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Skip to the result! - Skip to the photos! Challenge 1 - the flipper "I bet my robot can tip your robot over." Blue Team challenged us to a flipper battle. The winner would be the team that flipped or tipped the other robot the most. Bonus points will probably be awarded for awesome things like utterly destroying the enemy, or flipping it through a window. Rules All parts must be actual Lego components: no powertools or the like. Replacement pneumatic tubing is permitted, as are string, cables and batteries. Blue team has specified that there are no other rules, part restrictions or budget limits for this challenge. Mission briefing I see this as two priorities. Firstly, we need something to flip their robot. Secondly, we need to make it difficult for them to do the same to us. Intial Thoughts
Before we found time to begin development, Blue Team announced they had already tested several prototypes, and showed us pictures of their 'almost battle-ready' vehicle. I have to admit, it's a technological marvel. We weren't planning to make anything that clever. Build it! No development prototypes for us, we decided to just get on with it. With a simple design, it was time to test-build some components to see what was viable. The front wheels and castor arrangement were of particular concern. After assembling the front wheels, we decided it might be better to build them vertically, raising the chassis upwards. The newly proposed design was something like this:
The complete chassis was built on saturday morning, and taken for a spin. The swing-arm and castor wheels work perfectly, tilting happily on uneven ground and ramps. Forklift weapon was added in the evening, and works fairly well. The resulting weight is quite topheavy and makes the robot kick a wheelie when reversing. The additional weight also put extra strain on my chain drives, snapping them every few minutes. As a simple fix, we moved the XL motors directly onto the wheel axles. Not ideal, and spoils the whole elevated-body concept, but we'll manage. Changing face of the enemy At this point we were pretty confident. Blue team's machine used rack and pinion steering, and so could not pivot on the spot like ours. They were small, long and thin, ideal for tipping, with a short flipper that would pass harmlessly beneath our bodywork. When Blue Team saw our robot, they mentioned that they had completely dismantled their robot and were considering other designs. In short, our robot was purpose-built to fight an enemy that no longer existed, and they were going to engineer their new machine specifically to defeat our design. Grr. Weapon upgrade!
With this weapon in place and substantial strengthening beams added, the robot is pretty heavy and damn hard to tip over, even with your foot. Lifting a wheel causes no great upset, and the speed is reduced slightly, making it easier to control. Additional structural work will make the chassis stronger, and prevent loose wires and stuff catching during the fight. We are confident in our current configuration, and now all we can do is wait for Blue Team to build something and agree a date for the battle. Blue Team's machine, mk2 Wow. Their new machine is pretty big, a tracked monster with a huge lifting arm. They tell us this new machine can lift to a height of over 60cm, clearly expecting to use our ground clearance against us. Luckily, we have a diabolical plan... Sunday 30/8/2008 - Update, have seen photos of Blueteam's revised super-lifter, and can confirm that they are no threat whatsoever to our machine. I repeat, no threat whatsoever. The battle is set for next weekend, and should make for quite a short battle. Muahahaha! Monday 1/9/2008 - Update. The pivot rods for the castor wheels were under too much stress, and the wheels were sagging visibly. To counter this the castors have been rebuilt using large (4x4) turntables as the pivot, with a rod to hold them on.
Lastly, we have prototyped a modification which we believe will render Blue Team's lifter mechanism useless... Postponed Blue team have announced that they are unable to present a battleworthy robot in the time allocated. Despite their threats, they've admitted they don't feel their lifter mechanism would be capable of tipping our robot over. Even after several rebuilds, they don't feel ready. As of Friday 5th, Blue team had no robot with which to answer the challenge. They have promised that they will build something, but given no timeframe. After half a dozen prototyes, Blue Team finally presented a robot ready to take on the might of our monster machine. Comparing the machines:
What we found: Blue's lifter was in the centre of their chassis, and had to be driven under the target to get a good lift. We had a feeling this might be the case and installed side skirts to prevent such an attack. Blue's body, however, turned out to be too wide to fit between our wheels anyway. Red's lifter was able to get under the Blue robot easily, but struggled to get any decent lift. When it did get purchase, the small lifting reach wasn't enough to tip them over. Blue's lifter was able to get under Red's forks, when raised, but this meant they were working against the Red Robot's entire length, and lifting the heavy battery boxes. I don't think lego was ever intended to lift that kind of weight :p
Result: 1.5 points for Red, 1 point for blue.
Photos
 Blue team's robot. Tracked, with a collapsible lifter mechanism.
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Low, wide and simple, for starters. A bigger chassis will be harder to flip, requiring a longer flipper arm, which is harder to move. A useful weapon would be a lifter, working like a jack against the floor for leverage.
Due to the raised body, the proposed jack-lifter wasn't going to be possible, but we felt the elevated position gave us a good attach point for a forklift.
To solve the wheelie issue, we added a second weapon to the back end as ballast. It's nothing particularly clever, a vertical conveyor belt with studs, intended to snag onto edges and lift them so the robot can push the target over. We call this the Death-Grinder, because it sounds scary. Lacking enough motors to run this remote control, we have used a car motor with integral batterybox, and it runs during the entire battle. Nice and heavy, too.
Additional improvements include another motor which operates the switch for the Death Grinder. We've also found that with the improved support on the castors, the deathgrinder no longer reaches close enough to the ground. Luckily, extending the weapon in a simple matter.
