows a servo abnormality signal S3, and FIG. 6 (E) shows a speed instruction signal S1.

FIG. 7 shows a more detailed configuration of the conventional brake control circuit 4, and 8 shows an AC power supply (AC power supply) via a fuse 9.
, A rectifier connected to, a brake excitation circuit, and a fuse disconnection detection circuit. 12 is a timer circuit that receives a brake release command signal S5 from the positioning control unit as an input, and 13 is an interlock logic circuit that receives the brake release command signal S5 and the timer-on signal S6 of the timer circuit 12 as inputs, and outputs a brake abnormality signal S3 And a brake release signal S8 is output. Numeral 14 denotes a dynamic brake circuit which performs dynamic braking of the servo motor 3 based on a dynamic brake on signal S9 from the interlock logic circuit 13.

The brake control circuit shown in FIG. 7 controls the brake at the timing shown in FIG.
8 (A) shows the operation timing of the brake release command signal S5, FIG. 8 (B) shows the servo start command signal S2, FIG. 8 (C) shows the timer on signal S6, and FIG. ) Shows a dynamic brake operation command signal S8, FIG. 8 (E) shows a brake excitation command signal S9, and FIGS. 8 (F) and (G) show a motor rotation speed.

D. Problems to be Solved by the Invention Mechanical brakes used in industrial robots are
If the brake is applied while the motor is rotating, an excessive peak torque is generated on the motor shaft instantly when the brake is applied, which may cause a breakage in a speed reducer or the like. This peak torque tends to increase as the braking torque during normal braking increases. Therefore,
Generally, a holding brake (a braking force of 0.8 to 1.0 times the rated motor torque) is used without using a braking brake having a large braking torque (a braking force that is 2 to 3 times the rated motor torque).

However, when a holding brake is used for an industrial robot, the following problem remains.

(1) Although the peak torque at the moment when the brake is applied can be suppressed, the stopping time of the motor becomes longer because the braking torque in the steady state is small.

(2) If the brake is used while the motor is rotating at a high speed, the brake shoe will wear quickly and the durability will be significantly deteriorated.

 There were problems such as.

In order to solve the above problem, FIGS.
As shown in the figure, when a brake application command is input to the brake control circuit (when the brake release command S5 is released), a certain time Td ₁ set by the timer 12, that is, the timer operation time Tm It is braked by the dynamic braking (electrical braking), after the expiration of the timer set time Td _1, and a sequence to introduce a holding brake.

Thereby, when the brake application command signal is input to the brake control circuit while the motor is rotating, first, the motor is controlled by the dynamic brake,
When the motor speed is sufficiently reduced, the mode is switched to the holding brake (FIGS. 8C and 8D). However, in this sequence, when a brake application command is input in a state where the motor 3 is stopped or rotating at a low speed, the dynamic brake is hardly applied, so that a mechanism such as a robot arm (arm) or the like is used. Due to the load of its own weight, it falls for a while in the direction of gravity during the operation time of the dynamic brake (during the operation time of the timer 12) as shown in FIG. 8 (G), and stops after the holding brake is applied.

An object of the present invention is to solve the above-described problems and to provide a control device that does not fall in the direction of gravity even when a brake application command is input to a brake control circuit in a state where an operating unit of a robot is stopped. And

E. Means for Solving the Problems The present invention, in order to solve the above-mentioned problems, a motor as a power source for driving and operating a mechanism unit operated by a robot,
A motor rotation drive unit that drives the motor to rotate, a positioning control unit that controls the rotation drive unit to control the rotation position of the motor by using a rotation position detection signal of the motor as an input, and a command from the positioning control unit.
In a robot brake control device including a brake control unit that controls a brake unit having a dynamic brake and a holding brake for the motor, the brake control unit includes a timer circuit that operates based on a brake release command from the positioning control unit. An interlock logic circuit that outputs a command signal for causing the brake unit to perform a dynamic operation or a holding brake operation based on an operation signal of the timer circuit and the brake release command; and an output signal of the interlock logic circuit. An operating dynamic brake circuit and a holding brake excitation circuit; and an induced voltage of the motor is detected. When the induced voltage is equal to or higher than a predetermined threshold level, a logic signal “1” is input to the interlock logic circuit. A motor rotation speed detection circuit for inputting a logical signal "0" when the level is equal to or lower than a threshold level. Turn off the start command signal,
Means for operating the dynamic brake circuit by the output signal of the interlock logic circuit to operate the dynamic brake of the brake unit when the timer circuit is operating and the output signal of the motor detection circuit is a logical signal "1" When the brake release command signal is a logic signal “0”, the start command signal from the positioning control unit to the rotation drive unit is turned off, the timer circuit is operating, and the output of the motor rotation speed detection circuit is a logic signal. Means for disabling the dynamic brake and operating the holding brake of the brake unit in response to an output signal of the motor speed detection circuit when the signal is "0".

