A Study Of The Omnidirectional Mobile Robot With 5-DOF

Omni-directional wheel is different from traditional wheel structure. A mobile platform with multiple sets of omni-directional wheels has the characteristics of the omni-directional movement. Manipulator on the omnidirectional mobile platform can conveniently realize multiple task, which not only expands the robot application, but also greatly improve the efficiency. The work of this paper is to study the structure design, kinematics and error analysis of the new omni-directional mobile robot with parallel manipulator. The rationality and practicality of the designed mechanism are verified by the experiment.This paper first gives a general and scientific description about the MY series of omni-directional wheel structure designed in the laboratory. By analyzing the merits and shortcomings of the MY wheels, a new kind of omni-directional wheel is presented, named MY3 wheel. The structure of the wheel is improved, especially to change the installation from the traditional tandem form to parallel form. And the superiority of the new wheel structure is also proved by the FEM structural analysis. Based on the above efforts, omnidirectional mobile robot with 5-DOF is designed. Parallel manipulator on the mobile platform with four groups of MY3 wheel is built. According to the task requirements, the mainly mechanical parts selection of the parallel manipulator and the motor selection are introduced. Finally an experimental prototype of the robot is made.Based on the design scheme of the robot, the kinematics model of the mobile platform is presented. And the velocity anisotropy problem without considering the rotation of the platform is also analyzed to verify the validity of the kinematics model, for solving the later path planning problems. In addition, the kinematics model of parallel mechanism is established. Through motion simulation, the validity of the kinematics model is verified, and the drive motor speed curve from the simulation can also help the implementation of real-time motion control. According to the demand of high precision operation, the error analysis model of the parallel manipulator is established based on the vector differential method. The influence of the pose error from the structure parameter and posture parameter has been analyzed quantitatively by simulation, which proves that posture variation range and the selection of structure parameters are reasonable. These provide theoretical basis for high precision operation tasks.The lifting and turning experiment and the simulated assembly experiment of the prototype are carried out. Results have shown the errors in allowable ranges. The robot can accomplish the relevant task. It is showed that the design of the robot is rational.