1.1 Robotic Concepts and Robotic Indecision

As I have just said, nothing is ever as simple as it seems and even thinking about building a combat robot is hard enough on its own.


For those of you who were familiar with Robot Wars the diversity of the machines was incredible and even if 2 machines were similar they still operated and functioned very differently,, so picking a starting point for designing the robot was near impossible. I decide the best way to go about it was to draw down every design that entered my head then go through and dismiss the physically impractical ones and then again to remove the ridiculously expensive ones.


So after dismissing numerous mental designs, which included a full body spinner bases around 2 counter rotating planetary gear sets and a gigantic half conical crushing arm, I arrived at several plausible ideas. A wedge/flipper and spinning disc combination, a slightly different wedge/flipper and spinning disc combination, a full body hammer and lifting arm and another slightly different version of a full body hammer and lifting arm. (In short I did not have many options.)

Full Body Hammer Robot 1

Full Body Hammer Robot 2

 

Spinner Flipper Robot 1

Spinner Flipper Robot 2

 From the quick sketches I drew up some more accurate visualisations and from there I turned them into CAD models. It was at this point scale occurred to me. Solidworks demands the use of lengths and angles so obviously I had to pick some lengths to define the robot. The lengths determined size and a a result ,weight. 


Its probably a good idea at this moment to inform those of a non-robotwars background of the rules, specifically the weight categories which play a major role in what your machine is capable of. The full rules can be found here on the Fighting Robots Association (FRA) website.


http://www.fightingrobots.co.uk/documents/Build_Rules_2011.pdf


In summary the weight classes are Antweight [0 to 150 grams], Beetleweight [150 grams to 1.362kgs], Featherweight [1kg to 13.6kgs], Lightweight [12kgs to 27.5kgs, Middleweight [27.5kgs to 55kgs] ,Heavyweight [55kgs to 100kgs] and Super Heavyweight [100kgs to 145kgs].


Robotwars was mainly based around the Heavy weight category with a few fun incursions into the lower classes [If I recall correctly no super heavy weight fight has ever taken place in the british robot wars arena]. However the cost of building the heavier robots is considerably more than the smaller ones. If you are lucky with your purchase you can get an ant-weight in the box with a transmitter, for example 2 servos, receiver and the battery and that with a few modifications will serve you fairly well in an ant-weight fight. But the heavyweight ones cost a bomb! For example Chaos 2 is around £14'000, Wheeley Big Cheese is similar and Mortis was just over £30'000. Yes I know that some teams like 101 can famously build the whole robot for a pound and a penny but that is if you do this kind of thing for a living and have all the bits lying around.


For me the choice was fairly easy, Heavy weight and super heavy were far to expensive, middle and light had to few entrants to make it interesting and beetle weight and ant weight were to light to have fun with it.


Feather weight is a good place to start for most budding roboteers. Motors reasonably priced, the robot is small enough to cut down on expensive chassis materials, that old wheelbarrow rusting in the corner would make a good starting point for armour and you can even convert old windscreen wiper motors and wheel chair motors into drive motors if you can be asked.


But I digress...


With the weight limit established at 13.6Kg and a bit of maths later I worked out how big each of the chassis could be to take up 3.6kg of my weight limit. Each worked out to be between 0.5 and 0.4 of a meter long and 0.5 to 0.3 of a meter wide.


This is where things started to get expensive, well not for a short while anyway. With a size and weight established I now began to hunt down possible components for the robot and at the same time begin to buy everything Morrisons own brand if i was ever going to have money to spend on this machine.