JP2002166381A - Tool information self-diagnosis device for robot and method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tool information self-diagnosis device for a robot capable of enhancing safety and reliability of a system by diagnosing whether a tool information in a tool information storage means is an error or not. SOLUTION: A robot controller 6 is constituted of the tool information storage means 5 for storing the tool information; a gravity calculating means 6a for calculating gravitational torque actuating respective shafts from the information of the tool information storage means 5; a robot control device 4 including a position loop 4a for conducting P(proportion) control and a speed loop 4b for conducting P(proportion) control and I(integration) control; and a gravitational torque compensating means 6b for calculating a torque command value Ta from the position loop 4a and the speed loop 4b and adding a gravitational torque calculated value Tm of the gravitational torque calculating means 6a to the torque command value Ta in order to output an output value Tref to a servomotor. A monitor means 6 for monitoring an error between the tool information from the tool information storage means 5 and an actual tool information value Tint, and an alarm generation means 7 for alarming when the error exceeds a predetermined value are also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot using a servo motor as a drive source, which automatically detects that information (weight and center of gravity) of a jig such as a tool applied to a robot body is set erroneously. The present invention relates to a robot control device including a tool information self-diagnosis device that diagnoses, corrects a value, and issues a warning.

[0002]

2. Description of the Related Art When a robot is used, a tool (welding torch, hand, or the like) is usually added to the end of a robot arm to perform work. Normally, information (weight, center of gravity) of this tool is stored in a file or the like in the controller. The tool file includes a file manually input by the operator and a format in which the robot estimates and stores the file itself. The tool information stored there is used when calculating gravity and inertia acting on each axis of the robot. The calculated gravity value and inertia value of each axis are used in the following three ways to improve the control performance of the robot. (1) Compensate for torque due to gravity. (2) The time required for acceleration or deceleration is determined from the calculated inertia value and the value of the allowable torque that can be used. (3) A robot model is provided inside the robot controller, and a torque command required for an optimal operation is calculated using the model to reduce vibration and improve a trajectory. FIG.
Is a block diagram of a conventional robot configuration. In the figure, reference numeral 41 denotes a robot arm to be controlled;
Indicates a tool added to the tip of the robot arm;
Denotes a servomotor that drives one robot arm.
Reference numeral 48 denotes a robot controller, which includes a control unit 44 for controlling the servo motor 43, and a tool information storage unit 45 for storing information (weight and center of gravity) of the tool 42 as a tool file. Control unit 44
In general, proportional control is performed on the position, and proportional integral control is performed on the speed.

[0003]

