Coordinated Control for a Non-Holonomic Modular Omnidirectional Mobile Robot

本课题研究了一种非完整模块化全向移动机器人的协调控制，其中轮式单元的机构和控制器都是模块化的，这样我们就可以很容易地为机器人定制个性化的转移应用。本项目总结如下：1。设计了基于扩展卡尔曼滤波的机器人航位推算系统。船位推算系统可以精确识别机器人的位置和各轮单元的轮半径。车轮半径的精确估计成功地减少了车轮单元之间的运动相互作用。设计了一种运动控制系统来协调车轮单元，保证机器人的正确运动。在控制系统中，路径跟踪控制器根据阿克曼几何决定机器人的期望运动以跟踪其参考路径，协调控制器控制车轮产生机器人的期望运动。为了减少车轮单元之间的运动相互作用，我们构造了两种类型的车轮单元：主动车轮单元和被动车轮单元。主动车轮单元产生期望的机器人运动，而被动车轮单元修正自己的速度来模仿脚轮的行为。通过仿真和实验对航位推算和运动控制系统的性能进行了评价。针对一种配备倾底盘机构的模块化全向车辆，设计了一种由路径跟踪控制器和倾底盘控制器组成的运动控制系统。控制系统通过离心加速度防止机器人沿预定路径运动时发生翻滚。设计了机器人的航位推算系统。作为将所提方法应用于实际机器人的第一步，设计了大型全向AGV室外环境下的航位推算系统，并通过基础实验对其性能进行了评估。

This project studied a coordinated control for a non-holonomic modular omnidirectional mobile robot, in which wheel units assembled are modularized on their mechanisms and controllers, so that we can easily tailor the robot to individual transfer applications. The project is concluded as follows :1. A dead reckoning system for the robot was designed based on the extended Kalman filter. The dead reckoning system can precisely identify the robot position and the wheel radius of each wheel unit. The accurate estimation in the wheel radius succeeds in reducing the motion interactions among the wheel units.2. A motion control system was designed to coordinate wheel units and to ensure correct robot motion. In the control system, a path-tracking controller decides the desired motion of the robot based on the Ackerman geometry to track its reference path, while the coordinated controller controls wheels to produce the desired motion of the robot. To reduce motion interactions among the wheel units, we constituted two types of wheel units : active wheel units and passive wheel units. The active wheel units produce the desired robot motion, and the passive wheel units correct their own velocities to mimic caster behavior.3. The performance of the dead reckoning and motion control systems was evaluated through both simulations and experiments.4. A motion control system consisting of path-tracking and chassis-tilting controllers was designed for a modular omnidirectional vehicle equipped with chassis-tilting mechanisms. The control system can prevent the robot from tumbling by centrifugal acceleration while the robot following a predetermined path. A dead reckoning system for the robot was also designed.5. As the first step toward applying the proposed methods to real robots, a dead reckoning system for a large omnidirectional AGV in outdoor environments was designed, and the performance was evaluated through fundamental experiments.