Theory
A Scientific Approach
We decided to take a scientific approach to robot destruction. We need maximum energy to cause maximum destruction!
We found that the following equations were very useful when we were working out how to get the maximum out of our robot. If you click on them you can visit wikipedia where you can learn a bit more about the equations and their applications.
Some weaponry considerations
- A ramming robot can release linear kinetic energy of 4 kJ in a collision
- An axe can build up rotational kinetic energy of maybe 1kJ ~ 2 kJ
- A flywheel can build up rotational kinetic energy of maybe 40kJ over several seconds and release that energy in a millisecond
Design Considerations
- For maximum rotational energy (Iw2) we need a heavy flywheel rotating at a high speed.
- To get a large Moment of Inertia(I):
- A heavy disk or ring with its weight concentrated at the edge
- It was then decided that it should be half the mass of the robot, about 50 kg
- To obtain a high speed of rotation (w):
- It greatly depends on the motor rpm and the gear ratio
- The balance of the disk or ring may also limit the rpm as any out of balance force will cause vibration and wobbling. This could cause the weapon to self-destruct at high rpm
- It was decided that 1000rpm should be our design aim -> making the peripheral speed ~110mph!
- Nominal energy - 40 kJ
- Self damage potential is high
- Self Righting
- Difficult problem - nothing to attach a "self-righter" to!
- We decided on an alternative approach, exploiting the gyroscopic properties of the weapon ring.
- It must spin up as rapidly as possible
- The Centre of Gravity must be kept as low as possible
- Install low ground-skimming cutters to deflect attacks
- It relies on the property of a spinninning gyroscope to maintain its axis in space. The robot may be lifted, but it is very difficult to topple.
As you can see science (especially physics) can really help you make a destructive robot!
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