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The objective of STEM II was to work with a client and design a piece of assistive technology. My group ended up working on a wheelchair navigation system for visually impaired wheelchair users. Throughout the process we were expected to document our progress. The project was broken into segments, and we had to complete a preliminary design review, a critical design review, and a test readiness design review. Our project was titled LightSight: LiDAR and sonar-based real-time obstacle detection.



In the preliminary design review, we outlined three distinctive designs for our project. Our group, which consisted of seven people, dealt with separate subsystems, which included the different modes of obstacle detection and information relay. In the PDR we proposed the combined use of a LiDar sensor and stepper motor to create a topographic map of the environment and obstacles surrounding the wheelchair. We also proposed the use of a Raspberry pi and a camera for obstacle recognition and detection. In addition, we proposed the use of multiple sonar sensors for detection that could be relayed via vibration or audio-based feedback. The group also performed background research to examine the strengths and weakness of competitors, which is documented below. For the CDR (Critical Design Review) we chose to go with a sonar and LiDar based obstacle detection system that relayed information through vibration modules in wristbands to the user. Due to certain difficulties such as a power demand for the stepper motor, the group just chose to keep the LiDar sensor horizontal to detect obstructions such as walls. On the footplates of wheelchair were two ultrasonic HC-SRO4 sensors that could detect obstacles within half a meter of the user. Depending on the side of the wheelchair that there was a detection, either via the LiDar sensor or sonar sensors, the corresponding wristband was vibrated as a stimulus so the user could navigate in the opposite direction. Most of the casings and platforms for the electronics were 3d printed. Overall, the project was an enjoyable experience to work on, and from it I gained plenty of technical skills.

Presented below are some of the documents from each stage of the process:

  • Background Research
  • PDR Proposal
  • CDR Design Document
  • TRR Final Design Study
  • Final Presentation