motion robot for video tracking.

hudson

I'm going to make a robotic platform mainly for a web cam to sit on. It will use continuous turn servo combined with a cog belt and pulley for turning the base of the device. However, I need a tilt axis so it can look up/down. I was thinking I would use basically the same setup just arrange it so the cog belt is vertical along with the motor and axis. My issue is if I use a single pulley and cog belt I can see a potential problem with the servo motor not turning from the weight applied to the axis... for example taking your hand and moving the servo would obviously move the servo armature eventually... I'm trying to figure out how much weight it would take... are there other robotic motors that can "lock". If anyone has experience with this type of scenario any input would be very much appreciated.

Bruce Bates

hudson -

Take a look at these brackets, and how they can be very easily used to make a pan and titlt mechanism from two ordinary R/C servos. Note the arrary of pictures beneath the product:
http://www.lynxmotion.com/Product.aspx?productID=286&CategoryID=87

It doesn't get much easier than that!

Regards,

Bruce Bates

hudson

Hehehe thanks for helping. I was chat'n up #electronics on freenode. They suggested using stepper motors because they hare a holding torque rating or some such specification? I'm not sure if I just want a camera or if I will have other things as well, but it seemed like a good idea. So now I just have to read up on stepper motors they look fun! I'm gonna make my own driver circuit.

Forrest

If the web camera is just a few ounces, then this servo mount may work www.budgetrobotics.com/shop/index.php?shop=1&cart=278401&cat=118&

kelvin james

Although i am a stepper motor advocate, i really can not see the use for one in a pan / tilt camera application, unless some type of accurate positional repeatability is required. Basically, you are just dealing with the camera view FOV , unless you want to see behind you. Most servos are in the 140-180 degree range of movement, which is more than enough when dealing with a cam. Servos are a lot smoother moving and easily controlled, but may be more expensive overall than steppers. If you want to look around, some 1/4 scale hobby servos can push 30 lbs. when geared, so i would not worry about anyone being able to move one when energized. Both are current hogs, steppers have the ability to power off at position, but then have little holding torque.

kelvin