基于螺旋理论的冗余液压驱动四足机器人运动学分析

四足机器人的各种研究大多基于四条腿弯曲方向一致展开的。对于液压驱动且具有冗余度的四足机器人,静止姿态下,其前面两条腿与后面两条腿成对称弯曲状。为了研究这种机器人单腿运动和躯体运动状态,文中建立了基于螺旋理论的液压驱动四足机器人运动学模型,包括给出了单腿串联运动学逆解和躯体并联运动学正解。然后根据机器人行走过程设计出后面两条腿的髋关节与膝关节摆幅角度,通过建立的运动学模型,得到前面两条腿的关节变量及躯体姿态。最后通过MATLAB数值仿真和ADAMS虚拟样机实验,对机器人在一种行走方案下的躯体运动姿态进行仿真对比,验证了所建运动学模型的可靠性。     

四足机器人侧摆型trot步态的运动学分析及仿真研究

针对四足机器人在复杂环境中难以保持稳定行走姿态的问题,在四足机器人trot步态的基础上,改进设计了一种侧摆型trot步态,通过四足机器人侧摆肩关节处电机对四足机器人的步态进行规律调整,使四足机器人在行走过程中更易保持稳定姿态。首先对侧摆型trot步态进行步态规划,分析侧摆型trot步态的稳定性;然后根据D-H参数法建立四足机器人单腿运动学模型并进行运动学分析求解;最后在MATLAB/Simulink软件中建立四足机器人动态仿真模型,以复合摆线运动轨迹为例,对侧摆型trot步态进行运动特性仿真分析。结果表明,基于复合摆线的侧摆型trot步态运动轨迹曲线连续平滑,四足机器人运动平稳。通过侧摆型trot步态仿真分析,验证了所研究侧摆型trot步态的稳定性和合理性,可以为搭建实验样机控制系统提供理论依据。     

液压四足机器人内力抑制及实验研究

针对液压四足机器人在关节位置控制模式下引起的机器人内力问题,建立液压四足机器人单腿运动学方程和单腿动力学方程,分析机器人内力产生的机理及其对机器人性能的影响,提出基于动力学模型的机器人内力自适应抑制策略。自适应控制器利用关节理论力与实际力间的差值对位置指令进行补偿,以实现消除内力的目的。通过液压四足机器人HD平台进行控制策略验证,实验结果表明,机器人在位置控制模式下,机器人内力抑制策略可有效降低系统内力,使得机器人实际驱动力与理论驱动力接近,验证了控制策略的有效性。     

轮足混合式行走机器人运动学建模与仿真

结合足式机器人与轮式机器人的优点,提出了一种基于2(6-UPUR+3P)混联腿的轮足混合式行走机器人构型,并对该机器人进行了运动学建模与仿真分析.基于螺旋理论建立机器人并联腿部单支链的六维运动螺旋系,基于此得到1阶影响系数矩阵,进而推导出6-UPUR并联腿部的运动学模型;提出了机器人机身姿态调整算法,改善了机器人在静态步行步态下机身运动的平稳性;用Matlab算例仿真与Adams仿真对比验证得出运动学模型的正确性,用Adams/Simulink联合仿真验证得出机身姿态调整策略的有效性,为进一步进行轮足混合式行走机器人控制系统的设计奠定基础.     

液压四足机器人足端的力预测控制与运动平稳性

针对液压四足机器人在坚硬路面行走时,足端位置易受刚性冲击,导致运动姿态平稳性差的问题,提出一种液压四足机器人足端力预测控制方法.在分析液压四足机器人结构的基础上,根据运动学与力学模型构建了液压伺服系统的力控制模型;采用改进自适应布谷鸟优化BP神经网络算法建立足端力预测控制模型,通过仿真对比分析验证了该算法的可行性.最后...     

并联六轮腿机器人机身平稳性控制方法研究

轮腿式机器人在非结构化路面运动时,机身平稳性控制对于提高运动平稳性、降低系统能耗、提高定位与建图精度等具有重要意义。针对并联式六轮腿机器人在通过不规则地形时足端悬空、姿态倾斜、机身晃动等问题,提出一种融合足端力控制器、姿态控制器及重心高度控制器的机身平稳性控制框架。其中,足端力控制器通过阻抗控制算法抑制机器人足端受力因地形变化带来的突变扰动;机身姿态控制器对机身倾斜角进行解耦,并控制各腿的长度补偿机身的偏移量;重心高度控制器根据各腿的伸长量自适应地调节机身高度,保证腿部执行机构具有足够的运动空间。针对三种控制器相互耦合、对外部扰动抑制效果不佳等问题,利用串级控制的思想将三种控制目标统一为力跟踪控制,降低机身振荡的风险。在并联式六轮腿机器人上进行了实验验证,结果表明所提出的控制算法框架能有效抑制外部地形扰动,当机器人以大约0.6 m/s的速度前进时,机身的俯仰角及横滚角保持在-0.7°~0.7°范围内,足端接触力维持在期望力附近,且机身重心高度随地面起伏自适应地调整,确保了机器人的运动平稳性。     

