Determining the direction of rotation of a wheel

[MattNew]

Homework Statement

Hello All.
I am trying to design a system to determine the direction of rotation of a wheel.
I do not have access to a flywheel but only the wheels inner face.
Can anyone please recommend a sesnor or soultion to help me?
Many thanks

Homework Equations

The Attempt at a Solution

I have found a few hall effect sesnors with a quadrature output, which I should be able to use but unfortunatley they all seem to require like an encoder wheel or flywheel teeth. There are some ICs that do this but nothing that is roust enough for my application.

 

[vk6kro]

There is a possible way of doing this easily. I haven't tried it (I just thought of it), but it seems like it would work.

Make a S-R flip flop and put a LED on the Q output of it.

Glue a strong magnet to the wheel.

Have two Hall switches near each other and near the magnet when it passes. Only one Hall switch should turn on at a time.

Connect one Hall switch to the SET input and one to the RESET input of the S-R flipflop.

Whenever the magnet passes the SET Hall switch, the LED lights up. When it passes the RESET Hall switch, the light goes out.

Now, if you turn the wheel one way, the light will turn on and the wheel will rotate nearly all the way around before it goes out. If you turn it the other way, the light will come on briefly but only stay on for a short time until the magnet reaches the RESET Hall switch and this turns the LED off.
So, the lamp will be almost fully lit in one direction of the motor and almost fully off in the other direction.

 

[MattNew]

Hello vk6kro, and many thanks for you reply!

You are right in what you are saying.
I am using a PIC on the back end of this so I think if i had the 2 quadrature outouts from the sensor then I can interpret them ok.
Its just that this sensor is primarily a speed sensor based on a flywheel, and I am not sure it will suit just having access to a metallic stud or magnet

Please see link for closest switch I could find
http://sensing.honeywell.com/index.cfm/ci_id/146644/la_id/1/document/1/re_id/0
BY using the lead/lag of these 2 waveforms I shoud be able to determine rotation.

 

[vk6kro]

I'm not sure how that would work. What would the sensor be sensing?

I had another idea. An optical mouse can tell if it is being moved up or down on a surface. So what if the surface was moving and the mouse was stationary?
The mouse would give outputs as if it was moving.

 

[DeeNos]

I understand the importance of accurate and reliable data in any experiment or design. In this case, determining the direction of rotation of a wheel is crucial for the proper functioning of your system. Based on your description, it seems that you have considered using hall effect sensors with quadrature output, but have encountered difficulties due to the lack of an encoder wheel or flywheel teeth.

In order to accurately determine the direction of rotation of a wheel without these components, I would suggest exploring alternative sensor options such as optical sensors or magnetic sensors. These types of sensors can detect the movement of the wheel's inner face without the need for additional components. Additionally, you may also want to consider using multiple sensors to increase the accuracy and reliability of your data.

Another approach could be to design a custom encoder wheel or flywheel teeth that can be attached to the wheel's inner face. This would allow you to use the hall effect sensors you have already identified. However, I understand that this may not be feasible for your application.

In any case, I would highly recommend thoroughly researching and testing any sensor or solution before implementing it in your design. This will help ensure that you are able to accurately determine the direction of rotation of the wheel and achieve the desired results in your project. Best of luck in your endeavors.