As described above, in the conventional robot configuration, if there is an error in the information of the tool 42 set in the controller 48, there is no element for diagnosing the error. The gravitational value and the inertia value applied to each axis are erroneously calculated without being noticed. As a result, the following problems have occurred according to each usage method. (1) When the control unit 44 is performing gravity compensation, an accurate gravity value cannot be compensated, and the robot arm may drop in a direction in which gravity is applied, or may be lifted upward, resulting in a very dangerous state. Had fallen into the problem that had gone. (2) If the acceleration / deceleration constant is calculated using the wrong inertia value calculated from the wrong tool information, the motor value exceeds the allowable torque during acceleration / deceleration, the torque value saturates, and conversely, the rise time increases. There was a problem that it became very long. (3) There is a problem in that the control cannot be performed using the wrong robot model calculated from the wrong tool information, so that the vibration cannot be reduced or oscillates. In addition, problems such as a decrease in trajectory accuracy may occur. Furthermore, the invention described in Japanese Patent Application Laid-Open No. 7-256577 also relates to a method for controlling an industrial robot that performs control through detection of a position, a speed, an operating current, and the like on each drive axis of an industrial robot having a plurality of drive axes. Then, the current value and the like during operation of the motor driving each link of the industrial robot are detected, and the force and moment at the tip of the operating arm of the industrial robot are determined based on the detected current value and link value, and the mass of the link. And an alert based on the calculation based on the position of the center of gravity, and performs an alarm issuance and an abnormal stop control of the industrial robot. This also diagnoses whether the information of the tool set in the storage means is incorrect. Because it is not a thing, it is the same as above (1)-
(3) had the problem. The present invention solves these drawbacks, and includes a tool information self-diagnosis device capable of diagnosing errors in the information of the tool 42 set in the tool information storage means 45 of the controller 48 by itself. Thus, it is possible to avoid erroneous calculation of the gravity value and the inertia value applied to each axis.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the invention of a robot tool information self-diagnosis apparatus according to claim 1 of the present invention is directed to a robot controller for controlling a robot with a tool driven by a servomotor. A tool information self-diagnosis device to be used, wherein monitoring means for monitoring whether an error between the tool information from the tool information storage means for storing tool information and the actual tool information value is equal to or greater than a set value. It is characterized by having. According to a second aspect of the present invention, in the tool information self-diagnosis device for a robot according to the first aspect, an error between a monitoring result of the monitoring unit and a value of the tool information stored in the tool information storage unit and an actual value of the tool information is obtained. A warning issuance means for issuing a warning when the value is equal to or more than the set value is provided. According to a third aspect of the present invention, in the tool information self-diagnosis device for a robot according to the first or second aspect, the monitoring means performs I control (I-control ( (Integral control) using an output value of the integral control. According to a fourth aspect of the present invention, in the tool information self-diagnosis device for a robot according to the third aspect, the integrator monitoring means uses an integrated value in a stationary state of the robot as tool information from the tool information storage means. It is characterized by the following. According to a fifth aspect of the present invention, in the tool information self-diagnosis device for a robot according to the third aspect, the integrator monitoring means uses an integrated value in a motion state of the robot as tool information from the tool information storage means. It is characterized by the following. According to a sixth aspect of the present invention, in the tool information self-diagnosis device for a robot according to the third aspect, the integrator monitoring means uses an integrated value at the time of forward / reverse operation as tool information from the tool information storage means. It is characterized by. According to a seventh aspect of the present invention, there is provided a robot controller, wherein: tool information storage means for storing tool information; gravity calculation means for calculating a gravitational torque acting on each axis from the information in the tool information storage means;
A robot control device having a position loop for performing P control (proportional control), and a speed loop for performing P control (proportional control) and I control (integral control), wherein a torque is obtained from the position loop and the speed loop. A robot controller having a gravitational torque compensating means for obtaining a command value, adding the gravitational torque calculation value of the gravitational torque calculating means to the torque command value, and outputting the result to a servomotor. 6. A tool information self-diagnosis device according to any one of 6. According to an eighth aspect of the present invention, there is provided a robot controller according to the seventh aspect, a servo motor controlled by the robot controller, a robot arm driven by the servo motor, and a robot arm provided at a tip of the robot arm. And a tool comprising a welding motor and a power source installed on the robot arm. According to a ninth aspect of the present invention, in the robot according to the eighth aspect, the tool information self-diagnosis device is applied to at least one axis on which gravity acts. According to a tenth aspect of the present invention, in the robot according to the eighth or ninth aspect, the tool information storage means stores a value automatically estimated by the robot itself. According to an eleventh aspect of the present invention, in the robot according to any one of the eighth to tenth aspects, an operator can input a value of tool information into the tool information storage unit. An invention of a tool information self-diagnosis method for a robot according to claim 12 is a tool information self-diagnosis method applied to a robot controller that controls a tool-equipped robot driven by a servomotor, wherein the tool information is stored. And monitoring whether or not the error between the tool information therefrom and the value of the actual tool information is greater than or equal to a set value. According to a thirteenth aspect of the present invention, in the tool information self-diagnosis method for a robot according to the twelfth aspect, as a result of the monitoring, an error between a value of the stored tool information and an actual value of the tool information is equal to or larger than a set value. A warning is issued to the user. According to a fourteenth aspect of the present invention, in the method of self-diagnosing tool information for a robot according to the thirteenth aspect, an output value of I control (integral control) performed by a speed loop in the robot controller as the value of the information of the actual tool. Is used. The invention according to claim 15 is
The robot tool information self-diagnosis method according to claim 14, wherein the stored tool information is an integrated value of the robot in a stationary state. According to a sixteenth aspect of the present invention, in the tool information self-diagnosis method for a robot according to the fourteenth aspect, an integrated value in a motion state of the robot is used as the stored tool information. According to a seventeenth aspect of the present invention, in the tool information self-diagnosis method for a robot according to the fourteenth aspect, an integrated value at the time of forward / reverse operation is used as the stored tool information. As described above, according to the present invention,
If there is an error in the tool information of the tool information storage means 45, it is possible to easily diagnose the error by itself, and if it is incorrect, a warning is issued. Incorrect calculation of the value or the inertia value can be avoided, and the safety and reliability of the system are further improved.