一种双足机器人步态规划和运动仿真的研究

通过对人类行走步态的研究,结合双足机器人实际结构,规划机器人行走时的基本姿态及重心轨迹,建立运动学模型,根据规划的行走姿态及轨迹建立运动学方程。应用三维建模软件UG建立双足机器人的简化模型,导入仿真软件ADAMS中生成虚拟样机模型,并通过在Matlab中得到机器人行走的关节运动轨迹对虚拟样机模型进行控制,经仿真后,利用该虚拟样机模型对机器人行走步态进行运动学及动力学分析。应用虚拟样机方法,验证了步态规划的有效性。     

四足机器人砂砾地面对角行走控制方法

为解决四足机器人在砂砾地面上对角行走容易失稳的问题,提高机器人对松软和凹凸不平地面的适应性,在位置控制的基础上提出了一种机身姿态角的调整策略,并在机器人对角行走的过程中采取了一种变阻抗参数的阻抗控制方法。最后在实际的砂砾地面进行了四足机器人对角行走实验,实验结果证明这种控制方法和调整策略对于四足机器人对角行走在砂砾地面上具有较好的控制效果。     

液压四足机器人单腿竖直跳跃步态规划

针对机器人跳跃运动落地时冲击力大的问题,面向竖直跳跃运动,以液压四足机器人单腿为研究对象,建立液压驱动四足机器人单腿运动学模型,并分别对机器人单腿处于起跳相、落地相和腾空相时进行轨迹规划;根据关节参数,通过运动学逆解求得驱动函数,利用仿真软件ADAMS进行竖直跳跃步态仿真;搭建单腿实验平台,进行实验验证,依据得到的动态特性,分析步态规划的准确性及合理性,为后续液压四足机器人动步态的研究提供设计和控制依据。     

四足管道爬壁机器人周向运动位姿规划

为了实现四足机器人沿着管道内壁进行连续的周向运动,对运动过程中的位置和姿态进行规划.建立管道坐标系和机器人的位置、姿态方程,规划了一种包含足姿调整、机身旋转和机身平移的周向运动.为保证周向运动的连续性,对运动过程中位姿的角度、方向、位移进行规划,并通过足端运动实现周向运动位姿的规划.利用Matlab计算得到的周向运动关节角度曲线,对机器人样机进行爬壁实验.实验结果和滚转角分析验证了周向运动位姿规划的正确性.     

Energy efficiency analysis of quadruped robot with trot gait and combined cycloid foot trajectory

Quadruped robots consume a lot of energy, which is one of the factors restricting their application. Energy efficiency is one of the key evaluating indicators for walking robots. The relationship between energy and elastic elements of walking robots have been studied, but different walking gait patterns and contact status have important influences on locomotion energy efficiency, and the energy efficiency considering the foot-end trajectory has not been reported. Therefore, the energy consumption and energy efficiency of quadruped robot with trot gait and combined cycloid foot trajectory are studied. The forward and inverse kinematics of quadruped robot is derived. The combined cycloid function is proposed to generate horizontal and vertical foot trajectory respectively, which can ensure the acceleration curve of the foot-end smoother and more successive, and reduce the contact force between feet and environment. Because of the variable topology mechanism characteristic of quadruped robot, the leg state is divided into three different phases which are swing phase, transition phase and stance phase during one trot gait cycle. The non-continuous variable constraint between feet and environment of quadruped robot is studied. The dynamic model of quadruped robot is derived considering the variable topology mechanism characteristic, the periodic contact and elastic elements of the robot. The total energy consumption of walking robot during one gait cycle is analyzed based on the dynamic model. The specific resistance is used to evaluate energy efficiency of quadruped robot. The calculation results show the relationships between specific resistance and gait parameters, which can be used to determine the reasonable gait parameters.     

Design and simulation for a hydraulic actuated quadruped robot

This paper describes the mechanical configuration of a quadruped robot firstly. Each of the four legs consists of three rotary joints. All joints of the robot are actuated by linear hydraulic servo cylinders. Then it deduces the forward and inverse kinematic equations for four legs with D-H transformation matrices. Furthermore, it gives a composite foot trajectory composed of cubic curve and straight line, which greatly reduces the velocity and acceleration fluctuations of the torso along forward and vertical directions. Finally, dynamics cosimulation is given with MSC.ADAMS and MATLAB. The results of co-simulation provide important guidance to mechanism design and parameters preference for the linear hydraulic servo cylinders.     

