Spectral Subtraction of Robot Motion Noise for Improved Event Detection in Tactile Acceleration Signals

New robots for teleoperation and autonomous manipulation are increasingly being equipped with high-bandwidth accelerometers for measuring the transient vibrational cues that occur during con- tact with objects. Unfortunately, the robot\u27s own internal mechanisms often generate significant high-frequency accelerations, which we term ego-vibrations. This paper presents an approach to characterizing and removing these signals from acceleration measurements. We adapt the audio processing technique of spectral subtraction over short time windows to remove the noise that is estimated to occur at the robot\u27s present joint velocities. Implementation for the wrist roll and gripper joints on a Willow Garage PR2 robot demonstrates that spectral subtraction significantly increases signal-to-noise ratio, which should improve vibrotactile event detection in both teleoperation and autonomous robotics

Haptography: Capturing and Recreating the Rich Feel of Real Surfaces

Haptic interfaces, which allow a user to touch virtual and remote environments through a hand-held tool, have opened up exciting new possibilities for applications such as computer-aided design and robot-assisted surgery. Unfortunately, the haptic renderings produced by these systems seldom feel like authentic re-creations of the richly varied surfaces one encounters in the real world. We have thus envisioned the new approach of haptography, or haptic photography, in which an individual quickly records a physical interaction with a real surface and then recreates that experience for a user at a different time and/or place. This paper presents an overview of the goals and methods of haptography, emphasizing the importance of accurately capturing and recreating the high frequency accelerations that occur during tool-mediated interactions. In the capturing domain, we introduce a new texture modeling and synthesis method based on linear prediction applied to acceleration signals recorded from real tool interactions. For recreating, we show a new haptography handle prototype that enables the user of a Phantom Omni to feel fine surface features and textures

The Effect of Visual and Haptic Feedback on Manual and Teleoperated Needle Insertion

In this paper, we present a study that evaluates the effect of visual and haptic feedbacks and their relevance to human performance in a needle insertion task. A virtual needle insertion simulator with a four-layer tissue model (skin, fat, muscle, and bone) and haptic feedback is used for perceptual experiments. The task was to detect the puncture of a particular layer using haptic and visual cues provided by the simulation. The results show that the addition of force feedback reduces error in detection of transitions between tissue layers by at least 55%. The addition of real-time visual feedback (image overlay) improved user performance by at least 87% in scenarios without force feedback. Presentation of both force and visual feedback improved performance by at least 43% in comparison to scenarios without feedback. These results suggest that real-time image overlay provides greater improvement in performance than force feedback

An Augmentation System for Fine Manipulation

. Augmented surgical manipulation tasks can be viewed as a sequence of smaller, simpler steps driven primarily by the surgeon's input. These steps can be abstracted as controlled interaction of the tool/end-effector with the environment. The basic research problem here is performing a sequence of control primitives. In computing terms, each of the primitives is a predefined computational routine(e.g. compliant motion or some other "macro") with initiation and termination predicates. The sequencing of these primitives depends upon user control and effects of the environmental interaction. We explore a sensor driven system to perform simple manipulation tasks. The system is composed of a core set of "safe" system states and task specific states and transitions. Using the "steady hand" robot as the experimental platform we investigate using such a system. 1 Introduction Dexterous manipulation is a key element in the speed, safety, and, ultimately, the success of most surgical i..

Interaction of visual and haptic information in simulated environments: texture perception

This paper describes experiments relating to the perception of the roughness of simulated surfaces via the haptic and visual senses. Subjects used a magnitude estimation technique to judge the roughness of “virtual gratings” presented via a PHANToM haptic interface device, and a standard visual display unit. It was shown that under haptic perception, subjects tended to perceive roughness as decreasing with increased grating period, though this relationship was not always statistically significant. Under visual exploration, the exact relationship between spatial period and perceived roughness was less well defined, though linear regressions provided a reliable approximation to individual subjects’ estimates

A Steady-Hand Robotic System for Microsurgical Augmentation

: This paper reports the development of a robotic system designed to extend a human's ability to perform small-scale (sub-millimeter) manipulation tasks requiring human judgement, sensory integration and hand-eye coordination. Our novel approach, which we call "steady hand" micromanipulation, is for tools to be held simultaneously both by the operator's hand and a specially designed actively controlled robot arm. The robot's controller senses forces exerted by the operator on the tool and by the tool on the environment, and uses this information in various control modes to provide smooth, tremor-free precise positional control and force scaling. Our goal is to develop a manipulation system with the precision and sensitivity of a machine, but with the manipulative transparency and immediacy of hand-held tools for tasks characterized by compliant or semi-rigid contacts with the environment. 1. Introduction This paper describes the first steps in an ongoing development of a robotic assi..