Control system for industrial robot

Abstract

The invention provides a control system for an industrial robot, which can reduce the load applied to a mechanism part of the robot when receiving a command for applying an excessive load to the mechanism part, and can avoid interference with the surrounding environment, thereby safely stopping the robot. The present invention is provided with: a setting unit (4) that sets a delay time, a first threshold value, and a second threshold value that is smaller than the first threshold value in advance; a determination unit (5) that determines whether or not a command signal for controlling the robot (1) exceeds a first threshold value or a second threshold value; and a control unit (6) that, when the determination unit (5) determines that the command signal has exceeded the second threshold value, continues control based on the command for a period from when the command signal has exceeded the second threshold value until a delay time has elapsed. The robot (1) is stopped at a time when the deceleration control is performed such that the operating speed of the robot (1) becomes equal to or less than a predetermined predetermined operating speed.

Description

[0001] This application is a divisional application of the Chinese invention patent application with the application date of March 5, 2020, application number 202010146983.5, and invention name “Control system for industrial robot”. Technical Field

[0002] The invention relates to a control system of an industrial robot. Background Art

[0003] Typically, in the control of an industrial robot, the user specifies the target position, action form, operating speed, etc. for each line in the teaching program. The robot interprets each line of the teaching program and controls its movement while automatically interpolating the position of each control cycle from the current position to the target position in order to meet the required conditions.

[0004] On the other hand, there are also cases where the user generally generates and specifies the interpolation position for each control cycle automatically generated by the robot, and controls the movement of the robot according to the command.

[0005] At this time, if the command for each control cycle generated by the user is a command that applies an excessive load to the mechanism of the robot, such as the control axis, the mechanism may be damaged or broken.

[0006] Therefore, an allowable upper limit value is set in advance for the acceleration, jerk, etc. of each control axis, and the instructions are monitored. When an instruction causes the acceleration, jerk, etc. of each control axis to exceed the allowable upper limit value, an alarm is sounded and the robot is controlled to be stopped urgently to protect the robot's mechanical parts (for example, refer to patent document 1).

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application No. 2013-528121 Summary of the invention

[0010] Problem that the invention aims to solve

[0011] However, in the above-mentioned conventional industrial robot control system, when a command exceeding the allowable upper limit is received from the user side, the robot in operation is immediately stopped at a fixed speed or higher. In this case, the emergency stop control itself will generate an excessive load on the robot, and for example, due to repeated long-term control, the robot may be damaged prematurely.

[0012] On the other hand, in order to make the robot stop smoothly, it is also considered to automatically generate a trajectory to the stopping position. However, if the robot's trajectory automatically generated within the limits of acceleration and jump deviates from the user-specified trajectory, it may also interfere with the surrounding environment and cause property damage accidents.

[0013] Therefore, a method or means is strongly desired that can reduce the load on the mechanism of the robot as much as possible and stop the robot safely when receiving a command that will apply an excessive load to the mechanism of the robot.

[0014] Solutions for solving problems

[0015] One embodiment of the present disclosure comprises: a setting unit which pre-sets a delay time, a first threshold, and a second threshold which is smaller than the first threshold; a determination unit which determines whether a command signal for controlling the robot exceeds the first threshold or the second threshold; and a control unit which, when the determination unit determines that the command signal exceeds the second threshold, stops the robot at a time when the operating speed of the robot becomes lower than a predetermined specified operating speed during the period from when the second threshold is exceeded to when the delay time has passed.

[0016] Effects of the Invention

[0017] According to one embodiment of the present disclosure, when the command signal of the acceleration, jerk, etc. of the robot obtained based on the command exceeds the second threshold value, the motion control based on the user's command is continued until the delay time passes, and when the robot is decelerated to a predetermined operating speed during the period, the robot is stopped at that moment. Thus, when a command is received that will impose an excessive load on the mechanism part such as the control axis of the robot, the load imposed on the mechanism part can be suppressed as much as possible, and the robot can be stopped safely without disturbing the surrounding environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram showing a control system of an industrial robot according to an embodiment.

[0019] Figure 2 This is a diagram showing a control flow of an industrial robot according to one embodiment.

[0020] Figure 3 This is a diagram for explaining operation control of an industrial robot by a control system of the robot according to one embodiment, and is a diagram showing the relationship between the operation speed of the robot and time.

