Current Draw vs. Stall current

[Adam.garcia]

Originally Posted by Brandon Holley

Using one here is fine, but just make sure you are not also accounting for extra margin somewhere else and compounding your margin.

-Brando

Thanks, I will keep that in mind.

[kws4000]

[quote=Jared341;1077997]There are a few ways to defeat defense...


Pushing (works great against most, but just as with speed, you will eventually encounter a bot that can push you to a standstill)

In 2009 (remember the slick surface?) our lead rogrammer added in code to increase the allowable pushing power of our bot. We weighed 85 lbs on the chart, and we were pushing around 120 lb bots with those ungainly trailers.

//Traction control calculations
if(m_rightStick->GetRawButton(1) == 0) {
if (ncount1 == 0 && ncount2 == 0) {
ncount1 = count1;
ncount2 = count2;
} else {
speed_error1 = ncount1 - count1;
speed_error2 = ncount2 - count2;
ncount1 = count1;
ncount2 = count2;
}

//ajjy = ajjy * .95;

if (speed_error1 > 30 && speed_error2 > 30 ) {
float ajjy = ajjy * .9;
float ajx = ajx * .9;
printf("Motor Y: %f", ajjy);
printf("Motor X: %f", ajx);
}
}

It worked, and it might help with mechano wheels, but I don't think this code will really be usefull for at least another 5 years...

Ready for kickoff?

[the man]

Now ask your self how long will a 17 amp hour battery last while four motors draw 110 ish amps? How long untill your wire melts? I feel there is some thing wrong with your calculations.

[Adam.garcia]

Originally Posted by the man

Now ask your self how long will a 17 amp hour battery last while four motors draw 110 ish amps? How long untill your wire melts? I feel there is some thing wrong with your calculations.

The 121 Amps only occur when at max continuous load (ie. We are pushing against a wall, or an immovable robot). There is no feasible reason for pushing against an immovable object for more than a few seconds.

To get around ever having to go near this 121 Amps, our programmer is working on some code which will sense if the Amps rise too high while in high gear. If the robot senses high Amps, it will automatically shift to low gear in order to prevent possible breaking.

We just saw this a few days ago while looking at 399's drive code. Ingenuity to the max!

[Al Skierkiewicz]

Adam,
To add to your discussion, a motor draws stall current whenever the motor is not moving. That is why there is a current spike when you first apply power to the motor. The current is proportional to the applied throttle value. If you are at full throttle and using fully charged battery and low resistance wiring, you can expect near the rated stall current when starting.