Dynamics, Analysis and Experiments of Obstacle Negotiation for Wheeled Mobile Robots

Abstract Hybrid wheel-leg robots combine the high efficiency of wheeled locomotion with the obstacle negotiation abilities of articulated suspension. Effective performance indicators are needed as optimization goals for both mechanism design and trajectory planning to take full advantage of the abilities of these robots. This work investigates the concept of admissible kinetic energy and related performance indicators to develop a framework for obstacle negotiation analysis, design, and control. A four wheeled-legged robot was used as a test platform to analyze the suite of performance indicators based on velocity and joint position, and predict which wheels are in contact at the moment of impact. A physical test platform including current sensors, encoders and an accelerometer was designed and constructed to validate the simulation results. A dynamic model of the test platform constructed for impact analysis is validated through a combination of high-speed camera measurements, force measurements and current sensing. Selected performance indicators based on admissible kinetic energy are shown to influence the abilities of these robots to negotiate an obstacle, with and without accounting for the configuration dependent effect of traction.