DOI: 10.14457/tu.the.2023.1191
title: Design of electrostatic clutch with constant force range for haptic force feedback glove

description: The rapid evolution of technology has led to a surge of interest and research in haptic devices. The emergence of haptic technology has significantly transformed the audio and video industries over the past decade, and its implementation has been observed in various domains such as medicine, education, military, and entertainment. Haptic interfaces, including handheld, encountered, wearable, mid-air, and physical props, have demonstrated their potential in enhancing the immersive experience in virtual reality settings. Among these interfaces, the wearable haptic glove interface has gained considerable attention. Wearable haptic interfaces with force feedback have been widely utilized in the haptic industry. However, despite their advancements, several issues remain unaddressed, such as flexibility, compatibility, weight, degree of freedom (DOF), cost, and synchronicity. Electrostatic clutches have the potential to enhance the functionality of actuators in the field of robotic industries, offering benefits such as heightened precision, rapid response times, and improved energy efficiency. These clutches serve as flexible, lightweight, and cost-effective mechanisms that find applications in a variety of force-dependent tasks, including robotic grippers, clamping systems, holding fixtures, lifting and hoisting equipment, and VR haptic gloves. However, incorporating these clutches into practical designs has proven to be challenging due to the inherent variability in holding forces and their range caused by the changing position of the moving electrodes and the corresponding overlapping areas. To address this issue, we propose a novel conceptual design of an electrostatic clutch that employs cylindrical electrodes. The aim of this study is to maintain a consistent friction force range by ensuring a constant overlapping area. In demonstrating the proof of concept, we delineate the design specifications for a clutch that is customized for a haptic force feedback glove. The clutch is characterized by its compact length, lightweight construction, and cost-effectiveness. Furthermore, this propose clutch will designed with the specific intention of providing tactile force feedback by holding the fingers of users and addressing challenges related to wearability.The results revealed that the average force exerted was measured at 2.8 N. The proposed clutch demonstrates the ability to hold a maximum force of 3 N at 1000 input voltage, which should maintain the allowable move length with a fixed force range. Additionally, the response time of the proposed clutch is documented to be less than 270 ms.Furthermore, motion tracking in virtual reality (VR) settings and rehabilitation research has become increasingly important, with data gloves emerging as a popular solution. In this study, also we present a novel, lightweight, and detachable finger-tracking mechanism specifically designed for tracking finger movements in VR environments. The glove's design incorporates a potentiometer connected to a flexible rack and pinion gear system, enabling precise and natural hand gestures for interacting with VR applications. Initially, we calibrated the potentiometer to match the actual finger bending angle and verified the accuracy of the angle measurements recorded by the data glove. Furthermore, to assess the precision and reliability of our data glove, we conducted repeatability testing, with 250 measurements each for flexion (Grip test) and extension (Flat test) across five users. The Gage R \&R method was utilized to analyze and interpret the repeatability data. Additionally, we seamlessly integrated the mechanism into a SteamVR home environment using the OpenGlove autocalibration tool. The analysis of repeatability revealed an aggregate error of 1.45 degrees in both gripped and flat hand positions, a favorable outcome compared to assessments of nine alternative data gloves using similar protocols. Through these experiments, users successfully navigated and interacted with virtual objects, highlighting the precise tracking of finger motions provided by the glove. Furthermore, the proposed mechanism exhibits a low response time of 17 to 34 milliseconds and a back-drive force of only 0.19 N. Moreover, based on the evaluation of comfort using Comfort Rating Scales (CRS), the proposed glove system is wearable, meeting the criteria for WL1 level comfort.Finally, in this study, we integrated both the electrostatic clutch and rack-and-pinion gear mechanisms to develop a haptic force feedback glove. The cylindrical electrostatic clutch served as the force feedback actuator, providing haptic sensations to the user's hand, while the rack-and-pinion mechanism facilitated finger tracking. Subsequently, we connected this innovative glove to a teleoperation system (master-slave robot system) and assessed the feedback and finger-tracking performance using 20 healthy participants. According to user feedback, participants deemed the glove's weight suitable for use and reported no discomfort during tasks. Furthermore, responses to questions regarding the ease of donning and doffing the glove, as well as the time required for acclimatization, yielded positive average scores, indicating that participants found the glove user-friendly and intuitive. However, the query concerning the haptic feedback sensation garnered a slightly lower average score, suggesting potential for enhancement in this aspect of the glove's design.