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.

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The turbine shared support structure is used widely in aeroengines, but theoretical and experimental research on a rotor-bearing system containing a shared turbine support structure is lacking. This paper reports research into the coupling vibration response of a squeeze-film-damper rotor-bearing system that has two spools with different rotation speeds and is supported by a turbine shared support structure. The problem is addressed by means of experimental tests and the finite-element method. Based on the features of a turboshaft engine with a turbine shared support structure, a rotor-bearing test system with a shared support structure and squeeze film damper is designed, and a finite-element model of the test system is built based on Timoshenko beam elements. The experimental and simulation results indicate that the unbalanced response of the rotor-bearing system with a shared support structure may involve either the sum or difference of the fundamental frequencies of the rotors of the gas generator and power turbine. The simulations show that the unbalance of the power turbine rotor, the radial and bending stiffnesses of the shared support structure, and the radial clearances of squeeze film dampers at the shared support structure of the rotor-bearing system all affect the coupling response. The amplitude of the coupling response can be suppressed effectively by (i) selecting reasonable parameter values for the turbine shared support structure and (ii) exerting strict control over the spool unbalance.

To realize high performance and suppress the backward motion of the inertia piezoelectric actuator, a novel inertial piezoelectric actuator with double-stator cooperative motion is proposed, designed, fabricated, and tested. The structure and the operation principle of the proposed actuator are first explained in detail. Then the flexible structure is analyzed through the finite element simulation. In addition, the dynamic model of the actuator with double-stator working mode is established and simulated in MATLAB/Simulink, and the step characteristic is investigated, which provided a guidance for the design and optimization of inertial piezoelectric actuators with double-stator. Finally, an experimental investigation of the proposed actuator prototype was carried out and the results showed a significant improvement in the performance of the proposed actuator compared to the previous double-stator inertial piezoelectric actuators. The actuator exhibits a maximum speed of 32.84 mm/s, a maximum lateral load of 20 N, a maximum vertical load of 200 N, a minimum backward rate of 0.91%, and a minimum resolution of 127.5 nm. The actuator with double-stator can improve the maximum output performance to a certain extent, and suppress the backward rate, presenting a specific reference value for the design of future high-performance piezoelectric actuators.

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