Image Discuss: Team 356: Drive base ramp testing

[CD47-Bot]

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[Solace]

finally! I was beginning to think that we were the only team to have wheels that would always stay on the ground.

Looks good guys!

[foursixnine]

Nice looking drivetrain guys. That's one of the more original suspension systems I've seen yet. There is one major issue w/ it though, it looks like in starting position the coils you are using would have more than 20ft-lbs of stored energy.

[Joe Johnson]

Forsixnine,

I think you are wrong about that 20 ft-lb comment.

What I mean is that FIRST does not forbid storing as much energy as you want in a spring. What it forbids is storing more than 20 ft-lbs of energy in a spring that will be used to power your robot.

If the spring is not used to power your robot (and I suppose that a suspension system does not power the machine or its mechanism), then it is okay.

After all, a gas strut even when fully extended has a lot of energy stored in the gas chamber of the strut (I suppose several orders of magnitude more than 20 ft-lbs), but that energy is not available to power your robot, so I don't think rule M11 applies to that energy -- only the energy available to power your mechanism counts.

At least that is how I interpret M11.

What do other's think?

Joe J.

[foursixnine]

Energy used by FIRST Robotics Competition robots, i.e., stored at the start of a match, must come soley from:

- Electrical energy derived from the onboard 12Vdc battery;

- Storage achieved by deformation of springs or latex tubing; no more than 20ft-lbs (27.116 newton-meters aka joules) energy total stored at the start of a match;

- Compressed air stored in the pneumatic system, but only supplied by the Pump included in the kit and stored at a maximum pressure of 120 PSI;

- A change in teh altitude of the device's center of gravity.

I personally don't think rule M11 leaves much room for interpretation when it comes to springs, but then again I would venture to say that the "spirit" of the rule is similair to Joe Johnson's interpretation.

[Andrew]

The spring has a rate of 50 lb/in. It is compressed one inch.

If you use (1/2)*k*x^2, I read that we have 25 in-lb stored in the spring at full compression.

This is about 2 ft-lb which is significantly less than the 20 ft-lb. Even with 2 springs, we do not have a total of more than 4 ft-lbs stored.

Also, the springs are extremely well-contained and not likely to fly out of the robot, ever. So, no safety issues.

I haven't read M11 recently (or mods). So, please, correct me if I'm wrong. (I'm also really, really tired right now and my math and physics may be less than precise.) However, we did think through compliance with rules in our design and should be OK.