[0021] Description of Reference Numerals

[0022] 1: Robot (industrial robot); 1a: Tool head; 2: Robot control device; 3: External computer; 4: Setting unit; 5: Judgment unit; 6: Control unit; A: Control system of industrial robot. DETAILED DESCRIPTION

[0023] Below, refer to Figures 1 to 3 A control system for an industrial robot according to an embodiment will be described.

[0024] The control system of the industrial robot of the present embodiment is used to intentionally stagger the time when the command from the user exceeds the allowable upper limit of acceleration, jump, etc. and the time when the robot is actually stopped, when a position command is detected that will impose an excessive load on the mechanism part such as the control axis of the robot (industrial robot), so as to prevent excessive load from being applied to the mechanism part and stop the robot safely.

[0025] Specifically, if Figure 1 As shown, the control system A of the industrial robot according to the present embodiment includes a robot control device 2 that controls the motion (drive) of the robot 1 .

[0026] For example, the robot control device 2 is connected to an external computer 3 through a communication network, receives instructions from the external computer 3 through user operations, and sends the allowable upper limit values ​​of the current position, speed, acceleration, jump (jerk), etc. of the robot 1, alarm information, etc. to the external computer 3.

[0027] In addition, the external computer 3 generates an action instruction based on the information of the allowable upper limit values ​​of the current position, speed, acceleration, jump, etc. of the robot 1, and sends the action instruction to the robot control device 2. The robot control device 2 performs motion control of the robot 1 based on the information of the action instruction.

[0028] On the other hand, in the control system A of the industrial robot of the present embodiment, the robot control device 2 includes: a setting unit 4, which pre-sets a delay time, a first threshold value, and a second threshold value that is smaller than the first threshold value; a determination unit 5, which determines whether a command signal for controlling the robot 1 exceeds the first threshold value or the second threshold value; and a control unit 6, which, when the determination unit 5 determines that the command signal exceeds the second threshold value, stops the robot 1 at the moment when the spatial speed, i.e., the operating speed, of the tool tip 1a of the robot 1 becomes less than a predetermined specified operating speed until the delay time has passed, and when it is determined that the command signal exceeds the first threshold value, causes the robot 1 to be immediately emergency stopped.

[0029] Here, the robot 1 performs actions such as picking up and placing workpieces within the range of general-purpose actions. Therefore, it is desirable that, during the period from exceeding the second threshold value until the delay time elapses, the spatial speed of the tool tip 1a of the robot 1, i.e., the operating speed, becomes a predetermined operating speed at which the robot 1 can be safely stopped without applying excessive loads to the mechanism parts such as the plurality of control axes when the robot 1 is stopped.

[0030] That is, the delay time may be set to a time for an extremely exceptional case where the robot 1 continues to operate for a long time without decelerating to a speed lower than the prescribed operating speed. In other words, the delay time may be appropriately set to a value (time) that is considered to be slightly longer than the time for the robot 1 to continue to move at a speed higher than the prescribed operating speed, for example, about 5 seconds.

[0031] The spatial speed of the tool tip 1a of the robot 1, i.e., the operating speed, is basically calculated based on the command value, but can also be obtained by a sensor provided on the robot 1 or the like. Figure 3 As shown, the maximum operating speed of the robot 1 is, for example, about 4000 m / s, and the operating speed at which the robot 1 can be stopped smoothly and safely can be set to, for example, about 150 m / s (eg, a speed of about 5% of the maximum speed).

[0032] In the control system A of the industrial robot of the present embodiment, a first threshold and a second threshold are set for each control axis of the mechanism of the robot 1 , and the determination unit 5 notifies the control axis that exceeds the second threshold when the robot 1 is stopped according to the determination of the determination unit 5 .

[0033] When the determination unit 5 determines that the command signal exceeds the first threshold value, and when the delay time has passed since the command signal exceeded the second threshold value, the control unit 6 causes the robot 1 to be urgently stopped. That is, in this embodiment, priority is given to the time to immediately cause the robot 1 to be urgently stopped rather than to the excessive load acting on the mechanism of the robot 1.

[0034] Furthermore, in the control system A of the industrial robot of the present embodiment, the interpolation position of each control cycle automatically generated by the robot is usually generated and specified on the user side. When the movement of the robot is controlled by the command, Figure 2 (and Figure 3 ), the determination unit 5 calculates the acceleration of each control axis based on the command value and the previous command value for each control cycle, and determines whether it exceeds the second threshold value (step 1).

