arXiv subjects

Kequan Xia

Publications and source records attributed to Kequan Xia.

4 recordsLinked to original sources

arXiv2026

Magnetically Self-Sealed MR Haptic Actuator With PWM-Based Excitation and High-Fidelity Torque Control

Accurate and stable torque rendering is essential for safe and perceptive human--machine interaction. Magnetorheological fluid (MRF)-based actuators offer a compact and rapidly controllable solution for haptic feedback, but their practical implementation requires reliable fluid sealing, low-hysteresis excitation, accurate torque control, and stable long-duration operation. This article presents an integrated MRF haptic system featuring a compact magnetically self-sealed rotary actuator, low-hysteresis PWM operation, high-fidelity model-based torque rendering, and stable performance during long-time operation. Magnetostatic simulation guides the arrangement of magnetic and nonmagnetic materials to focus flux in the multidisk torque and permanent-magnet sealing regions, enabling a maximum 600 N$\cdot$mm/A output. Experiments show that higher PWM frequencies reduce hysteresis and improve repeatability. At 10 kHz, the response is represented by a nonlinear model that varies with the direction and speed of torque change. The real-time controller combines feedforward, hysteresis compensation, PI feedback, and sliding-mode correction. Compared with PID, it reduces square-wave overshoot, undershoot, and steady-state RMSE by 77.4\%, 61.9\%, and 68.3\%, respectively. It tracks sinusoidal and biomechanics-model-based references, and a 1.5-h test shows only a 2.5 $^\circ$C rise near the coil with no clear tracking loss. This high-fidelity torque rendering will fundamentally transform human--robot collaboration by making interactions safer, more efficient, and more intuitive.

cs.RO↗

arXiv2025

Intrinsic static/dynamic triboelectric pressure sensor for continuous and event-triggered control

Conventional pressure sensors often integrate two distinct mechanisms to detect static and dynamic stimuli, hindering the development of high fidelity human-machine interfaces. Here, we present an intrinsic static/dynamic triboelectric sensor (iSD Sensor) capable of reliably perceiving both continuous static pressure and transient mechanical shocks through a DC/AC signal decoupling strategy. By pairing hydrophobic expanded polytetrafluoroethylene (ePTFE) with elastic conductive sponge, a pressure-adaptive triboelectric interface is formed, where microscale and large-scale separations enable static and dynamic pressure sensing, respectively. Furthermore, by employing a charge excitation strategy, the device delivers enhanced voltage outputs over 25X in static and 15X in dynamic modes. Combined with a 3D gradient conductive sponge structure, the sensor achieves multi-region sensitivities of 34.7 V/kPa (static) and 48.4 V/kPa (dynamic) under low pressure (less than 1.8 kPa), and a detection limit as low as 6.13 Pa. By perceiving continuous static pressure and transient shocks applied by the human hand, the iSD Sensor enables robotic arm control via proportional grasping and dynamic, trigger-based sign language communication. This work advances high-sensitivity, self-powered pressure sensors toward intelligent, closed-loop human-machine interaction.

cs.RO↗

arXiv2024

Multi-Roller Structure Triboelectric Nanogenerator for Enhanced Water Wave Energy Harvesting and Energy Management

Wave energy harvesting is critical for advancing the development and utilization of marine resources. In this study, we present a novel multi-roller structure triboelectric nanogenerator (MR-TENG) designed specifically for efficient water wave energy harvesting. The MR-TENG leverages a coupled multi-roller design to significantly enhance its energy harvesting capabilities. The triboelectric layers are composed of polytetrafluoroethylene (PTFE) film and paper, with a grid copper electrode serving as the conductive element. Through an optimized energy output strategy, a single MR-TENG is capable of generating 602.045 {\mu}J of electrical energy within 100 s. The device achieves a short-circuit current (Isc) of approximately 2.06 {\mu}A and an open-circuit voltage (Voc) of around 166 V. We further investigate the impact of different connection modes, including parallel and series configurations, on the performance of MR-TENG arrays. Notably, the electrical energy produced by the MR-TENG array is sufficient to power 40 blue commercial light-emitting diodes (LEDs). This research not only introduces a versatile optimization approach and energy management strategy for roller-structured TENGs but also contributes significantly to the advancement of ocean-based TENG technology.

physics.app-ph↗

arXiv2024

Highly robust and efficient metal-free water cup solid-liquid triboelectric generator for mechanical energy harvesting and ethanol detection

Recently, low-frequency mechanical energy harvesters based on solid-liquid contact electrification have garnered widespread attention for their unique advantages in wear resistance, high charge transfer efficiency, and novel insights into electron-ion interactions at the solid-liquid interface, particularly in material identification. Hence, we designed an robust and efficient water cup triboelectric nanogenerator (WC-TENG) that only uses ordinary drinking water and plastic water cups as primary materials, achieving high-efficiency power output while eliminating the need for metal electrodes and effectively addressing the issue of corrosion in generator components. Experimental results indicate that, at an operating frequency of 2 Hz, the WC-TENG generates an open-circuit voltage (Voc) of 249.71 V, a short-circuit current (Isc) of 4.21 uA, and a transferred charge (Qsc) of 188.85 nC. The WC-TENG demonstrates long-term stability and reliability, maintaining stable voltage output over 1500 s. Moreover, the WC-TENG maintains stable performance under high humidity conditions, and its output enhances with increasing temperature, underscoring its robustness and adaptability for diverse environmental applications. Furthermore, the introduction of ethanol disrupts the potential balance at the solid-liquid interface by impeding electron transfer and reducing the WC-TENG's electrical output, but as the ethanol volatilizes, the device gradually returns to its original potential state, demonstrating its potential as a selective ethanol sensor. This design not only advances the development of corrosion-resistant, high-performance energy harvesters but also opens up new possibilities for low-cost, sustainable, and environmentally adaptable sensing technologies.

physics.app-ph↗