有躯干双足机器人被动行走及其稳定器

采用Matlab仿真的方式构建了一个简单的有躯干双足机器人模型,研究了该模型在斜坡上的被动行走,分析了模型步行的稳定性,并设计了一个全状态线性反馈步行稳定器.研究结果表明:无任何驱动器的有躯干双足机器人能够实现沿斜坡而下的被动行走,其步行方式有两种,但均不稳定;设计的全状态反馈稳定器能够较好地稳定模型的被动行走.     

基于脉冲推力作用的双足机器人半被动行走

研究了半被动双足机器人行走过程固定点的全局稳定性问题.使用罗盘机器人模型,在脚与地面冲击前,采用支撑腿的脉冲推力作为行走的动力源.通过引入一个限位器使两腿间的夹角在脚与地面冲击时保持为常数.采用庞加莱映射方法证明了半被动双足机器人行走固定点的存在性及其稳定性.分析了脉冲推力作用方向对双足机器人稳定行走的影响,并讨论了固定点存在的动力学附加条件.针对模型已知和未知2种情况,分别设计了行走控制律.理论分析和仿真结果表明,采用所提出的控制方法,半被动机器人可以在水平面上稳定行走,当脉冲推力作用方向与前腿垂直时控制效率最高.     

基于被动行走原理的双足机器人步态规划

为解决四连杆双足机器人的平面步态规划问题, 提出基于被动行走的平面步态规划。基于3毅向下坡面完全被动行走的动力学方程, 利用角度不变控制方法施加控制力矩, 得到机器人在水平面上的动力学模型。结合常数时间放缩方法对平面参考轨迹进行时间放缩, 得到机器人在水平面上步幅不变, 周期可变的行走步态。通过Matlab 软件数值仿真结果表明, 该研究方法是可行、有效的。     

欠驱动机器人强化学习算法仿真及结果分析

针对纯被动机器人对环境变化敏感,抗干扰能力差等问题,提出了一种基于Sarsa(λ)强化学习的底层PD控制器参数优化算法.在MatODE环境下建立双足有膝关节机器人模型并进行控制器设计.通过与传统控制器仿真结果的对比分析,得出该算法可使模型获得更加稳定的行走步态,同时提高了系统抵抗斜坡扰动的能力,增强机器人的行走鲁棒性.     

表征被动双足行走的二维无边轮辐的动力学及稳定性分析

为验证具有被动行走特征的二维无边轮辐稳定极限环的存在,使静止于斜坡上的无边轮辐以不同的初始运动条件开始运动,对其进行运动学及动力学分析,建立表征被动双足行走理论的无边轮辐模型的无碰撞阶段运动方程及碰撞瞬间切换方程.利用庞加莱映射理论进行斜坡上滚动的无边轮辐运动稳定性分析,结果表明,不动点与极限环为轮辐运动稳定性的表征参数,且不动点与极限环的存在与轮辐的辐条数目、惯性矩参数、运动初始条件和斜坡角度有关.利用M ATLAB软件对不动点与极限环的存在进行仿真分析,验证了在一定的斜坡角度和初始运动条件下无边轮辐可实现稳定持续的下坡滚动.基于无边轮辐模型可建立斜坡上行走的无驱动被动双足行走模型,将下坡时由重力提供的驱动力等同于主动驱动力施加到平面上行走的无驱动被动双足行走模型,可以减少驱动能量损耗及简化行走控制理论.     

不平整地面上双足机器人的步态控制

提出了一种不平地面环境下双足机器人的步行控制算法.该算法由步态规划和传感器反馈控制系统组成.在步态规划中,采用被动倒立摆模型设计双足机器人的质心位置,所生成的步态使机器人能够在平地上更自然有效地稳定行走.在线反馈控制系统用于处理地面环境的凹凸不平以及来自外界的未知扰动,可分为上身姿态控制、期望ZMP控制以及非线性落地控制3个部分.这3种控制分别针对不同的控制目标,并根据步行过程的具体阶段在线修正预先规划好的步态,维持双足机器人的步行稳定性.它们在结构上相互耦合,从而实现加速在线反馈控制系统的收敛速度、克服机器人柔性对控制作用的负面影响等效果.双足机器人在凹凸地面的步行实验验证了所提出步行控制算法的有效性.     

