摇臂转向架式星球车单索重力补偿

Gravity Compensation for Rocker-bogie Rovers Through Single String Tension

为简单、准确地进行摇臂转向架式星球车(简称星球车)低重力模拟,研究其单索重力补偿的问题。提出使用单根补偿吊索和摇臂配重模拟星球车所有姿态下全部车轮地面接触力的方法。以四、六轮星球车为例,建立崎岖地型上轮地接触力模型;通过分析模型的解结构,证明'正确补偿接触力'等价于'正确补偿狭义接触力(全部接触力水平分量为零时的特例)';给出吊索和配重(补偿力系)的施加方法;通过证明补偿后的狭义接触力与低重力环境中一致,证明补偿方法正确。仿真结果验证了此方法的优势和正确性。针对向车厢(封闭体)内部点施加补偿力的问题,提出相似悬挂原理:利用悬挂体和封闭体上关节点、受力点的全等位置关系,使连接于悬挂体上的吊索始终向封闭体内部点施加等效补偿力。为避免拆解星球车进行质心测量,提出使用不同姿态下的狭义接触力计算、校正补偿力系的方法;相应地,给出狭义接触力的测量原理和测量平台结构。实践证明,研究为星球车的低重力模拟提供了简单、精确的方案原理和方法。

The crucial problems encountered in gravity compensation （GC） for rocker-bogie rovers through single string tension are examined and tackled to enable easy and precise low gravity simulation. A GC approach utilizing single string and counterweights on rockers is developed to simulate all the wheel contact forces of rovers in all configurations. The contact force model of four and six wheeled rovers is constructed, through which the equivalence between ensuring contact force and defined contact force （wheel pressure）, the special case when the horizontal components of all contact force is nil, is proved. The approach is proved by showing compensated wheel pressure is identical with that in low gravity. The advantage and validity of such approach is future proved by software simulation. To equivalently apply compensation force onto the inner point of the carriage （a sealed body）, the similarly suspension mechanism is developed. The mechanism is such that the relative position between surface points and inner points of the sealed body is exactly identical with those of the suspension body; compensation force on the suspension body is equivalently applied to corresponding inner point of the sealed body. To avoid dismantling of rover for the center of mass measurement, an algorithm is established to relate the position and magnitude of compensation force system with wheel pressure. The method and equipment are established to measure the wheel pressure. These researches provide a precise and feasible plan for rocker-bogie rovers＇ gravity compensation, which is proved by their application in experiment.