Biped 4R2C six-bar mechanism with inner and outer feet

Most current biped robots are equipped with two feet arranged in the right and left which inspired by the human body system. Different from the existing configurations, a novel biped robot with inner and outer feet based on a spatial six-bar 4R2C(R and C denote revolute and cylindric joints, respectively) mechanism is proposed. It can move along a line or a curve by three walking modes that are dwell adjustment mode, limit position adjustment mode and any position adjustment mode. Kinematic, gait planning and stability analyses are performed respectively, and a prototype is developed. Lastly, a potential application is considered and two manipulating modes(sphere and cylinder manipulating modes) are carried out. This interesting mechanism feathering its single closed-chain structure and unique work performance is expected to motivate the configuration creation of biped robots.     

Kinematics and dynamics analysis of a quadruped walking robot with parallel leg mechanism

It is desired to require a walking robot for the elderly and the disabled to have large capacity,high stiffness,stability,etc.However,the existing walking robots cannot achieve these requirements because of the weight-payload ratio and simple function.Therefore,Improvement of enhancing capacity and functions of the walking robot is an important research issue.According to walking requirements and combining modularization and reconfigurable ideas,a quadruped/biped reconfigurable walking robot with parallel leg mechanism is proposed.The proposed robot can be used for both a biped and a quadruped walking robot.The kinematics and performance analysis of a 3-UPU parallel mechanism which is the basic leg mechanism of a quadruped walking robot are conducted and the structural parameters are optimized.The results show that performance of the walking robot is optimal when the circumradius R,r of the upper and lower platform of leg mechanism are 161.7 mm,57.7 mm,respectively.Based on the optimal results,the kinematics and dynamics of the quadruped walking robot in the static walking mode are derived with the application of parallel mechanism and influence coefficient theory,and the optimal coordination distribution of the dynamic load for the quadruped walking robot with over-determinate inputs is analyzed,which solves dynamic load coupling caused by the branches’ constraint of the robot in the walk process.Besides laying a theoretical foundation for development of the prototype,the kinematics and dynamics studies on the quadruped walking robot also boost the theoretical research of the quadruped walking and the practical applications of parallel mechanism.     

Static Force Analysis of Foot of Electrically Driven Heavy-Duty Six-Legged Robot under Tripod Gait

The electrically driven six-legged robot with high carrying capacity is an indispensable equipment for planetary exploration, but it hinders its practicability because of its low efficiency of carrying energy. Meanwhile, its load capacity also affects its application range. To reduce the power consumption, increase the load to mass ratio, and improve the stability of robot, the relationship between the walking modes and the forces of feet under the tripod gait are researched for an electrically driven heavy-duty six-legged robot. Based on the configuration characteristics of electrically driven heavy-duty six-legged, the typical walking modes of robot are analyzed. The mathematical models of the normal forces of feet are respectively established under the tripod gait of typical walking modes. According to the MATLAB software, the variable tendency charts are respectively gained for the normal forces of feet. The walking experiments under the typical tripod gaits are implemented for the prototype of electrically driven heavy-duty six-legged robot. The variable tendencies of maximum normal forces of feet are acquired. The comparison results show that the theoretical and experimental data are in the same trend. The walking modes which are most available to realize the average force of distribution of each foot are confirmed. The proposed method of analyzing the relationship between the walking modes and the forces of feet can quickly determine the optimal walking mode and gait parameters under the average distribution of foot force, which is propitious to develop the excellent heavy-duty multi-legged robots with the lower power consumption, larger load to mass ratio, and higher stability.     