[0005]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a block diagram illustrating a basic configuration of the present invention. In FIG. 1, reference numeral 1 denotes a robot arm to be controlled, 2 denotes a tool added to the tip of the robot arm 1, and 3 denotes a servomotor for driving the robot arm 1. Reference numeral 4 denotes a control unit for controlling the servomotor 3, which normally performs proportional control on position and proportional integral control on speed.
Reference numeral 5 denotes tool information storage means for storing information (weight, center of gravity position) of the tool 2 as a tool file. Reference numeral 6 denotes tool information self-information for determining whether the tool information stored in the tool information storage means 5 is correct. It is a diagnostic means. 7
Is a warning generating means for immediately issuing a warning when the tool information self-diagnosis means 6 determines that the information of the tool 2 is incorrect. Each unit from the control unit 4 to the warning generation unit 7 is provided inside the robot controller 8.

Next, the operation of each of these means will be described in detail with reference to FIG. FIG. 2 is a block diagram specifically showing the control unit and the tool information self-diagnosis unit of FIG. First, the contents of the symbols used in FIG. 2 are as follows. θref: Position command value Kp: Position loop gain Kv: Velocity loop gain Ki: Velocity loop integral gain S: Laplace operator (representing differentiation) 1 / S: Representing integration Ta: Torque command value before gravity compensation Tref: gravity Compensated torque command value Tmg: gravity torque calculation value Tint: speed loop integral value Next, the contents of the tool information self-diagnosis means will be described in detail. First, the tool 2 stored in the tool information storage unit 5
The gravity calculation unit 6a calculates the gravitational torque value Tmg acting on each axis using this information. Next, the gravity compensation unit 6b adds the calculated gravity torque value Tmg to the original torque command value Ta to be output to the motor 3 to create a torque command value Tref after gravity compensation. Tref = Ta + Tmg (1) As a result, the torque command value to the motor 3 becomes Tref. While constantly performing this process, the integrator monitoring unit 6c monitors the integrated value Tint by comparing the integrated value Tint of the speed loop 4b with a preset Tlimit. Here, the value of Tlimit is a value that can be set from the magnitude of friction or the like acting on each axis.

