Measure and Control of Stability for Mobile Robots

The stability of mobile robots would be degraded due to the complex environment in rough terrain and the requirements of operation. In this paper, we investigate the improvement of stability from two aspects: measure and control. To measure the stability, we put forward a new method called force-angle stability margin (FASM), then use it and its modified form to evaluate the stability for a three-wheeled robot and a six-legged robot, respectively. To control the stability, for the three-wheeled robot particle swarm optimization (PSO) method is used to search the optimum semi-active damping characteristics for reducing the vibration from roads, the cost function is defined by considering the FASM method. For the six-legged robot, when its stability is beyond the acceptable range obtained by the FASM, a leg makes one step forward to support the robot and prevent tipping over. To verify and examine the effectiveness of the FASM method and control approaches, we perform them in simulative pavement and external environment. The obtained results show the proposed FASM method is feasible and the control approaches yield substantially improved stability when robots negotiate rough terrain.