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.

Biomechanics and the wheelchair.

Wheelchair biomechanics involves the study of how a wheelchair user imparts power to the wheels to achieve mobility. Because a wheelchair can coast, power input need not be continuous, but each power strike can be followed by a period of recovery, with the stroking frequency depending on user preferences and the coasting characteristics of the wheelchair. The latter is described in terms of rolling resistance, wind resistance and the slope of the surface. From these three factors the power required to propel the wheelchair is determined, and must be matched by the power output of the user. The efficiency of propulsion is the ratio of this power output to the metabolic cost and is typically in the order of 5% in normal use. The features required in a wheelchair depend upon user characteristics and intended activities. The ideal wheelchair for an individual will have the features that closely match these characteristics and activities. Thus prescription is not just choosing a wheelchair, but choosing the components of the wheelchair that best serve the intended purpose. In this paper, each component is examined for available options and how these options effect the performance of the wheelchair for the individual. The components include wheels, tyres, castors, frames, bearings, materials, construction details, seats, backrests, armrests, foot and legrests, headrests, wheel locks, running brakes, handrims, levers, accessories, adjustments and detachable parts. Each component is considered in relation to performance characteristics including rolling resistance, versatility, weight, comfort, stability, maneouvrability, transfer, stowage, durability and maintenance. Where they exist, wheelchair standards are referred to as a source of information regarding these characteristics.

Lever drive system for wheelchairs.

The various stages of development of a lever drive system are described. The use of both roller and friction clutches are discussed and the means for controlling forward, reverse, and braking are included. The current system allows good maneuverability without requiring hand skills and may be effective for quadriplegics.

Effects of side slope on wheelchair performance.

Compensation for the downhill turning moment of a wheelchair on a 2-degree side slope results in retarding force approximately equal to the rolling drag of a wheelchair on a level surface. The total drag force on the wheelchair while transversing a sloping surface is, therefore, roughly double the rolling drag. In contrast, the net energy cost of propulsion on this side slope is only 30 percent greater than for a level surface. Side slope propulsion is managed by "dragging" the uphill rim while pushing the downhill rim. Although this results in increased mechanical efficiency through greater use of a smaller muscle mass, it is more difficult and tiring for the wheelchair user.

Comparative strengths of various anterior cement fixations of the cervical spine.

In vivo study, using cadaveric dog cervical spine, was performed in which the middle segment of the vertebral body was removed producing anterior instability. Eleven various methods of stabilization utilizing polymethylmethacrylate and other fixation devices were employed, and their static strength in hyperextension was tested and compared. A portion of the same dog's cervical spine in each case was used as a control. The results indicate that all fixation methods failed to regain the normal structural strength in extension. Cement with wire or chain methods of fixation were superior to other methods in this study. Fixation rigidity approaching rigidity of the normal spine appeared to be a significant factor determining the strength of the reconstructed cervical spine. Combined anterior and posterior fixation did not provide further strength, although it did increase the rigidity of the fixation.

Variable strengths of the wire fixation.

Three groups of wires- three strands of 24 gauge stainless steel, 18 gauge Vitailium wire and 16 gauge stainless steel wire were used in this study. The results revealed the braided wire increased the strength slightly when compared to the single strand and the twisting method not only weakened the wire strength but also resulted in loss of fixation rapidly through uncoiling. The knotting method or one half knot, followed by twisting, will double the fixation strength.

Biofeedback--background and applications to physical rehabilitation.

This paper presents a brief background to biofeedback applications including biofeedback techniques related to physical rehabilitation, and in particular, that of the cerebral palsied. Relevant literature is noted and there is an overview of 3 years research investigating the use of biofeedback in the management of cerebral palsied children. A theoretical framework for using biofeedback to ameliorate motor problems with the physically disabled in general is presented. The areas of investigation are head position, joint position, electromyography, spinal rotation, weight-bearing, response-feedback toys, jaw closure, and postural alignment. The results of these various programs indicate a preliminary outcome classification of feedback-sensitive, feedback trained, and feedback-learned. All children were feedback-sensitive, the majority could be trained, and several cases demonstrated a learned carry-over response. In conclusion, biofeedback training offers the advantages of therapy in natural training settings, and direct involvement of the patient.