Abstract: In order to improve the low speed performance of continuous rotary electro-hydraulic servomotor, the flow and pressure characteristics of motor airtight cavity are analyzed considering the changes of flow and pressure and the characteristics of leakage and friction in the course of pressure switch. In view of the complication of solving the problem, an improved genetic algorithm with initial population gradually drifting is introduced to carry out the structure optimization for improving low speed performance. The formula of pre-transitional curve of the stator and its angle range is derived, and the optimum dimension of triangle cushioning groove of the valve plate is also obtained. The analysis result of the simulation and experiment validates that the theory is reasonable and the algorithm is effective. This optimization method avoids premature convergence. Furthermore, by applying the technique of initial population gradually drifting to the improved genetic algorithm, the robust capability of initial value is also improved and the neighbor-function structure is more reasonable. By using the method to design the servomotor, the continuous rotary electro-hydraulic servomotor can track the ultra-low speed ramp signal of 0.001()/s and meet the requirement of the tolerance zone of 0.001. So, this method opens up a new way of solving this kind of problem.

Key words: Continuous rotary electro-hydraulic servomotor, Genetic algorithm, Low speed performance, Pressure impact