Abstract:Screw theory is an important tool in research of robots, also with its obvious advantages in computing, the geometric significance is more apparent in the process of modeling. By observing the hydraulic excavator as a single open chain mechanism with 4 degrees of freedom (4DOF), its dynamic equations were established with using screw-based Kane equations. The position and orientation variables of the trajectory of end bucket of excavator were separated based on screw theory, which laid a foundation for improving precision control, with its simplicity in computing, was helpful for implement real-time control of the trajectory of end bucket of excavator. The body Jacobian matrix of the upper rotational platform with the cab, boom arm and bucket of the excavator were gained based on the screw theory, which presented their generalized active wrench force and inertial wrench force in every respect. Through the screw type of Kane’s equations, the dynamics model of end bucket of the excavator rested on a rigid horizontal soil foundation was established. Finally the correctness of the established model is verified from the simulation results of related parameters of the excavator.