Dynamics synthesis and control for a hopping robot with articulated leg

To investigate the design and the applications of elastic underactuated mechanisms for improving the energy efficiency of dynamic mechanical systems, the dynamics and control of a one-legged hopping robot with articulated leg is studied in this paper. To ensure the controllability of the elastic underactuated mechanism, a dynamics synthesis method is proposed for designing the underactuated mechanism so that the dynamics of the system can be transformed into the strict feedback normal form. To improve the energy efficiency of the one-legged locomotion system, an optimal motion planning method is presented to optimize the trajectories of the robot joints. A nonlinear controller is proposed to stabilize the hopping robot to its balance configuration in stance phase, and a switched linear controller is proposed to stabilize the continuous hopping movement. The stability of the presented controllers is analyzed in theory and verified by some numerical simulations.     

工业机器人倍四元数轨迹规划算法的研究

针对工业机器人在笛卡尔空间的轨迹规划曲线的平滑性与实时性,提出一种用于描述超球面旋转的倍四元数对机器人运动轨迹进行球面线性插补,并结合正弦波加速度曲线升降速控制算法对轨迹规划的速度进行控制,为机器人的轨迹规划提供了一种新的位姿规划的解决方案。在六关节搬运机器人控制系统平台上进行了仿真与试验,验证了该算法解决方案的有效性。     

单腿跳跃机器人轨迹规划

将单腿跳跃机器人简化成一个三杆模型,研究机器人跳跃过程中各个关节的运动轨迹问题,并在总结跳跃过程现有轨迹规划方法的基础上,运用参数化优化方法实现关节空间的轨迹规划,优化目标为机器人关节的控制势最小。将跳跃过程分解成开始段、腾空段、站立段和结束段,并对各段的关节轨迹分别优化,最后得到从静止状态开始起跳到着地后恢复至静止状态的整个跳跃过程的关节轨迹。     

神光-Ⅲ精密光学模块侧装机械手运动学分析

为顺利将激光聚变试验所需的光学模块安装至主机试验装置中,设计了一种八自由度侧装机器人。通过D-H法建立机器人各杆件的参考坐标系并获得D-H参数,推导出该侧装机器人运动学正解。提出采用关节变量虚化法构建出一个虚拟六自由度机器人,并利用解析法求解虚拟六自由度机器人运动学逆解。基于关节占用空间最小的原则,结合麦夸特算法利用1stOpt软件对关节3和关节4的位置进行求解,进而求解八自由度侧装机器人运动学逆解,并通过实例验证逆解算法的正确性。对运动学分析求解可以用于机械臂末端执行器的精确定位和运动规划,为实现八自由度侧装机器人的轨迹规划及实时控制等提供理论参考。     

Off-line programming of an industrial robot for manufacturing

A procedure for the automatic generation of the robot programming used in manufacturing operations is introduced in the present paper. The off-line programming system developed here includes graphical simulation of the robot and its workcell, kinematic model of the robot, motion planning and creation of the NC code for manufacturing process. The proposed system is applied in a robot with five revolute joints for manufacturing operations and in a robot with six revolute joints for welding operations.     

新型仿生六足机器人自由步态中足端轨迹规划

设计了一种具有变形关节和轮式足端的新型仿生六足机器人,该机器人具备轮式、爬行、步行等运动模式,有较好的灵活性及环境适应能力。运用矢量法构建了机器人运动学模型,并利用几何关系对模型进行求解。对机器人沿给定的路径执行自由步态时机器人所允许的最大步幅进行了分析。基于不同的地形条件,规划了抛物线和直线-抛物线两种足端轨迹。仿真结果表明,机器人在沿给定的路径执行自由步态时,抛物线和直线-抛物线两种足端轨迹规划方法合理、可行。     

基于位姿反馈的三臂空间机器人抓捕轨迹规划

以三臂空间机器人为研究对象,针对经历奇异位形时出现的位姿误差问题,提出一种基于位姿误差反馈的轨迹规划算法。根据系统一般运动学方程并结合动量守恒方程建立系统运动学模型,利用位姿期望指令得到误差运动方程。以关节角速度为控制量,设计了基于位姿误差反馈的控制率,使闭环系统的跟踪误差按指数速度收敛。该方法能够减小机器人奇异点邻域内的位姿跟踪误差,且在离开奇异区域后能完全消除误差。仿真结果证明了该方法的有效性。     

