| Summary: | This Master of Science thesis report describes the development process which aims to create a concept for a new off-road electric wheelchair for Permobil, with a focus on the vehicle-to-ground interface. It was performed between January and July 2015 as part of the Master Degree program, Industrial Design Engineering at Luleå University of Technology.Everyone does not have the ability to walk or transport themselves by their own means at trails or rough terrain due to injuries or other kinds of disabilities. The project aims to investigate how a solution should be designed in order to suffice the needs of these kinds of users. In order to achieve the goals, a series of research questions was determined, one of which read: How does the vehicle-to-ground interface affect the traction of the vehicle and the comfort of the user?The theoretical framework presents research findings necessary to reach the aim of this project and focuses on topics such as modularity, terrain types, off-road capability, vehicle dynamics and comfort. The overall development process in this project used a method called Pulse Model. The first stage of the project was market research with a primary focus on Permobil’s X850 model, which was put through several tests. The main problems found were that its lack of lateral stability, low ground clearance, and overall harsh and bumpy ride comfort.The idea generation included both the use of LEGO® Technic bricks, the catalogue method and function prototypes, which resulted in a multitude of different suspension systems. A concept with front and rear trailing arms were chosen for further development and a full-scale prototype was fabricated and tested, which provided important feedback for the final concept.The prototype enabled a set of key aspects that should be considered when designing an off-road wheelchair. These were a ground clearance of at least 200 mm, four wheel drive, 50/50 weight distribution, 360 degree rear wheel steering, a front pivot bar suspension system and active lateral ...
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