How to find the rotation direction of a disc with sensor outputs?

[vlsi_freak]

Hi friends..

Below shown is a rotating disc which can rotate in both clk wise and anti clk wise.
Its some part is shaded. When the shahded part reaches the sensor a or b, it turns off, when tha white part of the rotating circle reaches both sensors gives a voltage. By taking the sensor outputs how can we find the direction of rotation of the circle??

 

[vlsi_freak]

Re: Disc Problem

Hi..

Can anyone suggest a solution for this.

Thanks

 

[A.Anand Srinivasan]

Re: Disc Problem

do the shading such that the adjacent are coded as binary with white and black.... paint the sections in ascending order so by decoding the number got the direction can be got........

 

[sanjay11]

Re: Disc Problem

There are 2 things.
1. If is disc is stable and started moving then u can capture first sensor followed by second sensor detection based on that u can figure out the direction.
Note : initial idle state is reference point.
2. If the reuqirement is to catch the direction when the disc is rotating, u need one more sensor. You can write a state machine then to decide the direction based upon sensor outputs, to decide the direction.