基于混合插值的工业机器人关节轨迹规划算法

B样条曲线由于其多阶导数连续和局部支撑性的特点,被广泛用于工业机器人关节空间的轨迹规划。标准B样条在起止点位置存在导数值的突变,致使工业机器人在启动和停止时产生振动。提出一种采用高次多项式与B样条混合插值优化的方法,使机器人关节运动学参数连续无突变,在不增加机器人控制系统运行负担的情况下,能够使机器人运行更加平稳,改善了机器人的运行状态。     

柔顺并联机器人动力学及轨迹跟踪

以含有开槽型柔顺关节的并联机器人为研究对象,对其动力学及轨迹跟踪问题进行研究。根据柔顺关节特性,建立系统分析模型,应用拉格朗日方法建立系统动力学方程。为补偿系统具有的不确定性,分别设计趋近律上界滑模控制策略和径向基函数(Radial basis function,RBF)神经网络趋近律滑模控制策略,基于Lyapunov理论证明了系统的全局稳定性。应用S型速度规划曲线,分别给出直线轨迹和圆轨迹的运动规划算法。仿真结果表明,系统模型及控制策略能够有效实现柔顺关节并联机器人的轨迹跟踪。     

欠驱动弹跳机器人最优运动姿态的驱动器配置

研究了具有一个被动关节的三关节单腿欠驱动弹跳机器人的轨迹规划问题。首先建立欠驱动机器人在着地阶段的动力学模型;然后采用数值迭代的方法,以主动关节驱动力矩最小为优化目标,得出了机器人各关节转角的运动规律;最后通过仿真得到三种驱动器配置情况下机器人的关节转角运动规律、姿态图以及驱动力矩,并对其进行了分析比较。结果表明：所提出的运动规划方法是可行的,采用髋关节和踝关节驱动是三种驱动器配置中最合理的情况。     

基于期望动力学的柔性关节控制器设计

协作机器人具有灵活,安全特点,已广泛应用于自动化领域以及中小企业中。为了保证与人交互的安全性,协作机器人通常采用中空电机与中空减速器配合的设计方案,以降低关节转动惯量,从而获得良好的外力感知与控制能力,这种设计导致协作机器人的关节具有了柔性。针对具有柔性关节的轻量级协作机器人,设计了一种基于期望动力学的柔性关节控制器,提高柔性关节机器人的轨迹跟踪精度和抖动抑制能力。在具有谐波减速器和力矩传感器的柔性关节上,基于连杆侧位置反馈与关节力矩反馈实现了从经典的电机侧控制到连杆侧控制的转变,并借助储存函数建立李雅普诺夫函数证明了该控制器的无源性与渐近稳定性。最后,通过Simulink仿真与单关节实验平台的关节轨迹追踪实验验证了柔性关节控制器的性能,结果显示其与全状态反馈控制相比具有关节力矩波动小、抖动抑制快以及轨迹跟踪误差小等优点。     

基于DSP的三肢体机器人关节控制器设计

基于TI公司的TMS320LF2407设计了一种直流伺服电机运动控制器,以实现三肢体仿生步行机器人11个运动关节的伺服控制.首先采用遗传算法对电机的PID参数进行优化,并对关节运动转角轨迹进行离散化,电机运动控制采取分段PID的策略,以减小关节转角误差.实验结果表明,设计出的控制器工作性能稳定,能够满足机器人运动控制的要求.     

仿人机器人头部设计及目标跟踪研究

设计了一种结构紧凑、光机电一体化的机器人头部.该头部具有仿人的3个自由度及外观造型,其颈部基关节采用差动机构,实现了耦合的俯仰和侧摆运动.头部内置2台高速相机,由1台PC处理视觉信息.采用分层控制结构,底层关节FPGA控制器和视觉处理PC分别通过串行总线和以太网连接上层中央控制器.采用了一种简单的基于位置的目标跟踪策略,并结合此策略提出了一种基于虚拟伸缩臂的D-H法求解逆运动学.     

