Powered Wheelchair Dynamic Stability Model

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WPI, MQP, Assistive, Technology, Resource, Center, ATRC, Stability, Wheelchair, Mathematical, Model


The goal of this project was to develop a mathematical model to the dynamic stability of powered wheelchairs. Dynamic stability is the study of the set of circumstances that causes tipping when a wheelchair strikes an obstacle. Since manual wheelchairs experience more tipping than powered wheelchairs, there are not many prior studies involving the dynamic stability of powered wheelchairs. Stability models can make the wheelchairs safer but manufacturers do not take them into account. These manufacturers and individuals who use wheelchairs could benefit with a better understanding of the circumstances under which their wheelchairs will experience tipping. Using a complete free-body diagram that showed all of the forces acting on the wheelchair, a mathematical model was developed separately for each of the following situations: accelerating uphill, accelerating downhill, turning, and turning on a sloped surface. Then, Newton’s laws were used to generate force and moment equations. These equations were solved under reasonable assumptions. Integrating these separate models into one, a flow chart was then created to give the final model a structured framework. The result was mathematical models for the dynamic stability of the powered wheelchair in the form of a flowchart. Using this flowchart, very few measurements are required to determine the correct model for a given set of circumstances. Also, turning models for stability were found to be much more complex than the uphill and downhill models.