Abstract: Different from strain gauge dynamometers,six-axis dynamometer based on fiber Bragg grating (FBG) adopts the structural force measurement principle,and one of its main performance parameters is the coupling error.Due to the limitation of its application scenario,in-place calibration is usually performed.The sensing structure and principle of the FBG six-axis dynamometer are analyzed,and an in-place calibration device without a standard force source is proposed according to the coupling error model.An in-place calibration method based on a robot arm for coupling error is also established,in which the calibration process is simplified and the source of uncertainty is reduced.The uncertainty of calibration results is analyzed with a practical example,and the effectiveness of the method is verified.

Key words: Fiber Bragg grating（FBG）, Six-axis force, Coupling error, In-place calibration