Abstract:

To explore new types of mobile mechanisms and their movement modes, a mobile serial-parallel mechanism with scalable platforms is proposed. The mechanism is comprised of two hybrid 3-RPR parallel mechanisms connected in series. Three mobile platforms of the serial-parallel mechanism are scalable. By combining the movements of platforms and limbs, the mechanism can achieve inchworm locomotion. The proposed mechanism possesses advantages of both series mechanisms and parallel mechanisms. The screw theory is used to calculate the degree-of-freedom (DOF) of the mechanism and the vector method is used to analyze the kinematics of the mechanism. The detailed gaits of inchworm locomotion are introduced by applying the mechanism to climbing the pipeline. The detailed mechanism structure is designed by Solidworks. Dynamic simulation of climbing pipeline is carried out by Adams to obtain the displacement curves of three platforms and length curves of limbs. A prototype is fabricated to verify the DOF characteristic and the inchworm locomotion gaits.

Key words: inchworm locomotion, over-constrainted, serial-parallel mechanism, 3-RPR