Robot arm calibration device and method thereof

A robot arm calibrating method, comprising:

• disposing a light emitter and a light sensing module on at least two robot arms respectively;
• driving the light emitter and the light sensing module on the at least two robot arms to a corrected position and a position to be corrected respectively;
• emitting a light beam by the light emitter to project the light beam onto the light sensing module;
• receiving the light beam by the light sensing module and converting the light beam into a plurality of image data, wherein the light sensing module comprises a plurality of light sensing units, and the light emitter sequentially projects the light beam onto the light sensing units respectively to generate the plurality of image data;
• calculating an error value between the corrected position and the position to be corrected according to the plurality of image data and the motion parameters of the at least two robot arms and analyzing the plurality of image data to output a corrected motion parameter;
• and
• modifying a motion command of at least one of the at least two robot arms according to the corrected motion parameter.