Pondering New Ways of Programming Lego EV3 Mindstorms Bricks

We’re due to update our first level residential school day long robotics activity for next year, moving away from the trusty yellow RCX Lego Mindstorms bricks that have served us well for getting on a decade or so, I guess, and up to the EV3 Mindstorms bricks.

Students programmed the old kit via a brilliant user interface developed by my colleague Jon Rosewell, originally for the “Robotics and the Meaning of Life” short course, but soon quickly adopted for residential school, day school, and school-school (sic) outreach activities.

tm129_rob_l1_f04

The left hand side contained a palette of textual commands that could be dragged onto the central canvas in order to create a tree-like programme. Commands could be dragged and relocated within the tree. Commands taking variable values had the values set by selecting the appropriate line of code and then using the dialogue in the bottom left corner to set the value.

The programme could be downloaded and executed on the RCX brick, or used to control the behaviour of the simple simulated robot in the right hand panel. A brilliant, brilliant piece of educational software. (A key aspect of this is how easy it is to support in a lab or classroom with a dozen student groups who need help debugging their programmes. The UI is clear, easily seen over the shoulder, and fixes to buggy code can typically be easily be fixed with a word or two of explanation. The text-but-not metaphor reduces typos (it’s really a drag and drop UI but with text blocks rather than graphical blocks) as well as producing pretty readable code.

For the new residential school, we’ve been trying to identify what makes sense software wise. The default Lego software is based on Labview, but I think it looks a bit toylike (which isn’t necessarily a problem) but IMHO could be hard to help debug in a residential school setting, which probably is an issue. “Real” LabView can also be used to program the bricks (I think), but again the complexity of the software, and similar issues in quick-fire debugging, are potential blockers. Various third party alternatives to the Lego software are possible: LeJOS, a version of Java that’s been running on Mindstorms bricks for what feels like forever is one possibility; ev3dev is another, a Linux distribution for the brick that lets you run things like Python, and the python-ev3 python package is another. You can also run an IPython notebook from the brick – that is, the IPython notebook server runs on the brick and you can then access the notebook via a browser running on a machine with a network connection to the brick…

So as needs must (?!;-), I spent a few hours today setting up an EV3 with ev3dev, python-ev3 and an IPython notebook server. Following along the provided instructions, everything seemed to work okay with a USB connection to my Mac, including getting the notebooks to auto-run on boot, but I couldn’t seem to get an ssh or http connection with a bluetooth connection. I didn’t have a nano-wifi dongle either, so I couldn’t try a wifi connection.

The notebooks seem to be rather slow when running code cells, although responsiveness when I connected to the brick via an ssh terminal from my mac seemed pretty good for running command line commands at least. Code popped into an executable, shebanged python file can be run from the brick itself simply by selecting the file from the on-board file browser, so immediately a couple of possible workflows are possible:

  • programme the brick via an IPython notebook running on the brick, executing code a cell at a time to help debug it;
  • write the code somewhere, pop it into a text file, copy it onto the brick and then run it from the brick;

It should also be possible to export the code from a notebook into an executable file that could be run from the on-brick file browser.

Another option might be to run IPython on the brick, accessed from an ssh terminal, to support interactive development a line at a time:

ev3dev

This seems to be pretty quick/responsive, and offers features such as autocomplete prompts, though perhaps not as elegantly as the IPython notebooks manage.

However, the residential school activities require students to write complete programmes, so the REPL model of the interactive IPython interpreter is perhaps not the best environment?

Thinking more imaginatively about setting, if we had wifi working, and with a notebook server running on the brick, I could imagine programming and interacting with the brick from an IPython notebook accessed via a browser on an tablet (assuming it’s easy enough to get network connections working over wifi?) This could be really attractive for opening up how we manage the room for the activity, because it would mean we could get away from the computer lab/computer workstation model for each group and have a far more relaxed lab setting. The current model has two elbow height demonstration tables about 6′ x 3’6 around which students gather for mildly competitive “show and tell” sessions, so having tablets rather than workstations for the programming could encourage working directly around the tables as well?

That the tablet model might be interesting to explore originally came to me when I stumbled across the Microsoft Touch Develop environment, which provides a simple programming environment with a keyboard reminiscent of that of a ZX Spectrum with single keyboard keys inserting complete text commands.

unique_script____main_-_TouchDevelop

Sigh… those were the days…:

zx_spectrum_keyboard_-_Google_Search

Unfortunately there doesn’t seem to be an EV3 language pack for Touch Develop:-(

However, there does appear to be some activity around developing a Python editor for use in Touch Develop, albeit just a straightforward text editor:

As you may have noticed, this seems to have been developed for use with the BBC Microbit, which will be running MicroPython, a version of Python3 purpose built for microcontrollers (/via The Story of MicroPython on the BBC micro:bit).

It’s maybe worth noting that TouchDevelop is accessed via a browser and can be run in the cloud or locally (touchdevelop local).

We’re currently also looking for a simple Python programming environment for a new level 1 course, and I wonder if something of this ilk might be appropriate for that…?

Finally, another robot related ecosystem that crossed my path this week, this time via @Downes – the Poppy Project, which proudly declares itself as “an open-source platform for the creation, use and sharing of interactive 3D printed robots”. Programming is via pypot, a python library that also works with the (also new to me) V-REP virtual robot experimentation platform, a commercial environment though it does seem to have a free educational license. (The poppy project folk also seem keen on IPython notebooks, auto-running them from the Raspberry Pi boards used to control the poppy project robots, not least as a way of sharing tutorials.)

I half-wondered if this might be relevant for yet another new course, this time at level 2, on electronics – though it will also include some robotics elements, including access (hopefully) to real robots via a remote lab. These will be offered as part of the OU’s OpenSTEM Lab which I think will be complementing the current, and already impressive, OpenScience Lab with remotely accessed engineering experiments and demonstrations.

Let’s just hope we can get a virtual computing lab opened too!

PS some notes to self about using the ev3dev:

  • for IP xx.xx.xx.xx, connect with: ssh root@xx.xx.xx.xx and password r00tme
  • notebook startup with permission 755 in: /etc/init.d/ipev3
    #!/bin/sh
    ipython notebook --no-browser --notebook-dir=/home --ip=* --port=8889 &

    Then commit this file as a start-up action: update-rc.d ipev3 defaults then update-rc.d ipev3 disable (also: enable | start | stop | remove (this don’t work with current init.d file – need proper upstart script?)
  • look up connection file: eg in notebook %connect info and from a local copy of the json file and appropriate IP address xx.xx.xx.xx ipython qtconsole --existing ~/Downloads/ev3dev.json --ssh root@xx.xx.xx.xx with password r00tme
  • alternatively, on the brick, find the location of the connection file, first via the profile ipython locate profile and then inside e.g. ls -al /root/.ipython/profile_default/security to find it and view it.

See also: http://www.beein.cz/en/idea/pc/lego-ev3-python