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Topic: How to attach a potentiometer to a servo motor shaft (Read 2298 times) previous topic - next topic

birddseedd

Jan 11, 2019, 04:44 am Last Edit: Jan 11, 2019, 05:05 am by birddseedd
I searched google but it was all about controlling a servo with a potentiometer. Thats not what i want to do. I want to have the servo motor turn the potentiometer so i can read the position of the servo motor. I know they often come with POs built in, but i will be turning the motor off and setting the position by hand. I looked at pics of them but i dont see how i would attach it to a shaft.

Thanks

raschemmel

#1
Jan 11, 2019, 05:02 am Last Edit: Jan 11, 2019, 06:40 am by raschemmel
Quote
I want to have the servo motor turn the potentiometer so i can read the position of the servo motor.

I know they often come with POs built in, but i will be turning the motor off and setting the position by hand.

 I looked at pics of them but i dont see how i would attach them to a shaft.  
"they" ?
"them" ?



Get a shaft coupler. Done. If you have heard of motors, (which, BTW, have SHAFTS)
then you must have heard of shaft couplers, since that's what everyone uses with their motors.

What exactly is your electronics background ?
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

Willpatel_Kendmirez

Nice save on the edit of the rude, condescending post there raschemmel; I was responding but it's a pity I didn't grab a quote in time.


birddseedd

I may need to pick out a Servo motor first. I found a couple of hours, they look simple enough to build. But all of the servo Motors on Amazon seem to be for little plastic robots. I need something big

Willpatel_Kendmirez

But all of the servo Motors on Amazon seem to be for little plastic robots. I need something big
So just to clarify, you are talking of the ones that look more like steppers in those big nema style casings, not the normal Arduino world rc servo?

(fwiw, adafruit do have the latter with 4 wires, the extra one being a take-off from the internal pot to bring the position out.)




raschemmel

#5
Jan 11, 2019, 05:32 am Last Edit: Jan 11, 2019, 06:09 am by raschemmel
So what's wrong with these ?


Quote
I may need to pick out a Servo motor first. I found a couple of hours, they look simple enough to build. But all of the servo Motors on Amazon seem to be for little plastic robots. I need something big
I worked with the kind of servo motors you are talking about with wafer lifters and they are hella
expensive.

Servo motors


What are the specs for the motor in question ?
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

Willpatel_Kendmirez

I'll repeat it for your benefit ...
(how rude is that ? Am I not allowed to say that ?)

Well obviously even you had second thoughts about having said it, else you wouldn't have removed it.


raschemmel

#7
Jan 11, 2019, 05:50 am Last Edit: Jan 11, 2019, 06:14 am by raschemmel


Quote
I may need to pick out a Servo motor first. I found a couple of hours, they look simple enough to build. But all of the servo Motors on Amazon seem to be for little plastic robots. I need something big  
Have you considered posting a description of you project with enough details for someone to pick out a servo motor or do want to do that yourself ?


Quote
I know they often come with POs built in
POs ?

What is that ?
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

wvmarle

I want to have the servo motor turn the potentiometer so i can read the position of the servo motor.
That just doesn't make much sense as you always know where a servo is: at the position you tell it to go.

If it's not there, then there's a malfunction of the motor, or it's not strong enough. Either way that's a design error, and should never happen. Therefore having a pot to read back the position of a servo is unnecessary.

That, or your description of the problem is flawed.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Willpatel_Kendmirez

.... you always know where a servo is: at the position you tell it to go.

If it's not there, then there's a malfunction of the motor, or it's not strong enough. Either way that's a design error, and should never happen. Therefore having a pot to read back the position of a servo is unnecessary.

That's very simplistic, and neglects the fact that it takes time for a commanded movement to happen, even when things are all nominal. The next step in a process might rely on this process completing, and only closed loop control (which is what this is) will tell you that.

And then, when things do go wrong, which is not necessarily a design or manufacturing flaw, but perhaps unusual untoward and unforeseen circumstances preventing completion of a commanded movement, it's imperative that the system as a whole, knows that. It would need to prevent that next step happening, or perhaps reverse the incomplete movement back to a checkpoint.

If what you say is correct, there would be no need for closed loop control and everything would work on open loop, dead-reckoning.




birddseedd

That just doesn't make much sense as you always know where a servo is: at the position you tell it to go.

If it's not there, then there's a malfunction of the motor, or it's not strong enough. Either way that's a design error, and should never happen. Therefore having a pot to read back the position of a servo is unnecessary.

That, or your description of the problem is flawed.
I will be turning the servo off to move it by hand

raschemmel

The OPhas not specified Radio Control servo.
He simply stated "serbo motor".
If he means RC servo , it should be explicitly stated as such .
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

birddseedd

The OPhas not specified Radio Control servo.
He simply stated "serbo motor".
If he means RC servo , it should be explicitly stated as such .
Not radio controlled

raschemmel

Then the previous comment about knowing the position because the Servo command takes a position argument does not apply.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

wvmarle

Why does it matter to a servo whether the command is relayed over a remote control system?

Unfortunately OP hasn't provided info on the actual servo in use, nor on the actual application, and only little information on why he would want to do this.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

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