基于并联机构的越野车辆发动机动态性能测试模拟平台构型综合与运动学分析

Synthesis and kinematics analysis of platform for dynamic performance test of off-road vehicle engine based on parallel mechanism

针对越野车辆发动机动态性能测试需求,综合出了一种基于新型2UPS-2RPU-PU*冗余驱动并联机构的模拟平台。运用螺旋理论研究并联机构连续转轴存在且通过动平台中心的条件,提出一种具有连续转轴的2R1T并联机构综合方法,综合并优选出新构型2RPU-PU-UPS,该机构能够实现惯性较小的连续转动;分析机构的自由度性质和运动特性,证明该机构可以实现发动机不同工况下的运动耦合,更加接近实际路况;根据模拟平台重载需求,添加了无约束分支,并设计了剪叉机构分支,最终得到2UPS-2RPU-PU*机构;推导该机构的位置正、反解,并分析其工作空间和奇异性。所提出的构型有助于拓宽并联机构在模拟平台领域的应用,运动学分析对后续样机研制具有一定参考价值。

A 2UPS-2RPU-PU*redundant actuation parallel mechanism is proposed and designed in the light of the dynamic testing requirements of off-road vehicle engines.The conditions that the continuous axis of the parallel mechanism exist and pass through the center of the moving platform are studied base on the screw theory.A synthesis method of the 2R1T parallel mechanism with continuous axis is proposed,and a novel 2RPU-PU-UPS mechanism is synthesized and optimized,which could perform continuous rotation with small inertia.The degrees of freedom and kinematic characteristics of the proposed mechanism are analyzed.It is proved that the proposed mechanism has the kinematic coupling of the engine under different working conditions,and it is closer to the actual road conditions.An unconstrained branch is added,and a branch of the scissors mechanism with the function of travel amplification is designed according to the heavy load requirements of the simulation platform.Finally,the forward and inverse position solutions of the proposed mechanism are derived,and its workspace and singularity are analyzed.The proposed mechanism broaden the applications of the parallel mechanism in the field of simulation platform,and the kinematics analysis provides a valuable reference for the subsequent prototype development.