J. Edward Colgate

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This paper addresses the performance of force-reflecting interfaces (“haptic displays”). We suggest that an important measure of performance is the dynamic range of achievable impedances — “Z-Width” — and that an impedance is achievable if it satisfies a robustness property such as passivity. Several factors affecting ZWidth — sample-and-hold, inherent(More)
Passivity of systems comprising a continuous time plant and discrete time controller is considered. This topic is motivated by stability considerations arising in the control of robots and force-reflecting human interfaces (‘‘haptic interfaces’’). Necessary conditions for passivity are found via a small gain condition, and sufficient conditions are found(More)
In this paper we discuss the theory, design and construction of a haptic display for creating texture sensations through variations in surface friction. Ultrasonic frequency, low amplitude vibrations between two flat plates have been shown to create a squeeze film of air between the two plate surfaces thereby reducing the friction [1][2]. We show that a(More)
When a human operator performs a task via a bilateral manipulator, the “feel” of the task is embodied in the mechanical impedance of the manipulator. ’Ikaditiody, a bilateral manipulator is designed for transparency; i.e., so that the impedance reflected through the manipulator closely approximates that of the task. “Impedance shaping bilateral control,”(More)
Touch interactions have refreshed some of the 'glowing enthusiasm' of thirty years ago for direct manipulation interfaces. However, today's touch technologies, whose interactions are supported by graphics, sounds or crude clicks, have a tactile sameness and gaps in usability. We use a Large Area Tactile Pattern Display (LATPaD) to examine design(More)
We describe a new robot architecture: the collaborative robot, or cobot. Cobots are intended for direct physical interaction with a human operator. The cobot can create smooth, strong virtual surfaces and other haptic effects within a shared human/cobot workspace. The kinematic properties of cobots differ markedly from those of robots. Most significantly,(More)
In recent years haptic interfaces (also know as manipulanda and hand controllers) have been developed for an impressive array of applications. For instance, Mussa-Ivaldi e t al. [ 181 describe a two degree of freedom manipulandum for studies of multijoint human limb movement, Adelstein and Rosen [ 11 a two degree-of-freedom manipulandum for studies of(More)
Design of haptic systems that guarantee stable interaction is a challenging task. Virtual environments are typically highly nonlinear—resulting in a nonpassive discrete-time model. This paper will investigate how nonlinear mass/spring/damper virtual environments can be designed to guarantee the absence of oscillations and other chaotic behavior in the(More)