上斜坡双足机器人行走的稳定性分析

为了研究上斜坡双足机器人行走周期步态稳定性,采用拉格朗日方法建立双足机器人行走脉冲混杂系统,构造庞加莱映射,再通过对映射不动点的分析得到机器人行走周期步态的存在性及稳定性条件。研究结果表明：在斜坡角为0.1 rad的条件下,当线性脉冲推力各项系数选取合适参数时,双足机器人上斜坡行走系统存在稳定的周期-1步态;当脉冲推力的常数项系数取值不同时,其对应产生不同类型的周期-1步态;当行走系统状态参数改变时,其产生不同运动状态的周期-1步态。     

基于粒子群优化算法的双足机器人步态优化

分析了髋关节位置对双足机器人步行稳定性判据零力矩点(ZMP)的影响,以ZMP稳定裕度为参数构造目标函数,利用粒子群优化算法(PSO)对基于3次样条插值方法规划的双足机器人步态进行优化,从而得到ZMP稳定裕度大的平滑步态.仿真实验表明:该方法规划的步态实现了双足机器人稳定、协调地行走.     

基于ZMP双足机器人稳定性控制策略与算法的研究

基于ZMP控制理论及其数学模型,通过预先给定双足机器人步态的运动轨迹,计算确定各关节的旋转角度并选定控制系统的控制算法.对遗传算法在双足机器人步行稳定性控制策略做了分析,主要解决如何产生稳定控制机器人步态的数据,在步态运行过程中保证双足机器人从一个稳定态到下一个状态时,同样也是稳定的,以实现机器人在实际行走过程中达到较好的稳定效果.ZMP     

带被动踝关节的双足机器人动力学及步态研究

欠驱动双足步行机器人是仿人机器人领域研究的热点之一.针对带有被动踝关节的双足机器人,建立了五杆四驱动模型,对模型进行动力学分析.根据拉格朗日原理,建立机器人单足支撑动力学模型和基于碰撞的双足支撑动力学模型.建立完整的欠驱动双足步行机器人动力学模型.对机器人步态进行了规划.规划了欠驱动机器人的时不变步态;利用贝塞尔多项式拟合出虚拟约束的轨迹,给出了欠驱动机器人轨迹规划的算法;采用极限环方法,通过验证庞加莱回归映射不动点稳定性,验证了极限环的稳定性,从而验证了机器人步态的稳定性.     

基于自适应网络的动态双足机器人模糊控制

提出一种基于步态规划分级结构的自适应网络模糊推理系统控制策略,该方法不需要确定双足机器人运动学和动力学模型.以一种动态双足机器人为例,建立机器人的Sugeno模糊模型,对机器人系统的不确定上界进行自适应参数估计,采用自适应控制器逼近未知不确定界,解决了一类非线性系统的稳定控制问题.控制器的设计只要求不确定性满足匹配条件,而无需知道不确定界,能够处理不确定参数变化范围更广的情况,减少控制系统设计中的保守性.设计的分级控制系统可以学习试验的输入输出数据,从而在动态平衡下进行行走.同时,模糊控制器的进一步在线学习能力可以显著地改善步行机器人的动态性能.     

A New Method of Desired Gait Synthesis for Biped Walking Robot Based on Ground Reaction Force

A new method of desired gait synthesis for biped walking robot based on the ground reaction force was proposed. The relation between the ground reaction force and joint motion is derived using the D'Almbert principle. In view of dynamic walking with high stability, the ZMP(Zero Moment Point)stability criterion must be considered in the desired gait synthesis. After that, the joint trajectories of biped walking robot are decided by substituting the ground reaction force into the aforesaid relation based on the ZMP criterion. The trajectory of desired ZMP is determined by a fuzzy logic based upon the body posture of biped walking robot. The proposed scheme is simulated and experimented on a 10 degree of freedom biped walking robot. The results indicate that the proposed method is feasible.     

