OutoSoft

Odd Software for Odd Jobs

DarcyBot, Mk. 2

This is the second iteration of the first 'robot' I ever built with my eldest son Darcy.

The first was a fairly bog-standard robot - it had two bumper-switches at the front. Move forward until one or both are triggered. Back-off, turn a bit, then proceed.

That was fun. We learned how to use H-bridges to control motors and how to make simple decisions.

We figured a new challenge would be to understand how to interface discarded bits of electronics - in this case, we had the transmitter and receiver of a broken remote controlled police car.

You can see the final result below - we even kept the flashing red/blue lights.

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The transmitter/controller was re-housed in a new box. Pretty simple - just wire up new buttons for forward/reverse/left/right to the circuit board and add a new battery holder:

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The robot itself is built upon a tracked chassis (Jaycar KR-3130, seems discontinued). In the picture below you can see the separate parts:

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The brain is a Freetronics Eleven (Arduino Uno compatible). There are then two shields plugged into the Arduino. The first shield, sandwiched in the middle between the Arduino & the top shield, is the H-bridge. We used a pair of L6202 full-bridge drivers, one for each side of the robot.

2016-01-31 21.10.22

On top of this is another shield that is used to interface the Arduino with the receiver from the broken toy car. The receiver is attached with some double-sided tape (high-tech). The black & red wires are for the flashing lights and the yellow wires are the control signals received from the transmitter - backwards, forwards, left, right.

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The control signals are fed into the Arduino via the analogue inputs. These are simply read and the motors controlled appropriately.

So, from this exercise we learned:

  • What are H-bridges and how they're used to control the direction of motors
  • How to program simple intelligence into a robot to allow it to make decisions based on stimuli
  • How to interface discarded bits of electronics to allow wireless control of completely different devices
  • To never throw away remote control stuff - it can be re-used for simple, one-way wireless communication (i.e. a weather station sensor)

The next iteration of the DarcyBot will probably be some sort of line or light follower - this will teach us how to use visual inputs.