基于准零刚度机构与间接力控制的恒拉力系统设计与分析

Design and analysis of constant tension system based on quasi-zero stiffness mechanism and indirect force control

现有的悬吊式微低重力模拟恒拉力系统常采用力传感器数值作为反馈直接控制系统,但实际情况下力作为反馈信号常会产生突变,影响系统控制精度。为了改进刚性控制策略下系统稳定性差与大冲击条件下力误差大的状况,文中设计了包含准零刚度机构的恒拉力系统,通过控制准零刚度机构长度间接对恒拉力系统输出拉力进行控制。对准零刚度机构进行受力分析,明确影响准零刚度机构性能的关键指标和准零刚度机构的工作行程区间,建立恒拉力系统动力学模型,设计控制系统。为了验证系统控制精度与系统抗干扰性能,进行了动力学联合仿真对设计进行验证,仿真结果表明:该恒拉力系统拉力的控制误差可控制在2%以内,且具有较好的鲁棒性。

Currently,the suspension-typed constant tension system characterized with micro-low gravity simulation often uses the force sensor values as the feedback to directly control the system,but in reality,the force as the feedback signal often produces sudden changes,which affects the system’s accuracy in controlling.In this article,in order to improve the system’s poor stability with the rigid control strategy and reduce the large force error with the large impact,efforts are made to design a constant tension system which contains a quasi-zero stiffness mechanism.By controlling the length of the quasi-zero stiffness mechanism,the output tension exerted on the constant tension system is indirectly controlled.The analysis is conducted on the force exerted on the quasi-zero stiffness mechanism,in order to work out the key influencing factors of the mechanism’s performance and working stroke range;besides,the dynamic model of the constant tension system is set up,and the control system is designed.In order to figure out the system’s accuracy in controlling and anti-interference performance,the dynamic joint simulation is conducted to verify the design.The simulation results show that the error of the force exerted on the constant tension system can be controlled within 2%,and the system has good robustness.