Stability analysis of the internal dynamics of a wheeled mobile robot

The stability of the internal dynamics of a wheeled mobile robot is analyzed. It is shown that the wheeled mobile robot exhibits unstable internal dynamics when moving backwards. Most control methods of wheeled mobile robots are designed based on input-output relations. Since the internal dynamics are not represented in input-output relations, stability properties of the internal dynamics are generally neglected. Nevertheless , the internal dynamics do affect the behavior of mobile robots. Taking the look-ahead control method as an example, it is shown that, by using a novel Liapunov function, the internal dynamics of a two-wheel differential-drive mobile robot are unstable when it is commanded to move backwards. Both simulation and experimental results are provided to verify the analysis.