Let's Make Robots!

CoAxial Wheeled Balancing Robot

Steerable radio controlled robot whcih balances autonomously on two co-axial wheels.



My other holy grail. The co-axial wheeled balancing robot. I've tried this several times. I didn't alwasy keep a photographic record, but here's one of my earlier ones. (And probably the one which came closest to working.)

Here is it stripped down. The two MFA motors are brilliant with their built in gearboxes, but they ain't cheap. Thay also work from an irritating 18V, so I controlled them by 3/4 PWM from a pair of 12V home alarm system batteries.

The two M8 threaded rods show how high up the centre of balance the batteries were located.

The chassis is made from bent sheet aluminium.


In the second photo, it has the PCBs and wheels added. There are two 2-layer PCBs here. One is teh MCU (the brains) and the other is the motor controller (298D based). As always, my PCBs are home-made. (Yes, fritzl, walkthrough to follow.)

At the bottom left of the PCBs ( at the top right of the leftmost tyre) you can see the accelerometer and gyroscope.

The accelerometer is one I speak about in http://letsmakerobots.com/node/100 and theComponentsentry for the R/C helicopter gyro will follow.

Since it never really balanced on its own (I think there was too much backlash in the drive train) I'm not sure if "completed" is the word I'd use, but I'm done with this version.

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There is a chat solution with Lego, which works REALLY well. If you use the IR sensor as a distance sensor. You point it down towards te ground and cause thebot to move the drive wheels back and forth such that the sensor is always the samedistance from teh floor. It works, but only on flat surfaces. 

God created the integers; all else is the work of man - Leopold Kronecker