AUTONOMOUS ROBOT
4 Person Team | October 2017Â - April 2018
Problem Statement
This was a multi-stage project for the course Cornerstone of Engineering, Northeastern University's introductory engineering course.
The overarching goal of this project was to develop a autonomous robot designed and programmed using an Arduino circuit board. This project occurred over the course of two semesters and was developed in a series of 3 prototype build stages.
The performance requirements for each design stage were as follows:
Robot must autonomously navigate throughout a room for 8 continuous minutes, without hitting any obstacles or other robots.
Robot must pinpoint and navigate to a light source in an otherwise dark room in under 5 minutes.
Robot must pinpoint and navigate to a rag soaked in isopropyl alcohol in under 5 minutes. The rag was placed in a random location.
Constraints & Assumptions
Budget: $50 for supplemental materials for each design stage (chassis & motor were provided)
Location: final testing would occur in a 9.75m x 6.4m squash court.
Battery life: the provided motor could run for about 10 minutes at a time, before slowing down considerably
Build Stage 1 - Autonomous Navigation & Obstacle Avoidance
Using Kepner-Tregoe Decision Analysis (KT/DA), we decided to use ultrasonic sensors for obstacle detection.
3 sensors were placed on the right, left, and front of the chassis.
Our Arduino code consisted of a nested loop to process ultrasonic feedback and inform robot of which direction to travel in.
Final testing was successful – the robot was able to navigate throughout a room for 8 minutes, while avoiding all objects in its path.
Build Stage 2 - Light Detection
This iteration built upon the design and code of Stage 1. 2 photoresistors were added to the front of the design (each angled 45° from the front axis).
I designed a MATLAB simulation of the robot’s anticipated trajectory to determine the most effective method of tracking the light source. With this simulation, we developed an Arduino code that allowed the robot to travel randomly throughout the room, until its light sensors were saturated to a determined threshold, where it would begin tracking the light.
Final testing was very successful – the robot successfully found the light source in 15 seconds, the fastest time in our class.
Build Stage 3 - Alcohol Detection
This design was an iteration of the second build stage, but it utilized alcohol sensors instead of light sensors.
Initial testing of the alcohol sensors yielded a wide range of differing results. We observed that the sensors had a very small detection range and would quickly become oversaturated in close range of alcohol. At this point, the sensors would be ineffective.
To determine a solution, I ran MATLAB simulations based on numerous potential tracking methods. Our final code included a series of conditional statements that accounted for the wide-range of values yielded by the alcohol sensors during use.
Final testing was unsuccessful – the air quickly became too saturated with alcohol during testing, and no robot was able to successfully find the alcohol source. Our robot came within a few feet of the alcohol source, but ultimately failed to stop. We attributed this to oversaturation of the sensors.
Example MATLAB simulations of robot's "random" motion with randomized starting points and alcohol locations
Future Improvements
Sensor quality: future iterations of this design should include sensors with much larger ranges and better accuracy.
Design aesthetics: future versions would focus strongly on industrial design. The addition of an exterior shell to hide wiring would greatly improve the appearance of the design.
Battery Life: the design would greatly benefit from the addition of a rechargeable lithium ion battery to improve motor performance.