Brushless can definitely go way faster than you need. My brushless motor is labeled to be able to go 70 mph (31.3 m/s so a theoretical potential run time of like .3 seconds) when on a 3 kg car and my car is like 1 kg. I've experimented with a lot of brushed motors and it doesn't seem like any 9 volt powered motors can provide enough torque and rpm to get a decent time, but i could be wrong. The best dc motor i found, with the optimal gear ratio and wheel size, I was just barely able to get a 5 second time. With brushless i'm able to break 1.5 (of course i have to use the correct algorithm for accelerating to avoid slipping and inconsistency).JonB wrote:antoine123 wrote:I really am not to experienced in motors so is a brushless motor going to give you a significant advantage over a brushed dc motor with decent torque and rpm's. Can you get a powerful brushless motor at the allowed voltage?
Well, you can get very fast brushless motors- which is really what you need.
Electric Vehicle C
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Re: Electric Vehicle C
Innovation =/= success
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Re: Electric Vehicle C
Actually, It isn't geared by much at all, it is nearly 1:1, perhaps 1:1.5 or so, not 100% sure. But I had used it at 7:1 and i was able to get within 10 cm and sometimes 5. Now i can do 5 consistently for the most part and once testing is done I SHOULD be able to get even closer, just need to do more testing because I'm changing my code at the moment.Bazinga+ wrote:I'm guessing you geared it a lot or some other solution, but the problem with gearing is that you sacrifice your accuracy. If you gear your steppers 1:2 then that means they are about half as accurate. This is usually not a problem since steppers are really accurate, but once you gear it more, the problem becomes very apparent.InfiniCuber wrote:My run time is 2.6 and i found a way to get it faster, although I have to admit it has been a long journey and a PAIN to do.windu34 wrote: Agreed. I highly recommend staying away from steppers due to speed problems.
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Re: Electric Vehicle C
If you are really getting the speeds you speak of using the stepper motors, then thats pretty good.
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Re: Electric Vehicle C
One of out teams wants to use a Vex microcontroller to act as a conduit for electricity to the motor and to use a coupled encoder to shut off the power. Even tho it is only acting as an on/off switch, some of the group thinks that it might not be allowed by the state ES under the interpretation of "anything" that controls the motor can not have a self contained additional power supply. The motor would be powered by the allowable battery pack thru a voltage step up device.. The microcontroller is acting as nothing but an "off" switch.
Comments please.
Comments please.
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Re: Electric Vehicle C
I'm not sure I understand: is the microcontroller in series with a battery pack, or does it have an additional battery that powers it?retired1 wrote:One of out teams wants to use a Vex microcontroller to act as a conduit for electricity to the motor and to use a coupled encoder to shut off the power. Even tho it is only acting as an on/off switch, some of the group thinks that it might not be allowed by the state ES under the interpretation of "anything" that controls the motor can not have a self contained additional power supply. The motor would be powered by the allowable battery pack thru a voltage step up device.. The microcontroller is acting as nothing but an "off" switch.
Comments please.
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Re: Electric Vehicle C
Finally someone does it... Did you have any issues hitting resonance points as you accelerate?InfiniCuber wrote:My run time is 2.6 and i found a way to get it faster, although I have to admit it has been a long journey and a PAIN to do.
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Re: Electric Vehicle C
My interpretation of the rules is that if any electricity used to power the motor is controlled in any way by the Vex microcontroller (even if the Vex is just a fancy on/off switch), then the Vex microcontroller's power supply also counts towards the limit specified in the rules.retired1 wrote:One of out teams wants to use a Vex microcontroller to act as a conduit for electricity to the motor and to use a coupled encoder to shut off the power. Even tho it is only acting as an on/off switch, some of the group thinks that it might not be allowed by the state ES under the interpretation of "anything" that controls the motor can not have a self contained additional power supply. The motor would be powered by the allowable battery pack thru a voltage step up device.. The microcontroller is acting as nothing but an "off" switch.
Comments please.
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2013 Events: Thermo, Circuit Lab, Experiment, Robot Arm
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2016 Events: Astro, Cell Bio, Chem Lab, Electric Vehicle, Time, Protein Modeling, Wind Power
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Re: Electric Vehicle C
Agreedfinagle29 wrote:My interpretation of the rules is that if any electricity used to power the motor is controlled in any way by the Vex microcontroller (even if the Vex is just a fancy on/off switch), then the Vex microcontroller's power supply also counts towards the limit specified in the rules.retired1 wrote:One of out teams wants to use a Vex microcontroller to act as a conduit for electricity to the motor and to use a coupled encoder to shut off the power. Even tho it is only acting as an on/off switch, some of the group thinks that it might not be allowed by the state ES under the interpretation of "anything" that controls the motor can not have a self contained additional power supply. The motor would be powered by the allowable battery pack thru a voltage step up device.. The microcontroller is acting as nothing but an "off" switch.
Comments please.
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Re: Electric Vehicle C
I believe there was a rules clarification or FAQ about this...windu34 wrote:Agreedfinagle29 wrote:My interpretation of the rules is that if any electricity used to power the motor is controlled in any way by the Vex microcontroller (even if the Vex is just a fancy on/off switch), then the Vex microcontroller's power supply also counts towards the limit specified in the rules.retired1 wrote:One of out teams wants to use a Vex microcontroller to act as a conduit for electricity to the motor and to use a coupled encoder to shut off the power. Even tho it is only acting as an on/off switch, some of the group thinks that it might not be allowed by the state ES under the interpretation of "anything" that controls the motor can not have a self contained additional power supply. The motor would be powered by the allowable battery pack thru a voltage step up device.. The microcontroller is acting as nothing but an "off" switch.
Comments please.
EDIT: FAQ. Here it is.
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Re: Electric Vehicle C
Actually, no I didn't! The acceleration is pretty smooth really. Acceleration is very necessary to get to the higher speeds, so I was a bit concerned about resonance but encountered none of it!iwonder wrote:Finally someone does it... Did you have any issues hitting resonance points as you accelerate?InfiniCuber wrote:My run time is 2.6 and i found a way to get it faster, although I have to admit it has been a long journey and a PAIN to do.
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