[0007] In the following, a description will be given of a value appearing in the speed loop integrator and a method of setting Tlimit in each state. 1. Stationary state: When stopped, the following two appear. Gravity + static friction Therefore, Tlimit may be set to a value equal to or larger than the static friction. 2. Exercise state: The following four act during exercise. Gravity + dynamic friction + acceleration / deceleration torque + interference force from other axes, centrifugal force, etc. In this case, the value including three other than gravity must be set for Tlimit. Therefore, the accuracy of tool diagnosis deteriorates. However, by operating at low speed,
Since the acceleration / deceleration torque, the interference force from other axes, the centrifugal force, and the like can be regarded as almost 0, in that case, Tlimit may be set to be equal to or more than the dynamic friction. 3. During forward / reverse operation: By performing forward and reverse operations at a low speed, the following is achieved. (1) Gravity + dynamic friction during forward operation (2) Gravity-dynamic friction during reverse operation As can be seen from (1) and (2), kinetic friction appears in the opposite direction with the same magnitude, so (1) and ( If the value of 2) is added, only the effect of gravity appears on the integrator. (1) + (2) Gravity + Gravity Therefore, if the integrator is monitored when the forward / reverse operation is performed at a low speed, it is not necessary to consider the influence of friction, and Tlimi
It becomes possible to set t very small. That is, the accuracy of diagnosis is improved. And Tint
When the absolute value of exceeds Tlimit, it is determined that the tool information is incorrect, and a signal is sent to the warning generator 7, which displays a warning on the operation panel or the program pendant. Further, the warning generation unit 7 can estimate which of the tool information at that time is wrong and write it in the warning information.

FIG. 3 is a block diagram showing a hardware configuration for realizing the robot control device of the present invention. In the figure,
The robot control device 30 has a main processor board 31 that controls the whole, and the processor board 31 has a processor 31a, a ROM 31b, a RAM 31c, and a nonvolatile memory 31d. Processor 31a is ROM 31b
Controls the entire robot controller 30 according to the following. R
The AM 31c stores various data. The operation program of the robot 100 and the like are loaded from the ROM 31b into the nonvolatile memory 31d. Processor board 31 is coupled to bus 37. Each calculation for the tool information self-diagnosis shown in the present embodiment is a function by software calculated inside the digital servo control circuit 32. The digital servo control circuit 32 is connected to a bus 37 and receives a command from the processor board 31 via a servo amplifier 33 to
1, 302, 303, 304, 305 and 306 are driven. These servo motors are built in the robot 100 and operate each axis of the robot 100. The serial port 34 is connected to a bus 37 and is connected to a teaching operation panel 38 and other RS232C devices 39. The teaching operation panel 38 is used for inputting teaching points to the robot. The large-capacity memory 35 stores teaching data and the like. Further, input / output of data, signals, and the like with the outside is performed via the I / O 36.

[0009]

As described above, according to the present invention, gravity compensation is always performed using the set value of the tool information added to the end of the robot arm, and the value of the integrator of the speed loop at that time is monitored. In order to diagnose whether the tool information automatically set by the robot itself is accurate,
In the unlikely event that the operator has information on the tool (weight and center of gravity)
If you enter the wrong information or if the calculation result of the automatic load estimation function is incorrect, the system judges whether the tool information is correct and issues a warning if it is incorrect. This has the effect of increasing safety and reliability.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of the present invention.

FIG. 2 is a block diagram specifically showing a control unit and a tool information self-diagnosis unit of FIG. 1;

FIG. 3 is a block diagram showing a hardware configuration for realizing the present invention.

FIG. 4 is a block diagram showing a configuration of a conventional device.

[Explanation of symbols]

1 Robot arm to be controlled 2 Tool added to the tip of robot arm 3 Servo motor for driving robot arm 4 Servo motor controller 4a Position loop 4b Speed loop 5 Information of tool 2 (weight, center of gravity) as tool file Tool information storage means 6 to be stored Tool information self-diagnosis means for judging whether the tool information stored in the tool information storage means 5 is correct 6a Gravity calculation section 6b Gravity compensation section 6c Integrator monitoring section 7 Tool information self-diagnosis section When the means 6 determines that the tool information is incorrect, a warning issuance means for immediately issuing a warning 8 Robot controller 30 Robot controller 301, 302, 303, 304, 305, 306 Servo motor 31 Processor board 31a Processor 31b ROM 31c RAM 31 Non-volatile memory 32 Digital servo control circuit 33 Servo amplifier 34 Serial port 35 Large capacity memory 36 I / O 37 Bus 38 Teaching operation panel 39 RS232C device 100 Robot θref: Position command value Kp: Position loop gain Kv: Speed loop gain Ki: Speed loop integration gain S: Laplace operator (represents differentiation) 1 / S: Represents integration Ta: Torque command value before gravity compensation Tref: Torque command value after gravity compensation Tmg: Gravity torque calculation value Tint: Speed loop integration value

