Memory based passivation method for stable haptic interaction

This paper proposes a new concept of passivation method to increase the dynamic range of impedance that a haptic interface can passively interact. The proposed method is motivated by force vs. position graph, which shows a pressing and releasing path when the haptic interface is interacting with the Virtual Environment (VE). The main reason of the active behavior was on the fact that the releasing path was higher than the pressing path in the force vs. position graph. To solve this issue, when the haptic interface is pressed, the computed force output from the VE is saved into fast accessible memory (such as FPGA) together with position data, and reused when the haptic interface is released to regulate the releasing path below the saved pressing path. The proposed method is tested with one-DOF haptic display, and shows better performance than recently proposed FPGA based time domain passivity approach.