[0035] When the second threshold value is exceeded, the determination unit 5 determines whether the first threshold value is exceeded (step 2).

[0036] When the determination unit 5 detects that the load exceeds the first threshold, the control unit 6 executes a stop process (step 3) to give priority to immediately emergency stopping the robot 1 over an excessive load acting on the mechanism of the robot 1. In addition, an alarm is sounded.

[0037] Furthermore, in the present embodiment, when the determination unit 5 detects that the second threshold value has been exceeded and the first threshold value has not been exceeded, the predetermined delay time is measured. Then, the control unit 6 receives information on the operating speed of the robot 1 until the delay time has passed, and checks every several milliseconds whether the operating speed is a predetermined operating speed suitable for stopping without applying an excessive load to the mechanism of the robot 1 (steps 4, 5, and 6), and executes the stop process of the robot 1 (step 3) when the predetermined operating speed is reached.

[0038] Here, if the predetermined operating speed is not reached before the delay time elapses (step 5), the stop process is immediately executed (step 3).

[0039] By performing the above-mentioned operation control, Figure 3 As shown, a certain delay occurs between the time when the threshold value is exceeded and when the stop process is actually executed. However, compared with the case where the stop process is executed immediately, the robot 1 can be stopped at a lower operating speed, thereby reducing the load on the robot 1.

[0040] Therefore, in the control system A of the industrial robot of the present embodiment, when the command signal of the acceleration, jerk, etc. of the robot 1 obtained based on the command exceeds the preset second threshold value, the robot 1 is stopped at the time when the operation speed is reduced to the prescribed operation speed until the delay time has passed. Thus, when a command that will apply an excessive load to the mechanism of the robot 1 is received, the excessive load applied to the mechanism can be reduced and the robot 1 can be stopped safely.

[0041] Therefore, according to the control system A for an industrial robot of the present embodiment, it is possible to reduce the load on the mechanism of the robot 1 due to the immediate stop process when an abnormality is detected and the risk of premature damage caused thereby.

[0042] In particular, regarding pick and place, which is one of the representative applications of the industrial robot 1, due to the nature of a series of actions such as holding a workpiece at a specific position, transporting the workpiece to a specific position, and then putting the workpiece down, there is a moment at a fixed time when the operation speed of the robot 1 becomes extremely small. If the operation control of this embodiment (the control system A of the industrial robot of this embodiment) is applied to such pick and place, the load applied to the robot 1 can be preferably reduced.

[0043] Furthermore, in the control system A of the industrial robot of the present embodiment, the first threshold value and the second threshold value are set for each control axis of the mechanism of the robot 1, and the control axis that exceeds the second threshold value when the robot 1 is stopped according to the determination of the determination unit 5 is notified, thereby being able to clearly capture and understand which control axis is loaded and stopped. Thus, for example, the degree of reduction in durability (degree of wear) of each control axis can be understood.

[0044] Furthermore, the industrial robot control system A of this embodiment can cope with situations where the robot 1 needs to be urgently stopped rather than an excessive load acting on the mechanism of the robot 1 by urgently stopping the robot 1 when it is determined that the command signal exceeds the first threshold.

[0045] An embodiment of the control system for an industrial robot according to the present invention has been described above, but the present invention is not limited to the above-described embodiment and can be modified appropriately within the scope of the present invention.

Claims

1. A control system for an industrial robot, comprising: a setting unit, which pre-sets a delay time, a first threshold, and a second threshold that is smaller than the first threshold; a determination unit that determines whether a command signal for controlling the robot exceeds the first threshold value or the second threshold value; and A control unit that, when the determination unit determines that the command signal exceeds the second threshold, stops the robot at a time when the operating speed of the robot becomes less than a predetermined specified operating speed during the period from exceeding the second threshold until a delay time has passed.

2. The control system of the industrial robot according to claim 1, wherein: The first threshold value and the second threshold value are set for each control axis of the mechanism part of the robot, The determination unit notifies the control axis that has exceeded the second threshold value when the robot is stopped according to the determination of the determination unit.

3. The control system of an industrial robot according to claim 1 or 2, wherein: When the determination unit determines that the command signal exceeds the first threshold value, the control unit causes the robot to make an emergency stop.

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