【作者】 任慧荣；

【导师】 孟庆浩；

【作者基本信息】 天津大学 ， 控制理论与控制工程， 2008， 硕士

【摘要】 近年来,随着机器人技术的发展,移动机器人轨迹跟踪问题受到了人们越来越多的关注。前轮转向、后轮驱动的轮式类车移动机器人与四轮汽车的运动学模型相近,因此对轮式类车移动机器人的轨迹跟踪控制问题的研究在汽车自动驾驶、智能交通等方面具有重要的意义。轮式类车移动机器人具有的非完整运动学约束特性给轨迹跟踪控制的研究带来了挑战。首先研究了在低速或参数变化不大时轮式类车移动机器人的横向轨迹跟踪控制问题。分别采用经典PID、径向基函数(RBF)神经网络自适应PID和模糊自整定PID三种方法对机器人轨迹跟踪过程实现了横向控制。在纵向跟踪速度方面,基于预瞄控制理论,设计了模糊速度控制器。其次,根据类车移动机器人的运动学模型,采用反步法(Backstepping)设计了一种类车移动机器人全局轨迹跟踪控制器,并利用Lyapunov理论证明了系统的全局稳定性。考虑到机器人的运动学约束,控制率中引入了机器人速度受限策略,保证了机器人运动平滑。利用MATLAB仿真环境,对三种横向跟踪控制和Backstepping方法进行了仿真研究,分析、比较了几种控制方法的优点及适用性。论文最后给出了基于视觉的类车机器人轨迹跟踪的初步实验,结果表明该文所用方法可以很好地跟踪地面铺设的轨迹线。更多还原

【Abstract】 With the development of robot technology, the trajectory-tracking problem of mobile robot is paid more and more attention. A wheeled car-like mobile robot, which is steered by two front wheels and driven by two rear wheels, has similar kinematic model to that of a four-wheel car. So the study on the trajectory-tracking problem of the wheeled car-like mobile robot is significant for automatic drive of car as well as intelligent transportation. Due to the intrinsic non-holonomic kinematical constraints of car-like robot, it is challenging to control the robot track the given trajectory.Firstly, the lateral trajectory-tracking problem is studied when the robot moves in low speed or parameters change little. Three methods, which include the classic PID, radial basis function (RBF) neural network based adaptive PID and fuzzy self-tuning PID, are adopted for the mobile robot to realize lateral control of trajectory tracking. To control the longitudinal speed of the robot, a fuzzy speed controller is designed based on the preview control theory. Secondly, a global asymptotically stable tracking controller is designed using the backstepping method on the basis of the kinematic model of the car-like robot. Meanwhile, the Lyapunov theory is used to verify the stability of the controller.Considering the kinematic constraints, the speed limited strategy is introduced to ensure the smooth motion of the robot.The validity of three lateral control methods as well as the backstepping method is simulated with MATLAB. The merit and applicability of each method are analyzed and compared. Finally, initial trajectory-tracking experiments are implemented, in which a CMOS camera is used to acquire trajectory information. Experimental results show that, with the methods presented in this paper, the robot can track the paved trajectory well.更多还原