具有张力反馈和关节位置全闭环的挠性驱动单元性能测试

对于仿人机器人,关节采用挠性驱动方式可吸收振动,减缓冲击,以减小对双足步行的影响。为此,设计并研制FDU-II型挠性驱动单元,与FDU-I型挠性驱动单元相比,具有轻量化、有安全保护、锁紧器使用方便、刚度高、输出精度高等优点;分别进行FDU-II型挠性驱动单元的转速测试、驱动能力测试、大转角频繁往复运动测试、频响测试、机器人步行样本测试等性能测试及用于双足机器人上的步行测试试验;针对等幅值下,频率越高电动机转速越大,机械系统受电动机额定功率所限无法测出其截止频率的问题,提出一种变幅值变频率的频响测试方法,即令电动机转动频率越高时,幅值越小,保证电动机始终不超过额定功率,该方法可有效解决电动机额定功率一定情况下系统截止频率的测试问题;测试结果表明FDU-II型挠性驱动单元在负载力矩12.6 N·m时,其输出转速达到77.5o/s,且频响达到6.1 Hz,表明FDU-II比FDU-I有更高带宽及更大功率;步行试验结果表明FDU-II型挠性驱动单元有足够的驱动能力驱动双足机器人髋关节等关节,并实现稳定的双足步行。     

Biped Robot with Triangle Configuration

A new biped robot with a triangle configuration is presented and it is a planar closed chain mechanism.The scalability of three sides of the triangle is realized by three actuated prismatic joints.The three vertexes of the triangle are centers of three passive revolute joints coincidently.The biped mechanism for straight walking is proposed and its walking principle and mobility are explained.The static stability and the height and span of one step are analyzed.Kinematic analysis is performed to plan the gaits of walking on an even floor and going upstairs.A prototype is developed and experiments are carried out to validate the straight walking gait.Two additional revolute joints are added to form a modified biped robot which can follow the instruction of turning around.The turning ability is verified by experiments.As a new member of biped robots,its triangle configuration is used to impart geometry knowledge.Because of its high stiffness,some potential applications are on the way.     

两足步行机器人并联腿机构的步态规划及仿真

应用虚拟样机技术,建立了两足步行机器人并联腿机构的仿真模型,并在仿真环境下对步行机器人的行走姿态进行了规划和仿真试验,为确定步行机器人腿机构的结构参数和参数优化提供了实验平台,为研究和开发新型两足步行机器人及其控制奠定了理论基础。     

双足机器人腿部新构型设计与试验研究

探究高动态性能双足机器人对腿部设计的要求,阐明机器人腿部设计准则、设计方案和实现措施。提出一种腿部串并联新构型方案,膝关节驱动器上移到髋关节,踝关节驱动器上移到膝关节,膝关节驱动器通过简化五连杆机构将运动传递到膝部,踝关节驱动器通过并联四连杆机构将运动传递到踝部。对踝关节并联机构和整个腿部关节进行运动学正逆解,建立新构型机器人的仿真模型。考虑运动控制算法,完成机器人动力学仿真。测试准直驱驱动器性能,并完成串并联构型腿部样机试验验证,机器人可实现0.4m/s的行走速度。结果表明,提出的腿部串并联新构型与传统串联构型比具有更高的运动性能,新构型机器人性能在真机测试中得到验证。该串并联新构型方案在双足机器人和其它服务机器人领域具有广阔的应用前景。     

两足机器人步行运动参数对单足支撑期ZMP点影响的研究

在两足步行机器人的研究中,一般将零力矩点(ZMP点)的位置与支撑范围的关系作为判别其步行稳定性的依据.提出一种通用的方法,来分析两足机器人的步行运动参数对ZMP点位置的影响,并通过对机器人单足支撑期运动的计算机仿真,试图得到步行运动参数的变化对稳定性影响的规律,以期对机器人动态步行的稳定性设计提供实用的参考.     

