A Haptic Feedback Device Actuated by Electromagnetic Torque

Haptic feedback enhances user interaction with systems by adding the sense of touch, thereby improving immersion and realism in applications like virtual reality (VR), augmented reality (AR), video games, education, and robotic surgery. To address the challenges in mechanically actuated haptic feedback devices such as limited mobility, mechanical wear, and complex mechanical structures, several research sought to develop electromagnetic haptic feedback systems. However, they also suffer from the rapid decay of magnetic force with distance, thus restricting their workspace size and application potential. In this paper, we propose a novel electromagnetic haptic feedback device that is actuated by magnetic torque instead of magnetic force. By controlling the magnetic torque, which decays with distance only at a thirdorder rate, our device achieves a large workspace - a 200-mm-diameter hemisphere - while still delivering perceptible realtime haptic feedback within the hemisphere. While using the device, the user wears a lightweight haptic thimble housing a permanent magnet on their finger, which enables 2 degree-offreedom (DoF) haptic feedback. A 13-coil electromagnet array serves as the source of the magnetic field. A mathematical model is proposed to determine the currents in the electromagnet array to generate the desired amount of haptic feedback torque. We conducted two experiments to prove the viability of the device. A haptic feedback accuracy experiment was conducted and validated the device's ability to generate sufficient torque within a large workspace. A user evaluation experiment showed that the device achieved an overall accuracy of 77.86% in a virtual enclosure exploration task, indicating its effectiveness and usability in haptic feedback applications.