Robust force tracking control via backstepping sliding mode control and virtual damping control for hydraulic quadruped robots

Abstract

In order to improve the force tracking performance of hydraulic quadruped robots in uncertain and unstructured environments, an impedance-based adaptive reference trajectory generation scheme is used. Secondly, in order to improve the robustness to environmental changes and reduce the contact force errors caused by trajectory tracking errors, the backstepping sliding mode controller is combined with the adaptive reference trajectory generator. Finally, a virtual damping control based on velocity and pressure feedback is proposed to solve the problem of contact force disappearance and stall caused by sudden environmental change. The simulation results show that the proposed scheme has higher contact force tracking accuracy when the environment is unchanged; the contact force error can always be guaranteed within an acceptable range when the environment is reasonably changed; when the environment suddenly changes, the drive unit can move slowly until the robot re-contacts the environment.

摘要

为了提高在不确定和非结构化环境下液压四足机器人的力跟踪性能, 采用了基于阻抗的自适应 参考轨迹生成方案。然后, 了提高对环境变化的鲁棒性并减少由轨迹跟踪误差引起的接触力误差, 将反步滑模控制器与自适应参考轨迹生成器结合使用。最后, 提出了一种基于速度和压力反馈的虚拟 阻尼控制, 以解决环境突然变化引起的接触力消失和失速的问题。仿真结果表明, 该方案在环境不变 的情况下具有较高的接触力跟踪精度。当环境发生合理变化时, 接触力误差始终可以保证在可接受的 范围内; 当环境突然改变时, 驱动单元可以缓慢移动, 直到机器人足端重新接触环境。