VEX Ball Contraption is a collaborative project where people bring "moving ball" modules that are chained together. Each module must transfer, by any means (preferably spectacular!) ball from its input hopper to the input hopper of the next module in the chain. This is always a hit with kids... and not-so-kids!
VBC at VEX Worlds 2016!
To get a taste of what it looks like, watch these videos! They were shot at the first VBC display at VEX World 2016, Super Users booth.
VBC specifications and discussion
To make this work, and guarantee interoperability between
modules built by different people, some rules must be followed.
Here are the specifications used during the first VBC event,
at VEX World 2016.
1b - Maximum input height = minimum output height = 16 hole beam height.
2c - More generally, no structure should prevent sending balls to the next module, or to receive balls from previous one (you must be able to place modules "close enough" to allow ball transfer.
2d - If your module is tall and could drop balls from a great height, you must provide some form of ramp to allow the balls to drop in the next module from a reasonable height (say less than 24 holes). Horizontal speed of balls must also be "low enough" (use shallow angle ramp, or provide some form of deflector/stopper at the end).
2 - While vertical dimension (16 hole beam maximum) must always be respected, horizontal dimension of the bucket is not so critical, especially in the direction of ball flow (though in a corner of the loop you may want to input balls from "back" side of module). Width is important only if output of previous module is large (generally batch type module), but many modules turn out to be of serial type, with a 1 ball width output. So narrower input bins, while they should be avoided, can generally be accommodated easily.
3 - Table width is limited! Your module shouldn't be too deep...
4 - 0.25 ball/second average speed is easily achieved. At VEX World 2016, measured average ball speed for the loop was about 0.33 ball/second. It is difficult to ensure that an output batch will never exceed 16 balls, but this provides an indication
5a -This means that if a module has a nice looking side, it must be oriented to show it to the public.
VBC tips and
Most modules are "dumb" ones, powered by a single motor. For these modules, you can either use:
Here is a Robot-C motor driver program for VBC events. It allows to power several simple VBC modules (single motor mechanical contraptions). Though the motors are not hot-plug on VEX-IQ brain (they are detected at brain power on), a clever trick (courtesy of Laurens Valk) allows to use any number of motors (function SetConnectedMotorSpeed).
Program starts with various power levels and direction, so it is usable without any further configuration, just by choosing the port offering the right setting for the module. It is nonetheless possible to change speed for each port using brain keys. Unfortunately, this configuration is not remembered after stopping the program (IQ doesn't support files)
Default speed values can be changed using brain
Pressing Up and Down keys together for 0.5s results in an emergency stop of all motors while keeping the programmed speed values. Press Up or Down to restart motors.
See a few VBC models here, with SnapCAD files!
Last updated 2016-04-29