Design and Modeling of a Novel Single-Actuator Differentially Driven Robot

This project aim to design and model a differentially driven robot using a single actuator. The differential drive is done by varying wheel diameters rather than angular speeds. The wheels are modeled as springs such that a mass moves along the axis of the robot to apply more tension in one of those springs than the other, thus changing the wheel diameters. This allows for the velocity of each wheel to differ based on the position of this mass. For forward motion, the mass acts as a pendulum, rotating about the axis of the robot allowing for velocity in the forward or backward direction due to inertial forces. Basically the wheels aren’t directly actuated but rotate due to the dynamics of the system. The full set of generalized coordinates constitute 2 planar position coordinates (x,y), 4 angles: steering angle θ, inclination angle β, actuated angle α, and wheel angle φ, and the mass pendulum distance from the center of the robot “d”. These can be, hopefully, later reduced due to the effects of d and α on β and φ, so that the final system can be completely modeled with the pose coordinates and the input. Figures 1 and 2 show proposed designs for the robot. Figure 2 will be updated as the design has changed for a pendulum with a single mass to a pendulum with two opposing masses, or a disk mass.
By: Mohamad Alsalman