A Five Dof Haptic Rendering Algorithm Using Multiple Contact Points

With the proliferation of haptic devices, there has been significant research toward realistic haptic rendering of virtual environments. Currently, the majority of haptic devices provide only three degrees-of-freedom (3 DOF), but 5 and 6 DOF devices are becoming more common. This paper presents a method of using existing 3 DOF rendering techniques to produce forces for a 5 or 6 DOF device when true 6 DOF rendering is unavailable. Point-force 3 DOF rendering that is most commonly used in commercial haptic applications is simple and fast for basic haptic rendering; however, this creates unrealistic haptic effects when an avatar other than a point is considered. As a solution, a 6 DOF force and torque algorithm is presented based on multiple contact points. Using the multi-point torque rendering approach, forces are rendered in three linear dimensions using existing 3 DOF algorithms, and up to three additional torque degrees-of-freedom are calculated based on the forces on multiple points. This capability enhances haptic realism without modifying the legacy rendering. Finally, this algorithm is demonstrated using a 5 DOF haptic interface. The results from test observations suggest that the 5 DOF rendering algorithm functions as expected.