There are a number of potential risks that have been identified in creating an inexpensive yet versatile wheelchair attachment. One of the primary concerns is safety. The team needs to ensure that all team members and wheelchair users are out of harm’s way at all times. When considering safety, there are concerns regarding the means of testing the wheelchair. As the wheelchair is primarily user-assistive, testing will require a user to be operating the wheelchair during some of the test stages. When possible, a variation of a test dummy for tests that do not require active user input will be used. For tests that require user input, the user will have proper personal protective equipment including but not limited to a helmet and additional padding. The testing will follow ISO 7176 guidelines and practices as shown in Table 4 and 5 [20].
Additionally, we are concerned with electrical failure and the waterproofing of all of the electrical components of the design. Electrical failure could result in both a broken wheelchair and an injured wheelchair user making it a top priority. As this attachment will be on a wheelchair that is used outside, it is essential that there are no electrical malfunctions that occur if the wheel chair is being used in rainy conditions. We plan to eliminate this risk by using waterproof housing wherever possible. If there is a malfunction in the device while it’s in use, we would like to have a way to safely shut the system down without harming the user. For this reason, we plan to include an emergency stop button in the primary user interface.
Outside of the potential risks with the electrical components, the team is cognizant of the risks involved with changing the loading on the wheelchair. Any alteration to the center of mass of the wheelchair could result in a wheelchair more likely to tip over potentially injuring the person in it. In order to mitigate this risk, center of mass calculations will be done to eliminate changes wherever possible as well as providing the system with an anti-tip device to function as a safeguard against possible tipping.
Additionally, the current design allows the user to be in contact with the wheel while the motor is engaged. In order to reduce the risk of an individual’s hand getting pinched or brush burned by the wheel, limits on the speed the motor can go will be added as well as considering the use of separate handles for user to wheel interaction. Specific speed limits and other ISO specifications can be found in Table 5. The team is planning on establishing any necessary training materials with the hope that the human-centered design will make the system largely intuitive. Finally, any additional safety mechanisms that can be used to prevent unnecessary harm to the user are continually sought as the project progresses.