A two-DOF ultrasonic motor, which could output linear motions with two degrees of freedom by using only one longitudinal-bending hybrid sandwich transducer, was proposed and tested. The motion in horizontal (X) direction was achieved by the hybrid of the second longitudinal and fifth bending vibrations of the motor, while the motion in vertical (Y) direction was gained by the composition of two orthogonal fifth bending vibrations. The proposed ultrasonic motor was designed and the principles for the two-DOF driving were analyzed. Then, the simulation analyses of the motor were accomplished to verify the described principles. Finally, a prototype was fabricated and its mechanical output characteristics were tested. The results indicated that the maximum no-load velocities of the motor in horizontal and vertical directions were 572 mm/s and 543 mm/s under preload of 100 N and voltage of 300 Vp-p, respectively. The maximum output forces in horizontal and vertical directions were 24 N and 22 N when the preload was 200 N. The simulation and experiment results verified the feasibility of the proposed two-DOF ultrasonic motor.

Multiple degrees of freedom (DOFs) motion manipulation of various objects is a crucial skill for robotic systems, which relies on various robotic hands. However, traditional robotic hands suffer from problems of low manipulation accuracy, poor electromagnetic compatibility and complex system due to limitations in structures, principles and transmissions. Here we present a direct-drive rigid piezo robotic hand (PRH) constructed on functional piezoelectric ceramic. Our PRH holds four piezo fingers and twelve motion DOFs. It achieves high adaptability motion manipulation of ten objects employing pre-planned functionalized hand gestures, manipulating plates to achieve 2L (linear) and 1R (rotary) motions, cylindrical objects to generate 1L and 1R motions and spherical objects to produce 3R motions. It holds promising prospects in constructing multi-DOF ultra-precision manipulation devices, and an integrated system of our PRH is developed to implement several applications. This work provides a new direction to develop robotic hand for multi-DOF motion manipulation from micro scale to macro scale.

Insertion into delicate tissue, such as retina vein occlusion, cell manipulation, and vitreoretinal injection, poses challenges to surgeons and biomedical researchers due to the high resolution, large movement range, compact structure, and multi-DOF output requirements. In order to meet these requirements, a 2-DOF arched needle insertion device driven by inertial piezoelectric actuator was proposed in this article. This device could perform theoretical unlimited translational movement and full rotation with high step resolution. A prototype was fabricated with compact structure, the length and diameter were 230 and 32 mm, respectively. The experimental tests were carried out, the insertion device output 2.47 μ m and 0.56 mrad step distance with maximum velocity of 382 μ m/s and 200.9 mrad/s under 120 V driving signals, the maximum insertion force of 32 mN was measured. Additionally, a handheld controller with friendly user interface was also developed for open-loop control utilization, which could automatically calculate and generate the required control signals according to the motion command. This device explores the biomedical application of inertial piezoelectric actuator within a compact size, providing a new choice for numerous innovative treatment and biological research involving precision operation.

A single-foot linear piezoelectric actuator is proposed in this paper, and a new exciting method for the stepping motion is discussed. The proposed actuator works in the hybrid modes of the second horizontal bending vibration and the second vertical bending vibration. Two intermittent sinusoidal signals with a phase difference of 90° are applied on the horizontal and vertical PZT elements, respectively, to obtain a discontinuous elliptical motion at the driving foot, which can move the runner linearly step by step. The structure of a single-foot linear piezoelectric actuator is designed and the mechanism for the linear driving is clarified. Then, modal and transient analyses are carried out by using ANSYS software to get the resonance frequencies of the bending modes and the movement trajectory of the driving foot. Finally, a prototype of the piezoelectric actuator is fabricated, and experiments are carried out. The experiment results show that the displacement resolution, the maximum velocity, and the maximum thrust of the proposed piezoelectric actuator are about 0.21 μm, 827.5 mm/s, and 27 N, respectively.

A non-resonant-type piezoelectric motor with a precise driving ability was proposed. The operating principle of the proposed motor is different from the previous non-resonant piezoelectric motors using either the clamping and feeding mechanism (inchworm mechanism) or the inertia drive mechanism. An oblique linear motion formed by the hybrid of two bending motions of a sandwich transducer was used to push the runner step-by-step. Two square-wave voltages were applied to the horizontal and vertical PZT elements to obtain the desired oblique linear motion. The mechanism of the proposed piezoelectric motor was illustrated in detail. Then, transient analyses were performed by ANSYS software to simulate the motion trajectory and to find the response characteristics of the motor. Finally, a prototype was fabricated to verify the mechanism and to test the mechanical output characteristics of the proposed motor. Under the input square-wave voltages of 500 Vp-p, the prototype achieved a step displacement of 5.96 μm, a maximum no-load velocity of 59.64 μm/s and a maximum thrust of 30 N. This paper provides a new mechanism for the design of a non-resonant piezoelectric motor with long stroke and precise driving ability.