Analysis of the kinematics of module climbing caterpillar robots

Based on the vermicular motion of the pine caterpillar and inchworm, this paper presents two novel module climbing caterpillar kinematics models. The analysis of the valid gaits and climbing safety of them indicates the differences of two models. The pine caterpillar model with all active joints has the disadvantage of introducing the redundant actuating to its locomotion but higher security than the inchworm model because of its more valid gaits. Two prototypes following the above two models are respectively constructed from some newly developed real adhesion and actuation modules to testify the climbing abilities of two caterpillar-like robots. The experiments show the sideslip of the suckers on the pine caterpillar robot induced by the redundant actuating and the locomotion ability of the inchworm robot on vertical wall. Besides that, an unsymmetrical gait is adopted by the inchworm robot to improve its adhesion reliability on the wall. At last, a new kinematics model of the pine caterpillar robot based on passive joints is proposed to solve the redundant actuating problem.