Rokenstorms - The Rokenbok/Mindstorms Project

Take one Rokenbok starter set, a Lego Mindstorms set, some wire cutters, heat shrink tubing, and some tiny pin and socket crimp connectors and what do you get? A nice radio control interface module for building Lego robots!

This page is meant to describe my initial attempt at integrating the radio control capabilities of Rokenbok with Lego Mindstorms robotics. Please note, think carefully before you attempt to duplicate this with your own Rokenbok set. The actions I describe here will definitely void the Rokenbok warranty and I imagine if you aren't careful you could destroy your Rokenbok vehicle. Follow these instructions at your own risk! Don't blame me if you break something.
With that said, if you are mechanically inclined and want enhance your Lego creations with radio controlled capabilities, this is a fairly straightforward and inexpensive process. The cost of materials (other than the Rokenbok and Lego systems) was under $10.

Why Rokenbok?

With many different radio control options available, you might wonder why one would use a Rokenbok system. There are a couple of reasons. First, the Rokenbok vehicles have 3 motor outputs (coincidentally the same number at the Lego Mindstorms RCX). Most low-cost radio control vehicles only give 2 outputs. Secondly, the Rokenbok base station has the capibility of controlling 8 vehicles on one radio channel, so if my friends want to build their own radio control Lego robots and do battle with me, we won't have to worry about radio frequency conflicts. Thirdly, the Rokenbok radio control module can run off the same power provided by a Lego power pack or even the power from a motor output on the RCX, so it will integrate nicely. Other radio control options would require specialized battery packs that would need to somehow be Lego-fied. With the Rokenbok system, I just have to build a Lego wrapper for the circuit board normally found inside a Rokenbok vehicle. And finally, the Rokenbok circuit board is relatively small - in Lego dimensions it is 7 x 11, coincidentally the same dimensions as to fit inside the battery box of the RCX brick.

How to do it

First, ensure you have everything needed: a philips screwdriver, needle-nose pliers, heat-shrink tubing, 9 pairs of crimp-style pin and socket connectors (a pack of unassembled male and female DB-9 connectors from Radio Shack is what I used. I just discarded the DB-9 casings, all you'll need are the pins and sockets), and one Rokenbok vehicle you don't mind possibly destroying. For my project, I chose the white Rokenbok RC Skip Track "bobcat" style vehicle.

Next, unassemble the vehicle. Note, you will want to disassemble the vehicle enough to free up the socket you normally plug the Rokenbok radio key into. If you plan on eventually using the vehicle again, take note of how you disassembled the vehicle so you can put it back together again.

Now that you have the vehicle apart, you'll have to CUT several of the wires so you can remove the circuit board. NOTE: you will NOT be cutting ALL the wires - you'll only be cutting those connecting the the circuit board to the battery, the 3 motors, and the antenna. Do NOT cut the wires leading to the socket for the radio key.

Once you cut all the wires, you should have just the circuit board, with the radio socket still connected.

Now you will need to take some lego electrical connectors and cut the wires in half:

Then split the ends of the wire.

Now, for all the cut wires on the Rokenbok circuit board and on the cut lego electrical connectors, you will have to add the crimp pin and socket connectors. First you will need to strip about 1/8 of an inch of the insulation off the ends of all the wires. Then you add the connectors. I recommend alternating pin and sockets (i.e. for every pair of wires, use a pin connector on one and a socket connector on the other). This has the advantage of allowing you to later reconnect the lego electric connectors halves back together in case you want to use them with Mindstorms. To attach a connector, just insert the bare wire into the connector, and squeeze the end of the connector with needl-nose pliers. A properly made connector should look something like this:

Once you add the pins and sockets to all the connectors, before you add the heat-shrink tubing, you should test the connectors to ensure they work. If you wire everything up properly and connect it to a lego battery back or the motor output on an active RCX motor port, the Rokenbok module should power on and the radio light should come on. If it doesn't, double-check all you connectors and also try rotating the power connector to ensure the power is going in the right direction for the Rokenbok module.

Once you verify the Rokenbok module powers up properly, test all 3 motor outputs by attaching a lego motor to them using the newly created lego connectors.

Once you verify it all works, you can add small pieces of heat shrink tubing to the connectors to ensure there is no exposed metal when the connectors are joined together. Here's what a connector looks like once the heat shrink tubing is added:

Note: This shows how you should leave the pin connector exposed, but completely cover the socket connector

Now that you've added all the heat shrink tubing, you should now be able to build a lego frame to hold the circuit board and electrical connectors. Below are some pictures showing the module I built.


Note how this module is exactly the same size as a Lego Mindstorms RCX brick.

If you want to see some pictures of my first vehicle created using this Rokenstorms module, click here.

A friend and I are going to have a competition to build some soccer playing Rokenstorms vehicles. The vehicle shown is my first pass attempt. I'll post the results when we finish.

Contact: brian@stormyprods.com