With the development of virtual reality, the practical requirements of the wearable haptic interface have been greatly emphasized. While passive haptic devices are commonly used in virtual reality, they lack generality and are difficult to precisely generate continuous force feedback to users. In this work, we present SmartSpring, a new solution for passive haptics, which is inexpensive, lightweight and capable of providing controllable force feedback in virtual reality. We propose a hybrid spring-linkage structure as the proxy and flexibly control the mechanism for adjustable system stiffness. By analyzing the structure and force model, we enable a smart transform of the structure for producing continuous force signals. We quantitatively examine the real-world performance of SmartSpring to verify our model. By asymmetrically moving or actively pressing the end-effector, we show that our design can further support rendering torque and stiffness. Finally, we demonstrate the SmartSpring in a series of scenarios with user studies and a just noticeable difference analysis. Experimental results show the potential of the developed haptic display in virtual reality.
Figure 1: We propose SmartSpring, a new passive device for haptic display. (a) The user wears the proposed SmartSpring to perceive haptic feedback. With continuous force signals from the VR scene as the input, SmartSpring intelligently updates its structure to provide desired forces, simulating the experience when pressing soft objects. (b)The prototype of SmartSpring. The spring-linkage structure, controlled by motors, adjusts the system stiffness, rendering different (c) forces or (d) torques when the user’s hand is in contact with the touching pad.
Figure 2: The 3D model of SmartSpring.
Figure 3: The overall system of VR interaction with SmartSpring.
Figure 4: The results of the constant-output experiments. We show the actual force (a) and torque (c) to reproduce target constant values under different displacement of the touching pad. We also plots several examples to show the distribution of the output forces (b) or torques (d) in constant-output experiments.
The authors would like to thank anonymous reviewers for their valuable comments. This work has been supported by
the NSFC under Grants No.92148205, 62133009, 62132017 and 62141217, the Natural Science Foundation of Jiangsu
Province under Grants No. BK20211159, the Shandong Provincial Natural Science Foundation under Grants No.
ZQ2022JQ32, the CIE-Tencent Robotics X Rhino-Bird Focused Research Program and the Fundamental Research Funds
for the Central Universities.