JPH0719982A - Inspection method for force sensor - Google Patents

Abstract

PURPOSE:To judge the performance of a sensor by obtaining the offset quantity from the first load vector determined from the known mass and the center of gravity position in the first attitude and the first load data detected by the sensor, and obtaining the error between the second load vector determined likewise in the second attitude and the second load data subtracted with the offset quantity after detection. CONSTITUTION:A robot main body 1 fitted with a member 10 is set to one attitude, and the center of gravity position and the mass of the member 10 are known. A controller 6 calculates the load vector passing through the center of gravity position of the member 10 from the information, receives the load data detected by a force sensor 5, and determines the offset quantity of the sensor 5 from both data. The robot main body 1 is set to another attitude, the load vector is likewise calculated, and the previously determined offset quantity is subtracted from the load data detected by the sensor 5. The error between it and the load vector is obtained, and the error value is displayed on the display device 9a of an operation section 9. The detecting performance of the sensor 5 can be inspected by this magnitude.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a force sensor, and more particularly to a position applied to a multi-degree-of-freedom working machine for taking deburring in various postures, polishing a curved surface of a work, and copying a curved surface. The present invention relates to an inspection method for diagnosing the detection performance of a force sensor provided as means for detecting a force applied to a work tool in a force control device.

[0002]

2. Description of the Related Art In a multi-degree-of-freedom work machine (hereinafter referred to as a robot) for performing work with a force such as deburring, a force sensor is provided on a wrist formed at the tip of a robot arm, and the force sensor Work tools are attached. A control device that generates a control command relating to position and force is used to control the operation of a robot that performs work involving force. In this position and force control device, information regarding the force applied to the work tool is obtained from the force sensor, and a control command regarding the position, posture, and force is created based on a control equation using the detected data regarding the position and the information regarding the force. To do. Therefore, in order to accurately control the force, it is required to maintain the detection performance of the force sensor that generates information on the force, that is, the sensor accuracy in a high state.

In the robot which operates based on force control as described above, it is necessary to confirm the detection performance of the force sensor for maintenance. Conventionally, there are three confirmation methods. The first method is a method in which a load is manually applied to a work tool at a manufacturing site to obtain detection values of force and moment by a force sensor, and the detection performance is confirmed. There is a method of confirming the detection performance of a force sensor by hanging a known weight on an arbitrary position of a work tool and obtaining a detection value by the force sensor. The third method is to request an inspection from a sensor maker and This is a method for accurately detecting the detection performance of.

[0004]

The above-mentioned conventional methods have the following problems. According to the first method, since the load is applied by the hand of the person who performs the inspection, that is, the operator,
This is a subjective judgment based on the operator's sense, which is insufficient as inspection accuracy. According to the second method, the distance between the place where the weight is attached and the load detection reference point in the force sensor cannot be managed accurately, so the inspection regarding the moment is insufficient in accuracy. As for the moment, it is determined by the human sense as in the first method. According to the third method, it is possible to obtain highly accurate information regarding the detection performance of the force and moment in each axial direction of the force sensor, but it takes time and cost to confirm the detection performance, which is a practical problem. Is.

An object of the present invention is to provide a force sensor inspection method capable of inspecting the detection performance easily and highly accurately at a manufacturing site.

[0006]

SUMMARY OF THE INVENTION A force sensor inspection method according to the present invention controls a position and force by inputting at least a detection signal of the force sensor and a main body portion to which a work tool is attached via the force sensor. A multi-degree-of-freedom operation that includes a control unit that performs a calculation necessary for execution and generates a control command, and causes the main body unit to take an arbitrary posture under the control of the control unit to move the work tool to an arbitrary position. This is a method applied to a machine, in which a member whose mass and center of gravity position are known is attached to the force sensor instead of the work tool, and data relating to the position of mass and center of gravity is stored in the storage device of the control means, and the main body part is In this posture, the first load vector is calculated by using the data regarding the mass and the position of the center of gravity, and the first load data is detected by the force sensor, and the first load vector and the first load data are taken. To obtain the offset amount, and then to let the main body take the second posture, and in this posture, calculate the second load vector using the data regarding the mass and the position of the center of gravity, and detect the second load data with the force sensor. Then, the offset amount is subtracted from the second load data, and the detection performance of the force sensor is determined by obtaining the error between the second load vector and the subtracted second load data. . Further, when the offset amount is known from the beginning, the error can be obtained by taking only one posture.

