Servo - March 2010

or as a participant — the next all weight class combat event will be at RoboGames, scheduled for April 23-

25 at the San Mateo County Expo Center. For further details, go to www.robogames.net. SV

Photos were taken and provided by Team Toad: Michael “Fuzzy” Mauldin, Kelsey Ross, and Sharon O’Mara. Title photo is courtesy of Sam Coniglio.

Z IDBERG: Thinking Outside the Box Project Zoidberg was conceived when a motor delivery for one of our other robots arrived at my teammate’s house, containing a surprising ‘extra’ component. The sender had accidentally packed a pair of Team Delta18V Dewalt ‘power drive’ gear motors. These powerful, drill-based units looked too nice to send back, so a deal was arranged. Not wanting to build another boring armored box, the seeds of new 30 lb robot were sewn.

Function

When designing the Zoidberg robot, it was immediately apparent that this was potentially the most capable drive system used in any of our featherweight robots. Looking at the technical specifications for the motors, it was calculated that a single pack of high capacity NiCad ‘C’ cells would suit the current requirements. A 40 Mhz radio system is used to control the robot

● by James Baker

(as we have a few spare), and the obligatory activation light and removable link were added to conform to UK rules. The electrical power system uses black and red high temperature silicon wire throughout.

A wooden base was made to test the power drives — directly driving 80 mm scooter wheels using custom-made hubs. These hubs were machined from high-grade aircraft aluminium, and bonded to the wheels with a special resin. From these first tests, it was decided that even though many people run these gear motors on 24V we would run the robot at 18V, as the performance was still very good compared to the majority of machines in the UK at the moment. The lower voltage also offered improved reliability and longevity while we got used to using the robot.

The controller chosen was the Robot Power Sidewinder. This is an over-specification solution, and allows us the option of increasing to 24V in the future without compromising reliability. We also have Sidewinders in several other robots, so spares are available if we have failures at events. The initial tests with the drive system showed a surprising amount of grip was available from the scooter wheels, so although a four wheel drive solution was investigated, it was not considered necessary (especially when the incredible agility of the two wheeled chassis impressed us during these first tests).