Research On Single Leg Control Algorithm Of Quadruped Robot

Nowadays, there has been much research on quadruped robot. Many scientific researchinstitutes developed prototype mechanism and studied on it, in which the most advanced is“BigDog” made by BostonDynamics in America. Compared to most quadruped robots withless degrees of freedom,“BigDog” has more dimensions on its each leg, which means moreflexibility and motility, as well as more difficult to control.On the other hand, for such a highly nonlinear and coupling system like a quadrupedrobot, precise position control is complicated, and the problem become more difficult becauseof the restrictions from the environment. Because restrictions reduce dimensions, and theenvironment produces a counter force to the leg for contact between the foot and ground. Toolarge force will damage the mechanism and the environment, so that it is needed to control theforce between the leg and the ground.To solve the problem of control of a quadruped robot, we take the single leg of aquadruped robot as research object and study on the control algorithm in this paper. Weestablish a simplified model of a single leg, design the control algorithms and validate themthrough simulation and experiment. The major content of this paper is as follows:Firstly, establish a simplified model of a single leg with three joints, deduce itskinematics and dynamics, including dynamics equation both in joint space and operate space.Then deduce the kinematics and dynamic equation of the single leg with spring and damper.Secondly, design traditional position control algorithms in joint space and operate spacebased on the kinematics and dynamics equation, and do some simulation and experiment.Thirdly, to control the force between the leg and ground, design a kind of position/forcecontrol algorithm in operate space based on the dynamics equation of the single leg withspring and damper, i.e. using position control in horizontal direction and using positioncontrol with inner force loop in vertical direction.At last, introduce the hardware and software of the quadruped robot experimentalplatform and emphasize the program framework of the lower computer.