基于Matlab的机器人轨迹仿真及关节控制

首先根据标准D-H参数法建立六关节臂型机器人的连杆坐标系,推导出运动学正解和逆解的方程,然后在Matlab中搭建了机器人仿真模型。运用Matlab机器人工具箱分别从关节空间和笛卡尔空间两方面进行机器人轨迹规划仿真,并基于关节空间生成的轨迹数据实现了机器人关节硬件在环控制和轨迹实时跟随。实验结果表明,该模型可以准确地实现机器人关节轨迹控制,其为机器人控制开拓了新的道路。     

Generation and Simulation of Robot Trajectories in a Virtual CAD-Based Off-Line Programming Environment

This paper presents a new approach to the generation and optimisation of the position and orientation trajectories in Cartesian task space, and simulation in a virtual CAD-based off-line programming environment. A novel concept of the robot pose ruled surface is proposed, and defined as a motion locus of the robot orientation vector, i.e. the vector of equivalent angular displacement. The planning for trajectories of robot end-effectors can be accomplished by generating the robot pose ruled surface and optimising its area under the constraints with good kinematics and dynamics performances. The established optimisation model is based on functional analysis and dynamics planning, and is simplified by using high-order polynomial space curves as the robotic position and orientation trajectories. The developed system, RoboSim, is a virtual integrated environment which can be used as a testbed for automatic motion planning and simulation for robots. Two examples are given to verify the feasibility of the proposed approach and models, and to demonstrate the capabilities of generation, optimisation, and simulation modules and libraries in the RoboSim package. The simulation results show that the approach and system are feasible and useful for motion planning, performance analysis and evaluation, and CAD-based prototyping and off-line programming in both the virtual and the real design and planning environment.     

载体位置、姿态均不受控的飘浮基柔性空间机器人的Terminal滑模控制

讨论了载体位置、姿态均不受控的飘浮基柔性空间机器人的Terminal滑模控制问题。为讨论既有柔性关节又有柔性臂的欠驱动系统,以一个具有两个柔性关节和一个柔性臂的飘浮基空间机器人为例,首先利用拉格朗日方程并结合系统总质心定义,得到了系统的动力学方程,然后利用奇异摄动法,将柔性空间机器人系统分解为一个柔性空间机械臂子系统和一个柔性关节快变子系统。以此为基础,提出了一种包含柔性空间机械臂子控制项和柔性关节快变子控制项的组合控制器。其中,柔性空间机械臂Terminal滑模子控制项实现了机械臂关节铰期望轨迹的跟踪,柔性关节快变子控制项使得快变子系统稳定在由柔性空间机械臂子控制项产生的机械臂关节轨迹上。系统的数值仿真结果表明,该方法能在抑制柔性关节的柔性振动的同时跟踪上机械臂关节期望轨迹。该控制方案的显著优点为不需要测量、反馈载体的位置、移动速度、移动加速度,同时可保证机械臂关节铰跟踪误差在任意指定有限时间内收敛到零。     

Tripod gait-based turning gait of a six-legged walking robot

The turning gait planning and improvement methods of a six-legged walking robot on the basis of tripod gait are presented in this study. A projection method that considers an unstructured environment is proposed for the turning gait planning of the six-legged walking robot. The body and foot motion trajectories of the swing legs are planned with polynomial curves to keep the robot steady while walking. Two basic turning gaits, namely, circling and spinning gaits, are successfully designed with the planning method. An optimized method is proposed to improve the turning angle, which is subjected to stability, kinematics, and relief amplitude constraints in the unstructured environment. The turning ability of the turning gait is improved with the optimized turning angle. The circling and spinning gaits are implemented in simulations and experiments. Results demonstrate that the planning and improvement methods for the turning gait are valid and correct.

     

NOVEL APPROACH FOR ROBOT PATH PLANNING BASED ON NUMERICAL ARTIFICIAL POTENTIAL FIELD AND GENETIC ALGORITHM

A novel approach for collision-free path planning of a multiple degree-of-freedom (DOF) articulated robot in a complex environment is proposed. Firstly, based on visual neighbor point (VNP), a numerical artificial potential field is constructed in Cartesian space, which provides the heuristic information, effective distance to the goal and the motion direction for the motion of the robot joints. Secondly, a genetic algorithm, combined with the heuristic rules, is used in joint space to determine a series of contiguous configurations piecewise from initial configuration until the goal configuration is attained. A simulation shows that the method can not only handle issues on path planning of the articulated robots in environment with complex obstacles, but also improve the efficiency and quality of path planning.