Robot ``Easter Egg Hunt'' discussion digest

                                                                                                               
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Date: 23 May 1999
DJ: Darrell Johnson
BH: Ben Hitchcock
KH: Ken Huntington
SB: Steven Bolt
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The size of the Egg Hunters


If no objections are received before June 1, this proposal will be
copied to the Contest definition:

SB> Participating robots must fit inside a 9cm x 9cm square. (Tactile
SB> sensors are allowed some reach beyond these limits.) They have to
SB> find all Eggs and deliver them into the gathering area, within a
SB> maximum time yet to be determined. If no robot manages to find
SB> and gather all the Eggs, the one who got the most wins the
SB> contest. If more `bots complete the task, the one who did so
SB> fastest is the winner.

Black walls for the Egg Hunt gathering corner


If no objections are received before June 1, this proposal will be
copied to the Playground definition:

SB> Gathering area: matt black surface (piece of black paper).
SB> Always this size (radius 20cm) and in a corner. The border of
SB> this area is also matt black.

SB> Border height is still 2cm.

Obstacle min/max. diameter


If no objections are received before June 1, this proposal will be
copied to the Playground definition:

SB> Ten obstacles: cylindrical, 2cm high, matt finish, kept in
SB> position with a central pin. The distance between them and
SB> between any obstacle and the border is 10cm or more. They may be
SB> anywhere on the Playground, except in the gathering area.
SB> Diameter between 2cm and 20cm.

Modulated IR Beacon


If no objections are received before June 1, this proposal will be
copied to the Playground definition:

SB> Modulated IR Beacon: Optional. Participants who wish to use an IR
SB> beacon must provide their own. The average current consumption
SB> must not exceed 10mA at 9V, and the emitter(s) must be at a
SB> height of no more than 5cm above the Playground floor, at the
SB> center of the gathering arc (as shown). If the beacon is to stand
SB> in the gathering area (instead of outside the Playground), it
SB> must occupy less than 25cm2. An unstabilized 9V source will be
SB> available.

Other topics being discussed:

Loopholes


SB> Note that the definition of the robot still has loopholes:

  "Participating robots must fit the Playground, which means that
   they must pass between the obstacles."

SB> I think that something like a cubic size, or at least a floor area
SB> should be specified:

SB> "Participating robots must not be larger than 9 centimeters in
SB> length or width."

SB> Comments/objections, anyone?

BH> Damn! There goes my idea of making a robot that looks like a
BH> crane. It has width 50 cm, length a couple of cm, and rolls on
BH> wheels that almost touch the walls of the playground. Suspended
BH> from the frame are lots of little bits of string with weights on
BH> the end. The crane goes to the far end of the track, lowers the
BH> 'broom', and sweeps all the easter eggs into the corner!

KH> Chear up! You aren't the only one to have that notion or one
KH> close to it :)

The color of the Obstacles


SB> The present obstacle definition allows for colors other than white;
SB> I was thinking of a little color to make photos more attractive.
 
KH> I would suggest that if colour is used, it be restricted 
KH> to the tops of the obstacles but even then one might 
KH> attempt to use that to an advantage but so what.

SB> I believe that Darrell is the only one seriously working on color
SB> discrimination. Let's wait until a real need develops, before
SB> limiting the obstacle colors?

DJ> I wasn't so much designing around different *colors*  I was more
DJ> suggesting middle value colors that are a medium grey when viewed
DJ> in black and white.. This differentiates the obstacles from the
DJ> floor and walls. what it doesn't really do is differentiate
DJ> between the obstacles and the foil balls since they are a middle
DJ> grey overall. This may or may not lead to problems.. I was just
DJ> making a suggestion..

SB> I think we can defer color changes for a while, until `eye'
SB> designs have matured a bit. Let's say that we'll accept proposals
SB> for the obstacle colors to be in a certain range, as long as some
SB> freedom of color is allowed. Unless there are objections, and
SB> unless there is a conflict between `eye' designs. And of course
SB> only the gathering corner will be black.

DJ>  Ok... I'll be quiet about the colored obstacles for now.. :)

KH> It seems that there may at least one problem. Black and white are
KH> reasonably easy but shades of gray or pastels would be very
KH> difficult to duplicate to the point where a non black/white could
KH> be useful on more than one playground.

SB> It's great that the Egg Hunt stimulates this kind of research!
SB> An effective and simple sensor for greyscale and/or color
SB> discrimination would be useful outside the Playground as well.

SB> But easy it is not, because the environmental light can't be
SB> controlled well enough. There will always be (temporary) shades
SB> and level changes, which in turn change the reflected light.
SB> Providing the sensor with a usable reference value may be
SB> difficult.

KH> For purposes of general robot vision, this is true but I think
KH> that for the development of robots sensing techniques the
KH> environment should be kept simple. There are already enough
KH> problems to be solved without adding more and if there are too
KH> many factors involved with the use of a given sensor,
KH> experimentation and development may be dropped in favour of a
KH> simpler one. To drop investigation of any sensor because the
KH> environment makes it too difficult seems counterproductive, IMHO.
KH> For our first efforts, the playground should be kept simple
KH> enough to broaden our thinking, I think :)

SB> Agreed, but the Egg Hunt home page already says:

  The Playground will be in an ordinary room, lit by ordinary natural
  or artificial light. Since the IR beacon is modulated, it should be
  easy to make sure that your Egg Hunter is not confused by mains
  modulated artificial light. But eye-challenged Egg Hunters may be
  offered a run in diffuse daylight on request.

SB> That will have to do, I think. We'll certainly won't bother the
SB> little guys with direct sunlight, photoflashes and so on.

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