Learn 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)
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 Z-Width — sample-and-hold, inherent(More)
—We describe a new robot architecture: the collabo-rative 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)
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)
—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)
—A general framework is presented for the design and analysis of cobot controllers. Cobots are inherently passive robots intended for direct collaborative work with a human operator. While a human applies forces and moments, the controller guides motion by tuning the cobot's set of continuously variable transmissions. In this paper, a path-following(More)
Existing prosthetic limbs do not provide amputees with cutaneous feedback. Tactile feedback is essential to intuitive control of a prosthetic limb and it is now clear that the sense of body self-identification is also linked to cutaneous touch. Here we have created an artificial sense of touch for a prosthetic limb by coupling a pressure sensor on the hand(More)
To date, haptic interfaces have rarely been used to display complex virtual environments such as those involving 3D mechanical assembly operations, or the use of hand tools. Of the limitations which have been encountered, one is the absence of suitable simulation techniques which provide a general, user-defined virtual environment. This paper discusses the(More)
— In physical and occupational therapy two people interact through force and motion. Other common examples of this interaction include lifting and moving a bulky object, teaching manual skills, dancing, and handing off a baton or a drinking glass. These tasks involve kinesthetic interaction , a communication channel distinct from spoken language and(More)