We are working on a tank with treads and a laser cannon gun turret. It’s a complex, long-term project with lots of CNC-machined parts as well a a variety of purchased components, but we’ve been making good progress on it. Today’s posting will focus on the base, which holds the electronics, provides mobility, and establishes a sturdy platform for the gun turret (not shown here).
The robot is powered by a large 8-cell 30 Volt LIPO battery, our first ever. So we’ve got lots of power for the motors and the laser cannon. We are driving the wheels (which are actually timing wheels) with two beefy gear motors and a Sabertooth dual 32-Amp Motor Controller. The treads are timing belts. There are two machined aluminum plates (separated by standoffs) on each side that provide the mounting for the wheels. We are using an Arduino Yun for the first time in this robot, which is a new microcontroller that integrates Linux and Arduino into a single board, which among other things, provides for a nice wifi layer, including WiFi-based software updates. We’re using an AnyVolt voltage regulator to bring some of the 30V down to 7.4V for the gun turret servos and the laser cannon. And we have a second voltage regulator for the 5 volt components. The Arduino will trigger relays (shown) to turn on the four targeting lasers and the main laser cannon (not shown), which will laser-burn targets using an autonomous targeting system. This photo also shows the four multi-tapped rails that we made to hold the robot together, including the track sub-assemblies on each side, the bottom plate, and top plate. The front plate and rear plate are held onto the bottom plate with six small #6-32 angle brackets. To better visualize the scale of this robot, the bottom plate is about 10″ wide and 13″ long.
The CNC-machined back plate includes the main power switch, a USB jack for programming (although we’ve been using the Yun Wifi for that), banana plugs for charging, and a fuse.
There are many things we like about this robot so far, but we were especially pleased with the smoke-gray acrylic top that we machined on our CNC. It’s transparent enough to see the circuit board lights on the electronics, but opaque enough to give it a nice blackish sheen. The main top plate is held onto the rails with a bolt pattern of ten 1/4-20 bolts. The difficulty with gun turrets is that you can’t get the top plate off the base without removing the gun turret, which is a pain, so we machined a slot into the main top plate. We didn’t want to use fasteners or a hinge on the acrylic, so we machined mating shelves (grayish area along the edge) so that the small back plate press fits perfectly into the top plate and stays there without needing any fasteners.