Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: bsamuels on November 13, 2010, 06:05:58 PM

Title: Are ESC's really necessary for controlling motors?
Post by: bsamuels on November 13, 2010, 06:05:58 PM
Do ESC's provide anything else other than speed control? I need propulsion for a robot, tried converting servos to continuous rotation, found out that it's a bitch to figure out which resistance will keep it at neutral, so am not looking at motors as an option. However, ESC's appear to be quite expensive (50 bucks? loool) and on first look seem to be unnecessary. Is it possible to get a motor to "go" using an analog port on the axon?
Title: Re: Are ESC's really necessary for controlling motors?
Post by: DUKELancelot on November 13, 2010, 07:26:05 PM
Quote
Do ESC's provide anything else other than speed control? I need propulsion for a robot, tried converting servos to continuous rotation, found out that it's a bitch to figure out which resistance will keep it at neutral, so am not looking at motors as an option. However, ESC's appear to be quite expensive (50 bucks? loool) and on first look seem to be unnecessary. Is it possible to get a motor to "go" using an analog port on the axon?

Uh, NO :(    (loool)

First off, do you even know what a Analog Port is. It's a input that RECEIVES a Voltage and is able to send the micro controller the number at a 8-32bit precision.

2. The Atmel ATmega640 can only withstand 20-30 mA per IO pin (A Standard DC motor pulls about 5000 mA at stall.) Thus placing a DC motor directly on a I.O pin would Fry/Kill your Axon instantly :P

3. A servo is nice because it has a built in ESC or Motor Driver, a gearbox, and a motor in a nice plug and play package. 

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ESC's appear to be quite expensive (50 bucks? loool)
A good assembled ESC or Motor Driver should run at $40-$5000.


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Is it possible to get a motor to "go" using an analog port on the axon?
[/quote] If you only want it to go only one way you could use a Power transistor.( not using a analog port of course.)

P.S This question has been ask before so I think a good hour of searching the forum for DC motors, and motor drives, and H-bridges would benefit you greatly.

As for a good quality Motor driver I recommend Pololu.com Motor drives.
Title: Re: Are ESC's really necessary for controlling motors?
Post by: rbtying on November 13, 2010, 09:41:42 PM
As for resistance on a servo, for pretty much 100% of servos, you could just glue the pot at the servo's measured 90deg.  No need to figure out resistance.
Title: Re: Are ESC's really necessary for controlling motors?
Post by: Soeren on November 13, 2010, 09:57:30 PM
Hi,

Do ESC's provide anything else other than speed control? I need propulsion for a robot, tried converting servos to continuous rotation, found out that it's a bitch to figure out which resistance will keep it at neutral, so am not looking at motors as an option.
You probably meant something else?


Is it possible to get a motor to "go" using an analog port on the axon?
No, but if you just want a motor to run, one direction, full speed, you can use a suitable transistor driven from a digital output. If you need speed control, same setup but use PWM on the output pin.

If you need speed control and direction, search the forum - I have posted a circuit to do both with a single transistor and a relay.