Author: Dan

Technically a brain in a jar.
Tutorials

Where to Start with Robotics

2017-04-20 Dan

In this post I’m going to talk about what I consider a robot (and not a robot), cover some of the basics to start with robotics, and give some examples from a successful class I have been leading at a local makerspace.
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News

Robot Overlord: Thoughts on building robot programs

2017-04-10 Dan

Programming robots visually is proving to be a big challenge. I thought I laid all the ground work but now I’m not so certain.

Each derivation of Robot has a derivation RobotMotionState (a snapshot of the robot at a moment in time). By comparing RobotMotionStates I hoped to test for robot/robot collisions.

I’ve also got a system to command a robot to move, which changes the RobotMotionState, checks that it’s internally valid (robot can reach that far) and externally valid (doesn’t hit anything in the world).

I’ve been stuck for months trying to build a system of RobotPrograms. Something like the Adobe Premiere or Flash timeline, where blocks of time have one command each. I couldn’t wrap my brain around it enough to come up with generalize-able cases that could be written once and work for all robots.

In a dream last night I flipped things around a bit. What if a timeline has keyframes and each keyframe is a RobotMotionState?

  • Move the timeline to a new position, move the robot to the new state, keyframe is automatically created.
  • Move to an existing keyframe, adjust the robot, done.
  • Delete an existing keyframe.
  • Drag a keyframe along the timeline.
  • Clone a keyframe.

Ideally there should be a way to interpolate between two RobotMotionStates. That way as the read head is moved along the timeline the robot(s) move between their states. There must also be a way to calculate the difference between two RobotMotionStates and send *just that change* to the robot as a command.

Oy. I’m not sure this is any easier.

Opinion Projects

Robot Overlord: A puzzle in Java

2017-03-29 Dan

Robot Overlord Java app contains lots and lots of classes, some of which are robots and their gui.

I want robot developers to have an easy time adding their robots to RO. A simple interface, minimal distraction, and examples to work from are Good Things. I’m told that RO can use a Service Provider Interface (SPI) to load a jar it’s never seen before, a jar that contains an implementation of the interface. I would then

  • make a RobotInterface,
  • make every robot I’ve already got use that interface
  • move each robot to a separate jar and load said jars through SPI
  • make a separate github project for each robot
  • advertise these plugins via tutorials so that you can fork a repo, adjust to taste, and publish your new thing.

What I’m discovering is that SPI is tricky tricky.

  • I can’t find any online examples where someone has done this successfully.
  • I have not yet got RO to load my first robot’s jar file, tho I’m trying. Is the jar packaged wrong? Maybe it doesn’t say “yes, I have that interface!” in the right way.
  • Is RO not even seeing the jar? I’m told SPI looks for any jar on the classpath. I printed out the classpath, then put the robot jar in one of those classpath folders and ran the app again. Nothing.

There are several possible points of failure, none of which can be clearly eliminated as possibilities. Worse, I’m not sure how these plugins would be debugged. Running RO would not give a lot of insight into the plugins’ inner workings. Would I still be able to tweak code in real time? That is a must.

So I ask you, dear reader: am I way off track? What do?

I should note here that I do not want to have to run RO from the command line with a custom classpath. While I’m able to do it, I doubt that the people who buy robots and use them will even know how to open a command line. Imagine a grade school teacher trying to set up for their students, or your aged mother who’s used to OSX. It ain’t happening. You don’t want that tech support phone call and neither do I.

News

Robot Overlord: Making it easier to develop your own robot

2017-03-28 Dan

To make RO easier for developers, I have published the API at http://marginallyclever.github.io/Robot-Overlord-App/

Next, the robots currently supported by RO will be moved to separate projects with their own github repositories.

A crucial feature here is keeping it easy for the end user, whom I assume (in a worst case) know nothing about computers. They shouldn’t have to modify the classpath or open a shell. I’d like it to be as easy as Arduino’s board support installer – pick from a list of plugins online, download on demand, and go.

Next, one or more tutorials will be made showing how to fork a repo, modify the robot type to your needs, and then publish your new plugin such that RO can find and install your plugin. Much easier than having to wade through the entire RO project and make a pull request.

After that I run out of ideas. Comment with your suggestions, please.

Here’s the latest robot I’ve added to RO: A new stewart platform.

Tutorials

Build your own falling block game like Tetris

2017-03-10 Dan

I’ve shown you how to use shift registers to drive an LED grid, including how to draw pictures on the screen from memory. Now we’re going to use those tools to make a game similar to the classic Tetris.  I’ll show you the circuit, how to draw pieces, how to create animations, respond to user input, and more.  Learning how to build complex behavior from simple parts is a great start to thinking about how robots behave.
https://www.instagram.com/p/BRMLTCeAd7y

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