## Motor Breaking HELP

GoldDigger
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### Motor Breaking HELP

I an currently using motor breaking for my vehicle following the diagram on the EV wiki page. However, my car goes hella fast like 1.7 seconds, and its not breaking as quick as i would like it. The car tends to skid with a 5-10 centimeter deviation. Therefore, I need to amp up my brakes to bring that deviation down to 0-3 centimeters..... How would i do that? Do i add resistors or capacitors and where? And could some one explain how electromagnetic breaking works? All the videos on youtube just go right over my head, with College students throwing bunch of physics laws and using high caliber scientific instruments that i have no idea what they mean. Thanks!!!!

Bazinga+
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### Re: Motor Breaking HELP

Which motor are you using? Regardless, you need to make sure you're not braking TOO fast. If you make the deceleration magnitude greater than gravity times your friction coefficient (so let's just say 9.8 meters/second squared for now) then it will slip and cause inconsistency. To make your car more consistent you would want to slow down slower, not faster. So if your wheels literally just stopped moving then your car would skid to a stop, which means it will be very dependent on the type of floor and stuff on the floor.
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GoldDigger
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### Re: Motor Breaking HELP

I currently am using a 9V DC motor powered by a single 9V battery. I am not sure how I would slow down my vehicle without programming the vehicle. I use a lever microswitch and a wingnut and basically cut of the power as mechanical breaks are applied. My switch turns off my motor 3 full turns of the wheels before the wingnut slams the mechanical breaks, allowing for a total of 75 centimeters of technically slowing down, but that is the best I got. Hope that explains how my vehicle works. However, I dont know how to make my vehicle brake faster, and how to introduce electrical breaking. Also, how do electromagnetic breaks work?

Thanks guys

Bazinga+
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### Re: Motor Breaking HELP

GoldDigger wrote:I currently am using a 9V DC motor powered by a single 9V battery. I am not sure how I would slow down my vehicle without programming the vehicle. I use a lever microswitch and a wingnut and basically cut of the power as mechanical breaks are applied. My switch turns off my motor 3 full turns of the wheels before the wingnut slams the mechanical breaks, allowing for a total of 75 centimeters of technically slowing down, but that is the best I got. Hope that explains how my vehicle works. However, I dont know how to make my vehicle brake faster, and how to introduce electrical breaking. Also, how do electromagnetic breaks work?

Thanks guys

I dont think that its plausible (or at least i'm not sure how) to make an accurate car that travels 8 meters in less than 2 seconds without using a micro-controller. Consider either switching to a micro-controller or slowing down your vehicle. Also I advise against using a 9 volt battery since they discharge very fast and your results will differ based on the charge of the battery. But I think most of your inconsistency is because you dont give enough time for the car to slow down before it hits the wingnut, so you should also try giving the car more distance to slow down before the wingnut stops it.
Last edited by Bazinga+ on March 22nd, 2016, 4:50 pm, edited 1 time in total.
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Bazinga+
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### Re: Motor Breaking HELP

Bazinga+ wrote:
GoldDigger wrote:I currently am using a 9V DC motor powered by a single 9V battery. I am not sure how I would slow down my vehicle without programming the vehicle. I use a lever microswitch and a wingnut and basically cut of the power as mechanical breaks are applied. My switch turns off my motor 3 full turns of the wheels before the wingnut slams the mechanical breaks, allowing for a total of 75 centimeters of technically slowing down, but that is the best I got. Hope that explains how my vehicle works. However, I dont know how to make my vehicle brake faster, and how to introduce electrical breaking. Also, how do electromagnetic breaks work?

Thanks guys

I dont think that its plausible (or at least i'm not sure how) to make an accurate car that travels 8 meters in less than 2 seconds without using a micro-controller. Consider either switching to a micro-controller or slowing down your vehicle. Also I advise against using a 9 volt battery since they discharge very fast and your results will differ based on the charge of the battery.

CORRECTION: It is possible if you add a capacitor in parallel with your motor. This way the capacitor will charge up while you are powering the motor and then as soon as you switch the power off the capacitor will still power the motor for a bit making the car slow down more consistently (not brake because of the internal resistance of the motor). To brake you would have to reverse the polarity so the motor applies torque backwards, but it seems that this is working out for you pretty well.
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GoldDigger
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### Re: Motor Breaking HELP

So where would the capacitors go on the circuit?

Bazinga+
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### Re: Motor Breaking HELP

GoldDigger wrote:So where would the capacitors go on the circuit?

In parallel to the motor (one end before the motor in the circuit one end after the motor), but now that i think of it it probably wont help you much since the motor resistance isn't whats stopping you in the end. Just make it so the car has a bit more distance to slow down before the wingnut comes into action (like .9-1 meter).
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iwonder
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### Re: Motor Breaking HELP

The capacitor is an interesting idea, it'd need to be very large, but it might work well. You could also probably set up the switch (double throw) to short the motor together when it's enabled, shorting the motor will make it act like a brake for smaller DC motors (large motors will need a resistor in series).

The way it sounds you're only using 1 of 2 axles to brake right now, anything you can do to brake with both axles will help dramatically.
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Bazinga+
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### Re: Motor Breaking HELP

iwonder wrote:The way it sounds you're only using 1 of 2 axles to brake right now, anything you can do to brake with both axles will help dramatically.

Would it? In theory it shouldn't.
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GoldDigger
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### Re: Motor Breaking HELP

Yeah one axle drive axle with gear ox and motor, while the other axle has the wingnut breaking and microswitch.

My car broke today. I'm screwed.... It originally traveled straight for up to 12 meters with only 10 cm of curvature, but now it f***ing curves 30 cm at just the 5 meters mark. Do i just kill me myself? I think i should

samlan16
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### Re: Motor Braking HELP

GoldDigger wrote:My car broke today. I'm screwed.... It originally traveled straight for up to 12 meters with only 10 cm of curvature, but now it f***ing curves 30 cm at just the 5 meters mark. Do i just kill me myself? I think i should

Um, no. We all deal with technical issues on our builds.

Try aligning your wheels again. If that fails, consider using a microprocessor to cut power to your motor instead of physical brakes.
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Bazinga+
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### Re: Motor Breaking HELP

GoldDigger wrote:Yeah one axle drive axle with gear ox and motor, while the other axle has the wingnut breaking and microswitch.

My car broke today. I'm screwed.... It originally traveled straight for up to 12 meters with only 10 cm of curvature, but now it f***ing curves 30 cm at just the 5 meters mark. Do i just kill me myself? I think i should

If time is an issue then you just need to find a quick way of realigning/adjusting one of your axles. If that's not possible then check if it curves consistently. If its curving consistently then just calibrate it with a curve and change the angle at which you launch it every time Not great but it'll work.
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iwonder
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### Re: Motor Breaking HELP

Bazinga+ wrote:
iwonder wrote:The way it sounds you're only using 1 of 2 axles to brake right now, anything you can do to brake with both axles will help dramatically.

Would it? In theory it shouldn't.

How wouldn't it?
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Bazinga+
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### Re: Motor Breaking HELP

iwonder wrote:
Bazinga+ wrote:
iwonder wrote:The way it sounds you're only using 1 of 2 axles to brake right now, anything you can do to brake with both axles will help dramatically.

Would it? In theory it shouldn't.

How wouldn't it?

It wouldn't help with his problem because you don't want both axles to completely stop moving because then the car will still skid to a stop. You want the axles to constantly deccellerate to a stop and be able to avoid error in skidding.
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windu34
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### Re: Motor Breaking HELP

Braking with both axles should help because there will be more contact with the floor thus the coefficient of friction should be increased
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