| Wheeled mobile robots (WMRs) have been an active area of research and development over the past three decades, This long-term interest is mainly because of the various practical applications WMRs can perform due to their ability to work in hazardous, potentially unstructured and large domains. A few applications where WMRs have been successfully employed are (i) automobile industry, (ii) mine excavation, (iii) planetary exploration, (iv) man-machine-interfaces for people with impaired mobility, (v) warehouse material handling/inspection and security, (vi) materials transportation, etc. Based on the wide spectrum of applications that WMRs can perform, it is clear that the WMB research is multidisciplinary by nature. That is, the aforementioned applications require sound mechanical design, accurate sensing of the environment, intelligent trajectory planning, and high precision control.; This thesis concentrates on the modeling, trajectory tracking, and actuator control algorithms for a class of omni-directional autonomous WMRs developed at Utah State University (USU). These omni-directional WMRs have multiple “smart wheels,” each with independent control of both speed and direction. Starting from Newtonian mechanics, a dynamic model of the class of robots is derived. Using Chis model, four different trajectory tracking controllers, namely, an exact feedback linearization controller, an exact feedback linearization with computed feedforward torque controller, an iterative learning controller, and a scalar spatial controller, are developed.; The aforementioned algorithms are applied to both the nonlinear model of a novel robotic platform, the USU Omni-Directional Vehicle (ODV), and to the actual ODV platform. The similarity between the simulated and the experimental results proves the correctness of the analysis and controller design. |
