Distributed Robust Control of Compliant Framed Wheeled Modular Mobile Robots

Abstract

A distributed robust controller for Compliant Framed wheeled Modular Mobile Robots (CFMMR) is studied in this paper. This type of wheeled mobile robot uses rigid axles coupled by compliant frame modules to provide both full suspension and enhanced steering capability without additional hardware. In this research, a distributed nonlinear damping controller using backstepping techniques for wheel-torque control is first developed for single-axle unicycle type robots. The controller is then extended to multiple-axle CFMMR configurations and is robust to disturbances created by modeling errors; especially highly nonlinear frame forces caused by axle interaction. In particular, the controller considers time-varying reference velocities and allows the robot to perform posture regulation, path following, or general trajectory tracking. A two-axle scout CFMMR configuration is used to evaluate the controller. Simulation and experimental results verify robust dynamic motion control of path following.