Inchworm piezoelectric actuators have the advantage of large strokes, but most of them usually can only carry out linear motion. Some inchworm piezoelectric actuators, composed of multiple piezoelectric stacks, can realize two-degree-of-freedom motion but still fail to simplify the complex structures and struggle to achieve high output speed without backward motion. Here, we design an inchworm piezoelectric actuator that can carry out planar motion with a compact centrosymmetric structure in which only three piezoelectric stacks are used. The amplification mechanisms based on flexure hinges are designed to increase the clamping force and step displacement. A working principle of single-dual mode is designed to effectively utilize the deformations of the driving units, and two steps in one cycle are realized, which improves the output speed of the proposed actuator. Utilizing its center symmetry structure to switch the direction of motion, which enables plane motion. The parameters of the driving units were optimized by theoretical analyses. Then, the finite element method and experiments were employed for the static and dynamic analyses. Experimental results demonstrated the actuator’s capability of point-to-point positioning and tracking a circle within the plane and revealed the maximum speeds of 2085 μm/s along the X-axis and 2407.5 μm/s along the Y-axis without backward motion. Herein, a combination of a simple structure and a good output speed without backward motion is achieved on a planar motion inchworm actuator.

In response to the challenges of difficult energy supply and high costs in ocean wireless sensor networks, as well as the limited working cycle of chemical batteries, a cylindrical wave energy harvester with symmetrically distributed multi-cantilever beams was designed with Galfenol sheet as the core component. The dynamic equation of the device was established, and ANSYS transient dynamic simulations and Jiles-Atherton hysteresis model analysis were conducted to develop a mathematical model of the induced electromotive force of the Galfenol cantilever beam as a function of deformation. Experimental validation demonstrated that the simulated results of the cantilever beam deformation had an average error of less than 7% compared to the experimental results, while the average error between the theoretical and experimental values of the induced electromotive force of the device was around 15%, which preliminarily verifies the validity of the mathematical model of the device, and should be subject to further research and improvement.

Purpose: This study aims to develop a self-powered triboelectric vibration sensor for continuous sensing of vibration direction under low-frequency excitation. Design/methodology/approach: A drum-type triboelectric nanogenerator (DT-TENG) with a symmetric eight-channel structure was developed. Eight-channel peak voltages were normalized into spatial response weights and processed using spatial orthogonal demodulation to obtain azimuthal and axial components. A baseline calibrated for structural symmetry rejected pseudo-angular outputs, while a bilateral activation index characterized response evolution under oblique excitation. Findings: The DT-TENG provided repeatable azimuth and principal-axis outputs at both reference and intermediate directions. The mean absolute azimuth error for localized vertical excitation was 2.29° and the mean absolute principal-axis error for in-plane vibration was 2.06°. Under 30°-60° oblique excitation, the response evolved from a localized one-sided pattern toward bilateral axial behavior, while the mean absolute principal-axis error remained 1.50°. Directional decoding also remained comparatively stable under the tested variations in amplitude, frequency, temperature and humidity, as well as under non-periodic excitation. Originality/value: The DT-TENG combines self-powered eight-channel spatial sensing with interpretable continuous azimuth and 180°-equivalent principal-axis decoding while enabling qualitative characterization of coupled oblique excitation.