Type Synthesis And Trajectory Planning Investigation On Heavy-load Parallel Stabilizing Platform

Under the influence of the wave disturbance, the rocket could produce larger slope and vibration during the ocean transportation. Stabilized platform can isolate the influence of the hull oscillation on the rocket, and then ensures the transportation safety of the rocket and the device on board. This article studies the problems that it’s hard to use the stabilized platform for the carriage of the rocket in view of the existing stabilized platform’s small load capacity. The main research contents are as follows:The force transmission performance and the carring capacity of parallel mechanism are analyzed. It gives the concept of force transmission performance of parallel mechanism, defines the force transmission performance evaluation index, and proposes a calculation method of computing standardized model’s withstanding maximum force extremum. According to the different forms of motions, the bearing capacity of the parallel mechanism can be divided into the static carring capacity and the dynamic carring capacity, and the calculation methods are put forward. The combination of the force transmission performance and bearing capacity can guide the heavy-loaded parallel mechanism for the designing and evaluation.The multi-inputs driving mode applicable to the heavy-loaded parallel mechanism is studied. Firstly, according to the differences of the redundant driving force’s characters and the moving platform’s effects, two methods of the classification of the redundant actuations are put forward. On the base of the different types of redundant actuations, three types of redundant actuations which respectively are the moving platform’s static load balancing driven redundant actuation, joints’ static load balancing driven redundant actuation and gravity balancing active redundant actuation are synthesized. A multi-inputs non-redundant actuation mode is proposed, which integrates the multi-inputs non-redundant actuations’ drive units and branches. On the basis of the driving modes above, three kinds of parallel mechanisms are constructed, the degrees of freedom of 3(2 UPS- R)/PU mechanisms greater than 6 are analyzed in details.Based on the screw theory, a research of the parallel mechanism’s jerk in the non-inertial frame is carried out. It defines the space jerk, the object jerk and the coupling object jerk of the rigid-body, and proves the space jerk and the coupling object jerk are screws, while the object jerk is not a screw. The expressions of adjoint transformation and adjoint mapping of jerks in multi-rigid-body system are deduced. On the basis of the expressions, the transform relationship of jerks between rigid bodies of the stabilized platform is obtained. The mapping model of jerks of the parallel mechanism is established, the third-order influence coefficient matrix which represents the mapping is obtained. Combining the transformation relationship of jerks between the stabilized platform’s rigid bodies and the mapping model of jerks of the parallel mechanism, it obtains the jerk’s mapping model of the parallel mechanism in the non-inertial frame. According to the relationship of the rigid-body angular velocity and the euler angle time derivative, the mapping of the rigid-body angular jerk and the third-order time derivative of euler angle is established.The trajectory planning method of the stabilized platform in non-inertial frame is studied.Taking the advantage of the characteristics of quasi-uniform B spline, the linear constraints of the moving platform’s motion parameters are established. The weighted sum of squares of the moving platform’s jerk and the stabilized platform’s active joints’ jerk is minimized to get the spline’s control vertex, and then to obtain the motion rules of the the moving platform relative to the inertial frame in the process of the transportation.The electric and software control system of the stabilized platform’s ground testing system are introduced. Participating in the devolopment of the ground testing system, on the basis of the experimental studies, it verifies that the increase of weights can effectively improve the mechanism’s bearing capacity. The equivalent motion of the moving platform of the stabilized platform in the inertial frame is implemented in the ground testing system, and that verifies the feasibility of the trajectory.