建立机器人-步行路径间的刚柔耦合模型,分析路径参数对机器人步态参数的影响规律。首先,采用基于自然零力矩点(ZMP)轨迹的步态规划方法,通过给定参考ZMP轨迹获取机器人质心轨迹,插值得到机器人在刚性路径下的步态;其次,基于Pasternak地基模型,在ANSYS中建立公路的多层柔性模型,导入ADAMS中与机器人多刚体模型耦合。通过3组柔性参数与理想刚性路面假设下的步行仿真,分析地面的柔性参数对机器人质心与ZMP轨迹、关节驱动力矩等参数的影响。研究结果表明:机器人在柔性地基公路上步行时质心高度比较稳定,波动小于2.6%,质心沿前进方向移动距离接近预期规划的步行距离,比刚性路径假设下的步行效率高;驱动力矩变化趋势与刚性路径变化趋势基本一致,其中支撑腿相应关节的驱动力矩突变峰值减少8.3%-33.4%,关节运动更平稳;足底接触力较刚性路径波动范围增大7.2%-16.7%,地面对机器人的冲击减少约8.0%。在自然柔性地面环境中,双足步行机器人的步态效率更高,运动更平稳。
A rigid-flexible coupling model between biped robot and its walking path was established to analyze the influence of path parameters on gait parameters. Firstly, with the method of gait planning based on natural ZMP trajectory,robot centric track was obtained by setting reference of ZMP trajectory, and then the gait on a rigid path was acquired by interpolation. Secondly, multilayer flexible model of road was established in ANSYS software based on Pasternak foundation model to be exported to ADAMS and coupled with the robot multi-rigid-body model, then the effect on mass trajectory, centric trajectory and driving torque of joint from flexibility data of ground were analyzed by simulating the robot walking in three groups of flexible surface and one ideal rigid surface. The results show that the height of mass center is more stable with fluctuation being less than 2.6%, moving distance along the forward direction is much closer to prospective walking distance and the walking efficiency on a flexible path is higher than that on a rigid path. Although the trend of driving torque is similar to that in a rigid path, its mutation peak in the joints on supporting leg is reduced by8.3%-33.4%, and so the joint can move more steadily. Moreover, the fluctuation range of pelma contact force is7.2%-16.7% more than that in the rigid path, and the impact from the ground upon the robot is reduced by 8.0%, which indicates that the biped robot is capable of walking most efficiently in natural ground environment.