MOTION PLANNING PROBLEM OF NONHOLONOMIC CAR-LIKE ROBOTS BY OPTIMAL CONTROL THEORY

(1)拖拉机坡道最优控制理论我们讨论了拖拉机在坡道上的最优时间/路线问题。首先，我们证明了这类问题本质上等价于非完整移动机器人的轨迹优化问题。其次，利用庞特里亚金最大值原理，对这类优化问题进行了解析论证。(2)拖拉机-机具系统自耦合的非线性反馈控制器基于两自由度技术，设计了拖拉机向后操纵的非线性反馈控制器。首先，利用非线性最优控制算法，通过离线计算预先获得参考轨迹。其次，利用LQ最优控制技术，我们构造了线性反馈控制器，使拖拉机能够渐近地输送到这样的…轨迹之一在此基础上，提出了适用于拖拉机鲁棒逆机动控制的非线性Feedbak控制器。(3)约束非完整系统的反馈控制设计本文针对约束非完整系统提出了一种时变反馈控制器，由前馈控制器和反馈控制器组成。我们的方法主要基于非线性系统的两自由度(2-DOF)技术。首先，我们通过离线计算得到了一类带状态约束的非线性最优控制问题的数值解。然后，利用这些最优解构造了前馈控制器。其次，利用相关线性化系统的调节器理论，构造了线性时不变反馈控制器。将这两种控制器结合起来，提出了一种简单的避障方案，提出了基于二自由度的时变反馈控制器。最后，通过数值仿真验证了该控制器的实用性。较少

(1) OPTlMAL PATH OF HEADLAND FOR TRACTORS BY OPTIMAL CONTROL THEORYWe deal with optimal time/path problems of tractors on the head land. Firstly we show that such problems are essentialy equivalent to trajectory optimization problems of non-holonomic mobile robot. Secondary making use of Pontryagine's maximum principle we analytically exprore such optimal problems. Lastly by means of trajectory optimization techniques we computationasly solve the optimal time/path problems of tractors on the headland.(2) A NONLINEAR FEEDBACK CONTROLLER FOR THE AUTO-COUPLING OF TRACTOR-IMPLEMENT SYSTEMSBased on the two-degree-of-freedom tecnique, we design nonlinear feedback controllers for the backward maneuvering of tractors. First, using nolinear optimal control algorithms we obtained reference trajectories in advance by off-line calculations. Next, using the LQ optimal control tecnique, we construct linear feedback controllers which let the tractor to asymtotically convege to one of such trajectorie … More s, we propose the nonlinear feedbak controllers, which are applicable to the control of robust bacward maneuvering of tractors.(3) A FEEDBACK CONTROL DESIGN FOR CONSTRAINED NONHOLONOMIC SYSTEMSWe present a time-varing feedback controller for constrained nonholonomic systems, Which consists of feedforward and feedback controllers. Our approach is mainly based on two-degree-freedom (2-DOF) tecniques for nonlinear systems. First, we obtain the numerical solutions for ceartain nonlinear optimal control problems with state-constraints throuh off-line calculations. Then, we construct the feedforward controller with the help of such optimal solutions. Next, we construct the linear time-invariant feedback controller by making use of the regulator theory on associated linearized systems. Combining such two controllers and introducing simple scheme on how to avoid the obstacles, the 2-DOF based time varing feedback controller is proposed. Lastly, we demonstrate by some numerical simulations the practicability of the proposed controller. Less