Tapping on surfaces in a typical virtual environment feels like contact with soft foam rather than a hard object. The realism of such interactions can be dramatically improved by superimposing event-based, high-frequency transient forces over traditional position-based feedback. When scaled by impact velocity, hand-tuned pulses and decaying sinusoids produce haptic cues that resemble those experienced during real impacts. Our new method for generating appropriate transients inverts a dynamic model of the haptic device to determine the motor forces required to create prerecorded acceleration profiles at the user's fingertips. After development, the event-based haptic paradigm and the method of acceleration matching were evaluated in a carefully controlled user study. Sixteen individuals blindly tapped on nine virtual and three real samples, rating the degree to which each felt like real wood. Event-based feedback achieved significantly higher realism ratings than the traditional rendering method. The display of transient signals made virtual objects feel similar to a real sample of wood on a foam substrate, while position feedback alone received ratings similar to those of foam. This work provides an important new avenue for increasing the realism of contact in haptic interactions.

Traditionally focused on applications where humans have been kept safely out of reach, the field of robotics is undergoing a major shift as recent developments have brought humans much closer to robots. While device hardware has progressed to fill this new field, the underlying controller and amplifier architecture has remained nearly the same as that developed for industrial robots decades ago. Herein we develop a new, integrated control architecture designed to address the unique requirements of human-interactive robotic devices. This new architecture takes advantage of recent technological advances to produce a single-loop, third order controller integrating both switching control and a fullstate observer. In this paper, we explore the performance on a simplified, first-order system, specifically focusing on the interaction between the controller and the DC motors found in many devices. Experimental testing demonstrates improvements compared to existing PWM and linear amplifiers, with the promise of future improvements for the field of human-interactive robotics.

In this paper we propose an integrated motion control architecture based on a full third order motor model. We investigate the advantages and feasibility of controlling a motor using very fast (MHz) switching using digital components in place of traditional amplifiers. A switching controller combines the current and encoder (position) feedback paths into a single loop, and a model based observer estimates the unsensed motor velocity. When compared to second order controllers built with traditional amplifiers, the proposed design promises increased performance, better efficiency, and unproved velocity estimation. Advances in semiconductor technology facilitate the implementation of these fast switches and the required logic using relatively standard components. Preliminary experiments verify good behavior of a DC motor driven up to 5 MHz.