Multibody Simulation of the Dynamic Behaviour of a Hybrid Leg-wheel Ground Mobile Robot

The paper presents the results of multibody simulations of the step-climbing process of a small-scale ground mobile robot for surveillance and inspection, named Mantis. Mantis is a hybrid leg-wheel robot, characterized by a main body equipped with two actuated wheels and two praying mantis rotating legs; a rear frame with two idle wheels is connected to the main body by a vertical revolute joint for steering; a second revolute joint allows the rear axle roll. The main hindrance to indoor inspection by means of small-scale robots is the presence of steps and stairs; therefore the shape of the Mantis rotating legs is specially conceived to overcome square steps. Multibody simulation is a useful tool to assess the influence of the geometric parameters of the robot on the efficiency of the step-climbing process in the design phase, and to coordinate properly the motion of wheels and legs in the development of automatic guidance systems. Simulation results are presented, discussed and also compared with the real behaviour of the robot prototype.