Research On Single-loop6R Linkage Rolling Mechanisms

ABSTRACT:The single-loop six-bar linkage composed of revolute joints, also called single-loop6R mechanism is studied in this paper. Single-loop6R mechanisms which are composed of planar RR chains, planar3R chains, spherical RR chains and spherical3R chains respectively are researched in theory, analyzed by simulation, and verified with experiment.Firstly, a planar6R rolling mechanism which is composed of three planar RR chains is researched. The planar6R rolling mechanism can transform geometric shapes among triangle, quadrangle, pentagon and hexagon. At the same time, the planar6R rolling mechanism can roll like the caterpillar. There are four kinds of control schemes of the planar6R mechanism:automatic mode, follow-up mode, infrared control and Kinect clntrol. Teaching products based on the planar6R rolling mechanisms with geometric deformations and rolling mobile permormance are developed and used as educational robots.Secondly, a Sarrus rolling mechanism which is composed of two planar3R chains is researched. Kinematics and rolling performance are analyzed. The Sarrus rolling mechanism’s rolling gaits are simulated taking advantage of the singular position of Sarrus rolling mechanism. Later, a single-loop8R rolling mechanism which can switch between planar6R rolling mechanism and Sarrus rolling mechanism is proposed. Then, the rolling gaits of the8R rolling mechanism are analyzed.Thirdly, a new spatial6R overconstrained rolling mechanism which is composed of three RR chains is proposed. Kinematics, freedom and rolling performance are analyzed. The rolling mechanism rolls in a continuous mode or a discontinuous mode and it can adjust the moving direction by switching the two rolling modes. A virtual prototype is established and mobile performance is analyzed by simulation. A prototype is manufactured to verify the proposed concept.Finally, a double-spherical6R rolling mechanism which is composed of two spherical3R chains is studyed. Two kinds of mechanisms rolling along a straight line and rolling along a broken line respectively are proposed and the two kinds of mechanisms’ rolling gaits are analyzed by simulation. The double-spherical6R mechanism can be simplified as a revolute joint, so that a fictitious planar4R mechanism based on the double-spherical6R mechanism is designed and a motion simulation experiment is carried out.