高低频复合驱动的并联调姿隔振平台的运动分析

Kinematics Analysis of Parallel Position Adjustment and Vibration Isolation Platform with High and Low Frequency Compound Drive

针对现有扰动补偿装置调姿和隔振功能分离的缺陷,研制了高低频复合驱动并联平台.通过多种复合驱动方式的性能比较,选用RRPRP构型的平面五杆机构作为复合驱动单元,并将机构构型确定为3-RRPRP-4S.运用约束螺旋理论来分析高低频复合驱动单元的等效形式以及机构的自由度.进而分别建立高频和低频2种驱动形式下的位置反解模型,其中对高频驱动形式下的分析应用逐步迭代法.基于旋量理论,构建2种驱动形式下的动平台与广义输入之间的1阶影响系数和2阶影响系数,进而得到从广义输入到动平台速度和加速度的线性映射.基于运动学分析结果,提出了瞬时锁定法作为机构的驱动策略,通过在高低频驱动下的数值算例对理论分析进行仿真验证,并进行了样机实验.结果表明,仿真曲线和理论曲线几乎完全重合,样机实验的复现率在93%~96%之间.因此,该平台应用高低频复合驱动的形式实现了调姿隔振的混合输出,突破了驱动器频率带对扰动补偿装置的限制,可对频率范围跨度较大的干扰信号进行补偿.

Existing disturbance compensation devices have a defect that the functions of the position adjustment and the vibration isolation are separated.To address the defect,a parallel platform with high and low frequency compound drive is developed.By comparing the performances of several compound driving methods,a planar five-link mechanism with RRPRP configuration is selected as the compound drive unit,and the configuration of the mechanism is determined as 3-RRPRP-4 S.Firstly,the constraint screw theory is used to analyze the equivalent form of the high and low frequency compound drive unit and the degree-of-freedom of the mechanism.Then,the position inverse solution models of the two driving forms,high frequency and low frequency,are established.Here,the step-by-step iterative method is used for analysis in the high frequency driving form.Secondly,the 1 st-order and the 2 nd-order influence coefficients between the moving platform and the generalized inputs are constructed under the two kinds of driving forms based on the screw theory,then the linear mappings,from the generalized inputs to the velocity and the acceleration of the moving platform respectively,are obtained.Next,the instantaneous locking method is put forward as the driving strategy of the mechanism based on the kinematics analysis results.Finally,the kinematics analyses are verified by the simulations on the numerical examples under the high and low frequency drive,and by the experiments on a prototype.Results show that the simulation curves and the theoretical curves almost coincide,while the recurrence rate is 93%~96% in the prototype experiment.Therefore,the platform with the high and low frequency compound driving,realizes a hybrid output of the position adjustment and the vibration isolation.In fact,it breaks through the limits to the existing disturbance compensation devices caused by the frequency band of drives,and can compensate the interference signals within a large frequency range.