JP2591057B2 - Precise measurement method by robot - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of the Invention The present invention relates to a precision measurement method using a robot, and is useful when a general-purpose robot measures the specifications of an object to be measured.

B. Summary of the Invention The present invention relates to a method for measuring the specifications of an object to be measured by a measuring device attached to a tip of a robot arm having a control unit which is a servo system, and in which all axes are set after positioning of the robot arm is completed. Is mechanically locked and the power of the servo system is turned off, and a predetermined measurement is performed in this state, so that accurate measurement can be performed.

C. Conventional technology When measuring static dimensional changes of an object to be measured, for example, the amount of run-out and eccentricity of a flywheel, for many objects to be measured, the measuring instrument is replaced when the number of measurement points increases. Since a great deal of labor is required for setting up such a method, a method is adopted in which a measuring device is attached to the arm of a robot having a control unit serving as a servo system, and teaching and playback are performed at a predetermined measurement position for measurement. In this measurement method, the robot with the measuring device attached to the tip of the arm is positioned to a predetermined position by the control unit, servo lock is performed by a positioning completion signal by this positioning, and in this state, predetermined measurement is performed by the measuring device. It is to do.

D. Problems to be Solved by the Invention When the above-described measurement is performed by a general-purpose robot, the position of the arm of the robot at the time of measurement is unstable, so that the measurement accuracy is limited.

On the other hand, in order to increase the measurement accuracy, it is conceivable to increase the resolution of a servomotor that drives each axis of the robot arm. For example, if the servomotor has a resolution of 11 bits per rotation and a reduction ratio of 158 and an arm length of 1 m (360 × π × 1000/158 × 2048 × 18
0) = 0.019 (mm), not only cannot obtain an accuracy of 0.01 (mm) or more, but even if the resolution is improved, the rigidity is low due to the structure of the robot arm, and an improvement in accuracy over a certain level cannot be expected. . Therefore, it is difficult to improve the accuracy to, for example, 10 μm or more only by increasing the resolution.

Further, a speed reducer is connected to the servo motor that drives each axis of the robot arm, and the arm swings due to the back crash of the gear of the speed reducer. In the case of, the stop position of the arm becomes extremely unstable on the pivot axis which is not affected by its own weight.

The present invention has been made in view of the above-described conventional technology, and has as its object to provide a precise measurement method using a robot that can perform accurate measurement by eliminating all unstable elements during measurement.

E. Means for Solving the Problems The configuration of the present invention that achieves the above object is to measure the specifications of an object to be measured by a measuring device attached to a tip of a robot arm having a control unit that is a servo system. In, the controller performs positioning of the robot to a predetermined position, performs servo lock by the positioning completion signal by this positioning, then mechanically locks the movement of all axes of the robot arm and turns off the servo system power In this state, perform a predetermined measurement with a measuring instrument, turn on the servo system power by the measurement completion signal accompanying the completion of the measurement, and release the mechanical lock of all axes of the robot arm. Features.

F. Function According to the present invention having the above-described configuration, the arm of the robot is mechanically locked when measuring the object to be measured, and the power supply of the servo system is also turned off.
Because it is in the F state, its position does not move,
Therefore, the measuring instrument is also fixed at a fixed position.

G. Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram showing an arm of a robot that realizes an embodiment of the present invention, together with an object to be measured. The object to be measured in this case is, for example, a flywheel 3 fixed to a rotating shaft 2 supported by a bearing 1, and the amount of deflection and eccentricity of the flywheel 3 in a stationary state is measured at multiple points (for example, 50 points). ). This measurement is performed by detecting the coordinates of the position of each point with respect to a predetermined reference position by the measuring device 4 and then performing a predetermined calculation similar to the conventional one by the control unit (not shown) of the robot. At this time, the measuring device 4 is attached to the tip of the arm 5 of the robot.

As described above, in the precision measuring method of the present embodiment using the measuring device 4 attached to the tip of the arm 5, the robot is first positioned at a predetermined position. Servo lock is performed by a positioning completion signal by this positioning, and thereafter, the movements of all axes 5a to 5f of the robot arm 5 are mechanically locked. For example, 0.5 seconds after that, the power supply of the servo system is turned off (even in this case) The control power remains ON). As a result, the position of the arm 5 is fixed and does not move erratically. In this state, predetermined measurement is performed by the measuring device 4, and data is taken in and coordinate calculation is performed. Upon completion of the predetermined measurement operation, a measurement completion signal is issued, and the power of the servo system is turned on and the mechanical lock of the arm 5 is released by the measurement completion signal. This completes the measurement at one point.

Subsequently, positioning to the next measurement point is performed, and the same operation is repeated to perform predetermined measurement on this point. A predetermined measurement is performed by repeating the same operation for each point.

H. Advantageous Effects of the Invention As described above in detail with the embodiments, according to the present invention, the arm of the robot is mechanically locked and the power supply of the servo system is in the OFF state at the time of measuring the object to be measured. So its position does not move. Therefore, the measuring device is also fixed at a fixed position, so that accurate measurement can be performed. Further, since the measuring instrument does not move from a fixed position during the measurement, it is possible to prevent an accident that the measuring instrument collides with the object to be measured and is damaged in both cases of contact and non-contact.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a robot arm for realizing an embodiment of the present invention, together with a measuring instrument and a device to be measured. In the drawing, 3 is a flywheel, 4 is a measuring instrument, 5 is an arm, and 5a to 5f are axes.

Claims (1)

(57) [Claims] When measuring the specifications of an object to be measured by a measuring device attached to the tip of a robot arm having a control unit which is a servo system, the control unit performs positioning of the robot at a predetermined position. Servo lock is performed by the positioning completion signal by this positioning, then the movement of all axes of the robot arm is mechanically locked, and the power supply of the servo system is turned off. A precise measurement method using a robot, characterized in that the servo system power is turned on and a mechanical lock on all axes of the robot arm is released by a measurement completion signal accompanying the completion of the measurement.