针对以3-RPS并联机构为核心的光电跟踪系统支撑结构,运用矩阵全微分理论,建立了基于Rodrigues参数的机构位姿误差模型。针对机构可达空间内各误差来源,提出了一种通过归一化描述灵敏度的新方法,并建立基于数学统计意义的灵敏度系数数学模型。通过此模型的数值仿真,可知在机构设计、加工以及装配过程中,对机构驱动误差与定平台上轴向误差需严格控制;当定、动平台结构比例系数改变时,其对整个运动空间各误差灵敏度系数百分比改变不大,即高灵敏度的误差源仍需严格控制。根据各误差的灵敏度系数可对其标定进行修正,达到有效减小误差灵敏度系数较高的运动学参数误差的目的,实现空中目标轨迹的实时跟踪瞄准。
3-RPS symmetrical parallel manipulator is the key part of the parallel supporting structure. By means of the complete differential-coefficient matrix theory, the mechanical position-stance error model expressed by Rodrigues Parameters including the main errors of the parallel supporting structure was established. The sensitivity percentage was proposed for describing the error sources of the parallel supporting structure, and the corresponding sensitivity model with statistical basis was achieved. According to the results of numerical simulation, the actuator errors and the errors of the moving platform along Z axis should be controlled strictly in the course of the design, manufacture and assembly of the manipulator. Although the structure scale was changed, the errors of high sensitivity should be considered fully. Based on the sensitivity analysis of the parallel supporting structure, the calibration is effective to reduce the errors of the kinematic parameters with high sensitivity.