Trajectory Tracking for a New One-Legged Hopping Robot

In this paper, the dynamic behavior of a new hopping robot as a hybrid system has been modeled and controlled. The hopping robot consists of three main segments, a flat foot, a leg, and finally an object with a notable mass. In addition to stance and flight modes which are the most common modes in hopping robots gaits, an underactuated mode occurs during the gait of the present robot which provides the robot with some novel features. The underactuated mode enables the robot to jump higher and longer and pass an obstacle which is right next to the robot. In order to model this hybrid system, the Lagrange’s equation is implemented and the motion equations of the robot in all of the modes are derived. Also, to generate a more precise model, the impacts which happen while modes are changing are formulated utilizing the invariance of angular momentum of the system during impact instants. Afterwards, two desired scenarios are designed to guarantee the stability of the robot during a jumping cycle and enabling the robot to make a reasonable jump and move forward. As the last step of this study, a PD controller is implemented to track the desired scenarios and the feasibility of the presented model and the behavior of the robot during a jumping cycle are investigated using numerical simulations. It is shown that the robot is capable of jumping and moving forward and could pass obstacles which are right next to the robot.

کلیدواژه ها:

hopping robot ، hybrid system ، trajectory planning ، PD controller.