Re: Has anyone ever used a Computer Mouse to locate themselves on the field
 

Very cool to know http://computer.howstuffworks.com/mouse4.htm

Re: Has anyone ever used a Computer Mouse to locate themselves on the field
 

Optical Mice would not be legal by last years rules.

We did some visual odometry using a pair of optical mice (chips) and different lenses a while back. We were only able to get it to work at fixed focal lengths - each length requiring a different lens. We were unable to get it to work with variable lengths, but I have to admit that optics isn't my strong suit.

You can buy optical mice chipsets on their own, which has the benefit of allowing you to pull the actual image out - this will help you focus.

Re: Has anyone ever used a Computer Mouse to locate themselves on the field
 

Assuming that X₀ and V₀ are given, and assuming that the update period dt is short enough that the acceleration is accurately approximated as a linear function of time, then the position is given by:

X₁ = X₀ + dt*V₀ + dt²*(a₁ + 2*a₀)/6

X₂ = X₁ + dt*V₁ + dt²*(a₂ + 2*a₁)/6

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.
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X_n = X_n-1 + dt*V_n-1 + dt²*(a_n + 2*a_n-1)/6

Re: Has anyone ever used a Computer Mouse to locate themselves on the field
 

my former team (1747) once considered trying the optical mouse routine in 2009. however, getting a mouse to track on the regolith while not touching the floor was next to impossible... and the need for it wasn't there in 2010. I was on a different team in 2011 and the idea was never mentioned

If one can get the robot and the mouse to communicate effectively, the rest is code, calibration, and some vectors. good luck on the project!

Re: Has anyone ever used a Computer Mouse to locate themselves on the field
 

It's clear to me that "exposed laser" means that the laser light itself can escape the assembly in which it is generated. A "laser ring gyro" which uses a sealed optical path would be permitted (as long as it satisfied all other rules, of course).

Which rule would rule them out?

The TechnoKats experiments with a "telephoto mouse" system showed early promise. We eventually found that the distance from sensor to carpet was a critical parameter, and a few millimeters of variation in height ruined the calibration between measured mouse motion and actual distance traveled. An FRC robot bounces enough while driving to make accurate odometry impractical.

Re: Has anyone ever used a Computer Mouse to locate themselves on the field
 

I think that if you placed a high speed mouse in a plastic mount with rounded sides to ride over obstacles and then pressed it against the floor with compression springs you might be able to make this work.

I have posted a CAD illustrating this (http://www.chiefdelphi.com/media/papers/2576?), and I tried to post some pictures, but for some reason they aren't showing up.

Re: Has anyone ever used a Computer Mouse to locate themselves on the field
 

In 2009 (Lunacy), 339 contacted a company that manufactured the optical sensors used in mice. They said they do not recommend their products for absolute motion tracking applications.

That doesn't mean a dedicated team couldn't get it to work, though.

Re: Has anyone ever used a Computer Mouse to locate themselves on the field
 

I agree with respect to ring laser gyros—in fact, those are specifically permitted per the 2011 rules.

The definition question depends on the conditions under which the laser is "exposed". Couldn't you argue that because the robot is designed to point the laser at the floor from within a shielded enclosure, that the combination of floor and robot serve to completely enclose the laser? Does the presence of an obvious failure mode (overturning the robot) negate this argument? (And what if the robot compensates for this by shuttering the laser as this failure is detected?) And given that <R02> is a safety rule, is exposure defined in terms of exposure to the surroundings in general, to humans, or to the laser-sensitive parts of humans (eyes, for ordinary lasers)? Furthermore, given that lasers are (almost completely) collimated, if the start and end points of a laser are not directly in any plausible line of sight (e.g. a laser beam across an opening in the robot), is that considered exposed? And what about reflected (i.e. substantially less collimated) light from a laser? Does that figure into exposure? Finally, there's the pedantic question of whether the rule is referring to a laser (the device), the aperture of a laser device, a beam of laser light, or some combination of those, when it talks about exposure.

It's not that your interpretation is unreasonable—quite the opposite. It's just that there are a number of other interpretations that might plausibly have been intended.

Re: Has anyone ever used a Computer Mouse to locate themselves on the field
 

I reject that argument. The laser in that application is designed to shine on something outside the robot (e.g. the floor). Only an exposed laser could do that. As you point out, if the floor isn't where it's supposed to be, the light escapes.

Without further detail in the rule, it has to be interpreted as the most general possibility. While one could reasonably assume that eyes won't be underneath or inside a robot during a match, a reflective surface could be anywhere.

I think the only reasonable answer to that question is the thing which makes a laser distinct from any other component: the laser light itself.

An easy relaxation to the "no lasers" rule would be to permit the equivalent of a cheap laser pointer by limiting the power of any emitted beam to a safe level (i.e. Class 1).

Re: Has anyone ever used a Computer Mouse to locate themselves on the field
 

I am pretty sure that this was mentioned before, but because it is continuously mentioned in this thread I would like to restate it. What most people refer to as a "Laser" mouse, is really just a camera pointed down at a flat surface that tracks the movement of the unit. The red light that you see coming out of the mouse ("laser") is an LED that illuminates the surface for easier tracking. There are a few true laser mice out there that replace the LED with a laser and use a slightly different type of camera, however, these are few and far between (I can only think of 3 or 4 models).

Because most "laser" mice don't actually contain a laser, just a camera and a red LED, I am pretty sure that they are legal as long as they abide by the rules governing custom circuits.

Re: Has anyone ever used a Computer Mouse to locate themselves on the field
 

My apologies - the models I have worked with had actual lasers.

Re: Has anyone ever used a Computer Mouse to locate themselves on the field
 

I forgot to post the computation for Vn:

V_n = V_n-1 + dt*(a_n+a_n-1)/2