Project 6 - Balancing Bot

For a while now, I have been gathering all the parts needed for a two wheeled balancing robot.  Finally, I had the motivation (not to mention a few nights) to design and fabricate the chassis.

Balancing Bot CAD Isometric View

Isometric View #1

Isometric View #2

Underside View

Side View

I'm using gear motors and wheels purchased from Pololu.  The unique thing about this design is the o-ring belt drive system.  At work, I am constantly using o-rings in their traditional means... sealing.  However, when I inspected the o-ring bible, published by Parker, they discuss using them as belts.  Odd?  Next time your taking apart that old printer, keep your eyes open... this method is used often when gears are not needed or optimal.

I have a few more parts to make, then the 'fun' begins.... How hard can it be?

Mini Sumo Bot

After getting cyclops up an running, I started to think about alternative chassis.  Sure the Tamiya track version is fine for a test-bed, but I needed something that was a little more robust and competition worthy.  I ended up buying Fingertech's Cobra chassis from Fingertech Robotics.

Fingertech Robotics 'Cobra'  Chassis

It has not yet arrived from Canada, but I'll be sure to transfer all of Cyclops's guts over to this beast.

Mini Sumo Robot Testing

I have made some serious progress (in comparison to what I usually do).  My Mini Sumo Robot has all the components secured to the platform (secured = tape) and a working program.

Instead of using home-built IR sensors (shown in the image in my last post), I opted to use the Sharp IR distance sensor to make things easier to start.  Since I only had one laying around, I have named him "Cyclops".  Obviously, the more sensors the better, but this is a good place to start.

Mini Sumo Robot - Cyclops

Mini Sumo Robot - Cyclops (Front)

Mini Sumo Robot - Cyclops (Back-Side)

Mini Sumo Robot - Cyclops (Back-Side)

Although he has not changed much in appearance since my last post, I have wired everything and created a simple program.  The program does the following.

1. Rotate
2. Sense target
3. Drive forward

Here is the IR Sensor working

And here is the first test (actually about the fourth after a bit of tweaking).

From here, I will refine the program to make him a bit smarter and 'tune' the IR sensor so it's not seeing the ground when the sensitivity is turned up (turned up in the code).    

My long-term goal is to design and build a 'professional' version.  I can use Cyclops to refine my design and keep me motivated.

Starting a Mini Sumo Robot Project

For a while now I have been intending to put together all the modules I have lying around to make a Mini Sumo Robot. I have a tank tread platform, a dual motor controller, an old battery pack from an RC car, and the board from my tachometer project. With those parts plus IR emitters and sensors, I have the beginnings of a sumo bot. Below is the approximate layout (not yet hooked up).

Pieced Together Mini Sumo Bot

My first attempt at creating the IR emitter and sensor circuit failed miserably... mostly because I was trying to do too much at once.  The other problem I think I am getting is the vast differences in the IR detectors I purchased from RadioShack.  I have one of the Sharp distance measuring units I bought from Sparkfun (GP2Y0A21YK) a while ago... I should probably purchase another and leave the building my own module for the future.

Completed Simplex Air Engine Drawing

Now that the engine is up and running, I have updated the drawing so that all of the bugs are out (or should be).  

Completed Simplex Engine Drawing

Working Simplex Air Engine

After a long time of starting and stopping work on the simplex air engine, I have finally got all the main parts made and assembled.  After a little tinkering, I got it working!

I'll updated the drawing and re-post it shortly along with a longer and nicer shot video.

Hole Tapping Guide with Spring

The best way to manually tap a hole, when the part is still on the mill, is to use a shaft which has a tapered end.  The tapered end interfaces with the hole on the end of the tapping handle.  This ensures your threads are "perfectly" normal to the part.

While tapping a hole during the Simplex Engine Project, I realized I did not have this helping taping guide.  The simple way to go would be to use the shaft with the tapered end as I described above.  Using that way would force you to move the quill as the tap moves downward, but who wants to do that?  So I came up with a three-part (plus one screw) design that uses a spring to save me from that 'extra' labor.

Assembled Tapping Guide with Spring

To use it, simply put the non tapered end into your chuck, put the tap and tapping handle in place, and move the quill down until you have compressed the spring a reasonable amount.  Now you can rotate the tap with the tapping handle while maintaining some axial force.

Although the drawing uses 1/4 rod, I ended up using a slightly larger diameter since that's what I had laying around.  Whatever you choose, make sure it's small enough to fit in your chuck.

Tapping Guide Parts

Tapping Guide Drawing