用于腿足式机器人落地缓冲的复合控制策略

A hybrid control strategy for legged robot buffering in landing process

针对腿足式机器人的腿部运动模式,提出一种变刚度落地缓冲策略,对机器人躯干质心处预期的冲击进行规划,针对不同落地阶段采用不同控制方式。在缓冲阶段,通过躯干加速度规划的方式计算预期足底力,将该力映射到关节空间。在其他阶段,采用比例微分(proportional differential,PD)控制与滑模控制(sliding mode control,SMC)相结合的方式,保证运动的快速性和稳定性,并用李雅普诺夫第二法证明稳定性。试验表明,机器人质心在1.65 m处下落,该方法可使足地冲击小于1.7g。此冲击力与人上台阶的冲击力相近,说明该方法可起到良好的缓冲效果。

A cushioning strategy with variable stiffness was proposed for an articulated legged robot.The strategy planed the impact on the center of mass of the robot torso.Different control laws were applied for different phases in the whole landing process.In cushioning phase,the expected foot-ground contact force was calculated through planning of torso acceleration,and the torques were achieved by the contact force through Jacobean matrix.In other phases,a hybrid control approach was used for maintaining stabilization and agility of the system.This method combined proportional differential(PD) control with sliding mode control(SMC).The stability of the method was proved by Lyapunov′s second method.According to experiments,the cushioning approach enabled the robot fall from 1.65 m high(torso′s center of mass to the ground) and land with the impact less than 1.7g,which was similar to the foot-ground impact of a person going upstairs.