Human Detection and Discrimination of Tactile Repeatability, Mechanical Backlash, and Temporal Delay in a Combined Tactile-Kinesthetic Haptic Display System

Abstract

Abstract-Many of the devices used in haptics research are over-engineered for the task and are designed with capabilities that go far beyond human perception levels. Designing devices that more closely match the limits of human perception will make them smaller, less expensive, and more useful. However, many device-centric perception thresholds have yet to be evaluated. To this end, three experiments were conducted, using one degree-of-freedom contact location feedback device in combination with a kinesthetic display, to provide a more explicit set of specifications for similar tactile-kinesthetic haptic devices. The first of these experiments evaluated the ability of humans to repeatedly localize tactile cues across the fingerpad. Subjects could localize cues to within 1.3 mm and showed bias toward the center of the fingerpad. The second experiment evaluated the minimum perceptible difference of backlash at the tactile element. Subjects were able to discriminate device backlash in excess of 0.46 mm on low-curvature models and 0.93 mm on high-curvature models. The last experiment evaluated the minimum perceptible difference of system delay between user action and device reaction. Subjects were able to discriminate delays in excess of 61 ms. The results from these studies can serve as the maximum (i.e., most demanding) device specifications for most tactile-kinesthetic haptic systems.

A Position-Control Based Approach to Haptic Rendering of Stiff Objects

“…For a step position reference, overshoot should be less than 2%, rise time less than 0.05 s, and settling time less than 0.1 s. Some of the parameters here are chosen from a pure control stand point while others are based on studies on human perception limitations [28]. Specifically, the settling time is based on the result reported in [29] that the minimal noticeable delay can be 61 ms for system delay and 132 ms for "front-end" delay. Additionally, the controller should be robust against random and sudden change of the user force.…”

“…-time state-space model demonstrated in(10). This is calculated by first solving the associated Discrete-time Algebraic Riccati Equation[29] that is where P is the solution to the equation and the "adDT" subscript for A and B matrices is dropped for keeping the equation clean. With P, KadDT is achieved through…”

Real-Time Gait Event Detection Based on Kinematic Data Coupled to a Biomechanical Model †

“…Furthermore, with exception from the method presented in Chia [6], all methods either relied on offline training, offline processing, or at best ran in quasi-real-time with an inherent delay due to signal processing and/or event definition. This despite the established knowledge that optimal delays for control should not exceed 100–125 ms [16], with 61 ms being the smallest delay noticeable by subjects [17]. …”

Five-Fingered Passive Force Feedback Glove Using a Variable Ratio Lever Mechanism

“…Furthermore, the weight of the SFVS glove needs to be further reduced to improve its wearability. Finally, the actual response time of the SFVS glove is higher than 45 ms, exceeding the limit of the perceivable delay between visual and haptic stimuli [14,15].…”

“…The response time for the maximum movement distance of the pivot was 44 ms, which is less than the limit of the delay (45 ms) a human can perceive between visual and haptic stimuli. Therefore, the actual response time of our FFVS glove can meet the interaction requirements in a virtual experience [14,15].…”