Study On Structure Design And Control Method Of A Quadruped Robot With Spine Joints

How to design and control a quadruped robot to make its structure and motion being closer to its bionic counterpart is difficult in the field of quadruped robots.In this paper,a bionic quadruped robot with chest and lumbar spine joints is designed through referring to cheetahs and other quadrupeds.The dynamic model,structural optimization and gait control methods are studied and verified by simulations.The main research work are as follows:The functions of quadrupeds' spine to their running motions and the gait generations are investigated.A scheme of a quadruped bionic robot mechanism including with two degrees of freedom spine joints of chest and waist is put forward.The engineering design is carried out according to the actual project requirements.A SLIP model with damper(D-SLIP)is proposed.The motion mechanism of a single leg with two segments is analyzed.The dynamic model of the quadruped robot with spine joints in bound gait is established using Lagrange method.The mathematical relationship among model parameters such as joint motion,driving force,damping and stiffness is derived.A coordinated control method for the spine and the legs of the quadruped robot is put forward by referring the running mode of cheetahs.The joint trajectory planning of the quadruped robot's spine and legs is carried out in bound gait.A multi-objective hierarchical optimization algorithm for transmission mechanism is designed.Based on the dynamic model and planned motion trajectory,particle swarm optimization algorithm is employed to optimize the dimensions and mechanics of the spine joint transmission mechanism.The joint design problem of joint trajectory parameters and transmission mechanism dimensions is solved.A hierarchical motion controller for the quadruped robot is designed.The continuous jumping control for the single leg is realized based on D-SLIP model and three-part control method.CPG gait model and finite state machine of the leg motions are designed based on the mechanisms of animals' rhythm motion,thereby realizes legs coordination and spine-leg coordination control.Attitude control of the quadruped robot is realized based on VMC method.The simulations of in-situ jumping,up and down stepping and rough terrain walking are carried out for the single leg using Webots.The results show that the single leg control method can realize speed adjustment and attitude stability control successfully.The quadruped robot running in bound gait,trot-gallop-trot gait transformation and trot gait on rough terrains are simulated.The correctness of the robot's mechanical structure design and the effectiveness of the planned trajectory and control model are verified.