A Novel Wheel-Leg Variable Structure Robotic System: Design and Fabrication

Facing the significant needs of special rescue and environmental survey, a novel wheel-leg variable structure robotic system inspired by the desert roller spider (Carparachne aureoflava) is proposed, which is equipped with four mechanical legs and can realize the switching of wheel mode and leg mode under different operating conditions by changing the direction of the servo spindle at the end of the mechanical leg. Simultaneously, the same degree of freedom of the leg joints are retained as that of a conventional spider-inspired robot (3DOF). One pair of mechanical legs on each side is connected to the DC worm gear motors of the main body through a rigid connecting plate and an axial structure installed with conductive slip rings. During leg mode, the motors are locked, and the mechanical legs can move multi-legged under the actuation of the servo; in wheel mode, the servo is locked after moving to the specified position of the wheel model, and the motor drives the wheel structure to rotate to realize the rolling control. The leg structure was kinematically modeled based on the DH method, and the workspace at the foot end was calculated via the forward kinematics method. Kinematic experiments of robot on the ground were implemented. The results verified the motion and deformation capabilities of the wheel-leg variable structure robot, which has the potential for better multi-terrain adaptive performance.