轮地力学模型参数灵敏度分析与主参数估计

Sensitivity analysis and dominant parameter estimation of wheel-terrain interaction model

在星球探测过程中,星球车需要估计地面力学参数以及时调整控制策略.快速适应地形变化。针对形式复杂,参数耦合的轮地相互作用模型,采用Sobol灵敏度分析方法,分别对模型中的地面承压特性参数和剪切特性参数的灵敏度进行定量分析,筛选出沉陷指数与内摩擦角作为模型的主导参数,用于反映地面承压特性和剪切特性的变化。基于轮地相互作用力学平衡方程,通过简化应力分布公式,进一步推导出主导参数的解析表达式。通过以典型值固定非主导参数.利用系统状态参数和滤波处理完成地面力学特性主导参数的估计。结果表明,所提出的地面力学主导参数解析式及相应的估计方法能够快速反映地形的变化,沉陷指数估计的平均相对误差为2.8%.内摩擦角估计的平均相对误差小于3%。估计结果可准确预测车轮牵引力,为实现实时控制提供必要信息。

During planetary exploration,the rover demands the capability of terrain characteristic estimation for timely adjustment of control strategies to quickly adapt to terrain changes.For the parameter-coupled wheel-terrain interaction model with complex forms,the Sobol analysis method is adopted to quantitatively analyze the sensitivity of terrain bearing and shearing characteristic parameters in the model,respectively.In consequence,the sinkage exponent and internal fraction angle are selected as the dominant parameters reflecting significant changes in the terrain bearing and shearing characteristics.Based on the mechanics equilibrium equation of wheel-terrain interaction,the analytical model of the dominant parameters is further derived by simplifying the stress distribution formula.By fixing the non-dominant parameters with typical values,the system state parameters and the filtering process are used to realize dominant parameter estimation of the terrain mechanical characteristics.The results show that the proposed analytical model of the dominant terrain mechanical parameters and the corresponding estimation method can quickly follow the change of terrain properties.The average relative error of the sinkage exponent estimation is 2.8% and that of the internal friction angle estimation is smaller than 3%.The estimation results can accurately predict the traction force of the wheels as well as provide necessary information for real-time traction control.