Raspberry Pi Robot from junk

Figure 1

In previous posts the idea of adding some programming into the a 'bot' made of junk, a junkbot, was briefly discussed (http://computingnorthampton.blogspot.co.uk/2014/07/physical-computing-junkbots-with-brain.html) and the use of LEGO to do this was discussed in a recent post (http://computingnorthampton.blogspot.co.uk/2014/08/controlling-lego-junkbot.html)

In this post the aim is to discuss using a Raspberry Pi and Scratch to do this. Including:
- Choice of motor controller card for the 'bot'
- Provide an example of a drawing junkbot controlled through Scratch and Raspberrry Pi


Choice of interface/Controller card
The card choosen was the 4Tronix PiRoCon card  (http://4tronix.co.uk/store/index.php?rt=product/product&product_id=182). Selected for four reasons
- Price is reasonable (in my opinion).
- Fits straight onto the Pi through the GPIO - no extra cables needed.
- ScratchGPIO has it as an addon so it makes programming it even easier (see http://cymplecy.wordpress.com/2013/10/31/pirocon-from-4tronix/).
- Others are using it for robot projects.

Use it is quite easy plug the board directly on to the GPIO connector of the Raspberry Pi (4tronix provide some advice in section 15 of http://4tronix.co.uk/blog/?p=22 on mounting the board). The only other changes that were needed were because the motors were not powered through the DC input jack, changesto the jumper settings next to Vin Connector (see http://4tronix.co.uk/blog/?p=41 for layout)  were neededto reflect this.



Example: Drawing Raspberry Pi Junkbot
Now for the fun bit get the whole thing to draw (see Figure 1 and the video at the end)!

The junkbot itself is made up of a drinks can, three supports (we used LEGO here but it equally could be straws, sticks), a pen/pencil, and a  motor and broken propeller combination to create an unbalanced motor.

With the Raspberry Pi off, the the motor's wires are connected to the controller card at the connections for MotorA and the battery is also connected. Turn the Pi on and run ScratchGPIO5plus.

Figure 2

Figure 3

Figure 4

The first task is to make the variables AddOn (which will be used to tell the program we are using the PiRoCon card) and MotorA for the motor (see Figure 3).

In Figure 4 the program can be seen, essentially the left and right key spin the junkbot clockwise or anticlockwise by setting the Motor to either +ve or -ve values from 0 to 100. The space bar is used to stop the motor.

As it moves because one of the supports is a pen it draws. See the video below to watch it draw a squiggly line - control is still a challenge.
 The bot was developed by Hayden Tetley and Scott Turner. Hayden's time was paid  for through the Nuffield Research Placements  Scheme (http://www.nuffieldfoundation.org/nuffield-research-placements).

Related Links

Junkbot Raspberry Pi: 1 ScratchGPIO 

Junkbot Raspberry Pi: 2 Raspberry Pi Junkbot in action

If you would like to know more about the Junkbots project contact scott.turner@northampton.ac.uk. The views and opinions is the authors and should not be taken as representing the views of any organisation the author is associated with.

Controlling junk with LEGO

In a recent post (http://computingnorthampton.blogspot.co.uk/2014/07/physical-computing-junkbots-with-brain.html)  adding Mindstorm NXT brick and motors to a drinks can to produce a junkbot was consider as an idea. As a new stage for the Junkbots project (http://junkbots.blogspot.co.uk/ ) some preliminary work has been done into this.

Up to this point the junk bot building has largely being about building a moving (or drawing) 'bot' moved by vibration - limited control, but fun. A Nuffield funded bursary student, Hayden Tetley,  has being working within staff from the University of Northampton on whether LEGO NXT or Raspberry Pi based solutions can be incorporated with the bot to add some control of the movement (still by vibration).


Idea One 

Is to add a LEGO NXT brick, to move a junkbot similar.The motor and broken propeller combination in the earlier junkbots is replaced with the NXT brick and LEGO motor. A good potential feature is it a self-contained unit with power and control together, as well as being potentially fairly simple to set-up. This is the focus of this post. 

Here are some videos showing idea one in action using LEGO motors, brick and the software that comes with the LEGO Mindstorms NXT (LEGO):





For more information on how this was done go to: http://legojunkbots.weebly.com/uploads/3/7/2/2/37227791/nuffield_nxt_mindstorms.docx or http://legojunkbots.weebly.com/

Idea Two

Is to do a similar approach as idea one but keep the motor and broken propeller combination but control the motors via a Raspberry Pi. This will be discussed in another post.

Details of the work will be published on the Junkbots Blog (htttp://junkbots.blogspot.co.uk/ ) as the project progresses.