Development of SPIDAR-HMD for a Standalone HMD

Abstract

The head-mounted display (HMD)-integrated force sense presentation device, SPIDAR-HMD, which we had developed, allows users to experience not only visual but also force sense in virtual reality (VR) space by attaching the force feedback device on the HMD. In addition, because it is an HMD-integrated type, there is no need to wear another device with the HMD, which reduces the load on the user. However, the conventional SPIDAR-HMD has the following problems: the target HMD is the Oculus Rift S, which requires wiring to a high-performance PC to function, it can only operate under a Windows environment, and the update frequency of force feedback is as low as 300 Hz. In this study, we focused on Oculus Quest, which is a standalone HMD and uses Android as its operating system. Thus, we changed the microcomputer used for the conventional SPIDAR-HMD controller from PIC24F to ESP32 and added Wi-Fi UDP communication implemented in Unity standard C# and Bluetooth serial port profile (SPP) communication function implemented in Java for Android. In addition, a function for multiple players was implemented, making it possible for multiple users to share the VR space with haptics. In the evaluation experiment, the magnitude of the force and the update frequency were measured. Regarding the presentation force, we could obtain two times the magnitude of the conventional SPIDAR-HMD. Regarding the update frequency, stable presentation of 800 Hz was possible in the Wi-Fi AP mode and Bluetooth SPP, but the performance was low in the Wi-Fi STA mode. These results showed that higher performance could be obtained using Bluetooth SPP.