# servo motor vs stepper motor

i was given two DC servo motor to do a self stabilizing platform project.
knowing that it is better to use closed loop stepper motor to given feedback, it is possible or is there any way to use an open loop DC servo motor to achieve the same feedback function as the stepper motor???

Adafruit sell modified servos with a feedback wire: perhaps you can mod yours like that?

my teacher insist that it is possible to be able to create a stabilizer without a feedback of the motor.
is it really possible to do that?

my current state is that i am able to read the angle shifted from the imu , but how am i suppose to do for the coding in order to know the correct servo angle without feedback?

Arduinolearner9:
my teacher insist that it is possible to be able to create a stabilizer without a feedback of the motor.
is it really possible to do that?

I doubt it: it relies on the assumption that the servo actually managed to reach the angle you commanded it. If it got jammed somehow you would not know that and you would assume it had finished moving.

i really very lost in my teacher's theory, use the imu detected angle eg. 20 degree and divide by 60 then move the servo 6 degree in one second etc... any clue what he is referring to?????
becus i really think the motor need a feedback to move that 6 degree on top of the current angle eg (currentangle + 6 degree???)

Arduinolearner9:
i really very lost in my teacher's theory, use the imu detected angle eg. 20 degree and divide by 60 then move the servo 6 degree in one second etc... any clue what he is referring to?????
becus i really think the motor need a feedback to move that 6 degree on top of the current angle eg (currentangle + 6 degree???)

Yeah....... I can see what you mean. That is.... I see what you mean by it not making sense.

The proper plan is to work toward reducing that tilt angle in a nicely controlled manner. This involves measuring the angle (eg. 20 degree), then make a motor turn something (eg wheels) in the direction that makes the tilt angle smaller and smaller until the tilt angle reaches relatively small values.

Ah ok then by Southpark's description it's not servo feedback we need as such (as in, did it get where we told it to go) but rather how are we doing with getting the table back to level.

hmmmm, so with the sensor measuring the angle angle that has been tilted, what should i do the get back the same leveling? to be honest i really bad at arduino, i nvr had contact arduino until i was given this project

Well first I think it might be best to design the equipment, then establish the relationship between tilt angle and the servo position.

Reason I say that is, if the angle is out, you need to know if that implies say a clockwise or anticlockwise movement of the servo. You can't just randomly move the servo in the hope that it makes the angle better; it might make it worse. (Like you know that if the bath water is too cold, add hot water. You don't randomly add cold water....) You need to know what direction your change will have on the process.

But that said I know nothing about control other than odds and ends I've picked up in the forum....

my teacher had told me to setup something like this with the sensor placed on top of the pcb.

We can't see that image.

You need to attach it with the link under the box where you type. Choose reply not quick reply else the link isn't there.

sorry i attached the pic wrongly, this is the pic

OPâ€™s pic hereâ€¦

ya, the pic is uploaded in landscape ..... sorry

so with this setup, when the sensor measured the angle , what should i do to get back the same leveling?? btw thanks alot for willing to help out.

In simple terms you need to make a small movement of the motor and check the angle again. If it is still wrong make another small movement. Continue until the angle is correct.

...R

Arduinolearner9:
so with this setup, when the sensor measured the angle , what should i do to get back the same leveling??

Decide which way the servo should turn I'd guess, and then move it a little that way. Measure the angle. Move a bit further, or back a bit....

I'm no expert, that's what logic tells me.

Incorporate a bit of proportional control by moving the servo more if the error is big and only move a little if the error is small.

Do some experimenting....