Simulation tools for zero turn radius mobile robots

Modeling and simulation tools for the computer aided design and analysis of mobile robots and vehicle systems are presented in this dissertation. The kinematics, dynamics, control and design issues for multi-body modeling are integrated within the framework of the (4 x 4) matrix method. These general tools are specifically applied to a zero turn radius mobile robot system in order to explain and offer solutions to the observed anomalies in that mobile robot.; The modeling and construction of a fully 3-D spatial analytical model of the vehicle as a constrained mechanical system is presented using the (4 x 4) matrix approach developed by Denavit-Hartenberg as refined by Sheth & Uicker. The detailed kinematics address the modeling of the vehicle platform as a free floating body with the use of Euler parameters, the bevel gears which model the transmission, a flexible wheel model to reflect motions and forces, the internal gear trains and the modeling of the synchro drive mechanism. The dynamics model of the vehicle uses Lagrangian formulation and allows a modular development and assembly of each of the constituent bodies in the formulation of the entire system dynamics. The issues of rolling resistance, wheel rocking, damping and stiffness are considered and a static equilibrium analysis is included as a part of the dynamic model.; The issues of slip and friction for higher pair contacts such as wheels are addressed by a new method which incorporates the friction and rolling constraints directly in the dynamic model. An algorithm is presented to handle cases of rolling and slip for a wheel without any loss in the independent degrees of freedom of the entire system.; The motor models are developed for the electro-mechanical system. A PID based control is presented with the help of different sensing strategies. The effect of point to point profile planning based on the desired positions and velocities is implemented. A general non-linear control law based on a Lyapunov function based approach is developed and applied to the specific vehicle system to drive the system to its desired states.