[0007]

In the present invention, an inspection member whose mass and center of gravity are known is attached to the force sensor provided on the robot main body, and in this state, the robot main body is allowed to assume two postures. It is possible to check the detection performance. In the first posture, the zero point offset amount of the force sensor is first obtained based on the load vector calculated and the load data detected by the force sensor. In the second position,
Similarly, based on the load vector calculated by the calculation and the load data detected by the force sensor, the load vector obtained by the calculation using the above zero offset amount and the final force detected by the force sensor. An error from the data is obtained, and the detection performance of the force sensor is determined based on the magnitude of this error.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the overall structure of a force control robot to which a force sensor is applied. In FIG. 1, reference numeral 1 is a robot body, and an arm 2 having a plurality of joints is attached to a base 3. A drive device such as a motor is arranged in each joint, and each joint has a function of moving in a predetermined direction. Due to the movable function of each joint portion of the arm 2, the posture of the entire arm changes to a posture required for work, and the tip of the arm 2 moves to a position required for work. The robot body 1 takes at least two or more various postures. A 6-axis force sensor 5 is attached to the wrist portion 4 at the tip of the arm 2. At the tip of the force sensor 5, a work tool (not shown) for performing a grinding work or the like on a work (not shown) during normal work is attached. Reference numeral 6 denotes a controller, and the controller 6 is composed of, for example, a computer. The controller 6 has a control program for calculating preset arithmetic expressions for controlling position and force in its storage device, and uses the control program and parameters and teaching contents relating to given working conditions. , Which controls the operation of the robot body 1.

The controller 6 gives a command for controlling its operation to the robot body 1 through the signal line 7. Further, the controller 6 is provided with a signal relating to the force and moment detected by the force sensor 5, that is, a force signal 8. Reference numeral 9 is a teaching operation device for giving various conditions regarding work to be executed to the controller 6 and setting the conditions in the memory. The operation device 9 has a ten-key pad, operation switches for giving various commands, and a display device 9a. With this operating device 9, for example, teaching of a grinding operation, setting of grinding work conditions, and the like are performed.

In the configuration shown in FIG. 1, the robot body 1
For the purpose of confirming the detection performance of the force sensor 5 from the need for maintenance, a member 10 whose mass and center of gravity position are known in advance is fixed to the tip of the force sensor 5 with bolts or the like. The member 10 is a member for inspecting the performance of the force sensor. In the state shown in FIG. 1, the force sensor inspection method according to the present invention is performed as follows.

A method of inspecting the force sensor 5 will be described with reference to FIG. As shown in FIG. 2A, the force sensor 5 has a member 1
The robot body 1 to which 0 is attached takes one arbitrary posture. In the figure, P means the position of the center of gravity of the member 10, and O means the load detection reference point of the force sensor 5. The positions of the center of gravity P and the load detection reference point O are known in advance. When the robot body 1 takes the first posture shown in FIG. 2 (A), the controller 6 stores the information about the mass of the member 10 and the position of the center of gravity P known in advance stored in the storage device. The load vector L1 passing through the position P of the center of gravity of the member 10 is calculated using the above. Here, the load vector means a vertical force vector that acts on the center of gravity of the object due to its mass. Next, the controller 6 inputs from the force sensor 5 data relating to the load of the member 10 detected at the load detection reference point O of the force sensor 5 (load data or force data), and the load data and the load vector obtained by the above calculation. And the offset amount at the zero point of the force sensor 5 is obtained. The calculated offset amount is stored in the storage device of the controller 6.

Generally, the force sensor 5 has a zero-point offset. Therefore, in order to inspect the detection performance of the force sensor 5, it is necessary to take the first posture and obtain the zero-point offset amount in advance as described above. is necessary.

