Question Optical sensor instead of pot?

Hello guys,

is there anyone who used an optical sensor as position feedback?
What are the (dis)advantages compared to hall sensors, pots or encoders?


Attached is the datasheep of the sharp GP2Y0A41SK0F distance sensor.

I want to use them for linear actuators and don't want to use a belt or gears (want to keep it easy).
I already have the linear ballscrews. They have 300 mm traval distance, so the sensor should suit fine. The sensor have an analog output from 0..5V. So it should be OK?
I'm not sure about the sampling rate, but it looks like it has about 50 Hz. Is that enough?

I'll use sabertooths with Arduinos with SMC3-SPS. I also have kangaroos.


So, are there any problems i'll face if i use these sensors?

Thanks
My.stAr

Hi @My.stAr if memory serves me well , this has already been asked and the answer was No , mainly due to the resolution and focusing by the sensor light source . cant remember the thread here but there are other options for non contact sensors which should provide a decent alternative to belts and pots .. so user will stick with the Multi turn pot arrangement basically on the premise that they work so if it aint broke don't fix it LOL.

Im moving to the AMT103-v Sensor mounted by belt take off to the ballscrew shaft. ideally if the motor had acess to a rear shaft then these sensors would be ideal for direct mounting , Good Noise imunity and great resolution options , i'll post a link to where im doing this sensor test later if your interested .

Hey @wannabeaflyer2 thanks for your answer

that's an interesting idea with this encoder The encoder I saw before were with a shaft... Isn't it possible to mount the encoder directly to the front shaft of the Motor?! Why are you using a belt?
And yes, I would really be interested to follow your progress, always enjoy reading your posts So, would be happy about a link to your thread and also to the thread with the optical sensors.

One more question about the optical sensor: What resolution would be necessary?

hiya @My.stAr the resolution of this sensor has a programmable range from 49PPr to 2048 PPR and reliable counts at max resolution up to I believe 7000 rpm the resolution is set via dip switch on the module and comes with setup tool ect ..I started posting some info in https://www.xsimulator.net/communit...imulator-controller.10517/page-27#post-176877 the AMC128USB post but will be moving back to my Project posting once I get my but into gear .

for me the reason to use the belts was access , My motor does not have rear output shaft like Silentchills motors so mechanically it had to be fitted mid point between Motor output shaft and the Coupler and .. you may just about see what I had to do , funny enough I have just had to place the order for another 6 sets of Belts and Pulleys ( to upgrade the othet actuators Now that this test has had great results ( so far LOL )

If you have direct access to motor shaft that def the best setup .. like I said so far im happy with the testing so on the strength of that im moving to this method of feedback .. Just a Note , that its still early days and these tests with the AMT103/V sensor are done without full load but the positional Repeatability seems fine and 1 wont get full use of 2048 resolution as the Controller is set to 10 Bits so I think im running at the default 1024 (need to check that later ) .. Cheers

thanks once again @wannabeaflyer2

I don't plan to buy an AMC128USB board. I have Arduinos atm. I remember that you wrote somewhere (maybe i'm wrong) that you also tried an encoder with the Arduino board and SMC3? If so, why did you stop testing?

Afaik the kangaroo x2 can handle encoders. Since I have some of them I could use them instead of the Arduino... have to dig deeper into this stuff

hello
I think optical sensor will not have a good precision to work correctly.
direct sensor can have more point and make the PID more efficient

You cannot say this generally. It may be true for cheap sensors, but not expensive ones. They can be VERY precise. But my point was to build something cheap and easy. So I went the route with an optical encoder It's very easy and also not expensive.