Biomedical subjects

D M Brienza

Publications and source records attributed to D M Brienza.

5 recordsLinked to original sources

PubMed1996

A system for the analysis of seat support surfaces using surface shape control and simultaneous measurement of applied pressures.

A system for the design and analysis of seat support and buttock tissue interfaces has been developed. It has the ability to control the seating surface shape while measuring the pressure applied to the buttocks by the surface. Pressures are measured over an 11 x 12 rectangular array of support elements using silicon pressure sensors mounted in a swiveling head atop each support element. Control of surface shape is mediated by selective linear translation of the support elements along their respective vertical axes. Closed-loop control of the system allows for the dynamic formulation of a support surface on the basis of programmable criteria. The system is intended to function as a research tool to facilitate the study of the relationships between support surface shape and interface pressure, and support surface shape and soft tissue distortion. The purpose of this paper is to present the system instrumentation and the rationale behind its design and development. The paper also presents the results of several tests to evaluate the accuracy and performance of the system. This evaluation included a pilot study on 10 able-bodied subjects. The results of these system evaluations indicate that the system is capable of making repeatable and precise measurements of pressure and surface element position and can formulate support surface shapes that satisfy specified optimization criteria.

Back↗

PubMed1996

Seat cushion design for elderly wheelchair users based on minimization of soft tissue deformation using stiffness and pressure measurements.

A method for designing seat support surfaces using interface pressure and soft tissue stiffness criteria was evaluated. An algorithm designed to drive a rigid support surface on a programmable seating system to a shape for which the externally applied pressure is inversely related to the measured stiffness of adjacent soft tissue was evaluated on 30 elderly subjects (age 65 years or older). The resulting support surface shapes were transferred to compliant foam cushions and evaluated using interface pressure measurements. Pressure and stiffness measurements on the seating system indicated the surface shape control algorithm met the desired programmed criteria by achieving an inverse relationship between pressure and stiffness, as it converged to an "optimal" support surface shape. Evaluation of interface pressures on the compliant foam cushions showed that the pressure distributions on the cushions contoured to the optimal surface shapes were more uniform and had lower values than distributions on flat foam cushions and foam cushions contoured to shapes measured using state-of-the-art load-deflection devices. The results suggest that support surfaces designed using tissue stiffness as a criteria can provide loading conditions intended to minimize relative deformation and, thus, stress in load-bearing soft tissue.

Aged↗

PubMed1996

A force feedback joystick and control algorithm for wheelchair obstacle avoidance.

Many powered wheelchair users have difficulty manoeuvring in confined spaces. Common tasks such as traversing through doorways, turning around in halls or travelling on a straight path are complicated by an inability to accurately and reliably control the wheelchair with a joystick or other common input device, or by a sensory impairment that prevents the user from receiving feedback from the environment. An active joystick with force feedback to indicate obstacles in the environment has been developed. Two force feedback schemes designed to assist a powered wheelchair user have been developed and implemented using the active joystick. The development of the joystick and associated control algorithms are described.

Algorithms↗

PubMed1993

Seat support surface optimization using force feedback.

The development, implementation and evaluation of an algorithm designed to find optimal seat support surfaces is presented. The algorithm has been developed and implemented on an active contour measurement device. The device consists of an array of positioning elements equipped with force sensors for feedback. With a patient seated on the array, the algorithm is designed to find a seat contour that optimally satisfies given performance criteria. The performance criteria are based on measured stiffness of the soft tissues. A theoretical development of the algorithm is presented along with the modifications made to the algorithm during implementation. The results from several tests using man-made test bodies and a prototype contour gage are presented to verify the algorithm's performance.

Algorithms↗

PubMed1992

A manufacturing system for contoured foam cushions.

The design, application and evaluation of a specialized, personal computer-based manufacturing system for contouring foam cushions is presented. The topics discussed include both the hardware configuration and the software design. The target applications of this device are local or centralized fabrication of custom-contoured seat cushions. Although the technologies used for the development and implementation of this system are not new, using a personal-computer-based (PC) controller in place of a stand-alone numerically controlled (NC) motion controller significantly reduced the cost associated with this component. Further reductions in cost resulted from an optimization of the mechanical configuration for the dedicated task of carving foam cushions.

Computer-Aided Design↗