Analysis on motion compensation for a horizontal stable platform

Abstract

Research being done on a stable platform is to isolate moving carrier’s motion, which can keep attached equipment stable and reduce the influence of the moving carrier. Motion compensation is analysed for a horizontal stable platform by means of coordination transformation and the parallel mechanism’s direct and inverse kinematics solution. The platform has only three rotational degrees of freedom (DOFs) in three directions, which is composed of a 2-DOF spherical mechanism and a motor on it in series. When the carrier’s orientation has changed, the 2-DOF spherical parallel mechanism can keep the platform horizontal by utilising the motors’ drive. Firstly, the platform’s kinematics are analysed and the transformation matrix of the 2-DOF parallel platform, independent of motion carrier is derived. Then by the method of coordination transformation the analytical resolution of motors’ compensation is obtained, which is for keeping the parallel platform horizontal when the motion carrier’s orientation changed, the result is verified by the numerical method and experimental process. Because of the influence of objective factors, the experimental results are approximately in agreement with the theoretical results, but there are numerical deviation and time lags. Finally, when the parallel mechanism is used for stable platform, some of the research work that should be solved is discussed. The research of this paper provides a theoretical basis for the application of a stable platform, and lays the foundation of the experiment.