Dynamic Seating System Design

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atrc, assistive, technology, resource, center, mqp, dynamic, seating, stability, wheelchair


The goal of this MQP was to create a model of a dynamic seating system to be used to relieve discomfort that individuals often experience due to the rigid seating systems present in standard wheelchairs. Due to the rigidity of the seating system, individuals seated in wheelchairs may experience lumbar extensor spasticity, which is the involuntary extension of the lumbar muscles of the lower back. This causes discomfort and an inability to maintain an upright posture for the user of the wheelchair. A dynamic seating system can alleviate this problem by supporting the user and responding to any changes in the user’s position while seated in the wheelchair, while still maintaining the functionality of the seat. The design team modeled a system that would mimic the motion of an individual having a spasm in the lumbar muscles while seated in the wheelchair. Another objective of the design was to ensure that the seating system would force the user to return to his/her initial seating position after the completion of the spasm. The group considered the interactions between the user seated in the wheelchair and the wheelchair itself in order to model the points of contact as points of either rotational or translational motion. From there, three designs were selected for analysis of static stability on different angles of inclination in both the forward and rearward directions. By evaluating the forces due to the damper of the system at the point of attachment on the seat back and the spasm forces experienced at the shoulder blades, the design team determined the stability of the dynamic seating system in the different allowable positions. This project provided a model to determine the effect that the load on the wheelchair has on the dynamic movement of the seating system. This report also provided experimental values and analysis that can be used in future analysis and development of dynamic seating systems.