20 July 2012

Electronics - Building a Robotic platform for my show! - Part 2

**GEEK ALERT!**
This post has a lot of "tech-talk". If you're not into electronics/robotics then you can skip this post! This is my contribution to the robotics community..


Building a robotic platform... Part 2!

To continue from my previous post, this prototype..

THIS WENT INTO THE TRASH!


I'm starting anew from scratch with a new idea!

Instead of servos, I'll be using geared motors. As the saying goes... With new motors, comes new motor mounts.. (not quite how the saying goes but..)

After a bit of researching, I decided on these.. These are 12v DC motors geared down to about 45rpm.


Nicely mounted to a piece of clear acrylic and testing it out with a direct drive from a battery.
 Using a geared motor instead of servos has its benefits. I can now use Li-ion battery instead of a Li-poly with a voltage regular. The geared motors draws much less current than a servo.

This time I'll be using a programmable motor driver instead. This is also from Pololu (I love Pololu!) This little board allows many adjustments. You can program the acceleration, the speed and even mix the signals across multiple boards. It even has built-in temperature sensors, over-current protection and fail-safe options!


Mine came as a kit, but you can buy them ready-made. I enjoy the "making" process and I wanna change a few pins connection method, so I'll solder my own board :-)

Testing out the controller over an RC receiver...
 Another great thing about this board is that it has a built-in voltage regulator. I can run this with a single 12v battery and it automatically regulates the voltage to power the board and the RC receiver, so no separate power is needed!

Once I got it working, time to add a second board!

Programming the drivers...



Testing it out!
video

If you notice, using a geared motor made it much more quieter (as compared to servo motors)

The final layout! (Yeah, lots of scotch tape  :-P )

Putting it to the test!


Having each driver drive 2 wheels each allows me to move them in the X & Y axis.. I still a rotating function to compensate for the little offsets while trying to travel in a straight line, also a need for it to rotate on the spot. I would need one motor driver for each wheel. I ordered some and now I'm waiting for it to arrive. 

Check back for new updates!

With love,
  - Kiki Tay

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