Study On Design And Control Of A Compliant Quadruped Robot

With the development of scientific research on legged robots, the locomobility of legged robots has been extending from static walking to advanced performances such as jump and run. Rigid mechanical structure cannot satisfy the requirements for achieving these advanced motion capabilities. It is necessary to develop compliant structures in order to improve legged robot’s performances. In this paper, a novel compliant quadrupedal robot mechanism with local passive degrees of freedom was proposed to improve walking stability and reduce force of the footend from the ground. The conctrol method was proposed for this robot, and an experimental platform was built to conduct walking experiments and evaluate the robot’s performances. The main work of the dissertation is:At first, a novel compliant quadrupedal robot mechanism was proposed which has four elastic legs and two flexible waist joints. The elastic legs are composed of a linear sliding pair constrained by compression spring at the end of each leg. The flexible waist is constituted with two rotating joints in roll and yaw, which are constrained by torsion springs. A simplified dynamic model of robot was built and the compliant characteristic parameters were determined mathematically. Then the prototype was built.Secondly, a sine-function-based center pattern generator(CPG) model was established as the trajectory planner of the robot, the parameters of the CPG model was optimized.Thirdly, A assessment method was proposed to evaluate the effect of the compliant structure, and a motion evaluating system was built which consists of ground force detectection subsystem and posture measurement subsystem.At last, walking experiments were implemented on the compliant quadrupedal robot with the elastic legs, the flexible waist in roll and the flexible waist in yaw respectively. The experiment results were analyzed by comparing with the results from the controlled experiments on rigid robot.Comparative experiments show that compliant structure can effectively reduce the ground impact force and decrease the swing of the body. It is effective for improving walking coordination and postural stability for legged robot.