中文摘要：

本文以农用拖拉机为研究对象,提出了一种基于饱和方法的直线路径跟踪导航算法.该算法可以为农用拖拉机导航中普遍存在的输入饱和控制问题提供一种有效的解决办法.首先,基于直线导航系统运动学模型,将其线性化得到易于控制设计的线性系统模型.其次,设计非饱和控制器,使得系统在该非饱和控制器作用下全局镇定.最后,结合饱和函数和非饱和控制器,构造出饱和控制器,并证明在该饱和控制器作用下系统全局渐近稳定.该控制方案的优点在于：控制器结构较为简单,且饱和控制器中从外到内的饱和度并不需要按照递减顺序选取,从而提高了闭环系统的收敛性能.仿真结果验证了上述方法的有效性.

英文摘要：

For an agricultural tractor, a linear path-tracking navigation algorithm is developed by using the saturation method, providing an effective solution to the ubiquitous input saturation control problem in agricultural tractor navigation. First, based upon the kinematics of the straight-linear navigation system, a linear system model for control design is obtained by linearization. Secondly, a non-saturated controller is designed to stabilize the system globally. Finally, by integrating a saturation function with the non-saturated controller, we obtain a saturated controller under which the closed-loop system is globally asymptotically stable. This controller is simple in structure without the need of sequential decrement of restriction on the saturation levels from outside to inside, thus improving the convergence of the closed-loop system. Simulation results validate the effectiveness of the proposed method.