Biomedical subjects

K E Barner

Publications and source records attributed to K E Barner.

6 recordsLinked to original sources

PubMed2000

Optimal digital filtering for tremor suppression.

Remote manually operated tasks such as those found in teleoperation, virtual reality, or joystick-based computer access, require the generation of an intermediate electrical signal which is transmitted to the controlled subsystem (robot arm, virtual environment, or a cursor in a computer screen). When human movements are distorted, for instance, by tremor, performance can be improved by digitally filtering the intermediate signal before it reaches the controlled device. This paper introduces a novel tremor filtering framework in which digital equalizers are optimally designed through pursuit tracking task experiments. Due to inherent properties of the man-machine system, the design of tremor suppression equalizers presents two serious problems: 1) performance criteria leading to optimizations that minimize mean-squared error are not efficient for tremor elimination and 2) movement signals show ill-conditioned autocorrelation matrices, which often result in useless or unstable solutions. To address these problems, a new performance indicator in the context of tremor is introduced, and the optimal equalizer according to this new criterion is developed. Ill-conditioning of the autocorrelation matrix is overcome using a novel method which we call pulled-optimization. Experiments performed with artificially induced vibrations and a subject with Parkinson's disease show significant improvement in performance. Additional results, along with MATLAB source code of the algorithms, and a customizable demo for PC joysticks, are available on the Internet at http:¿tremor-suppression.com.

Algorithms↗

PubMed2000

Tremor suppression through impedance control.

This paper presents a method for designing tremor suppression systems that achieve a specified reduction in pathological tremor power through controlling the impedance of the human-machine interface. Position, rate, and acceleration feedback are examined and two techniques for the selection of feedback coefficients are discussed. Both techniques seek a desired closed-loop human-machine frequency response and require the development of open-loop human-machine models through system identification. The design techniques were used to develop a tremor suppression system that was subsequently evaluated using human subjects. It is concluded that nonadaptive tremor suppression systems that utilize impedance control to achieve a specified reduction in tremor power can be successfully designed when accurate open-loop human-machine models are available.

Acceleration↗

PubMed1999

An audio- and speech-based interface for computer-controlled scientific instruments.

Laboratory instruments are intrinsic to research and work in a wide array of scientific fields. They are used for the control of devices, data storage, and data analysis. The control of instruments is increasingly changing from independent on-instrument controls to multiple instrument integrate software control. Unfortunately, the graphical representation of controls and data makes it difficult for an individual with a visual impairment to independently operate laboratory instruments. Alternative interfaces have been previously developed for these individuals but have often proved limited in scope and accuracy, or otherwise expensive. The resulting inaccessibility to affordable and accurate scientific instrumentation, unfortunately, discourages many individuals with a visual impairment from entering scientific fields of research or work. This paper introduces an alternative interface method developed for LabVIEW, National Instruments' instrumentation software package. The method is specifically designed for individuals with visual impairments, and uses alternative navigation techniques as well as audio feedback. The developed user interface uses simple keyboard inputs to traverse through a hierarchical tree-based menu system. Speech and audio tones are used to alert the user to system settings and errors, as well as a help mechanism and data analysis tool. At this time, alternative interfaces have been developed for the following basic laboratory instruments: an oscilloscope and function/arbitrary waveform generator. The interface methodology, however, can be extended to include any scientific instrument that can be controlled by LabVIEW.

Clinical Laboratory Techniques↗

PubMed1999

Design of a haptic data visualization system for people with visual impairments.

Data visualization is a technique used to explore real or simulated data by representing it in a form more suitable for comprehension. This form is usually visual since vision provides a means to perceive large quantities of spatial information quickly. However, people who are blind or visually impaired must rely on other senses to accomplish this perception. Haptic interface technology makes digital information tangible, which can provide an additional medium for data exploration and analysis. Unfortunately, the amount of information that can be perceived through a haptic interface is considerably less than that which can be perceived through vision, so a haptic environment must be enhanced to aid the comprehension of the display. This enhancement includes speech output and the addition of object properties such as friction and texture. Textures are generated which can be modified according to a characteristic or property of the object to which it is applied. For example, textures can be used as an analog to color in graphical displays to highlight variations in data. Taking all of these factors into account, methods for representing various forms of data are presented here with the goal of providing a haptic visualization system without the need for a visual component. The data forms considered include one-, two-, and three-dimensional (1-D, 2-D, and 3-D) data which can be rendered using points, lines, surfaces, or vector fields similar to traditional graphical displays. The end result is a system for the haptic display of these common data sets which is accessible for people with visual impairments.

Blindness↗

PubMed1997

Automatic visual to tactile translation--Part I: Human factors, access methods, and image manipulation.

This is the first part of a two-part paper that motivates and evaluates a method for the automatic conversion of images from visual to tactile form. In this part, a broad-ranging background is provided in the areas of human factors, including the human sensory system, tactual perception and blindness, access technology for tactile graphics production, and image processing techniques and their appropriateness to tactile image creation. In Part II, this background is applied in the development of the TACTile Image Creation System (TACTICS), a prototype for an automatic visual-to-tactile translator. The results of an experimental evaluation are then presented and discussed, and possible future work in this area is outlined.

Algorithms↗

PubMed1997

Automatic visual to tactile translation--Part II: Evaluation of the TACTile Image Creation System.

This is the second part of a two-part paper that develops a method for the automatic conversion of images from visual to tactile form. In Part I, a variety of topics were reviewed including issues in human factors, access technology for tactile graphics production, and image processing. In this part, the material presented in the first part is used to motivate, develop, and support the methods used in the development of a prototype visual-to-tactile translator called the TACTile Image Creation System (TACTICS). The specific choices made in the design of the system are discussed and justified, including selection of software platform, tactile output format, tactile image creation procedure, aggregate image processing sequences used, and principles from the discipline of psychophysics. The results of four experiments on tactile image discrimination, identification, and comprehension are reported and discussed, and future directions in this area are proposed.

Adult↗