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remote webcam

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Kane2oo2

New Member
hey all
this is the project idea.
I will take an ordinary webcam and want to fix it to 2 suitable mechanisms which will enable me to rotate the camera left/right and up/down.
This will be controlled by a PIC and will eventually be linked to the computer.

The problem i have is i dont know what to use to turn/rotate the camera..

should i use stepper motors/servos...or what?
id rather not use stepper motors as this would be an expensive option and i want to make it as cheap/simple as possible.

Any ideas?

Thanks Guys
Kane
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Kane2oo2 said:
hey all
this is the project idea.
I will take an ordinary webcam and want to fix it to 2 suitable mechanisms which will enable me to rotate the camera left/right and up/down.
This will be controlled by a PIC and will eventually be linked to the computer.

The problem i have is i dont know what to use to turn/rotate the camera..

should i use stepper motors/servos...or what?
id rather not use stepper motors as this would be an expensive option and i want to make it as cheap/simple as possible.

Use servo's, they are cheaper and more powerful than steppers, also they provide 'absolute' positioning, whereas steppers are only 'relative'.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Kane2oo2 said:
thanks...
do servos need any special type of drive? or do you just supply a voltage?

Kane

They just require an HT supply (about 6V or so), and a variable width pulse - between 0.5mS and 1.5mS wide on the input, every 20mS or so. The width of the pulse tells the servo where to position it self.
 

falleafd

New Member
No Nigel,

I'm not agree with you in this case. For a auto-camera, we should use the stepper. The holding torque of a stepping is stronger than servo motor, because the magnetic field inside the stepping is constant when you hold it.

And if we use a big servo, it will bigger than a stepping to get the same holding torque.

In fact, they used stepping for auto-camera like in this application. And Douglas W. Jones is one of the professors who build those kinds of auto-camera.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
falleafd said:
No Nigel,

I'm not agree with you in this case. For a auto-camera, we should use the stepper. The holding torque of a stepping is stronger than servo motor, because the magnetic field inside the stepping is constant when you hold it.

And if we use a big servo, it will bigger than a stepping to get the same holding torque.

I would disagree there, a servo has loads more power than a stepper, and likewise loads more holding power, also how do you know where the stepper motor is positioned? - it hasn't got absolute positioning like a servo.
 

falleafd

New Member
Because the camera need a slow speed to turn, therefore, the stepping give strong torque at low speed. And we well know exactly the position of the stepping. And if we need a feedback, we can add an encoder to the motor.

The fact that the servo creat strong torque because of its gear box inside the motor. It's not the real torque from the motor. Therefore, if we also use the gear box to the stepper, we will get stronger torque than the servo. The servo hold the rotor buy continuously changed magnetic field, however, the stepper hold the rotor by constant.

And I saw in most of auto-camera, like this application, they used steppers.

yes, perhaps, for a small webcam, for example, a servo will be good. But I don't think it's good for heavier camera. Because it will vibrate with the magnetic field.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
falleafd said:
Because the camera need a slow speed to turn, therefore, the stepping give strong torque at low speed. And we well know exactly the position of the stepping. And if we need a feedback, we can add an encoder to the motor.

That's the point, you DON'T know the absolute position of a stepper motor, only a position relative to where it last was (and even then, only if it didn't miss any steps) - with a servo you know it's absolute position at all times.
 

stef

New Member
RC servo's would do fine, as they're cheap and readily available. If you need to see the images on screen as the camera moves, you can slow the servo down by "stepping" successively in software untill the position is reached.

To implement the sync & signal pulses should be easy as normal RC rx's use 4.8V anyway, so you should be able to drive the signal line of the servo straight from the mc port. No stepper control IC etc. You just have to get the timing right. :)
 

tansis

New Member
The name escapes me at the moment but do recall a singles bar/cafe
where every table has a webcam with servo mount. The system seemed to work quite well and comercial hardware and webcam freeware / project info are to be found on the web.
 

yogeshwar_ade

New Member
hi,
i am going to prpare a project on topic " Industrial Robo". Have you any idea on this topic which will make my project more applicable in Industries.
my mail is
yogeshwar_ade@yahoo.co.in
 
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