双足机器人并联踝关节优化设计

通过对人的踝关节运动机理分析,设计一种新型的双足机器人踝关节并联机构。建立并联机构的参数化模型,并对该模型进行运动学和动力学分析,得出该并联机构的一阶影响矩阵、伸缩运动的驱动力与零力矩点(Zero moment point, ZMP)轨迹关系。由于实际双足机器人行走时踝关节驱动力矩与角速度差异较大,为解决双足机器人步态行走中踝关节的动力学不平衡特性,结合并联机构的运动特点,迭代计算优化并联机构的结构参数,使踝关节两个驱动元件的驱动功率峰值和速度趋于一致。进行双足机器人步行试验研究,结果表明,优化后的并联结构踝关节的驱动功率峰值是串联结构下功率峰值的50 %左右,降低驱动元件的功率设计要求。在满足双足行走时踝关节的运动性能要求下选择小功率的驱动元件,有利于减小关节的体积和质量,减小能耗。     

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.     

四足并联腿步行机器人动力学

基于模块化和可重构理论,提出一种助老助残四足/两足可重构并联腿步行机器人。该机器人既可组合成两足步行机器人,亦可作为四足步行机器人使用。运用影响系数理论和虚功原理,对四足步行机器人静态步行时的摆动腿和机体机构进行动力学建模,导出摆动腿的动力学方程和机体机构超确定输入下的协调方程,按加权最小二乘法对四足并联腿步行机器人机体机构的动载进行最优协调分配,解决了机器人在行走过程中各分支运动约束而产生的动力耦合问题。     

Study on a ultra-light dual revolute manipulator with high joint torque

This paper details a study performed on a new proposed twelve degree-of-freedom dual robot arm, which is very light but capable of handling heavy loads. The proposed robot arm has a higher value for the ratio of the load capacity/robot weight than conventional robot arms, which are actuated by motors with speed reducers, such as a harmonic drives, since it adopts a new type of robot actuator based on a closed chain mechanism. Because of the high value of the ratio of the payload capacity/robot weight, it can be used as a robot arm for mobile robots and for walking robots. Analyses of the design scheme and of the mechanism of the joint actuator used for the robot arm are presented. Also, the control system developed for the robot arm is introduced. The superior characteristics of the new proposed robot arm, handling heavy payloads with light weight links compared to industrial robots, are presented through carrying out various payload capacity tests. Since the robot arm is designed with light links, it has some deflections and these deflections of the links are analyzed using the Finite Element Method (FEM). The results of performance tests are presented to check the correctness of the FEM analysis and to demonstrate the actual capability of handling heavy payloads applied to the robot arm.     

两足步行椅机器人及其稳定性计算研究

两足步行椅机器人是一种为残疾人设计,用来替代轮椅和假肢的助残机器人.本文介绍了两足步行椅机器人的整体机构设计,并以前向运动为例,详细讨论了利用ZMP理论进行步行稳定性计算的方法,最后通过计算机仿真验证了这一计算方法的有效性.     

变胞机器人重构及转向时足着地柔顺性控制

变胞机器人能够根据外界环境变化在轮式行驶和足式行走两种运动模式间自然切换,因此兼具在平整结构路面上快速行驶和在崎岖山地越障行走的能力。基于广义坐标法建立了变胞机器人转向重构过程的运动学模型,考虑到重构过程中摆动腿与环境接触时存在较大冲击,提出了利用阻抗控制方法实现摆动腿着地柔顺控制。在传统阻抗控制的基础上,基于李雅普诺夫渐进稳定性定理设计了自适应阻抗控制器,并利用粒子群优化算法对阻抗控制参数进行了优化。通过在不同环境刚度下仿真分析,证实了经过参数优化后的自适应阻抗控制器能够很好地实现对期望接触力的跟随,提高了变胞机器人对未知多变环境的适应性。最后针对变胞机器人转向重构过程中足着地进行了路面实验,进一步证实了优化后的自适应阻抗控制方法的优越性。     

