Team X – Prototype II Final Report: Wheelchair Curb Detector

 

Introduction:

The second prototype for the wheelchair curb detector was to implement the system on to a wheelchair. If the system detected a curb ahead then it will stop the wheelchair and the system will reset when the joystick is in the neutral position. Our first goal was to interface with the joystick. We did this by opening up the joystick module and determined what wires controlled the forward and backward movement. The yellow wire in our joystick module controlled forward and backward movement. A reading of 4 volts made the wheelchair move forward while a voltage of 1 made it go in reverse. A voltage of 2.5 correlates with the joystick being in the neutral position. With this data we had a way to reset the system when a curb was detected.

The second prototype did not differ much from the first prototype. The main difference is a wheelchair is used instead of a RC car. We used 2 IR sensors to read the distance in front of the wheelchair. We used a relay to switch control from the wheelchair to the arduino. We added a potentiometer to change the value of the difference between the distance and average to detect a curb. A red LED was used to visually indicate that a curb was detected. We used a capacitor inbetween the IR sensor and arduino to smooth out the voltage. We used wires to mount the IR sensors to the wheelchair. The code for system compares the distance with the average distance. If the distance becomes greater than the average by more than 6 inches then system will trigger the relay to switch control from the wheelchair to the arduino. The arduino will return control back to the user when the joystick is back in the neutral position.

 

Description:

We powered the system off one of the 12 volt batteries of the wheelchair. We mounted the arduino under the seat of the wheelchair and mounted the sensors using solid wires infront of the wheelchair. 

Diagrams:

 Wheelchair code

 

Reflection:

Our prototype worked as intended. Interfacing with the joystick was not too difficult. I think more rigorous testing  is needed .Since we know how the joystick operates we can add another feature like a backup sensor.

 

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