Research On Dynamics Modeling And Control Strategy Of Joints Considering Planetary Gear Backlash

The planetary gear transmission joint is regarded as an important unit of mechanical systems with high bearing capacity and long working life, and has been widely used in large space manipulator, space robot and capsule. Whereas, owing to the existence of backlash, the effect can be taken between each gear train. However, with the increase of backlash, violently vibration will happened in space manipulator. As a result, the precision will be affected. What’s worse, it will lead to a task failure. Therefore, the further study of dynamics characteristics analysis and control strategy of space manipulator system with backlash has important theoretical and practice value.For the on-orbit operation task of space manipulator, the paper focuses on dynamics modeling and control strategy, considering backlash in planetary gear joints. The main research contents are as follows:Firstly, according to actual characteristics of the space manipulator, dynamics model of space manipulator is established in comprehensive consideration of flexible gear teeth, meshing damping, backlash and meshing error.Then, in view of the strong nonlinear characteristics of dynamics parameters in joint model, numerical method is used to solve the model in Hamiltonian system. At the same time, the effects on the change of nonlinear factors such as backlash and meshing stiffness are analyzed through simulation experiment.Finally, the research on control strategy of space manipulator joins has been carried on. Based on the reverse compensation, a sliding mode controller is designed to achieve high accuracy trajectory tracking task. Compared with PID control strategy, the advantages of sliding control method in terms of accuracy and system stability are validated through simulation experiment. In addition, a method based on disturbance observer (DOB) combined with sliding mode control is developed to compensate the effects of backlash. For one thing, the introduction of disturbance observer can eliminate the nonlinear influence of clearance. For another, the use of sliding mode control strategy can further weaken the interference of DOB disturbance observer.