F. Function When the rotation speed of the motor becomes lower than the rotation speed of the threshold level due to the dynamic brake, the brake is promptly switched to the holding brake. When a brake application command is input while the motor is stopped, the dynamic brake is not operated and the holding brake is applied immediately. If the dynamic brake is not effective for some reason and the rotation speed of the motor does not fall below the threshold level even after the timer set time has elapsed, the holding brake is forcibly applied to stop the motor.

G. Embodiment An embodiment of the present invention will be described below with reference to FIGS.

The major difference between the brake control device of this embodiment and that of FIG. 5 is that a motor rotation detection circuit 15 is added. The motor detection circuit 15 outputs a high-level signal (logic 1) as a motor operation signal when the induced voltage of the motor is higher than a predetermined threshold level, and a low-level signal when the induced voltage is lower than the threshold level. It has a function of outputting (logic 0) to the interlock logic circuit 13.

The motor rotation detection circuit 15 is a dynamic brake circuit
14 and the brake signals S11a and S11b from the motor 3 are input, and the motor operation detection signal S12 is input to the interlock logic circuit 13.

Next, the operation of the brake control device having the above configuration will be described.

After the brake release command signal S5 switches from high level to low level (after the brake application command is input),
When the motor operation S12 of the motor rotation detection circuit 15 is at a high level (logic 1) and the timer 12 is operating, dynamic braking is performed, and the motor operation detection signal S12 of the motor rotation detection circuit 15 is at a low level (logic 0) or The holding brake is applied after the operation of the timer is completed (after setup).

That is, when the brake application command signal is input while the motor 3 is rotating at a high speed, the operation is performed at the timing shown in FIG. More specifically, first,
As shown in FIG. 2B, in a state where the brake release command S5 is switched from the high level to the low level (in a state where the brake application command is input), as shown in FIG. Starts operation. In this state, since the motor 3 is rotating at a high speed, a motor operation detection signal S12 of logic 1 is input from the motor rotation detection circuit 15 to the interlock logic circuit 13. Accordingly, the dynamic brake operation condition is satisfied, and the dynamic brake is applied as shown in FIG. Next, when the number of revolutions of the motor 3 decreases and the induced voltage of the motor 3 falls below the threshold level as shown in FIG. This is input to the logic circuit 13, whereby the operation of the dynamic brake is stopped as shown in FIG. 2 (F), and the holding brake is turned on as shown in FIG. 2 (G). Therefore,
As shown in FIG. 2A, the rotation of the motor 3 is stopped smoothly and quickly.

The operation when the brake application command is input to the interlock logic circuit 13 while the motor 3 is stopped is as shown by the timing in FIG. That is, as described above, the timer circuit 12 starts operating with the brake release command signal S5 switched from the high level to the low level. In this state, since the motor 3 is stopped, the signal S12 of logic 0 is input to the interlock logic circuit 13 from the motor speed detection circuit 15. Therefore,
The dynamic brake is not applied as shown in FIG. 3F, and the holding brake is applied immediately as shown in FIG. 3 (G). Therefore, the arm of the robot stops with almost no drop in the direction of gravity. The operation when the dynamic brake is inferior, that is, when the inertia of the load of the motor 3 is large, or particularly when the brake application command is input while the brake application motor 3 is rotating at a high speed, is the fourth operation.
It is as shown by the timing in the figure. When the brake release command signal S5 switches from a high level to a low level while the motor 3 is rotating at a high speed, the timer circuit 12 starts operating (FIG. 4 (B)). D)). In this state, since the motor 3 is rotating at a high speed, as shown in FIG.
The signal S12 of logic 1 from 15 is the interlock logic circuit 1
Output to 3. Accordingly, the operating condition of the time brake is satisfied, and the dynamic brake is applied (fourth step).
Figure F).

