[robocup-small] Proposal for energy budget

[Voith Peter]

Hi all!

According to this proposal I wanna state my personal opinion below (not vienna 
cubes team opinion.


Quoting Beng Kiat Ng <nbk at np.edu.sg>:

> 
> Hi all!
> 
> Here's my crude proposal to introduce a energy budget constraint to SSL.
> It's an old idea that some of us has thought of before, and I have put it
> into something more concrete to get the rest of the community thinking
> about it. If theres' enough support, I hope to have this in place in 2007,
> maybe even 2006.
> 
> First of all. I believe having an energy budget make the game more
> interesting. This is another research area that teams can work on. If you
> think about it, energy constraint is in every kind of competition, be it
> human soccer, F1 racing etc. In fact, if we lengthen the games to 1 hour,
> almost all teams would face the constraint (assuming they are not allowed
> to change batteries).
> 
> My proposal is based on a quick calculation based on my robot, which is
> among the lightest in the league.
> My robot weight is 1.45kg. It's battery supply comprises 5 cell
> Li-Polymer1050mAh in series. Currently, our robot is able to play about 35
> minutes continuously. 5 cell of Li-polymer is equivalent to 15 cells Ni-Mh.
> Currently, AAA cells Ni-Mh is about 1000mAh in capacity. My proposal is to
> restrict each robot to about 8 (maybe less, 6) cells of AAA Ni-Mh
> batteries. THis is based on the fact that most robots are heavier than 1.5
> kg and thus would not have enough energy to run top speed for 20 minutes.
> Moreover, Ni-Mh batteries would not be able to source very high current,
> and thus limit the top speed indirectly.
> 

For this reason you force every team to use the very expensive Li-polymer 
cells. The reason is that standard NiMH cells have only a voltage of 1,2V this 
means with 6 or 8 cells you only get a voltage range from 7,2V - 9,6V. Our 
(vienna cubes) robot has a Microcontroller which only works with 12V power 
supply. How should this work?
Other teams (I think Big Red) use 2 separate power supplies, one for the 
Controller(s) and radio communication and the second package only for 
supplying the motors. 
If you fix the number of used cells the different approaches for technical 
solutions will be restricted.
  

> Robots would be limited to 1 set of batteries per game. There would be
> limited number of substitution robots, maybe not more than 2. Some kind of
> holding area for robots can be used to make sure that no teams can change
> the batteries during games or half time.


OK! It's fair.


> 
> When robot's energy is limited and speed lowered, it's reach would be
> smaller and we would not need a bigger field!
> 
> Some teams believe there's no need to limit robot speed or ball speed. I
> beg to differ. Unless we are into some kind of speed game, like the F1, we
> should constantly try to limit them. The thing is that the robot speed and
> kick speed is a critical factor in the outcome of the game. There's no way
> a group of kids below 10 can beat a young adult group simply because they
> are are not as fast and powerful (let's ignore the height difference). If
> we do not limit, robot speed & ball speed can easily double, especially
> when the field gets bigger. If we limit the speed to something easily
> achieveable, it levels the playing field. Hardware investment need not be
> so expensive, which means SSL can again be an affordable entry league.

I disagree in this point. I don't remember any speed restrictions in the F1 
(except in pitlane). There is a natural limit for acceleration according to 
used material for wheels, engine power (according to weight) and the drift. 
Last year we discovered many problems with accelerating our robots. Our 
engines are very strong, but we have not enough weight (app. 2kg) or enough 
grip with our wheels to use our motor's power efficiently.
At the RoboCup 2004 and 2005 I've seen two different approaches to "solve" 
this problem:
-) RoboCup 2004
FU-Fighters had the fastest robot on the field and with heavy wheelspin. In 
order to move accurately they found a way to control their robots, but burning 
their engines. 

-) RoboCup 2005 
Big Red had the smoothest moving robot I've ever seen. But it was not that 
quick. They used onboard sensors to control their robots movement.

Which solution is the better and more scientific one I don't want to mention 
here, but what I wanted to point out is that there is a natural speed limit,  
it only depends on the goal you want to achieve.

Limiting the ball's speed:
I think that there's also a natural limit and the SSL almost reached it. The 
most important thing is not always to point out the "negative" and 
inconvenient developments. Regard it as a challenge!
If the defence of one team is good then the fastest shot won't have any 
chance. The AI has to calculate possible risks in advance and react, but don't 
think that some teams only shoot goals because of their fast shot.
We still have sometimes the same discussion about the chip kicker. Regard it 
as challenge to improve the vision system!
What can we do to make it the next time better! Don't think about what we have 
to restrict to avoid it! 

> 
> Regards
> BengKiat
> 
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> 

Best regards,
Peter Voith
(vienna cubes)