Research On Modeling And Control Of A Two-Wheel Mobile Robot Whit Auxiliary Arms

Because of their flexibility,efficiency and stable mobility,wheeled mobile robots have important applications in logistics,exploration and rescue,material handling,service and entertainment.The two-wheeled robots have attracted many researchers' attention for its outstanding advantages like arbitrary radius turning,flexible obstacle avoidance and simple structure.However,the structure of the twowheeled robot determines that the two-wheeled robot is an under-actuated and essentially unstable system.During the movement,the driving wheel and the upper body have strong coupling,which inevitably causes the upper body inclination during acceleration and deceleration.Aiming at this problem,this paper proposes a twowheeled robot with a pair of auxiliary arms to achieve that keeping the body of twowheeled upright all the time while moving on the uneven surface or during acceleration and deceleration on flat surface.The research is carried out in the following aspects.Dynamic modeling of two-wheeled robots with auxiliary arms.Using the Newton-Eulerian method,two-wheeled robot with auxiliary arms on uneven surface is derived.The equilibrium point analysis of two-wheeled robot dynamic system is conducted,which is the foundation of the control algorithm of the robots.Research on two-wheeled robot control algorithm and auxiliary arms control strategy.Based on sliding mode control theory,the sliding mode control algorithms for the two-wheeled robot are derived,which serves as the bottom control layer for the robots.Based on the dynamic model of the robots,the uneven surface inclination angle estimation algorithm based on extended Kalman filter for both traditional and novel two-wheeled robot are proposed to estimate the road inclination in real time.For the case of uniform motion on uneven road surface and the acceleration and deceleration motion on the flat road surface,the control strategy based on the center of gravity(CoG)is proposed.The position of the center of gravity can be adjusted by the trajectory of the upper auxiliary arms to keep the body of two-wheeled robot upright all the time.Simulations and experiments of two-wheeled robots.Based on MATLAB,the simulation of the uniform motion on uneven road surface and the acceleration and deceleration motion on the flat road surface is carried out to verify the effectiveness of the algorithm and tune the parameters.The experimental platform of the twowheeled robot with auxiliary arms is built,and the experiments on the uneven and the flat road surface are carried out.The effectiveness of the sliding mode controller,road surface inclination angle estimation algorithm and the CoG-based auxiliary arms control strategy are proved on the actual platform.The presence of the auxiliary arms can improve the anti-disturbance ability and flexibility of the two-wheeled robot,and keep the body of the two-wheeled robot upright during the movement.