Kinematic modeling of wheeled mobile robots

We formulate the kinematic equations-of-motion of wheeled mobile robots incorporating conuentionaI, omnidirectional, and ball wheels. While our approach parallels the kinematic modeling of stationary manipulators, we extend the methodology to accommodate such special characteristics of wheeled mobile robots as multiple closed-link chains, higher-pair contact points between a wheel and a surface, and unactuated and unsensed wheel degrees-of-freedom. We survey existing wheeled mobile robots to motivate our development. To communicate the kinematic features of wheeled mobile robots, we introduce a diagrammatic convention and nomenclature. We apply the ShethUicket convention to assign coordinate axes and develop a matriz coordinate transformation algebra to derive the equations-of-motion. A wheel Jacobian matriz is formulated to relate the motions of each wheel to the motions of the robot. We combine the individual wheel equations to form the composite robot equation-&motion. We calculate the sensed forward and actuated inverse solutions and interpret the conditions wbich guarantee their existence. We interpret the properties of the composite robot equation to characteriee the mobility of a wheeled mobile robot according to the mobility characterization tree. Similarly, we apply actuation and sensing characterization trees to delineate the robot motiohs producible by the wheel actuators and discernable by the wheel sensors, respectively. We apply our kinematic model to design, kinematics-based control, dead-reckoning and wheel dip detection. To illustrate the development, we formulate and interpret the kinematic equations-of-motion of six prototype wheeled mobile robots.