The goal of this subsystem is to have a user-friendly interface that allows the wheelchair user to control the system. This includes control over whether the system is automatic, semi-automatic, or manual as well as altering the speed and direction of the wheelchair in automatic mode and the assistance level in semi-automatic mode. There will also be an LCD screen that allows the user to check the battery level, speed, effort level, and which mode their wheelchair is in.
Table 5: Electro-Mechanical Integration Team Specification and Metrics
| # | Metric/Specification | Minimum Value | Maximum Value | Unit | Maximize /Minimize/ Target/ Constraint | Constrained Max/Min |
| E1 | Resolution of controllable speed in automatic mode | 0 | 0.2 | mph | Minimize | 0.5 |
| E2 | Resolution of propulsive force of the user relative to the device in semi-automatic mode | 0 | 2 | % | Minimize | |
| E3 | System should not overheat | 104 | °F | Minimize | 302 | |
| E4 | Ability to quickly disable electronics and motors | Necessary |
- If the wheelchair is in automatic mode, the user should be able to accurately adjust the speed of the wheelchair. The accuracy of the desired speed read from the potentiometer should be ± 0.2 mph. The user must feel comfortable in the wheelchair and the way in which it is performing. If the wheelchair is going faster than the requested speed by a noticeable amount the user may feel unsafe and if the wheelchair is going slower than the requested speed the user may be worried about the functionality of the device. A difference in speed of ± 0.2 mph is the beginning of what is noticeable and less than 10% of the average walking speed.
- The user will change the amount of assistance desired in semi-automatic mode by a potentiometer on the interface housing. The user should be able to be within ± 2% of the desired effort level in order to ensure the user is comfortable using the wheelchair. The user will operate the chair differently based on the percentages of the propulsion force that they expect the chair to provide. If the device does not provide an accurate and consistent propulsion level, the user could be going faster or slower than they are comfortable with. A force difference of 2% from expected is noticeable.
- Fans are being used to remove the heat inside the housing from the electrical components. The system should not overheat and damage any of the internal electrical components. At 104°F , the user may be uncomfortable touching the interface, defeating its purpose, and at 302°F, the interface itself will begin to melt.
- An emergency stop button will be on the side of the interface housing for the user to press in the case of an emergency. Pressing this button will stop all electronic components and the running motor. The emergency stop returns the wheelchair to its manual mode.