有限频域约束下串联弹性驱动器的刚度控制

Stiffness control of a series elastic actuator with restricted frequency domain specifications

中文关键词  人机交互  串联弹性驱动  阻抗匹配  频域分析  广义KYP引理

英文关键词  human-robot interaction  series elastic actuator  impedance matching  frequency domain analysis  generalized KYP lemma

中文摘要

      工程实际中的被控对象都具有明显的有限频域特性, 但目前的物理人机交互研究大多是针对全频域性能指标来设计阻抗控制器, 由此得到的控制器往往失之保守. 本文针对绳牵引串联弹性驱动下的人机物理交互问题, 采用有限频域性能约束方法来提升系统在设定频段的刚度控制性能. 首先, 分析绳牵引串联弹性驱动的刚度控制目标并将其转化成有限频域性能约束下的H∞控制问题. 其次, 根据广义Kalman-Yakubovich-Popov (KYP)引理, 将有限频域性能约束转化成矩阵不等式条件, 进而分解变换成有关全信息控制器和待求的静态输出反馈控制器的条件. 然后, 求解出一个满足条件的全信息控制器, 并迭代优化得到输出反馈控制器. 仿真和实验结果都表明, 本文方法在设定频段取得了更加精确的刚度控制效果.

英文摘要

      Despite the fact that the controlled objects in practical applications generally possess restricted frequency domain characteristics, the impedance controllers in physical human robot interaction are usually designed with respect to performance constraints over the entire frequency domain, which inevitably brings conservatism. In this work, a restricted frequency domain control method has been established to augment the stiffness control performance at the desired frequency band for physical human-robot interaction with a cable-driven series elastic actuator. Firstly, the stiffness control problem was analyzed and reformulated as an H∞ synthesis problem with restricted frequency domain specifications. Secondly, these specifications were transformed to linear matrix inequalities with the generalized Kalman-Yakubovich-Popov (KYP) lemma, and then, converted to conditions regarding a full information controller and the desired static output-feedback controller. Thirdly, a full information controller satisfying the specifications was obtained, which was used to calculate the desired controller by iterative optimization. Finally, both simulations and experiments were conducted to verify the efficacy of the proposed method, and more precise stiffness control performance has been achieved at the desired frequency range.