Janez Cimerman J.cimko@gmail.com

This is a follow-up on previous post available here.

So the second thing I did is the drive system. I picked Servos mentioned in BOM available in the first post and modified them so they can be rotated 360 degrees. Two of them are used to drive the wheels of robot. Wheels will be the only thing that robot will interact with environment around it; all other sensors will be used to gather information about location and other vital information.

Buttons that I will put as interactive front bumper of the robot is made from navigational buttons used on MP3 players. I chose these buttons because they can be pressed in all directions from which obstacle hits them and are thus ideal in one sense but time will show if they are robust enough for the job. I wired them so that only one signal is sent from each button pressed in any direction, but they can be wired so that they trigger different pins for each direction. The schematics of buttons and how to wire them is documented in their documentation which can be found on link supplied in BOM.WP_000641

 

Note to myself in the future: right about here is the best time to start indicating the wires for each button, or else you will have to do it later when the whole robot is put together with software which takes three times longer!

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Micro controller that will be used to drive the servos and get information form sensors is Arduino ADK that is the same as Arudino MEGA but with additional micro USB port that will not be used in this project. It is however important that micro controller with many pins is used because buttons alone need 8 and more will be required to connect other sensors.WP_000695 WP_000731

Sensory is the main part of robot environment perception. In this part I added simple IR sharp and ultrasonic distance sensors but in future I suspect they will be replaced with cameras or better precision sensors. The housing of sensors was drawn in CAD and printed on MakerBot.
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All the wires were put in typical wire holders, but I later found out that they were to small. The wiring required more than suspected at first; around 50 meters of wires. I suggest using colored wires for orderliness.WP_000740

 

I’ve written the basic software and pin mapping in Arduino IDE in C++. It served as a test of all the elements installed on to the robot. From that point on I modified it nearly every time I had to change something so there is not a basic software written yet. Basically there was a lot of measurement work for me to calibrate the rendering of sensor data.WP_000802And there is the end of the first part of the project: MAKE THE ROBOT.