Electric Vehicle C

[windu34]

What are you using infintycuber?

[Bazinga+]

What are you using infintycuber?

I'm confounded already... What is this mysterious design...

[andrewwski]

Does this mean the brushless motor-arduino combo is now dead? With the amount of voltage the arduino is going to use, there's not much left for the motor. As we saw in that other thread, even if you step up the voltage, it messes with the ESC. Using an arduino is suddenly a lot more difficult.

Power doesn't work this way - voltage is not "used up" unless you're wiring things in series, in which case the voltage drop across a component is proportional to its current (linearly if resistance is constant). But you typically don't want to wire devices in series.

Rather, you would want to run the devices in parallel, where the voltage delivered to each parallel component is the same, but current can be "used up" (assuming a constant current source). The Arduino does not draw much current - about 25 mA at 5V - which is pretty much insignificant compared to the motor. So it won't really have much of an impact. Since batteries have some amount of internal resistance, any current draw will cause a voltage drop - but the low consumption of the Arduino will not have a significant impact on the total voltage. What I would be concerned about, rather, is the motor causing a voltage drop below the minimum voltage required for the Arduino - but that does not actually seem like it will be the case.

Alkaline typically has high internal resistance but NiCd/NiMH typically have lower internal resistance. I've found that with a charged 7.2V 2500 mAh NiMH pack, a 380 or 540 motor does not cause a voltage drop significant enough to drop out a 7805 regulator. So you can use a regulator to supply 5V to an Arduino from the same 7.2V pack that you're running the motor on. You can get low dropout (LDO) regulators that can provide a regulated 5V with an input voltage of about 6V, which should give you plenty of margin assuming you're keeping your batteries charged. Even the 5V regulator built into the Uno, for example, drops out at about 6.2 V - which should be fine. So even if you're using a higher-current motor (which I suppose is quite possible with some brushless motors), it does not seem like there should be a problem using an Arduino.

So no, I don't see it as a significant roadblock to using an Arduino/ESC, presuming you're using a decent (Sub-C cell or larger) NiCd or NiMh pack.

[InfiniCuber]

What are you using infintycuber?

I'm confounded already... What is this mysterious design...

Stepper motors, anyone?

[Bazinga+]

What are you using infintycuber?

I'm confounded already... What is this mysterious design...

Stepper motors, anyone?

I dont know of any step motors which can give you a good run time (2-3 sec), but they definitely give you good accuracy. Unfortunately, speed is multiplied by 10, so being 2 or 3 seconds slower than someone else is the same as automatically being off by 20-30 cm.

[windu34]

I'm confounded already... What is this mysterious design...

Stepper motors, anyone?

I dont know of any step motors which can give you a good run time (2-3 sec), but they definitely give you good accuracy. Unfortunately, speed is multiplied by 10, so being 2 or 3 seconds slower than someone else is the same as automatically being off by 20-30 cm.

Agreed. I highly recommend staying away from steppers due to speed problems.

[InfiniCuber]

Stepper motors, anyone?

I dont know of any step motors which can give you a good run time (2-3 sec), but they definitely give you good accuracy. Unfortunately, speed is multiplied by 10, so being 2 or 3 seconds slower than someone else is the same as automatically being off by 20-30 cm.

Agreed. I highly recommend staying away from steppers due to speed problems.

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.

[antoine123]

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?

[JonB]

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.

[Bazinga+]

I dont know of any step motors which can give you a good run time (2-3 sec), but they definitely give you good accuracy. Unfortunately, speed is multiplied by 10, so being 2 or 3 seconds slower than someone else is the same as automatically being off by 20-30 cm.

Agreed. I highly recommend staying away from steppers due to speed problems.

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.

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.