Variable Shape and Stiffness Feedback System for VR Gloves Using SMA Textile Actuator

Abstract

Currently, when direct human contact is limited owing to the coronavirus era, virtual reality systems are a technology that enables interaction without spatial restrictions. In this study, a system capable of feedbacking various shapes and stiffness when touching an object in virtual reality was conceived using the SMA textile actuator, which is a shape memory alloy (SMA) that remembers by training at 500 degrees C for 15 min with training tools that fixed shapes of SMA origin, and it returns to the shape at 40.13 degrees C or higher by Joule heating. SMA textile actuators were fabricated by zigzag stitching with 0.5 mm intervals. Various shapes were feedback because the SMA textile actuators on gloves interfere with the movement of the finger joints and the feedback force levels of stiffness are divided based on the number of actuators operating, and feedback is possible in three levels. We verified shape feedback that matches sensing points that are placed on the virtual finger joints created by Unity 3D, which is a software for making virtual reality to feedback points on VR gloves with three events using Unity 3D logs. We measured the forces of each feedback force level with SMA diameters 0.4 of 0.6 mm. The results showed 2.3 N with 0.6 mm; however, owing to its rigidity, 0.5 mm SMA textile actuator is appropriate. Finally, by implementing one feedback point of the VR gloves, we verified the operation of the system from the occurrence of an event by touching an object in virtual reality to control the feedback force level through the MCU and relay.