Mechanism of Spine Motion About Contact Time in Quadruped Running

The current research of quadruped robot focuses on the quadruped robot with spine motion. Contact time is a very important part of system performance. However, the mechanism of spine motion about contact time has not been clearly elucidated. In this paper, the e ect of spine motion on contact time is studied deeply from dynamic view.Firstly, a simplified model of the quadruped robot with spine joint is set up, its dynamic equations are derivated, and a method that can generate passive periodic locomotion is proposed. Secondly, according to the vertical spring oscillator model, the two-dimension planar locomotion of the simplified model is regarded as a special vibration in the vertical direction, and the approximate formula of calculating contact time is obtained. Finally, the approximate formula of calculating contact time is verified by the simulation results of passive periodic locomotion, and the e ect of spine motion on contact time is deeply discussed based on the approximate formula of calculating contact time. The discussion proves that spine motion indeed has little e ect on contact time, but spine motion can slightly reduce body pith movement and regulate the leg sti ness in leg contact phase. This research proposes an e ective research method which can be used to study the motion mechanism of the quadruped robot with spine motion,and the mechanism of spine motion about contact time is clearly elucidated which is helpful to set the parameters of mechanical structure and study control algorithm about the quadruped robot with spine motion.     

A new approach for development of quadruped robot based on biological concepts

This paper proposes the design and development results of a new quadruped robot. The proposed new quadruped robot has a couple of advantages of flexible locomotion. The quadruped robot is designed and modeled based on a new concept that is the structure model with three segments of quadruped legs. New leg configuration with the simplified operation of four hip actuators is introduced. The posture of the new quadruped robot is more similar to the posture of dog than that of the previous quadruped robots. The objective of this paper is to develop a quadruped robot, which can walk and run in a trot gait with a simple PID controller. Numerical simulation and experimental results are shown to prove the locomotion performance of the proposed controller for the proposed quadruped robot.     

四足机器人改进型对角小跑步态研究

传统的四足机器人对角小跑步态一般在机体坐标系中进行规划,在实际应用中存在着摆动腿无法同时着地、机体翻转无法有效抑制等问题,这些都降低了机器人运动的稳定性和精确性。针对以上问题,提出了一种在世界坐标系下规划的改进型对角小跑步态方法,该方法通过浮动机体运动学对摆动相进行规划,在足端的雅可比矩阵中引入机体姿态相关项,从而保证了摆动腿能同时着地,同时在支撑相和摆动相之间增加了四腿同时着地的调整相,对机器人机体位姿进行调整。对比仿真和样机试验结果表明：与传统方法相比,所提方法能够使摆动腿同时着地并能连续调整机体位姿,使机器人获得更好的运动稳定性和更高的位移控制精度。     

足式机器人单腿跳跃仿真与实验

针对跳跃运动足地冲击大的特点,基于仿生学设计一种液压驱动四足机器人单腿,分别建立单腿着地相和飞行相的运动学和动力学模型。为了满足单腿跳跃性能要求和减少足地冲击,提出基于三次曲线轨迹跟踪的跳跃方法。使用MSC.ADAMS和Simulink对单腿竖直跳跃过程进行仿真,并搭建了单腿竖直跳跃实验平台和闭环控制系统。     

液压机器人作动器建模及关节转角跟踪控制

针对液压四足机器人作动器伺服精度较差问题,分别推导电液伺服作动器在摆动相、刚性支撑相和弹性支撑相的等效模型,分析各作动器模型特点,提出比例内环自适应幅相控制外环的复合控制策略,应用比例控制器保证位置内环的稳定性,采用自适应幅相控制器进行幅值和相位补偿。通过机器人单腿测试平台进行控制策略验证,实验结果表明:所提控制策略可使系统幅值衰减小于2%,相位滞后小于4°,验证了此方法的有效性。     

液压四足机器人元件与液压系统研究现状与发展趋势

针对液压四足机器人结构布局混乱、能量损失大及控制策略复杂等问题,从机器人整机、液压系统和控制策略3个角度分析了液压四足机器人的研究现状。首先,对各团队的机器人进行介绍,指出国内外的技术差距;然后,从动力来源、系统类型、液压回路和伺服执行元件4个方面对液压系统的主要2大构成分别阐述,着重介绍了以节能为目的的阀控系统和集成化、一体化的伺服执行器;接着概述了主流的几种控制策略,并分析各自的优缺点;最后,指出液压四足机器人的发展方向将集中在高速高压化、轻量化、节能降噪以及先进的控制算法,以实现液压四足机器人的高动态性能和行业应用。