Research On Motion Planning And Tracking Control Of Wheel-leg Hybrid Quadruped Robot

In recent years, disasters frequently occur and damage the environment. So the environment that people have to face is more complex and dangerous. To complete the search and rescue missions, while ensuring the safety of rescue personnel, we hope that robots can replace people to complete the rescue mission in the dangerous environment. Therefore, our issue is around the "Search and Rescue" theme. And we produce a wheel-leg hybrid quadruped robot to research on the movement of the robot in some kinds of roads.Firstly, we build a three-dimensional model of the robot in the Pro/E, then we import this three-dimensional model into ADAMS to generate a virtual prototype model. The virtual prototype model is the object that we study on in this paper. Subsequently, we analyzed the kinematics analysis of leg of the robot. In the different road conditions, the body of robot is parallel with the ground or not, so we deduce the relation between the coordinate of hip joint, the coordinate of end point of leg, and rotational data of three joints of leg with these two different conditions. According to this relationship, we plan two kinds of gait on the plane:COG back gait and S-shaped gait, and we apply these two gaits to climb up and down stairs.With COG back gait, robot need to adjust the COG of robot several times in one gait cycle, which make the COG of robot backwards, so the velocity of robot moving sometimes is positive and sometimes is negative. But thanks to the robot’s COG backward movement, the robot can provide sufficient stability margin to swing a leg, and the swinging distance is large. S-shaped gait is relatively much simpler than the COG back gait. Because S-shaped gait adjust the body two times in one gait cycle, and the adjustments are symmetric. In addition, the moving between left legs and right leg is symmetrical too. But the largest shortage of S-shaped gait is that the moving distance is small in one cycle, so S-shaped gait is very suitable for such a robot as moving fast but a little distance.For wheel-leg hybrid robots, we also need to research on movement of wheel. We researeh on the trajectory tracking. The trajectory consists of many ordered points. At the same time, we design a fuzzy controller, which has two inputs and two outputs. The distance between reference point and the target point and error of direction make up of the inputs; and the speed of mobile robots and change rate of direction angle make up of the outputs. Then we change the outputs into left and right angle velocity according to a speed conversion module. We hope that the wheel-robot can track a list of planning points of trajectory through the controller. After simulating between MATLAB and ADAMS, we confirm the feasibility of the controller.At the same time, we also analyzed the robot’s movement in the smooth plane. By adjusting the parameters of the robot joints, the robot can move with different speeds as ice-skating; In addition, we also study on the rotational movement that robot mobile on the smooth plane.