Research on Application of Stewart Platform in Uniform Scanning

The space spectral imaging camera is planned to use a Stewart 6-DOF platform to drive a mirror for scanning and imaging, which requires the accuracy of the platform to reach the order of arcsec under the condition of multi-struts dynamic coupling. A Stewart platform realizes high angle resolution mainly by designing high-resolution linear driving struts. The resolution index of the 6-DOF Stewart platform is 2”, which needs the struts to achieve a high resolution of 60 nm. Based on this requirement, a driving strut with 50 nm resolution based on BLDC motor, ball screw, grating ruler is designed, which effectively ensures the high resolution of the platform. The transfer function of the single drive strut is identified by time domain method, and the closed-loop control model of the single drive strut is established. The dynamic performance of the single drive strut is simulated and analyzed. Finally, the dynamic performance of the 6-DOF scanning platform is experimentally studied. The experimental results show that the angular resolution of the 6-DOF Stewart platform is 2”, the swing angle range of the constant speed scanning is −1~1 degree, the nonlinear error of scanning angle in place curve is less than 0.2%, and the rotational speed is adjustable from 40”/s to 1800 ”/s, all the indicators meet the design index. This research has laid a solid foundation for the aerospace application of Stewart Parallel Platform.