Servo - October 2008

the development of the robot concept was refined over and over.

Upgrades and improvements were undertaken, often pre-emptively. The original concept of a simple, low cost robot was all but gone, and the highly advanced design was starting to look like a

30 lb version of a very successful larger robot.

Hmmm ... this got us thinking. More upgrades and design changes were authorized, and the four cheap drill motors originally planned for the drive system were replaced with six Team Whyachi TWR15 gear motors and wheels.

This, of course, resulted in a controller upgrade and new batteries as we planned to over-volt the motors. Since this well known, heavier robot was now the basis for my robot (named Savage), the owner was contacted and he was kind enough to offer his blessing. Now the project continues with renewed enthusiasm to do everybody proud. A number of features in this robot were inspired by other awesome machines. The pneumatics system, for example, is based on a liquid draw CO₂system as used successfully in many robots on the British Robot Wars TV show. My own heavyweight robot ‘Wheely Big Cheese’ uses an almost identical concept on a larger scale. I was also inspired by the old British warship, HMS Warrior. This ship made everything else on the water obsolete when it entered service in the 1860s.

600 g CO₂bottle, pressure relief valve, dump valve, 1/2” solenoid valve, and custom-made ram.

The ship’s design feature I was most interested in using for the robot was its armored citadel principle. On HMS Warrior, the center of the ship — including gun deck and steam engines — were enclosed in a thick iron box of armor — an internal chassis that formed the core strength of the entire ship’s structure. The rest of the ship basically bolted to this inner box. For Savage, I wanted to try out this same idea, so I used a chassis milled from a solid billet of 2L97 aluminium alloy from which everything would be mounted. To compliment this high core strength, the armor covering the robot is 8 mm titanium, with some 4 mm titanium and 4 mm Hardox 400 wear plate in strategic places. All the aluminium used for supports, flipping arm, etc., is the same 2L97 alloy used in the main citadel.

If we think of Savage as a ship, the upper deck is fully enclosed within the chassis citadel and houses the pneumatic system, flipping arm, batteries, speed controller, and radio system. Below this (beneath the waterline, if you will), sit the six Whyachi gear motors upon which

The test rig with the planned parts.

Lots of machine work has gone into every part.

Custom-made ram for liquid CO2 use.

the robot runs. The titanium armor extends downwards from the chassis to the floor, protecting the motors and wheels.

When designing the flipper, I wanted to ensure that the mechanism was mechanically strong, effective, and an integrated part of the armor of the robot. The pneumatic system that powers it is also very powerful, but I felt I needed to leave options to upgrade later. I built a test rig system with a custom made, aluminium manifold to allow me to experiment with different configurations and components. The ram currently used is a custom design that was of a size specifically chosen to allow the body to be tapped at its base to 1/2” BSP thread. This can then be screwed directly into the solenoid valve, negating the need for fittings.