单足机器人垂直跳跃落地碰撞冲击力分析

为研究落地碰撞冲击力的变化规律,针对垂直跳跃单足机器人球面尼龙足底与橡胶地面的碰撞过程,建立由支撑腿和机身的动力学模型、橡胶地面大变形黏弹性力学模型和气缸上下腔气体热力学模型组成的整体数学模型和仿真模型.仿真结果表明:压缩阶段递增的弹性力和先增后减的阻尼力使地面冲击反力先增大后减小,恢复阶段快速减小的弹性力和反向阻尼力共同作用导致冲击反力单调减小;最大冲击力随下落高度、橡胶贮能模量的增大和橡胶垫厚度的减小单调增大,随橡胶耗能因子与频率比值的增大先减小后增大;单足机器人0.1 m垂直跳跃落地碰撞的实验结果表明,实验数据与仿真结果的相对误差7.6%,验证了所采用理论分析方法和仿真结果的正确性.

Analysis of landing impact force of the one-legged robot vertical hopping

Studying the dynamic regulation of the landing impact forces and influence factors for landing impact is the basis of analysis of the dynamic stability of robots. Considering that the rubber mat in landing phase is in large deformation during the landing process of robot, the dynamic model and simulation model of the landing impact process that consists of the dynamic models of robot''s leg and body, the viscoelastic model of rubber floor in large deformation and the thermodynamics model of gas in cylinder chambers are built. In addition, the simulation results show that the change of foundation elastic reaction and damping force in the compression phase makes impact force increase quickly, reach a maximum and then decrease, that the maximum impact increases as the falling height and the storage module of rubber increase, decreases as the thickness of the rubber increases, and that the larger ratio, the smaller maximum impact when the ratio of the dissipative energy scale factor to the vibration frequency is less than 0.01, and the larger ratio, the larger maximum impact when the ratio is more than 0.01. The maximum relative error of simulation results and experiment results of the robot for 0.1 m free fall is less than 7.6%, which verifies the simulation results.