Next, the rotation speed of the motor 3 should be reduced promptly by the dynamic brake. However, when the moment of inertia of the load of the motor 3 is large or when the motor is rotating at a particularly high speed, the dynamic brake is further increased. If the dynamic brake does not work well due to a circuit break or other failure and does not drop below the motor speed after the timer reset time Td ₁ has elapsed, release the dynamic brake and forcibly apply the holding brake. . As a result, the motor stops immediately.

H. Effects of the Invention The present invention is as described above, and as a means for obtaining the timing for switching between the dynamic brake and the holding brake, by using the logical condition based on the number of rotations of the motor and the set time of the timer. The following effects are obtained.

(1) The rotation speed of the motor is
If the speed drops below the threshold level,
Since the switching to the holding brake is quickly performed, the stop time of the motor is reduced.

(2) If a brake application command is input while the motor is stopped, the dynamic brake does not operate,
Since the holding brake is applied immediately, the motor stops without the robot arm or the like dropping by its own weight.

(3) When the dynamic brake is inferior, the holding brake can be forcibly applied to stop the motor, so that the motor can be reliably stopped and reliability is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a brake control unit according to an embodiment of the present invention, and FIGS. 2 (A) to 2 (G), 3 (A) to 3 (G), and 4 (A) to 4 (G) 1 is an operation timing diagram of the brake control unit in FIG. 1, FIG. 5 is a block diagram of the robot control device, FIG. 6 is an operation timing diagram of the device in FIG. 5, and FIG. 7 is a block diagram of a conventional brake control unit. , Eighth
The figure is an operation timing chart of the brake control unit. 2 ... Servo amplifier that is the motor rotation drive part, 3 ...
DC servo motor, 4 ... Brake control circuit, 7 ... Brake, 10 ... Brake excitation circuit, 12 ... Timer circuit,
13… Interlock logic circuit, 14… Dynamic brake circuit, 15… Motor rotation speed detection circuit.

Claims (2)

(57) [Claims] 1. A motor as a power source for driving and operating a mechanism unit operated by a robot, a motor rotation driving unit for rotating the motor, and a rotation position detection signal of the motor as an input to the rotation driving unit. A positioning control unit for controlling the rotational position of the motor, and a robot brake control device including a brake control unit for controlling a brake unit having a dynamic brake and a holding brake for the motor based on a command from the positioning control unit, A timer circuit that operates based on a brake release command from the positioning control unit; and performs a dynamic operation or a holding brake operation on the brake unit based on an operation signal of the timer circuit and the brake release command. Interlock logic that outputs a command signal A dynamic brake circuit and a holding brake excitation circuit operating based on an output signal of the interlock logic circuit; and detecting the induced voltage of the motor, and detecting the interlock when the induced voltage is equal to or higher than a predetermined threshold level. A logic circuit having a motor speed detection circuit for inputting a logic signal "1" to the logic circuit and inputting a logic signal "0" when the logic level is equal to or lower than the threshold level; And when the start command signal from the positioning control unit to the motor rotation drive unit is turned off, and the timer circuit is operating and the output signal of the motor detection circuit is a logic signal "1", the interlock logic Operates the dynamic brake circuit according to the output signal of the circuit Means for operating the dynamic brake of the brake unit, the brake release command signal is a logic signal "0", the start command signal from the positioning control unit to the rotation drive unit is off, and the timer circuit is operating. Means for disabling the dynamic brake and operating the holding brake of the brake unit by the output signal of the motor speed detection circuit when the output of the motor speed detection circuit is a logical signal "0" A brake control device for a robot, comprising: A brake release command signal supplied from the positioning control unit to the timer circuit and the interlock is a logical signal "0"; and the brake control unit sends the brake release command signal from the positioning control unit to the rotation drive unit. Is turned off, the timer circuit is stopped, and a signal from the motor rotation detection circuit to the interlock logic circuit is a logic signal "1".
2. The robot brake control device according to claim 1, wherein said control device is constituted by means for operating said holding brake.