Study on turning in place of a spherical robot based on stick-slip principle

The paper deals with the motion of turning in place of a spherical robot for military reconnaissance and unknown environment exploration developed by us. The robot belongs to a nonholonomic and under-actuated system. The robot has 3 DOF and 2 inputs. The motion of turning in place can make a spherical robot with higher dexterity and environmental adaptability. The mathematical model of the turning motion is established by theory of moment of momentum. The relationship between the motion parameters is deduced, which is the basis of motion simulation and control system. Based on the analysis of mathematical model, a stick-slip principle is proposed for turning in place of the robot which is driven by double ballast masses. The stick-slip process is divided to three stages which are interpreted in theory. The principle is verified by numerical simulation and prototype experiment. The results confirm the effectiveness of the principle. The errors between theoretical analysis and experiment are analyzed at last.