A New Method of Desired Gait Synthesis for Biped Walking Robot Based on Ground Reaction Force

A new method of desired gait synthesis for biped walking robot based on the ground reaction force was proposed. The relation between the ground reaction force and joint motion is derived using the D'Almbert principle. In view of dynamic walking with high stability, the ZMP(Zero Moment Point)stability criterion must be considered in the desired gait synthesis. After that, the joint trajectories of biped walking robot are decided by substituting the ground reaction force into the aforesaid relation based on the ZMP criterion. The trajectory of desired ZMP is determined by a fuzzy logic based upon the body posture of biped walking robot. The proposed scheme is simulated and experimented on a 10 degree of freedom biped walking robot. The results indicate that the proposed method is feasible.     

Human-like Three-dimensional Walking with Natural Dynamic

Natural dynamics can be exploited in the control of biped walking robots: the swing leg can swing passively, the compliant ankle can naturally transfer the center of pressure along the foot and help in toe off.These mechanisms simplify control and result in motion that is smooth and natural looking.Imitated human being's behavior, we presented a control strategy for HIT-III biped robot, in which active and passive motions were combined.The experiment result shows that robot walked at a faster speed (approximately 0.25m/s) than previous and had a natural and smooth looking gait.     

Human-like Three-dimensional Walking with Natural Dynamic

Natural dynamics can be exploited in the control of biped walking robots: the swing leg can swing passively, the compliant ankle can naturally transfer the center of pressure along the foot and help in toe off.These mechanisms simplify control and result in motion that is smooth and natural looking.Imitated human being's behavior, we presented a control strategy for HIT-III biped robot, in which active and passive motions were combined.The experiment result shows that robot walked at a faster speed (approximately 0.25m/s) than previous and had a natural and smooth looking gait.     

基于髋部质量的被动步行机器人稳定性和鲁棒性

采用一种更接近于人类行走的匀质圆规步态模型,运用Lagrange法和碰撞时刻角动量守恒原理分别建立机器人的摆动模型及碰撞模型。基于对模型步态收敛域与外界扰动快速抑制的准确描述,将全局稳定性分析与局部稳定性分析相结合,对模型进行初始的参数优化配置,并建立Proe样机模型;通过单次与连续外界扰动下不同样机模型步态的自身调节变化分析,最终获得模型参数的最优化配置,并通过实物样机的行走实验进行理论分析验证。仿真结果表明:具有合理髋关节质量的被动步行机器人有更强的行走稳定性与鲁棒性。     

两足机器人质量分布与步行稳定性及效率关系研究

研究两足机器人质量分布对步行ZMP(zero moment point)稳定阈度及步行效率的影响.采用稳定的参数化步态,在步态不变的情况下,改变机器人各连杆的质量分布,观察其对ZMP稳定阈度及步行效率的影响.仿真实验结果表明,合理选择大腿、小腿和上身的质量分布可以显著增加ZMP稳定阈度和步行效率.     

Analysis of period doubling bifurcation and chaos mirror of biped passive dynamic robot gait

With a reasonable parameter configuration,the passive dynamic walking model has a stable,efficient,natural periodic gait,which depends only on gravity and inertia when walking down a slight slope.In fact,there is a delicate balance in the energy conversion in the stable periodic gait,making the gait adjustable by changing the model parameters.Poincaré mapping is combined with Newton-Raphson iteration to obtain the numerical solution of the final state of the passive dynamic walking model.In addition,a simulation on the walking gait of the model is performed by increasing the slope step by step,thereby fixing the model’s parameters synchronously.Then,the gait features obtained in the different slope stages are analyzed and discussed,the intrinsic laws are revealed in depth.The results indicate that the gait can present features of a single period,doubling period,the entrance of chaos,merging of sub-bands,and so on,because of the high sensitivity of the passive dynamic walking to the slope.From a global viewpoint,the gait becomes chaotic by way of period doubling bifurcation,with a self-similar Feigenbaum fractal structure in the process.At the entrance of chaos,the gait sequence comprises a Cantor set,and during the chaotic stage,sub-bands in the final-state diagram of the robot system present as a mirror of the period doubling bifurcation.