JPH11235065A - Working device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a working device which can stop with a very short braking distance, without increase of the size of the device, and without a harmful influence upon a mechanism. SOLUTION: A torque limiter unit 2a which applies a predetermined limit to a torque command outputted from a controller 1. A driving motor is driven by a torque to which a limit is applied by the torque limiter unit 2a if necessary. At the time of an emergency stop, for instance, a command torque which is logically infinite is outputted in accordance with a speed command which requires a speed to become zero instantaneously. The command torque is limited by the torque limiter unit 2a so as not to exceed a predetermined value, and a working device is decelerated and stopped with a torque which does not exceed the predetermined value. With this constitution, for instance, the working device can be stopped with a shortest braking distance within a range in which a harmful influence is not given upon a mechanism. Further, as it is not necessary to provide a braking device, etc., increase of the size of the device and the complexity of the device can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a working device provided with a drive motor for driving the working device and control means for controlling the driving motor. It relates to a working device that can be used.

[0002]

2. Description of the Related Art As a method generally used for an emergency stop of a working robot (working device) such as an articulated robot, a stop method with deceleration, a stop method without deceleration, a method using a brake, and the like are used. is there. Hereinafter, the features of the above three methods will be briefly described. Stop method with deceleration As shown in FIG. 4, a method in which a control device outputs a deceleration command (deceleration curve) to a driving device, and the driving device controls the motor according to the deceleration curve, thereby stopping the work robot. It is. Since it can be stopped smoothly, there is an advantage that there is no fear of applying an excessive load to the work robot, but there is a disadvantage that control is complicated and a braking distance is extended.

As shown in FIG. 5, a speed command is output from the control device to the drive device such that the speed becomes zero instantaneously, and the drive device receives the speed command and stops the motor rotation. This is a method of stopping the work robot by operating to stop instantaneously. On the other hand, there is an advantage that the control is simple and the braking distance can be shortened. On the other hand, there is a disadvantage that a large inertial force of the robot mechanism is applied to the bearing portion when the robot stops, which adversely affects the mechanism itself. Therefore, the application range is limited, for example, when stopping the operation of a micro robot or an extremely low speed operation. Method using brake As shown in FIG. 6, the control device outputs a brake closing command to the driving device, and upon receiving the command, the driving device closes the brake connected to the motor, thereby stopping the work robot by frictional force. Is the way. On the other hand, there is an advantage that the control is simple and the braking distance can be made relatively short. On the other hand, since a brake device and a drive circuit for the brake device are separately required, there is a disadvantage that the device becomes large.

[0004]

As described above, each of the above-mentioned conventional stopping methods has advantages and disadvantages, and there has been no working apparatus using the stopping method that can solve all of the above-mentioned disadvantages. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a working device capable of stopping without increasing the size of the device, with a very short braking distance, and without adversely affecting the mechanism. It is to provide.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a work equipment having a drive motor for driving the work equipment and a control means for controlling the drive motor. A torque limiting means for applying a predetermined limit to a torque command output from the control means to the drive motor in response to the speed command when the speed command is suddenly changed based on the command. It is configured as a device.

[0006]

According to the working device of the present invention, during smooth acceleration and deceleration during normal operation, the working device is driven based on a torque command from the control device without limiting the torque by the torque limiting device. Control is performed that makes full use of the allowable torque of the drive motor. On the other hand, at the time of an emergency stop such as when the emergency stop button is pressed, the control means outputs a theoretically infinite command torque according to the speed command such that the speed becomes zero instantaneously. The command torque is limited by the torque limiting means so as not to exceed a predetermined value, and the working device is decelerated and stopped with the torque not exceeding the predetermined limit value. As a result, for example, the working device can be stopped at the shortest braking distance within a range that does not adversely affect the mechanism. Moreover, since there is no need to provide a brake device or the like, the device does not become large and the structure is not complicated.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and examples of the present invention will be described below with reference to the accompanying drawings to facilitate understanding of the present invention. The following embodiments and examples are mere examples embodying the present invention, and do not limit the technical scope of the present invention. Here, FIG. 1 is a control block diagram of the work robot A1 according to the embodiment of the present invention, FIG. 2 is a control block diagram showing a control state at the time of an emergency stop of the work robot A1, and FIG. FIG. 4 is an input / output relationship diagram illustrating an example of setting a torque limit value. The work robot A1 according to the present embodiment mainly includes a control device 1, a drive device 2, and a motor 3, as shown in FIG. Further, the driving device 2 includes a torque limiting unit 2.
a (corresponding to torque limiting means). Here, the control device 1 and the driving device 2 are an example of a control unit.

