Spring-based measurement equipment for evaluation of 3-DOF haptic rendering algorithms

Evaluation of haptic rendering algorithms is an important topic to achieve realistic haptic simulation. In this paper, we developed a spring-based measurement equipment to enable quantified evaluation for 3-DOF (Degree of Freedom) haptic rendering of contact between a point-shaped tool and a complex-shaped object. We proposed a new method to formulate the trajectory of the haptic tool, which will be the input signal for the target haptic rendering algorithm. Using three springs between human's hand and the probe's tip, we can precisely mimic the limited Z-Width characteristic of current haptic devices. Furthermore, we introduced a spatial registration algorithm to establish the transformation from the local frame of the force sensor to the normal of contact point, thus maintain the computed normal force is always along the normal direction. Preliminary contact experiment against a planar surface is carried out to validate the performance of our method. Experiment results showed our method can capture the real-time force and motion signal during contact, and can be utilized to evaluate performance of various haptic rendering algorithms.