Peter Needs A Pint

Created for the 2013 MolyJam at the Durham location.

Peter is down at the pub and needs some drinking buddies. Gather up the townsfolk so he won’t have to drink alone.


Play by yourself or with a friend. Earn more beer for yourself by bringing the most people down to the pub. If you have a MolyBot, it will pour your beer for you at the end of each round; otherwise you’ll have to pour the beer yourself (MolyBot and beer not included).

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Robotender Mk3

Finished Robotender Mk3 just in time for my halloween party (with literally minutes to spare). This one is a pretty radical departure from the previous designs, using a robotic arm instead of pressurized dispensing. I managed to pick up a Scorbot ER-III arm and controller off of eBay. They were originally used for teaching robotics and motion planning at universities, and are generally pretty used-and-abused (two motors were almost falling out of their mounts on this one), but it runs quite nicely after everything was cleaned and tightened up.

Robotender Mk3, wide view

It’s a little slow compared to the Mk1, but it’s a lot of fun to watch, can hold more bottles, and is easier to maintain. It uses custom bottle carriers that hold 710 mL soda bottles, and can hold up to 24 such bottles. There is a digital scale hooked up to the computer as well, which gets zeroed once a bottle reaches the pour site, letting it determine how much liquid has been poured much more accurately than the simple time-based approach used in Mk1.

Pouring an ingredient

I took a number of pictures during construction on this one, so I may do a build log post later.

Next steps:

  • I’m going to look into building a new motor controller for it, so I can get better feedback and drive it faster while still keeping a solid grip on bottles (can’t currently ignore the gripper stall state for fear of missing any other motor stalls, meaning I have to do a slow 1/10th speed backout on the gripper to get the max grab force I can).
  • The bottle holders are on their 6th iteration already, but positive grip is still a bit of a problem, so I’m probably going to redesign the bottle holders with a triangular slot and make some triangular nylon plates for the gripper. This might also allow me to be a little less precise in the back-off, and speed it up without a new motor controller.

Speedy Gonzales the robot

For my Building Intelligent Robots class at the University of Missouri – Columbia, we worked in teams of two to create (and recreate) a robot for a number of different tasks.

The robot’s brain is a MIT Handyboard, and we used LEGO bricks and motors to actually build the thing.  We designed him for high torque, and as a consequence he was one of the slowest robots in the class, earning him the moniker Speedy.  The sombrero came during a late night build session after taping out some boundaries on the floor…

The final project report is available, and it includes more pictures, prose, and the source code.