Haptic Rendering and Psychophysical Evaluation of a Virtual Three-Dimensional Helical Spring

This paper presents the development of a new deformable object for haptic interaction in the form of a 3D helical spring. This haptic and visual simulation is based on an analytical model of a quasistatic spring. The model provides a real-time computationally efficient method for rendering a deformable spring using a magnetic levitation haptic device. The solution includes equations for reaction forces and resisting moments experienced during compression, elongation, shear and tilting of the spring. The system is used to conduct psychophysical experiments that quantify human perception and discriminability of spring stiffness magnitude with and without vision and demonstrates the effectiveness of the device and the simulation for rendering springs. Experiment results show that spring magnitude perception follows a linear trend, and presence of vision enables better discrimination between different spring stiffnesses.