Claims (17)

[Claims] 1. A tool information self-diagnosis device used for a robot controller for controlling a robot with a tool driven by a servomotor, wherein tool information from tool information storage means for storing tool information and actual tool information are stored. A tool information self-diagnosis device for a robot, comprising monitoring means for monitoring whether an error of a value of tool information is equal to or greater than a set value. 2. A warning generating means for issuing a warning when a difference between the value of the tool information stored in the tool information storing means and the value of the actual tool information is equal to or larger than a set value as a result of the monitoring by the monitoring means. The tool information self-diagnosis device for a robot according to claim 1, wherein: 3. An integrated value monitoring means using an output value of I control (integral control) performed by a speed loop in a robot controller as an actual tool information value. 3. The tool information self-diagnosis device for a robot according to claim 1 or 2. 4. The tool information self-diagnosis device for a robot according to claim 3, wherein the integrator monitoring means uses an integrated value in a stationary state of the robot as tool information from the tool information storage means. . 5. The tool information self-diagnosis device for a robot according to claim 3, wherein the integrator monitoring means uses an integrated value in a motion state of the robot as tool information from the tool information storage means. . 6. The tool information self-diagnosis device for a robot according to claim 3, wherein said integrator monitoring means uses an integrated value at the time of forward / reverse operation as tool information from said tool information storage means. 7. Tool information storage means for storing tool information, gravity calculation means for calculating a gravitational torque acting on each axis from the information in the tool information storage means, and P control (proportional control) A robot controller having a position loop and a speed loop for performing P control (proportional control) and I control (integral control), wherein a torque command value is obtained from the position loop and the speed loop, and the torque command is obtained. 7. A robot controller comprising: a gravity torque compensating unit that adds a gravity torque calculation value of the gravity torque calculation unit to a value and outputs the calculated value to a servomotor. A robot controller comprising a tool information self-diagnosis device. 8. A robot controller according to claim 7, a servomotor controlled by the robot controller, a robot arm driven by the servomotor, and a tool provided at a tip of the robot arm.
The robot according to claim 1, wherein the tool is a welding motor or a power source installed on the robot arm. 9. The robot according to claim 8, wherein the tool information self-diagnosis device is applied to at least one axis on which gravity acts. 10. The robot according to claim 8, wherein a value automatically estimated by the robot itself is stored in the tool information storage unit. 11. The robot according to claim 8, wherein an operator can input a value of tool information into the tool information storage unit. 12. A tool information self-diagnosis method applied to a robot controller for controlling a robot with a tool driven by a servomotor, wherein tool information is stored, and the tool information from the tool information and the actual tool are stored. A method of self-diagnosing tool information of a robot, which monitors whether an error in the value of the information is equal to or greater than a set value. 13. The apparatus according to claim 12, wherein, as a result of the monitoring, a warning is issued when an error between the stored tool information and the actual tool information value exceeds a set value. Robot tool information self-diagnosis method. 14. The value of the information of the actual tool is as follows:
14. The tool information self-diagnosis method for a robot according to claim 13, wherein an output value of I control (integral control) performed by a speed loop in the robot control device is used. 15. The tool information self-diagnosis method for a robot according to claim 14, wherein an integrated value of the robot in a stationary state is used as the stored tool information. 16. The tool information self-diagnosis method for a robot according to claim 14, wherein an integrated value in a motion state of the robot is used as the stored tool information. 17. The method according to claim 14, wherein an integrated value at the time of forward / reverse operation is used as the stored tool information.
Robot tool information self-diagnosis method described.