Study On Gear System Dynamics And Active Control Strategy Of The Gear Transmission Error In Space Environment Characterized By Temperature Alternating

With the rapid development of China's space industry, gear transmission systems are widely applied to the space environment. Space environment is very complex, there are some factors different from earth, such as high temperature and low temperature alternating, microgravity, vacuum, magnetic interference, which put forward higher requirements to the gear transmission mechanism applied to the space environment.Based on a single degree of freedom straight tooth cylindrical gear transmission system, a nonlinear dynamic model including alternating temperature factor for a spur gear pair system is established, in which the time-varying meshing stiffness and the transmission error are considered. The model reflects alternating temperature in the space environment. The nonlinear single-degree-of-freedom equations were solved by employing variable step size Runge-Kutta integration method. The nonlinear dynamics characteristics of the system were discussed for different system parameters and classified based on diagrams phase portraits and Poincare map and the bifurcation diagram with the effect of alternating temperature or not.The results showed that:(1) Gear System with clearance exhibit strong nonlinear, with parameters(damping ratio, clearance, etc.) changing, gear system show rich nonlinear characteristics;(2) With the amplitude of alternating temperature increasing, the responses of the system become bad, it will become quasi-periodic motion from periodic motion; Gear mesh frequency of the gear system should try to avoid the frequency of the alternating temperature, the ratio ?h / ?T at least should be greater than 10, in order to avoid the occurrence of chaotic motion, and B <0.1.Space environment temperature alternating in a great range leads to backlash alternating of the gear transmission system with same frequency, which has a great influence on the precision of the gear transmission system. Therefore, in this paper, the author put forward a active control option aim at gear transmission error based on Giant Magnetostrictive Materials Actuator(GMA): indirectly compensate the backlash changing because of temperature alternating in a great range, by directly controlling the size of center distance of a pair of meshing gear, which is realized by force and displacement that GMA impose on the shaft unfixed, i.e. one shaft(including the gear) of a pair of meshing gear can be in tiny moving along with the direction of the line of the two shafts center. Thus, the clearance always stays within the appropriate value scope in which the performance of gear system transmission is well enough.To avoid the influence of hysteresis nonlinearity of GMA, the author builds Prandtl-Ishlinskii(PI) hysteresis model for hysteresis nonlinearity of GMA, and controls the nonlinear hysteresis of the GMA by PI inverse model.A Preisach hysteresis model and a transfer function of the dynamic system composed the model used later, and the PID control combined inverse model control of hysteresis is used to the model. The results show that the control strategy can achieve precise positioning control, and that the control strategy for compensation the change of backlash of the gear transmission system due to the large range of alternating temperature is feasible.