Shaft rotation sensor

[Philip Rotor]

Hello
Help needed with circuit design for sensing slow shaft rotation, having two separate outputs. ON for either clockwise or counter clockwise rotation. OFF when shaft stationary.

Specification
Range of rotation: 180 degrees
Operating voltage: 12 vdc
Switched output: 12 vdc @ 1A
Shaft can have potentiometer / sensor at one end only

Any help appreciated.

PHILIP ROTOR

 

[KMoffett]

Philip,

I'm assuming that you can't monitor the power that drives the motor (?) that turns the shaft. What's the speed of rotation? Is the speed fixed or variable?

Ken

 

[Gary B]

What about a segmented disk sensor? Two bands minimum if you need to tell direction. If you need more resolution than can be achieved by minimum segment size, add another band offset by a half segment. You read the thing with a photo detector for each band and light source.

 

[Philip Rotor]

Hi Ken

I 'm sensing the rotation of a steering box output shaft, so rotation speed is variable and very slow.
This is a project I 've started to consider adding assistted steering to a classic car.

Many thanks for your interest.

Philip

 

[KMoffett]

How much of a change in angle of rotation do you need to sense for detecting motion? It's looking like a high resolution quadrature encoder, as Gary alluded to, would be the solution.

Ken

 

[Wade Hassler]

Here's a description of how shaft-encoders work and a way to make your own:
How to Build a Robot Tutorial - Society of Robots

 

[Philip Rotor]

Angle change sensing would start at 2 degree's. I think you are right about Gary's solution.

Philip

 

[KMoffett]

Actually, you wouldn't need a quadrature output, since direction isn't of concern. Just an optical interrupter with a 90 line/180° disk, followed by a retriggerable monostable multivibrator. Or, a 45 line disk followed be an edge-detector, and then a retriggerable monostable.

Ken

 

[Sceadwian]

Magnetize the shaft and use hall sensors. The actual magnetization in the appropriate pattern would be the hard part.