how to make a stepper motor step gradually?

Hello,
I have a stepper motor which rotates a platform at 3.6deg/step. There's an object on the platform. At each step I have to take a photo of the
object. The motor is in full step mode. The problem is, when I'm performing a step for the next photo, the platform quickly moves (quite brutally) to the new position, and the object slips on the platform (not enough adderence I suppose). What I want to know is if there's an easy method to make the platform/motor move slowly to the new position. I don't want to do microstepping or the like, I need the simplest idea.
Could this be done with capacitors? Any other ideas?
Thanks, Cosmin.
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You could try just reducing the drive voltage to the stepper to reduce torque. That may be enough, but it could en up being marginal (missing steps with a heavy load). A superior solution is 'microstepping'. It involves ramping the applied voltages to the windings using PWM and can make for much smoother motion and greater positioning accuracy (though there are practical limits on how much additional accuracy can be gained).
Tim
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On Fri, 02 Jun 2006 13:34:50 +0100, Tim Auton

Depending on the setup, attacking the problem at another point might be easier. For example, using a belt-driven system with the small pulley on the stepper, large on the turntable, and a "soft" resilient belt.
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more specifically i think you mean you want to reduce the current. in dc motors the torque is proportional to current, speed is proportional to voltage.
although by reducing voltage i suppose in effect, you are reducing the current.
if you reduce the torque enough you should be able to slow the angular acceleration down at each step.
Tim Auton wrote:

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CosminB [BRT] wrote:

There is not an easy electronic solution to my knowledge, since you rule out microstepping.You can consider mechanical solutions to damp it a bit; for example, if you decouple the platform and motor, recouple them through a helical spring, and add oil-damped vanes to the platform, you might achieve the desired effect (at a loss of positional accuracy).
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Maybe reduce the voltage or current driving the stepper so it had less power? A simple resistor might work.
Or increase the mass of the platform so the power of the stepper would create less of a jerk.
Gear down the motor so that each step created less of a jerk and change your code to make it step more times.
Gear it down using a rubber drive belt to reduce the shock (like some of the old record turntables? Or use some type of soft coupling on the shaft to reduce the shock?
Attach your object more firmly to the platform so it didn't slip?
That's about all I can think of.
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Someone else mentioned a spring type of dampener. I think another easy solution would be to use a piece of rubber as the coupler. Perhaps a length of pencil eraser (the white kind, which seem to last much longer before rotting). The lenght of the rubber would control the softness or stiffness.
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