User:Josh Dunbar/Individual Weekly Update

Project Preference
Through the choice of projects we wanted to work on the power wheel the most and if we couldn't get that then our next choice would be the robot hallway navigation.

Problem Statement
The power wheel's main objective is to design and build a given power wheel to navigate around obstacles/ drive autonomously using sensors such as cameras and motors to operate the steering wheel and gas pedal. One big rule of the power wheel project is that the team may not use any existing power or tap into the wiring of the power wheel. All group made equipment must be able to be added/ removed from the power wheel without damaging it and design it to become battery powered.

Project Plan
Our specific groups tasks are to test and make sure that the previous groups coding and steering motors work. Then we will begin the task of designing and implementing an actuator to control the gas pedal.

Week 1 Narrative
During week one we took a look at the previous groups progress. At first we looked at their wikiversity pages to see how they wired the arduino and see their coding for the steering wheel motor. After hooking up the power wheel to the power supplier and running the code we could see that the motor was not turning but we could hear the sounds of humming then a pause then humming again. These sounds let us know the arduino was sending the code to the motor and the motor was trying to turn but was jammed some how. After taking the motor off of the power wheel we examined the gears and noticed the previous team put metal bumpers on the gears of the arm of the motor which prevented the motor from over-extending and run off the track. These bumpers were not high enough and were sliding under a metal guard so they were getting caught were the drive gear would be turning. From week one we discovered the coding for the steering seemed to work and we found the problem with the motor not turning for the steering which we will have to fix in week two.

Week 2 Narrative
After knowing what had to be done about the motor we looked closer at how the bumpers were attached to the gears, we found that a thin strip of metal seemed to be glued to both sides of the gear. when we attempted to take them off we discovered it was epoxy but after getting that off we folded the metal back a couple more times to hopefully make it so the metal won't slip under the safety guard. We also tested how much force is needed to push the gas pedal by lifting the back of the power wheel up to make the pedal parallel to the ground. We put weight on the pedal till it would be pressed in, this took 2 kg of weight which is about 4.4 lbs. After knowing how much force was needed we began thinking of different types of actuators. Our original idea was a stepper motor that would turn slightly with some sort of rubber end that would rotate and press the pedal in and then rotate in the opposite direction to depress the pedal. After considering this we began looking at linear actuators which would be much easier to attach to the power wheel. However after researching it many of the linear actuators could not handle 5 lbs of force and the few that could were too expensive. This is why we went back to the stepper motor idea and decided that we would obtain another motor from a car's power window at a junkyard.

Week 3 Narrative
After Discussing With our team we had decided that the main focus of the project is to design something for ourselves and worry less about fixing the previous groups projects. Personally I had made some designs as well as my partner Graham for how to operate the gas pedal with an actuator. My specific job was to make models using CAD software in order to give a clear picture of what we want the design to look like. These models will allow a 3 dimensional perspective vs. a 2 dimensional sketch, These models are well on their way and took slightly longer than expected due to the fact that I have been redoing and fixing many parts of them to be sure they are to scale so they will be as accurate as possible. They will be posted on my page as soon as they are finished which is projected to be 10/07/13.

Week 4 Narrative
This week we have discovered that the force needed to push in the pedal is .2 Newton Meters. We brought in a lever system that was designed to minimize the force required to push the pedal however it did not work as expected and was difficult to operate. With this we went back to the design idea of the screw that will go through a set nut and act as a linear actuator when the motor spins and extrudes it to push in the pedal. I have made some sketches of this in my notebook and creating a new version of the model using CAD software. This week we also worked on the CDIO report we are in the design phase so that was the category we are writing about. I worked specifically on the problem statement, and utilization of knowledge in design as well as editing bits and pieces of other parts of the report.