Next, as shown in FIG. 2 (B), the posture of the robot body 1 is changed to take the second posture. It is assumed that the position data and the like regarding the second attitude are stored in advance in the storage device of the controller 6 and are known by the controller 6 side. Even when the robot body 1 takes the second posture, the load vector L2 passing through the center of gravity P of the member 10 is calculated in the same manner as in the first posture.
That is, since the mass and the position of the center of gravity of the member 10 are known, by using these data and the data regarding the second posture of the robot body 1, the load vector passing through the position of the center of gravity P as shown in FIG. 2B. L2 can be obtained. On the other hand, when the load data detected by the force sensor 5 is input in the second posture and the zero point offset amount obtained in the first posture is subtracted from this load data, the posture of the robot body 1 becomes the first posture. The load data L2 'generated by changing from the second posture to the second posture is obtained.

Here, when the force detection performance of the force sensor 5 does not deteriorate and the detection performance as designed is maintained, the load vector L2 and the load data L calculated are obtained.
It should match 2 '. Further, when the detection performance of the force sensor is deteriorated, an error occurs between the load vector L2 and the load data L2 '. Therefore, the detection performance of the force sensor 5 can be inspected by obtaining the error between the load vector L2 and the load data L2 'and checking the magnitude thereof. The failure of the force sensor 5 can be determined according to the magnitude of the error. In general, the obtained numerical value of the error is output and displayed on the screen of the display device 9a of the operating device 9.

In the above-described embodiment, the zero attitude offset amount of the force sensor 5 is first obtained by taking the first attitude, but when the zero attitude offset amount is known in advance, the steps relating to the first attitude are omitted. Of course you can.

[0017]

As is clear from the above description, according to the present invention, regarding the quality of the detection performance of the force sensor of the force control robot, the worker himself / herself can easily, in a short time, and highly accurately at the manufacturing site. Can be inspected and even a failure of the force sensor can be determined.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a force control robot to which a force sensor is applied.

FIG. 2 is a diagram for explaining an inspection method of a force sensor.

[Explanation of symbols]

 1 Robot Main Body 2 Arm 5 Force Sensor 6 Controller 9 Teaching Operator 10 Member for Inspecting Force Sensor

Claims (2)

[Claims] 1. A body part to which a work tool is attached via a force sensor, and at least a detection signal of the force sensor is input to perform a calculation necessary to execute position and force control and generate a control command. And a control means for controlling the force sensor according to the present invention, wherein the force sensor is applied to a multi-degree-of-freedom work machine that moves the work tool to an arbitrary position by causing the main body portion to assume an arbitrary posture under the control of the control means. A member whose mass and center of gravity position are known is attached to the force sensor instead of the work tool, and data relating to the mass and center of gravity position is stored in a storage device of the control means, In this posture, the first load vector is calculated by using the data relating to the mass and the position of the center of gravity, and the first load data is detected by the force sensor. The offset amount is obtained from the cutout and the first load data, the main body portion is set to the second posture, and in this posture, the second load vector is calculated by using the data regarding the mass and the center of gravity position. The force sensor detects the second load data, subtracts the offset amount from the second load data, obtains an error between the second load vector and the subtracted second load data, and calculates the error. An inspection method for a force sensor, characterized in that the detection performance of the force sensor is determined. 2. A body part to which a work tool is attached via a force sensor, and at least a detection signal of the force sensor is inputted to perform a calculation necessary for executing position and force control and generate a control command. And a control means for controlling the force sensor according to the present invention, wherein the force sensor is applied to a multi-degree-of-freedom work machine that moves the work tool to an arbitrary position by causing the main body portion to assume an arbitrary posture under the control of the control means. Using a member whose mass and center of gravity position are known, the main body part is allowed to assume an arbitrary posture, and in this posture, the load vector is calculated using the data relating to the mass and the center of gravity position, and the force A method of inspecting a force sensor, wherein load data is detected by a sensor, and an error between the load vector and the load data is obtained to determine the detection performance of the force sensor.