多移动机器人协同模式及其倾翻稳定性研究

针对山地果园单个移动机器人爬坡能力不足及稳定性差等问题,提出了一种多移动机器人协同操作的方法。在原有六足机器人结构的基础上增加了用于多机协同操作的连接件,得到了用于多机协同操作的机器人单体。将3个六足机器人单体通过协同操作得到了3种典型协同模式：串行模式、并行模式、三角模式。最后采用稳定锥法对足式移动机器人系统的单体模式及3种典型协同模式在6种典型地形情况下的静态、动态稳定性分别进行了分析。理论分析及仿真实验结果表明：3种典型协同模式间可进行两两切换;在6种典型地形情况下,通过多机协同操作及协同模式切换的方式可提高足式机器人系统的稳定性。     

足的形状对被动动力步行机器人性能的影响

研究了双足被动动力步行机器人足的设计问题,及足的形状对运动过程中的能量转换和稳定性的影响。比较了质点型足、直线形足和圆弧形足三种双足机器人在运动过程中能量的变化情况。对机器人模型进行简化后的研究证明：直线性足的机器人与质点型足的机器人相比,在稳定的步行运动中的运动速度更大,而圆弧形足比直线形足又有优越性。数值仿真也验证了机器人模型具有同样的性质。最后给出了足的形状的设计方法。     

基于MATLAB与ADAMS的双足步行机器人特性研究

以模块化类人机器人为研究对象,通过对其进行结构分析,建立数学模型,提出双足机器人的特性参数,设计稳定性函数和能耗函数。通过MATLAB与ADAMS相结合,计算出双足机器人在不同行走速度下和不同摩擦系数下的稳定性和能耗,采用单因素分析法对计算结果进行分析,得出双足步行机器人在不同工况下的稳定性和能耗变化。通过搭建双足步行机器人实验平台,测量双足步行机器人在不同工况下的能量消耗情况,与仿真计算结果进行对比分析,验证了稳定性函数和能耗函数的有效性,这可以作为改善和优化双足机器人结构和参数的依据。     

双足欠驱动机器人能量成型控制

研究欠驱动双足机器人在3D空间稳定行走控制器。建立双足机器人的3D动力学模型,通过构建概循环拉格朗日函数,把欠驱动双足机器人的3D动态系统解耦成前向和侧向部分。针对前向2D欠驱动部分设计势能成型和动能成型控制器,为了求解能量成型控制器,将匹配方程分解成分别与角度和角速度相关的两个子条件,再将非线性偏微分方程变为线性偏微分方程,求解出能量成型控制器对前向行走进行控制,使前向行走获得稳定且具有仿生特点。对侧向部分采用零动态控制,在保证侧向稳定同时,还满足系统的动态解耦条件。对不同步长行走进行仿真试验,仿真结果表明,动态步行收敛于稳定的极限环,步态符合仿生规律,验证了所提出理论的可行性和有效性。     

复合运动模式四足机器人机构设计及分析

研制了一种轮足复合运动的四足智能移动机器人,该机器人可以步行前进,原地转弯,楼梯爬越,也可在良好路面利用足底轮以较高速度滚动前进。阐述了机器人的机械结构和参数,运动学分析和运动空间描述。利用ADAMS建立了三维仿真模型,进行了多种步态的仿真。得出稳定裕度合适的步态,实验验证了机器人的性能。     

考虑足地作用的足式机器人环境表征与路径规划

足式机器人在行走过程中,足端与地面之间的相互作用影响机器人的地面通过情况。足地作用与地表的几何形状和地面的物理特性息息相关,因此仅基于几何特性地图进行路径规划难以满足野外环境下规避松软沙土等非几何危险的需求。针对该问题,考虑足地作用力学提出包含几何与物理特性的环境模型进行足式机器人路径规划。通过简化和统一软硬地面下的足地作用模型,提出表征地面法向松软特性和切向摩擦特性的参数化指标,结合几何特性构建更全面的环境模型。综合考虑影响机器人通过性的地面几何与物理特征,重构路径规划的优化目标,通过图搜索算法实现最优路径规划。以六足机器人Elspider为对象进行仿真和试验,验证了所提出的方法能够有效规避非几何危险,实现了更安全、通过性更强的路径规划。