| With the development of robotics, omni-directional technology is getting mature.Increased concern has been reported in omni-directioanal mobile device with mecanum wheels for its advantages such as stable movement and simple structure. The omni-directional mobile platform has all the three degrees of freedom on the plane, which greatly improves the efficiency of movements and will have a high research value in the fields of logistics transportation, industrial production and services,specially in narrow workspace. In this paper, a omni-directional platform is designed and researched, design processes of mechanical structure and control system are introduced,and the software co-simulation is applied to accelerate research progress. On this basis, a physical prototype is assembled and tested. The main jobs of this paper are shown as blow:(1) The mechanical structure is researched. The kinematic model of omni-directional mobile platform is derived. A kind of damping structure is presented to optimize the problem of deficient contact between mecanum wheels and ground. Based on the analysis of moving accuracy with body parameters' changing, motion error has been limited in a reasonable range.(2) Synergic controllor of fuzzy PID is designed. The principle of fuzzy PID controller is given, and the dynamic parameters of platform is analyzed which leads to the work of motor selection. A direct-current motor closed-loop control system is built with the environment of MATLAB/Simulink, and the simulation result proves the validity of algorithm.(3) Virtual prototype for co-simulationin ADAMS and MATLAB is built, and the simulation experiment is carried out. This paper detailedly lists the prototype building steps and completes the simulation in typical moving condition. At last, the simulation results are analyzed in detail.(4) Mechanical structure is made and control system is debugged. This paper introduces the feature of mechanism and general planning of electrical system, of which the wheels closed-loop control and human-computer interaction are programmed in the platform of STM32 which is a high-performance microprocessor. The control software runs in personal computer is developed in the environment of VB.NET. Finally, the performance of physical prototype is tested by moving experiment.Combined with simulation of virtual prototype and experiment of physical prototype,body structure and control system of the omni-directional mobile platform are deeply analyzed and optimized, which has practical value for this kind of mobile device to have a widespread use. |
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