[robocup-small] Proposal for energy budget - PART-II

[Beng Kiat Ng]

Hi all!

I'm glad to get quite a number of responses to my email. The foremost
objective of my proposal is to get members thinking about the nergy budget
issue. I'll try to answer all the various issues raised in these emails so
far. Hopefully, through further discussion, we can come out with something
workable.

First of all, a comment on using global vision as a means to enforce. The
way I look at it, unless we have someone who everybody can trust to
volunteer to implement it, this idea will never work. Moreover, the
maintenance would be a big issue as rules are changed, field size is
changed. Who is going to update the vision monitor? Though this method is
much more flexible and superior, I think we can rule it out as it is not
going to materialise.

Some said current robots cannot be used with this proposal. Well, I think
only a slight modification is needed. You need a DC-DC converter. If you
need 12 volts, use converter to step up the voltage. For teams using a
power hungry board, they will be disadvantaged. Motors need not be changed
unless you want better performance like using a lower voltage motor.
Remember, it's going to draw more current.

To counteract the tendency towards lighter robot, we can stipulate a
minimum robot weight of ,say 2 kg. If teams were to use big capacitor to
give the robot short energy burst, I think that would make the whole game
more interesting. We should encourage that.

Battery type? Since I think the current AAA NiMh batteries capacity is just
about right for 20 minutes of play (maybe more for extra time), any brand
will do. Hopefully teams will share information on which brand is better
and most teams will end up using similar brands. Anyway, there's not that
many good brand to choose from and teams should be able to find what's best
for them.

If we were to just lengthen current play time without restricting
batteries, it would not work. My robots have enough room to install 3000mAh
batteries, enough for more than 100 minutes of play.

Someone mention restricting wheel grip. I have thought about that too. I
was thinking about the double row rollers that some teams used to use. But
that would require teams to rebuilt their robots. With batteries
restriction, you just need a DC to DC converter. No mechanical modification
is needed. Of course, the robot software need to be change to slow down the
robot so that it is not overdrawing current.

Racing restriction. In F1, NASCAR etc, there's quite a bit of restriction
on engine and fuel tank. No car can run the whole race without refueling.
And planning when to refuel and how much to refuel can be critical to a
race.

Remember, with an engery budget, there's a whole new area we can work on!
Instead of just making the robot faster and kicking more powerful. I think
it's much more interesting. Your robot can still move fairly fast, but not
all the time.

Regards
BengKiat



                                                                           
             James Bruce                                                   
             <bruce at andrew.cmu                                             
             .edu>                                                      To 
             Sent by:                  sean.verret at gmail.com               
             robocup-small-bou                                          cc 
             nces at cc.gatech.ed         robocup-small at cc.gatech.edu         
             u                                                     Subject 
                                       Re: [robocup-small] Proposal for    
                                       energy budget                       
             15/09/05 06:09 AM                                             
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




Sean Verret wrote:
> I very much like this proposal and would urge the TC to consider it
> perhaps not necessarily for 06 but indeed for 07.  I think Raul's
> suggestion also has merit but it involves a vision system monitoring all
> the robots and monitoring their health.  Not to mention, who's going to
> create the "virtual referee", my guess is that it will not prove to be
> reliable in the near future, nor is it a research topic that is
> necessarily "interesting" for most teams.

I fully agree.  That's always the problem that sidelines the automatic
referee; Who's going to keep it calibrated and working on four fields?

> This suggestion by Beng will stop the arms race that has been happening
> every year for the past 5 years.  Instead of coming home from Robocup
> and saying, we have to get faster, we have to build stronger kickers, we
> have to build chip kickers, we need more powerful dribblers, teams will
> come back and say, we have to pass better, we have to play as a team
> better, we have to be smarter, we have to monitor our health, etc.
> These are the "interesting" problems in my mind.

This is an unrealistic expectation in my opinion.  There will always be
an arms race, but instead of being power it will be in terms of
efficiency.  Teams will have capacitors (maybe even expensive
supercapacitors or ultracapacitors) to store extra battery charge so
they can temporarily outrun their opponent.  Titanium and carbon fiber
will shave weight where steel and aluminum were before.  Nothing much
will have changed, except competetive robots will cost even more.  Just
like in professional motorcycle racing, having cc limits on motors did't
stop the hardware arms race.

Furthermore, it has negative effects on onboard computation.  Allowing
seperate batteries for the computer makes the rule essentially
unenforcable; Power from "computer" batteries can easily (and even
accidentally) be routed to the motors.  Limiting the total battery power
forces teams to remove substantial oboard computing power, thus making
things like local vision difficult or impossible.

That said, I do like rules that encourage more soccer-like play.
Removing the 90deg walls in 2000, outlawing side dribblers in 2004, and
limiting dribbling distance to 500mm all helped to encorage accuracy and
team play.  This year we can proudly say that most of the top 8 teams
had passing which was used regularly throughout the game.

Fixing the batteries is a much more extreme change, and also makes just
about every current robot illegal.  That's not to say we can't improve
things over the current situation.  A few people mentioned disallowing
battery changes during the game, or lengthening the halves.  Both would
go a long way toward reducing "excessive" power usage since teams would
have to lug all the batery capacity they would need for the whole game.
  To make this concrete, I imagine something like the following proposal:

Every team is limited to a maximum of 7 robots and 7 battery packs for
the entire duration of the game.  There would be some maximum number of
robot interchanges (3 or 4 maybe?).  Each half would be 15 minutes (up
from 10).  Since fewer hardware changes can be made during a game, we
can keep the overall duration of the match the same by decreasing
halftime and timeouts to 5 minutes each (down from 10).

With these rules, teams would have to ensure their robot can go for 30
minutes of play, and is robust enough that robots are not constantly
being interchanged during a game.  At the same time, it doesn't enforce
a particular voltage or battery type on teams.

Jim Bruce
CMDragons/CMRoboDragons
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