为了提高双足步行机器人对真实环境的适应能力,提出1种基于3-D步行序列的步态规划方法,模仿人类行走行为并考虑地面高度的变化.首先定义考虑足部踝关节旋转运动和机器人质心(COM)竖直高度变化的3-D步行序列.其次,在单足相阶段(SSP),基于运动最优控制(OC)理论和线性倒立摆模型(LIMP),求解零力矩点轨迹;采用5次多项式插值,生成双足相阶段(DSP)的零力矩点轨迹,并且实现质心竖直高度变化.基于足部的运动参数,使用分段连续3次Hermite插值得到足部运动轨迹.然后,通过牛顿?拉斐逊迭代法求解关节角度解.最后,基于NAO机器人样机进行平地和倾斜地面行走的动力学仿真和样机实验.研究结果表明:本文规划方法可行,且机器人行走平稳;在平面和斜坡2种地面工况的样机实验中,足底接触力的波动幅度比相应的仿真结果分别减少37.01%和59.94%,髋关节力矩波动幅度分别减少69.13%和62.75%.%In order to improve the adaptability of biped walking in the real environment, a novel gait planning method based on 3-D walking sequence was proposed. By imitating human walking behaviour and taking the change of ground height into consideration, 3D walking sequence (WS), which also considers the rotational motion of ankle joint and the vertical height of the robot, was firstly defined. Then, during single support phase (SSP), optimal control (OC) theory and linear inverted pendulum model (LIMP) were adopted for generation of zero moment point (ZMP) trajectories. The 5th order spline interpolation was used to generate ZMP trajectories and to produce the center-of-mass (COM) height variation during the double support phase (DSP). By employing motion parameters of the foot, the foot trajectory was also obtained by piecewise continuous cubic Hermite interpolation. After that, the Newton-Raphson method was used to solve the desired joint angle. Finally, dynamic simulation and hardware experiments of bipedal walking on flat and slope ground were carried out by employing the NAO robot. The results show that the proposed method is effective in practice and that the robot walks more stably in the real environment. Fluctuation range of the foot contact force of NAO robot in flat and slope conditions decrease by 37.01% and 59.94% respectively compared with those in simulation test, and fluctuation range of the hip joint decrease by 69.13% and 62.75%, respectively.
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