Modeling for a metamorphic quadruped robot with a twisting trunk: Kinematic and workspace

摘要

Up to now the quadruped robots are equipped with the trunks which are rigid bodies or consist of two blocks connected by passive joints. This paper proposes a metamorphic quadruped robot with a moveable trunk which can implement active trunk motions, called MetaRobot I. Its trunk is constructed by a planar 6-bar linkage. Due to this linkage, it can change its trunk into multiple shapes, which give the robot the ability to imitate different animals, as well as more actions of natural quadrupeds. Specially, it can imitate the natural quadrupeds to perform trunk twisting which never been done by any quadruped robots before. Due to the twisting trunk, kinematics of this metamorphic quadruped robot is different from traditional quadruped robots. Also through the trunk twisting the body and leg workspace of the quadruped robot are increased. The mathematical model of kinematics and inner relationship between body and leg workspace and the twisting angle are analyzed in the paper. The increased body and leg workspace will help to increase the stability margins and locomotion speed. At last a simulation and an experiment on physical prototype are carried out to show the stability margins and locomotion speed impacted by the increased body workspace and leg workspace.