【作者】 毛宁；

【导师】 曹国华； 苏波；

【作者基本信息】 长春理工大学 ， 机械电子工程， 2014， 博士

【摘要】 月面巡视器是搭载各种仪器执行月面探测任务的重要载体,是登陆月球表面进行探测任务的最直接工具。月面环境的特殊性要求巡视器必须从结构上、控制上提高其移动能力,必须通过构建虚拟月面环境来验证巡视器在未知地形上的通过能力,从而保证巡视器在月面作业的平稳性与可靠性,防止出现由于车轮沉陷或者悬架卡死、底盘托底等导致巡视器无法前进的事故。以上功能的实现需要以精确且高效的巡视器模型为基础,基于此,本文对非结构化环境下六轮摇臂巡视器样机的多体运动学模型、动力学模型及控制模型进行了深入研究,在此基础上对巡视器的移动特性、轮壤作用特性进行了仿真试验,并构建了虚拟月面环境的六轮摇臂巡视器仿真系统,从而为巡视器预测设计、性能试验以及样机预演提供验证平台。论文首先推导了六轮摇臂巡视器三维运动学方程,并充分考虑车轮侧滑、滚动滑移以及转向滑移对移动系统的影响,提出了两种高效求解巡视器逆运动学解析解的方法。在此基础上,对整车构型进行了仿真试验,该构型地面适应性强,通过能力高；并且,所建模型的转向驱动角度误差低于0.4%,驱动轮转速精度仅为2.5%,完全可满足控制器设计需要,为下面的地面力学、动力学或者静力学研究提供了理论基础。从提高整车的通过性能与驱动效率入手,深入分析了轮壤作用的力学关系,根据车轮轮齿效应、静态沉陷及动态沉陷的机理,推导并建立了刚性筛网轮-土壤作用动力学模型。基于试验验证需求,研制了低重力模拟月壤,并设计了轻小型刚性筛网轮与低重力试验测试装置,以此为基础开展轮壤模型研究并根据试验结果对模型沉陷系数进行了修正。通过模型仿真与试验比对整体误差为3%,为巡视器动力学、静力学建模以及控制器设计、虚拟月面环境仿真系统搭建奠定了基础。在试验过程中,利用试验数据分析了功率系数与驱动效率,发现车轮驱动效率在滑转率0.2时最高,由此得出了滑转率控制模型设计的最佳控制区域。在上述运动学与轮-壤动力学模型基础上,建立了六轮摇臂巡视器静力学模型,对其爬越复杂地形状况进行了仿真试验分析,得到的最优牵引力与各轮滑转率可以进行车辆移动性能评判以及滑转率控制设计。同时,在整车动力学建模过程中,以巡视器空间位姿、各关节角度和六维力作为广义坐标,推导了非结构化环境下六轮摇臂巡视器的牛顿-欧拉递归方程,该方法具有模块化建模特点,便于其它有效负载的动力学模型构建。并以此为基础,进行巡视器非常规车辆的轮壤模型重载,实现了虚拟月面环境六轮摇臂巡视器动力学仿真系统的搭建,经验证效果良好,为后续巡视器控制系统仿真试验、通过性能验证等提供了平台。本文最后,基于前述六轮摇臂巡视器运动学、动力学模型进行了控制模型的研究。针对动力学模型参数不确定的非线性系统,建立了基于滑模变结构的滑转率控制模型,经仿真验证系统具有很强的鲁棒性能,能够有效提高移动系统的牵引性能。基于六轮摇臂巡视器运动学模型,建立了基于车轮滑转动力学模型的牵引控制模型,并利用线性二次型最优控制法对其求解。以此为基础,对多种复杂地形进行了仿真试验,该模型可高效控制各轮滑转率,增强了巡视器的爬坡能力、通过沟壑以及跨越障碍的能力,适用于巡视器的工程应用条件。综上,本研究成果可为六轮摇臂巡视器结构优化、控制器设计、准实时/高保真月面虚拟仿真奠定理论及试验基础,提供工程设计支撑。更多还原

【Abstract】 Lunar rover is an important carrier to detect lunar by carrying a variety of instruments. It’s direct-detecting tool by lunar landing. We must improve the trafficability of lunar rover and ensure the stability and reliability of the system by building virtual environment to improve the machine and control system. In this paper, the prototype of six-wheeled rocker rover multi-body kinematics model, dynamic model and control model under unstructured environment were studied, and the rover moving characteristics and wheel-soil impact were simulated, and the virtual lunar surface environment of six-wheeled rocker lunar rover simulation system was built, which provide the verification platform for predicting design, performance test and prototype preview.Firstly, the kinematic equations of six-wheeled rocker lunar rover were deduced in accordance with the engineering prototype of the definition of the motor polarity in this paper. In kinematics modeling analysis, this paper fully considered the influences on the mobile systems from the sliding, rolling slippage and steering wheel slip. And all of these are helpful for providing analytical foundation for wheel-soil dynamics. Two methods were put forward which can solve efficiently the inverse kinematics analytical solution in this paper. On this basis, the simulation test was carried out on the rover configuration, and the configuration possesses strong adaptability to the ground and high capacity. And the solving method is simple, small amount of calculate, high precision. It is verified by simulation, and the steering angle error is below0.4%, and the drive wheel speed accuracy is at2.5%, which can meet the needs of controller design, and provide the theoretical basis for analysis of terramechanics, dynamics and statics.To improve the efficiency of the rover trafficability and drive efficiency, the relationship of wheel-soil mechanics must be analyzed. With deep analysis of Beeker and Reece model, and based on the wheel teeth effect and static and dynamic sinkage, the rigid wheel-soil dynamics model was established. For experimental verification, low gravity simulated lunar soil and the light-small rigid mesh wheel and low-gravity test device were designed, and then the wheel-soil dynamics model was amended by the simulation comparing with experiment, and the overall error is3%. This will lay the foundation of dynamics modeling, statics modeling, controller design and virtual environment simulation system building. Power coefficient and drive efficiency were analyzed through the test data, which can be found that drive efficiency is the highest when slip rate is0.2. Accordingly, the optimal control area of the slip rate control model is obtained.Based on kinematics and wheel-soil dynamics model, the statics model of lunar rover was derived. Under the condition of optimal energy consumption, simulation analysis is proceeding for the climb over complex terrain. The optimal traction and the slip rate were got which can be used for evaluating the rover motion performance and designing slip rate control system. In the process of rover dynamics modeling, with space position, each joint angle and the six dimensional forces as generalized coordinates. Newton-Euler recursive equation was deduced. This method has the characteristics of modular modeling, which is facilitate for other payload dynamic modeling on this rover. Finally, virtual environment of six-wheeled rocker rover dynamics simulation system were realized, the effect is good, which provides a good test platform for the simulation of control system and trafficability of six-wheeled rocker lunar rover.In the end, the control model was studied based on the kinetic model and dynamic model of six-wheeled rocker lunar rover. For parameters uncertain nonlinear system of dynamic model, slip rate control model based on sliding mode variable structure was established. It has strong robust performance, and can effectively improve the traction performance of mobile system. The traction control model based on wheel slip model was put forward based on the kinematic model of six-wheeled rocker rover, and can be solved by the linear quadratic optimal control method. On this basis, a variety of complex topography simulation test has been carried on, and each wheel slip rate can be efficiently controlled. The ability of climbing, cross obstacle and ravines have been strengthened effectively. And the model is suitable for engineering application.In conclusion, the research can provide engineering support for structure optimization, controller design and quasi real-time/high fidelity virtual simulation theory and experiment foundation of six-wheeled rocker lunar rover.更多还原