Ashley Hale, Emily Car (University of New Hampshire)
ABSTRACT
This project is intended to provide assistance for visually impaired individuals concerning the operation of a bicycle. Utilizing several sensors, buzzers and a microcontroller the bicycle will have the ability to detect objects and their relative location with respect to the rider. The bicycle was about 80% effective at successfully navigating through an obstacle course without hitting anything while operated under low visibility.
BACKGROUND
The joy of being able to ride a bicycle is something that every child should be able to experience. There is nothing more exhilarating than that sense of freedom and independence that comes with riding a bike. Unfortunately not every child is physically able to enjoy this childhood experience.
My younger sister Megan is legally blind. She can see somewhat but her vision is severely limited and had less than 20/200 vision after the correction provided by her glasses. She will never be able to obtain a driver’s license because of this. To her riding a bike is as close as she will ever be able to get to driving.
Megan riding a bike has also been a bit of a challenge for my mother. She must be outside with Megan to shout at her to avoid obstacles and keep her safe. Our goal was to modify a bicycle so that a visually impaired child could ride it safely and without fear of crashing. These modifications will enable visually impaired children to be more independent and to enjoy a sense of freedom.
PROBLEM STATEMENT
Our goal was to equip a bicycle with sensors and buzzers to be able to detect for oncoming objects as well as notify the rider of which way to turn. We also want the design to be able to grow with the child and be transferable from one bike to another.
DESIGN
Bicycle
Three Wheeled Cruiser
The type of bike to be used was originally going to be a regular trike bike. But we spoke with the folks at Northeast Passage and they gave us some very helpful advice. The Northeast Passage is an organization located on the UNH campus that helps people enjoy outdoor activities regardless of their disability. They suggested that we use a smaller three wheeled bike that allows for the riders center of gravity to be lower to the ground, decreasing the risk of tipping. With a three wheeled bike the rider could start pedaling in a comfortable stable position, as opposed to a two wheeled bike which requires balance. To account for a childs growth over the span of the bikes lifetime we made sure to chose a bike with adjustable length.
Sensors
Three Ultrasonic Sensors
The sensors chosen were three ultrasonic sensors with a range of about 16 feet and a 15 degree operating angle (7.5° left and 7.5° right). A sensing distance of 16 feet was chosen due to the large turning radius of a bike with rear wheel turning. However when looking for sensors to meet this criteria we discovered that in order to achieve the distance we would have to sacrifice its angle of operation. We got three 15 degree sensors so we could position the sensors together to gather information for 45 degrees in front of the bicycle.
Microcontroller
Arduino Microcontroller
To tie the system together an Arduino microcontroller was used. The microncontroller had the right amount of I/O ports for the amount of sensors that we ended up needing while also being user friendly. Once we acquired the Arduino we wrote a piece of code that would take the input signals from the sensors and translate them into output signals for the buzzers. This was done using the program that was included with microcontroller, written in C computer language.
Buzzers
The bike was equipped with two buzzers, one mounted on each of the rear fenders. These were used to alert the rider of an upcoming object. The buzzers we chose for our design were able to produce different frequency sounds. This was helpful to better distinguish between right and left.
System Design
The sensors will send out a signal and will time how long it takes it to bounce off an object and come back. Based on the timing it can be determined how far away the object is. This distance measurement is sent to the microcontroller where it is input into an algorithm. The microcontroller then uses this information to determine when to send an output signal to the buzzers. It will also determine which buzzer should beep based on which sensor sends in distance data. For example if the right sensor detects something, the right buzzer will go off indicating that the rider should turn left. If the center sensor detects something both of the buzzers will go off.
COST ANALYSIS
Three wheeled cruiser $240
Bike Basket $30
Arduino Microcontroller $75
Arduino Battery Pack $50
(3) Ultrasonic Sensors $60
(2) Buzzers $10
Total cost $435
EVALUATION
The final design was tested outside on level pavement with buckets as obstacles that were to be avoided. As the bike would near the obstacle it would beep on the corresponding side in time to avoid crashing into it. We also tried closing our eyes while riding to simulate the effects of blindness. Two test trials through the course were performed and the bike was able to successfully navigate through 80% of the time without hitting any obstructions in its path.
DISCUSSION
All of our goals were met in the final design. The bike will successfully notify the rider about an oncoming object. However the sensors chosen could have been of greater quality and there are some inconsistencies with the range of operation. This means that on occasion an object will be in front of you and the beepers won’t go off. This design was meant to be used as a proof of concept and will need some improvement.
FUTURE IMPROVEMENTS
There are many additions that could be made to this design to make it better. First and foremost if we had a bigger budget and more time we would have looked into some higher quality sensors with greater range and less inconsistencies. Another idea that we had was to have a voice notification system where the bike actually talks to you and says “left” or “right” rather than just beep. If a rider dislikes the voice or the beeping sound another idea was to have the handle bars vibrate. Finally we wanted to make the bike self-sustainable by adding a generator to power the microcontroller. This would provide all the power required to run the system from the rider themselves without greatly inhibiting the riders ability to pedal the bicycle. This way a child wouldn’t have to worry about whether or not the bike was charged before they wanted to go for a ride.
ACKNOWLEDGEMENTS
Dr. John LaCourse (ECE Department Chair, University of New Hampshire)
Dr. W. T. Miller (Professor, University of New Hampshire)
Northeast Passage