头盔伺服系统的主动柔顺控制

 对头盔伺服系统(HMDPM)主动柔顺控制策略的主要内容——轨迹规划和控制方法进行了研究。首先,采用基于力反馈和滑动杆动力学模型的头部运动预测法进行轨迹规划,该方法利用并联机构(PM)分支杆长与运动平台位姿间的映射关系,通过力反馈信息和6-3UPS并联机构滑动杆动力学模型对头部运动进行预测,为头盔伺服系统的位置控制提供期望轨迹;然后,基于头盔伺服系统的动力学模型对系统的惯性项和非线性项进行了计算,设计了惯性项和非线性项补偿控制器,在进行头部运动跟踪的同时,实现了头盔显示器与头部间接触力的控制;最后,采用SimMechanics模块建立了HMDPM—人交互模型,并进行了相关验证实验。仿真结果表明,基于力反馈和滑动副滑动杆动力学模型的头部运动预测法能实时地、较为准确地预测出头部运动位置;基于动力学模型的惯性和非线性项补偿控制器不仅可以较为准确地跟踪头部运动,而且还能有效地减小头盔显示器与头部间的接触力,降低执行机构的刚度、减少系统摩擦力等非线性因素对使用者的干扰。

Active Compliance Control of Helmet Mounted Display with Parallel Manipulator

In this paper,an active compliance control strategy and its key elements for helmet mounted display with parallel manipulator(HMDPM) is investigated.Firstly,the methodology of predicting head motion based on force feedback and a dynamic model of the extensible leg of a 6-3UPS parallel manipulator(PM) is proposed to plan the trajectory.Based on the relationship between the length of the extensible leg and the position and orientation of the platform,the information of head motion is predicted by means of sensor datum and solution of the dynamic model of the extensible leg,and then it is used as the desired trajectory of HMDPM position control.Secondly,the inertia term and nonlinear term of the HMDPM dynamic model are calculated,and the compensations of them are considered in the design of the HMDPM controller so that the contact force between head and helmet will be controlled easily while tracking control of the head is progressing.Finally,the SimMechanics module in MATLAB is adopted to construct a human-robot interactive model of HMDPM,and the feasibility of the novel control strategy is verified by developing some related numerical simulations.The simulations show that head motion will be predicted rapidly and precisely using the proposed method,and the stiffness of HMDPM and contact force are reduced evidently by compensating for the inertia term and the nonlinear term in the HMDPM controller while tracking control of the head is conducted,and user comfort is obviously enhanced.