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Re: Electric Vehicle C
Posted: September 5th, 2015, 11:24 am
by windu34
Regardless, it will be interesting to see which direction teams decide to take whether it be fast motors with creative breaks or precise motors with creative speed increasing (gearing).
Re: Electric Vehicle C
Posted: September 7th, 2015, 1:48 pm
by retired1
If you are using a stepper motor it will need to be geared so that the driven tires do not spin.
I seriously doubt if many teams will get to sub centimeter accuracy. Everybody should be able to get to under 5 cm which is going to make speed very important since time is multiplied by 10.
It would be nice if all states had photogate timing because 3 people can rarely time within 0.1 seconds of each other.
Re: Electric Vehicle C
Posted: September 7th, 2015, 3:03 pm
by windu34
The time problem was a huge problem during the 2008-2009 season which is probably way they changed the event from predicting a time to just going as fast as possible because at the regional and state level, there shouldn't be too many people with really good time and at the nats level, there will be a photogate system so it won't be a problem.
Re: Electric Vehicle C
Posted: September 10th, 2015, 11:04 am
by Flavorflav
JonB wrote:Flavorflav wrote:I strongly suspect speed and torque will not be very important in this event, but as iwonder said we won't really know anything until we see the rules.
Rules are out. Speed is part of the score (time score). Basically, it's how they determined run time for scrambler.
I must say that I am really, really surprised there are not more restrictions in the rules (brushed vs brushless).
Well, there goes my credibility! I was expecting to see |predicted-actual|/actual again. This makes for a very different event.
Re: Electric Vehicle C
Posted: September 10th, 2015, 3:01 pm
by windu34
Yeah I was expecting that too, I even built a perfect vehicle over the summer with stepper motors for extreme precision. Back to square one.
Re: Electric Vehicle C
Posted: September 11th, 2015, 6:15 am
by chalker
Some general insight on the 'brushed' vs. 'brushless' issue. Here's a quick experiment: do a google image search for each type. Notice how many different shapes, sizes, and form factors each type come in? It can be a little overwhelming and hard to distinguish by sight which type is which. We will have over 300 SO tournaments this year all over the country, each with a different set of event supervisors. Since those supervisors are volunteers, many won't have any background in motor types and would have trouble telling whether a given vehicle is brushed vs. brushless (particularly when the motor is embedded deep within the chassis.
When writing the rules, we try to balance the burden we are placing on event supervisors with the ability to have a generally 'level playing field' for all teams.
Re: Electric Vehicle C
Posted: September 11th, 2015, 8:17 am
by windu34
Thanks for the insight chalker, that make a lot of sense.
Do you know why the committee didn't go with predicted time (used in 2008-2009) instead of the fastest time?
Re: Electric Vehicle C
Posted: September 11th, 2015, 9:29 am
by bearasauras
The last time we did predicted time instead of run time, it was more advantageous to run it the vehicle very slowly, especially right before it stopped. It made it challenging for the Event Supervisors to determine when the vehicle stopped.
Re: Electric Vehicle C
Posted: September 11th, 2015, 12:45 pm
by windu34
bearasauras wrote:The last time we did predicted time instead of run time, it was more advantageous to run it the vehicle very slowly, especially right before it stopped. It made it challenging for the Event Supervisors to determine when the vehicle stopped.
I would think it would be easier for event supervisors to record run time accurately when the times are slower because reaction time has less of an effect.
Re: Electric Vehicle C
Posted: September 11th, 2015, 1:46 pm
by retired1
That puts a premium on using photogate timers as much as possible. Using lasers significantly reduces timing errors. Having timers practice several times has proven to decrease the variability between timers.
Another thought, If you go really fast thru the 8.5m gate you are going to have a bit of a problem stopping the car if the ES choses to have the end point at the allowable 9.0 m.