A Hierarchical Error Calibration Strategy for Macro-Micro Manipulator

Kinematic parameter calibration is crucial for the accurate operation of the manipulator. The high redundancy and large arm span of the macro-micro manipulator of the space station pose challenges to calibration. When the existing basic methods are used to deal with the high redundancy manipulator, it is difficult to accurately calibrate the kinematic parameters even if the end error is compensated, resulting in model deviation. High redundancy also increases the data needed and amount of computation, so there is room for improvement in efficiency. Therefore, this paper proposes a hierarchical error calibration strategy, taking the macro-micro manipulator on the Chinese Space Station as research object. Firstly, the macro and micro arms are calibrated in parallel in the single-arm state, and then the arms are combined to calibrate only the newly introduced errors. This method can reduce parameter errors, reduce calculation time, and allow parallel calibration to reduce operating time. Compared with calibrating the macro-micro manipulator as a whole directly, the proposed method can almost eliminate parameter deviation when free from random interference, and has a higher upper limit of parameter accuracy when random interference exists (the maximum error of length parameter is 0.034 times, and angle parameter 0.044 times that of the direct method). In terms of calculation, the time consumption can be reduced to 0.691 times of that of the direct method as the data increases.