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In this paper, a novel sandwich-type traveling wave piezoelectric tracked mobile system was proposed, designed, fabricated and experimentally investigated. The proposed system exhibits the advantages of simple structure, high mechanical integration, lack of electromagnetic interference, and lack of lubrication requirement, and hence shows potential application to robotic rovers for planetary exploration. The tracked mobile system is comprised of a sandwich actuating mechanism and a metal track. The actuating mechanism includes a sandwich piezoelectric transducer and two annular parts symmetrically placed at either end of the transducer, while the metal track is tensioned along the outer surfaces of the annular parts. Traveling waves with the same rotational direction are generated in the two annular parts, producing the microscopic elliptical motions of the surface particles on the annular parts. In this situation, if the pre-load is applied properly, the metal track can be driven by friction force to achieve bidirectional movement. At first, the finite element method was adopted to conduct the modal analysis and harmonic response analysis of the actuating mechanism, and the vibration characteristics were measured to confirm the operating principle. Then the optimal driving frequency of the system prototype, namely 35.1 kHz, was measured by frequency sensitivity experiments. At last, the mechanical motion characteristics of the prototype were investigated experimentally. The results show that the average motion speeds of the prototype in dual directions were as 72 mm/s and 61.5 mm/s under the excitation voltage of 500 VRMS, respectively. The optimal loading weights of the prototype in bi-directions were 0.32 kg and 0.24 kg with a maximum speed of 59.5 mm/s and 61.67 mm/s at the driving voltage of 300 VRMS, respectively.

A novel tracked travelling system driven by a Langevin piezoelectric transducer is proposed. It has advantages of large driving force, high mechanical integration, well reliability, requiring no lubrication, and having the potential application in planetary exploration. The tracked travelling system comprises of an actuating mechanism and a track. The actuating mechanism includes a Langevin piezoelectric transducer and two annular parts symmetrically placed at two ends of the transducer. The track is pressed in contact to the outer surfaces of the annular parts. Traveling rotating waves are generated in two annular parts, and then the microscopic elliptical motions at the outer surface of the annular parts will be generated to drive the track to move by friction force. The actuating mechanism is analyzed by using FEM, and the simulation results are compared with the vibration measurements results. And then the prototype of the tracked travelling system was assembled and investigated experimentally for its performance. The maximum average velocities to bi-directional movements were 72mm/s and 61.5mm/s under the excitation voltage of 500Vpp and frequency of 35.1 kHz, respectively.

A novel type piezoelectric tracked travelling system with potential application to planetary exploration is proposed. The tracked travelling system includes a piezoelectric transducer and a metal track. When the piezoelectric transducer is excited by two electric signals with a phase difference of π/2, the metal track will be driven by friction forces. Firstly, the design and operating principle of the tracked travelling system are presented in detail. Secondly, the operating modes of the piezoelectric transducer are analyzed by FEM and compared with the vibration measurement results. Thirdly, the prototype is manufactured and assembled, and the motion characteristics experiments of the system are carried out to valid the feasibility. When the voltage is 460V and the frequency is 65.2 kHz, the maximum velocity of the system can reach to 51.5mm/s. The results show that the tracked travelling system has a potential application in rover robots for planetary exploration.

A novel traveling wave piezoelectric-actuated tracked mobile robot with potential application to robotic rovers was proposed and investigated in this study. The proposed tracked mobile robot is composed of a parallelogram-frame-structure piezoelectric transducer with four rings and a metal track. Utilizing the converse piezoelectric and friction effects, traveling waves were propagated in the rings and then the metal track was actuated by the piezoelectric transducer. Compared with traditional tracked mechanisms, the proposed tracked mobile robot has a simpler and more compact structure without lubricant, which eliminates the problem of lubricant volatilization and deflation, thus, it could be operated in the vacuum environment. Dynamic characteristics were simulated and measured to reveal the mechanism of actuating track of the piezoelectric transducer. Experimental investigations of the traveling wave piezoelectric-actuated tracked mobile robot were then carried out, and the results indicated that the robot prototype with a pair of exciting voltages of 460 Vpp is able to achieve a maximum velocity of 57 mm s−1 moving on the foam plate and possesses the obstacle crossing capability with a maximum height of 27 mm. The proposed tracked mobile robot exhibits potential to be the driving system of robotic rovers.