# Motor Choice Question

Hi Guys

I am doing a project where a camera would be mounted on the motor(Servo/Stepper). I want to rotate the camera 360 degrees (1 rotation) which will be controlled by a joystick. It will take a photo and and record/mark the current angle(angle reading need to be quite accurate).

I have a few questions:

1. Is there a unhacked servo motor that can do 360 degrees (1 rotation)?
2. Is it possible to read current position of a 360 degrees (1 rotation) on unhacked or hacked servo motor?
3. If I were to use a stepper motor, roughly how many degrees offset will there be? (Need to read a accurate angle)

Please define â€śquite accurateâ€ť - 5 degrees? 1 degree? 10 minutes of arc?

How heavy is the camera?

1. Is there a unhacked servo motor that can do 360 degrees (1 rotation)?

There are "winch servos" used on model boats that can turn 360 degrees or more.

1. Is it possible to read current position of a 360 degrees (1 rotation) on unhacked or hacked servo motor?

No. You tell the servo where to go and assume that is where it ends up.

1. If I were to use a stepper motor, roughly how many degrees offset will there be? (Need to read a accurate angle)

Not sure what you mean by 'offset'. If you know what angle the stepper is at when you start and you know how many steps you have moved the stepper you should know exactly where the stepper is pointing.

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MarkT:
Please define "quite accurate" - 5 degrees? 1 degree? 10 minutes of arc?

How heavy is the camera?

1-3 degree accuracy.

Weight of camera: ~150 grams

Hey johnwasser

Thanks for your reply. Will look into winch servos. I would probably hack the servo to get the position. What i meant to say was number of degrees inaccuracy does the stepper motor has.

anura92:
What i meant to say was number of degrees inaccuracy does the stepper motor has.

A typical stepper has 200 steps per revolution or 1.8 degrees per step.

Geared stepper motors often have thousands of steps per revolution.

Bonjour

j'ai trois programme et je vaurdais les mettre dans un seul programme est ce que y une possibilitĂ© d'appeller c'est 3 trois programme dans un seul programme sur le langage de arduino

merci les amis

The position accuracy of a winch servo may not be very good from what I've heard.

zoomkat:
The position accuracy of a winch servo may not be very good from what I've heard.

Using servo.writeMicroseconds() instead of servo.write() will give more resolution if not more accuracy. You get 1000 steps between 1000 and 2000 microseconds instead of 180 steps between 0 and 180.

johnwasser:

zoomkat:
The position accuracy of a winch servo may not be very good from what Iâ€™ve heard.

Using servo.writeMicroseconds() instead of servo.write() will give more resolution if not more accuracy. You get 1000 steps between 1000 and 2000 microseconds instead of 180 steps between 0 and 180.

From what Iâ€™ve seen most standard servos have ~5us dead band to limit hunting. In my servo tinkering a standard servo was capable of ~426 discrete steps in ~190 deg. of rotation. If the winch servo is geared to still use a one turn pot, then resolution per degree of rotation may be degraded compared to a standard servo.

An inexpensive, readily available, and well documented motor is the 28BYJ-48 5-Volt Stepper. For just a few bucks you get the motor and driver. Lots of library is avaialable. - Scotty

johnwasser:

anura92:
What i meant to say was number of degrees inaccuracy does the stepper motor has.

A typical stepper has 200 steps per revolution or 1.8 degrees per step.

Geared stepper motors often have thousands of steps per revolution.

Thanks. Will look in this too.

scottyjr:
An inexpensive, readily available, and well documented motor is the 28BYJ-48 5-Volt Stepper. For just a few bucks you get the motor and driver. Lots of library is avaialable. - Scotty

Are there libraries that allow me to move in degrees? Eg. instruct the stepper motor to move to 200 degrees.

In degrees.