Response surface model and genetic algorithm-based multi-objective optimization of stator structures of hollow-type traveling wave ultrasonic motors

The stators of hollow-type traveling wave ultrasonic motors have certain problems stemming from their complex and hollow structures, significant differences between the two orthogonal modal frequencies, incomplete separation of the design model and interferential model, low-vibration amplitude, and significant localized inner stress during vibration, etc. In this paper, a dimensional parameterized finite elemental model for the motor was established by utilizing the finite elemental method. Afterwards, modal assurance criteria were used to identify the vibration models with various objectives for optimization established from this and integrating multiple objectives for optimization into a single optimization objective. Then a response surface model was established in the design space the Latin-hypercube random sampling method. Finally, a globally optimal solution was obtained according to the self-adaptive genetic algorithm and the response surface model. In order to prove the reasonableness of the optimized result, the stators are processed according to the sizes determined before and after the optimization. This paper describes the vibration of stators tested by a Doppler vibration tester. The Z-direction amplitude of the optimized stator changed from 1.0 µm to 2.5 µm. According to the testing results, the structural optimization plan used in this paper is reasonable and obviously helpful for vibration optimization of the stator.