Abstract: A bionic cockroach robot based on the double four-bar linkage is designed, which can solve the problem that the robot based on the directly serial leg mechanism has weak bearing capacity and rigidity, as well as the position and orientation of the robot cannot be controlled accurately if the degree of freedom (DOF) of one leg is less than three. The inverse kinematics is solved in order to obtain the position of the driven joint. Then, the statics analysis of the robot is carried out, from which the driving torque needed by the joint driven motor is obtained. A visual method is used to analyze the workspace of the mechanism. Two concepts, the fast workspace and obstacle-cross workspace, are proposed to measure the planar motion performance and obstacle-surmounting performance of the robot. Finally a prototype is fabricated for walking test. Compared with the robot based on the directly serial mechanism, the newly designed prototype not only increases the moving speed, but also strengthens the bearing capacity, thus verifying the rationality and feasibility of the above-mentioned design.

Key words: Cockroach robot, Four-bar linkage, Kinematics, Statics, Workspace