One-dimensional traveling wave type linear piezoelectric moving platform driven by a new two-frequency two-mode excitation method

The traveling waves of linear traveling wave type piezoelectric motors are not easy to stabilize due to its finite boundary structure. The traditional two-mode excitation method is a method which can excite two modes to generate traveling waves in a finite structure. However, the drawback of the traditional method is that it does not allow for adjustment of the final output velocity. Also, this method is characterized by having low efficiency. The velocity of the generated traveling waves is constant unless the excited modes are changed. In this paper, we propose a novel method, called a two-frequency two-mode excitation method which uses a piezoelectric actuator to simultaneously excite two modes to generate traveling waves. The two frequencies chosen possess a ratio where the excited frequencies are close to two resonant modes. In addition, the two excited frequencies are simultaneously an integer ratio to a specific frequency and have a least one common multiple, as small as possible. This approach can generate stable traveling waves such that the velocity of the traveling waves can be adjusted by the two frequencies. Our theoretical predictions were validated by numerical calculations and experimental data. A Hilbert transform was used to optimize the traveling waves generated. A morphological opening was used to track the traveling wave trajectories. The obtained results show that this method can generate stable traveling waves where the wave velocity can be adjusted by mixing the frequency signals.