PDA

View Full Version : Rule clarification



Shebang
05-15-2013, 08:03 PM
Hello all,

I would like to ask a few questions to clarify some of the mech warfare rules.

1) Would retro reflective tape be allowed to be put on the opponents targets? The rules allowed colored tape, but does not state anything about retro reflective tape.

2) Would two IR cameras at a separation distance of 30cm (~1 foot) be allowed? I will be using them to track the retro reflective tape autonomously in 3D. This IR video will not be shown to the pilot and will only be used for autonomous tracking.

3) Would a Klann linkage (http://en.wikipedia.org/wiki/Klann_linkage) be allowed? The rules say no cam driven legs, however this is a different linkage type.

Thank you in advance,

Larry

ArduTank
05-15-2013, 08:07 PM
On number 3, a Klann linkage would not be allowed because it uses motors and/or continuous-rotation servos.

On the other two, ask Tyberius.

Shebang
05-15-2013, 08:47 PM
There is a rule that states:


In order to allow autonomous bots, and those using visual tracking, competitors may bring a visual fiducial of any color which may be applied to an opponent's target plates using tape of any color.

The rule allows a colored tape. Retro reflective tape, is tape that will reflect light back from where it came from. The retro reflective tape looks grey, so it kinda falls under this rule. I just want it clarified if retro reflective tape can be used.

tician
05-15-2013, 08:56 PM
The rule allows a colored tape. Retro reflective tape, is tape that will reflect light back from where it came from. The retro reflective tape looks grey, so it kinda falls under this rule. I just want it clarified if retro reflective tape can be used.
IIRC there was a prohibition against any devices that could blind other players, and retroreflective tape makes it sound like you will be using rather powerful IR LEDs near each camera to illuminate the tape. Lots of digital cameras can be a bit sensitive to IR...

Shebang
05-15-2013, 09:11 PM
Actually, they don't have to be powerful LEDs. Cameras that can see IR will just see a light like a regular LED. You can try this by looking through a camera at a TV remote and pressing the buttons on the remote. It should look something like this: https://www.youtube.com/watch?v=Sco6vrXdAaU (warning: loud music). The pilot will just see purple light from the LEDs.

tician
05-15-2013, 09:36 PM
Actually, they don't have to be powerful LEDs. Cameras that can see IR will just see a light like a regular LED. You can try this by looking through a camera at a TV remote and pressing the buttons on the remote. It should look something like this: https://www.youtube.com/watch?v=Sco6vrXdAaU (warning: loud music). The pilot will just see purple light from the LEDs.
Have you actually built and tested your system in a non-lab environment? It just seems to me that illuminating a large scene containing small retroreflector tags at significant distances would require rather powerful wide-angle IR lights that might cause problems for other cameras when directly viewed.

jwatte
05-16-2013, 12:29 AM
I saw people use post-it notes, which aren't "tape" at all, so, yeah, I think the retro-reflective tape would be totally within the rules. Strong flood lights with IR might not be OK, given the "no blinding" rule, as suggested above, but IR reflectors may work with pretty dim illumination. Personally, in trying the same thing, I'm going for fluorescent colored tape and visible-spectrum markers, though.

I've seen mechs with backwards facing cameras (but none of them that were actually competetive.) You can likely send as much video to the operator as you want. If you want to send the IR data back to the operator, I would think you're free to do that. One big caveat: 802.11g spectrum really sucked at the San Mateo convention center. Like, REALLY sucked. My UDP based protocol ended up working once I turned down the picture resolution enough, but throughput was really bad, and those using webcam based solutions did best to stay at 320x240 or smaller pictures to avoid slide show syndrome.

Two cameras with 30 cm distance would be fine. The mech must fit the streets in the arena, which are at least 3' wide; many mechs have a footprint wider than 30 cm. Just make sure the cameras or mounts for them do not get in the way of the target panels!

Klann linkages: I think someone already asked about those, and I think the answer is "no." The leg design must use actual actuators. I think a reasonable interpretation of the rules is that actuators that can rotate 360 are fine, as long as they are actually closed-loop servos, and you use more than one degree of freedom to operate each leg.

Janis
05-16-2013, 05:05 AM
I agree that Klann linkage is cam driven and therefore not allowed. OTOH, I'd really like to see a capable quad with such leg design given that you need to have some turning capability, too.

Lupulus
05-16-2013, 09:46 AM
I agree that Klann linkage is cam driven and therefore not allowed.

This rule has seemed a bit ambiguous to me, since "parallel leg motion" linkages are allowed. One example is HD2's legs. I think that the key point is the "continuous rotation." Mechanical advantage designs are fine, but it can't be driven by a motor running in just one direction.


OTOH, I'd really like to see a capable quad with such leg design given that you need to have some turning capability, too.

I actually think a cam design could be very capable--you could use a cam for the tibia/femur, and normal servo for the coxa. Or, possibly use a wasp-waist design with the angle between front and back legs controlled by a servo.

DresnerRobotics
05-16-2013, 10:05 AM
This rule has seemed a bit ambiguous to me, since "parallel leg motion" linkages are allowed. One example is HD2's legs. I think that the key point is the "continuous rotation." Mechanical advantage designs are fine, but it can't be driven by a motor running in just one direction.

This is correct. I'm in the process of rewriting the ruleset entirely to be more direct.

IR reflective tape is allowed on target panels. IR LEDs are allowed so long as they're not flood lamping it up and blinding competitors. It's up to the builders to be aware of this and do testing, if you show up to a competition and are blinding your opponent (be it laser or IR) you'll forfeit the match.

There are no restrictions on the number of cameras you may use, so long as they only transmit on a single 2.4ghz and/or 5.8ghz analog channel. Each competitor is allowed one channel on each frequency type (meaning you're allowed to have a wifi cam and a 5.8ghz cam on the same mech for redundancy or extra views)

Shebang
05-16-2013, 10:23 AM
Thank you for the clarification.

Also, there is a rule saying:


Cameras should be mounted roughly in the center of the mass of the robot, where the 'cockpit' would be.

I was wondering if the two IR cameras are allowed to be at a separation distance; since 30 cm is apart is not "roughly the center of mass".

DresnerRobotics
05-16-2013, 10:46 AM
Thank you for the clarification.

Also, there is a rule saying:



I was wondering if the two IR cameras are allowed to be at a separation distance; since 30 cm is apart is not "roughly the center of mass".

That's fine. The Rule is in place to prevent people from putting a gun and camera on a boom and shooting around corners without exposing target panels. Again, rule rewrite will clear this stuff up, it is a bit ambiguous.

With two cameras for stereo I see no problem at all with the spacing. The intent is for depth perception, not for a blind firing advantage.