新型四足步行机器人串并混联腿的运动学分析

针对串联四足机器人行走惯量大,自重/载重比大的问题,提出一种新型串并混联四足步行机器人,并对该机器人的串并混联腿进行运动学分析。该机器人由一个运载平台和四条结构相同的串并混联腿组成,每条腿均由髋关节、大腿、小腿顺次连接构成,其中髋关节为3-RRR并联机构。以能耗最小姿态为最优姿态,基于矢量法求解了该串并混联腿的运动学正解和反解,利用MATLAB和ADAMS软件验证了正解和反解的正确性;基于矢量法和微分变换法求出了该混联腿的速度雅克比矩阵和加速度矩阵,分析了其奇异性,并利用MATLAB软件绘制出该腿的工作空间。结果表明:该腿在髋关节连杆直径d=22mm,大腿杆件直径D=50mm,膝关节转角θ4∈105°,155°]时,工作空间呈球冠形,最大内接圆半径R=400mm,高度为H∈500mm,900mm]。本研究对该新型串并混联四足步行机器人的刚度分析、动态性能、机构优化设计和系统控制等的进一步研究具有重要意义。

Kinematics analysis on the serial-parallel leg of a novel quadruped walking robot

As the robot based on a directly serial leg mechanism has great walking inertia and a larger weight/load ratio, a novel series-parallel hybrid quadruped walking robot is presented. The robot consists of a load platform and four serial-parallel legs. The kinematics characters of serial-parallel legs for the robot are analyzed. Each leg is connected by a hip, a thigh, a calf sequentially and the hip joint is a 3-RRR parallel mechanism. By considering the least energy-consuming posture as the optimal posture, the forward kinematics and inverse kinematics are derived based on vector method and they are verified by ADAMS and MATLAB softwares. The velocity Jacobian matrix and acceleration matrix of the serial-parallel hybrid leg are obtained based on vector method and differential transform method and their singularity is analyzed, then the workspace of the hybrid leg is figured out by MATLAB software. Calculations show that when the linkage diameters of the hip and thigh are 22 mm and 50 mm and the angle of knee θ₄ is within105°,155°], the workspace of the hybrid leg is part of a sphere, whose radius of the inscribed circle R is 400 mm and altitude H is within500 mm,900 mm]. This research has great significance to a series of further studies on stiffness analysis, dynamic properties, mechanism optimal design and system control of the novel series-parallel quadruped walking robots.