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Single-phase driven piezoelectric actuators have attracted more and more attention due to their advantages of simple driving circuit, more flexible design and more compact structure. However, the single-phase driven piezoelectric actuators generally have some problems, such as no common node for clamping, the steering function cannot be realized, and structural form cannot be directly integrated with the host system, seriously limiting their applications. In order to solve the above problems, a novel standing wave rotary piezoelectric actuator driven by single-phase signal is proposed in this study. The stator of the proposed piezoelectric actuator is mainly composing of a piezoelectric composite beam and a ring with driving teeth and stimulated to produce two different vibration modes. Each vibration mode of the stator can be independently utilized to drive upper and lower rotors, which simultaneously move in the opposite directions through friction, and the steering function can be realized by switching the two vibration modes. To reveal the dynamic characteristic of the stator, its electromechanical coupling dynamic model is first developed by using the transfer matrix method. In addition, the vibration measurements are conducted on the stator prototype to confirm the correctness of the developed electromechanical coupling dynamic model. Finally, experimental investigations are carried out to evaluate the output performances of the actuator prototype, and experimental results verified the feasibility of the structure design of the proposed piezoelectric actuator and the correctness of its operating principle.

Torsional piezoelectric actuators have been widely applied in many fields due to their specific vibration mode. However, the conventional torsional vibration piezoelectric actuators require circumferentially polarized piezoelectric ceramics or special structural designs, increasing manufacturing difficulty and processing costs, and seriously limiting their applications. In order to solve these problems, a novel excitation method of torsional vibration is proposed in this study through the arrangement of the regular piezoelectric ceramic plates polarized along their thickness direction, and then two surface-bonded type torsional piezoelectric actuators are constructed to stimulate the odd and even order torsional vibration modes, respectively. A novel transfer matrix model of describing the torsional vibration, which involves in the mechanical and electrical properties, is created first for the piezoelectric composite beam element. Then a general electromechanical coupling dynamic model is developed to reveal dynamic behaviors of the proposed surface-bonded type torsional piezoelectric actuators. In addition, the finite element simulation and experimental investigations are carried out to confirm the validation of the proposed excitation method of torsional vibration and to verify the correctness of the developed electromechanical coupling dynamic model. The comparisons showed that the results calculated by the developed theoretical model, simulated by the finite element method, and tested by the experiments matched well, indicating that the developed electromechanical coupling dynamic model is correctness and the excitation method of torsional vibration is effective. Finally, the output characteristics of the two proposed actuator prototypes are measured, further confirming the feasibility of the proposed torsional vibration excitation method.

Traditional traveling wave robots have strict requirements on the operating interface due to the fact that they usually only work on smooth and flat surfaces, holding the disadvantages of poor load capacity and complex driving mode, and limiting their application range. In order to overcome the above problems, a novel traveling wave piezoelectric actuated wheeled robot is proposed in this study. The robot is composed of a bonded-type piezoelectric actuator and wheel mechanisms. Rotating traveling wave can be produced in the annular parts of the piezoelectric actuator to drive the wheel mechanisms. In order to study the dynamic characteristics of the piezoelectric actuator, an electromechanical coupling model is developed by using the transfer matrix method. Then the prototype of the piezoelectric actuator is fabricated and assembled, and its vibration characteristics are measured to confirm the feasibility of the developed transfer matrix model. Finally, performance evaluation investigations of the proposed traveling wave piezoelectric actuated wheeled robot are conducted. Under the excitation voltages of 350 V pp and the phase difference of 90°, the robot prototype achieved a step climbing angle of 75°, a maximum no-load velocity of 136.8 mm s−1, and a maximum payload of 320 g. The proposed traveling wave piezoelectric actuated wheeled robot presents expected terrain adaptability and obstacle climbing capability.