The control operation of the work robot A1 will be described with reference to the control block diagram shown in FIG. Here, G1, G2, G3, and AMP in FIG. 1 indicate predetermined gains. In the control device 1, first, a speed target value is output from G1 by inputting a deviation between the target position and the operation amount of the motor 3 (obtained from the encoder 3a and the counter 3b), that is, a position command. Further, a deviation between the target speed value output from the G1 and the time derivative of the operation amount of the motor 3, that is, a speed command is obtained, and is output to the drive device 2. The speed command is converted to a command torque in G2. In a conventional working robot, this command torque is directly converted into a current command and output to the motor 3, but in the working robot A1, the torque limiting section 2a uses the torque limiting command from the control device 1 based on the torque limiting command. Thus, any limitation can be added to the torque command. The output torque output from the torque limiting unit 2 a is converted into a current command by the AMP and output to the motor 3. The relationship between the input (command torque) and the output (output torque) in the torque limiting section 2a is set, for example, as shown in FIG. This shows an example in which two types of switching, that is, no torque limitation (normal time) and torque limitation are possible, but a plurality of torque limit values can be set and selected as needed. . The torque limit value set here is
For example, it is set to a value as large as possible within a range that does not adversely affect the mechanism. At the time of smooth acceleration / deceleration during normal operation, the motor 3 is driven based on the torque command according to the speed command from the control device 1 without performing the torque limitation in the torque limiting section 2a, and the allowable torque of the motor is sufficiently reduced. Control that makes good use of it is performed.

On the other hand, at the time of an emergency stop such as when the emergency stop button is pressed, as shown in FIG. 2, a speed command (simple command) is issued from the control device 1 to the drive device 2 so that the speed becomes zero instantaneously. In addition to the output of the stop command, the control device 1 outputs a torque limit command to the torque limiting unit 2a. As a result, a theoretically infinite command torque is output from G2, but the command torque is limited by the torque limiter 2a, and the motor 3 is decelerated at a torque not exceeding a predetermined limit value. . As a result, for example, the working device can be stopped at the shortest braking distance within a range that does not adversely affect the mechanism. Moreover, since there is no need to provide a brake device or the like, the device does not become large and the structure is not complicated.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the above embodiment, the torque limiting section 2a has been described.
Although the example in which the torque limitation is performed only at the time of an emergency stop has been described, the torque limitation may be performed as needed even during normal acceleration / deceleration. Of course, in that case, the torque limiting value in the torque limiting section 2a can be set arbitrarily according to the case.

[0011]

As described above, according to the present invention, a speed command based on a predetermined emergency stop command is provided in a working device including a drive motor for driving the working device and control means for controlling the drive motor. A torque limiter for applying a predetermined limit to a torque command output from the control means to the drive motor in response to the speed command at the time of a sudden change in speed. Therefore, for example, the working device can be stopped at the shortest braking distance within a range that does not adversely affect the mechanism. Moreover, since there is no need to provide a brake device or the like, the device does not become large and the structure is not complicated.

[Brief description of the drawings]

FIG. 1 is a work robot A1 according to an embodiment of the present invention.
FIG.

FIG. 2 is a control block diagram showing a control state at the time of an emergency stop of the work robot A1.

FIG. 3 is an input / output relationship diagram showing an example of setting a torque limit value in a torque limiter 2a.

FIG. 4 is a control block diagram showing a conventional stop method with deceleration.

FIG. 5 is a control block diagram showing a conventional stop method without deceleration.

FIG. 6 is a control block diagram showing a conventional stopping method using a brake.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control device 2 drive device 2 a torque limiting unit 3 motor

Claims (1)

[Claims] A driving motor for driving the working device;
A control device for controlling the drive motor, wherein a torque command output from the control means to the drive motor in response to the speed command when the speed command is suddenly changed based on a predetermined emergency stop command. A working device comprising a torque limiting means for applying a predetermined limit to the working device.