基于三质点模型的仿人机器人节能步行  

Energy-efficient bipedal walking for humanoid robots based on a three-mass model

作　　者：何杰 张晓晖 肖晓晖[1] 丁加涛[1] HE Jie;ZHANG Xiaohui;XIAO Xiaohui;DING Jiatao(School of Power and Mechanical Engineering,Wuhan University,Wuhan 430072,China)

机构地区：[1]武汉大学动力与机械学院,湖北武汉430072

出　　处：《中南大学学报（自然科学版）》2020年第12期3396-3406,共11页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51675385,51175383)。

摘　　要：为了实现高能效的双足步行,提出基于三质点线性倒立摆模型(3MLIPM)的步态生成与优化策略。首先,定义表征单位能耗的步态周期(UEWC),利用三质点模型,对机器人进行运动学建模与步行能耗评估,建立机器人步行过程的能耗评价模型,分析各质量块的运动性质,提出基于质心(CoM)加速度优化的二次型步行能耗评价指标;其次,对3MLIPM进行动力学建模,将CoM运动分为稳定分量与不稳定分量,CoM最优轨迹求解转化为求解运动分量误差项,通过跟踪参考的零力矩点(ZMP)轨迹,利用无约束优化算法求解对应的能耗最低的CoM轨迹;最后,实现了步态的在线生成,并且为消除腿部质量摆动导致的躯干质心附加运动,通过二分搜索的修正算法,修正3MLIPM的步行参数输入(步长和步宽),进一步降低了双足步行的能量消耗。通过仿真和试验验证了算法的可行性和有效性。研究结果表明:提出的能耗评价指标能够表征三质点步行系统的真实能耗,并且能够用于指导最优CoM轨迹生成;利用双足稳定支撑域,可以优化参考ZMP轨迹以实现低能耗步行;通过修正三质点模型的名义步行参数输入,消除等效ZMP产生的附加运动,针对不同形式ZMP参考轨迹,修正后的三质点模型相比于传统单质点模型,可以有效降低步行能耗。With the aim of realizing the energy-efficient bipedal walking,a novel strategy was proposed for gait generation and optimization based on the three-mass linear inverted pendulum model(3 MLIPM).Firstly,walking cycle of unit energy cost(UEWC)was defined,and the mathematical model for evaluating the energy cost of humanoid robots during the walking process was derived by exploiting the three-mass model.After analyzing the motion property of each lumped mass,the quadratic evaluation index was proposed based on the optimization of the acceleration of center of mass(CoM).Secondly,the dynamic model of the 3 MLIPM was built to decompose the motion of CoM into stable component and unstable component.Therefore,the solution of the CoM optimal trajectory was transformed into the solution of the motion component error term.By tracking the reference zero moment point(ZMP)trajectory,the corresponding CoM trajectory of the minimal energy consumption was solved by an unconstrained optimization algorithm.Finally,the walking pattern was generated online.To eliminate additional movement of torso CoM caused by the mass swing of the legs,the nominal step parameters,including step length and step width,were modified by modifying binary search algorithm.Therefore,the energy cost would be reduced to a further degree.The feasibility and effectiveness of the proposed method were demonstrated by simulation and experiment results.The results show that the proposed evaluation index can characterize the actual energy consumption of the three-mass walking system and can be used to guide the optimal CoM trajectory generation.Besides,by utilizing the allowable support region,reference ZMP trajectories can be optimized to realize energy-efficient walking.Furthermore,through modifying the nominal step parameters inputs of the3 MLIPM,additional motion generated by equivalent ZMP is eliminated.Compared with traditional single-mass model,the modified three-mass model can effectively reduce walking energy consumption for different forms of ZMP referen

关 键 词：三质点线性倒立摆模型(3MLIPM) 零力矩点(ZMP) 能量效率 双足步行 仿人机器人 

分 类 号：TP242[自动化与计算机技术—检测技术与自动化装置]