Is it possible/practical to measure movement from stepper motor? - Page 1
Forum section: electronics / projects

author: aaronhance
author_rank: Regular Contributor
timestamp: September 11, 2020, 03:40:28 pm
content: Hello,I'm designing a custom yoke for playing flight simulators. I want it to have variable stiffness, auto centring and force feedback. I've seenother peopleuse stepper motors. I think they are using pots for reading the position, but I was wondering if there is a practical way to measure the stepper motor for movement, or any affordable IC that would do this? Thanks!

author: sokoloff
author_rank: Super Contributor
timestamp: September 11, 2020, 04:01:31 pm
content: I might be more inclined to use an encoder to keep things in the digital realm, but there’s no easy way to count missed steps precisely using only the stepper. You can probably look at the back EMF and have a chance to surmise that there were missed steps, but I doubt you be able to tell the difference between missing 1, 3, and 7 steps reliably and repeatably.

author: Mecanix
author_rank: Frequent Contributor
timestamp: September 11, 2020, 04:05:23 pm
content: AS5600-ASOM (12-bits).

author: ataradov
author_rank: Super Contributor
timestamp: September 11, 2020, 06:12:07 pm
content: Yes, axial position sensor is a way to go here. They are not cheap, but work well.

author: james_s
author_rank: Super Contributor
timestamp: September 11, 2020, 06:41:07 pm
content: Forget steppers, they cog so they are a terrible way to try to implement force feedback. Go with a servomotor with an optical encoder, they're not particularly expensive and modern electronics make them fairly easy to drive.

author: wizard69
author_rank: Super Contributor
timestamp: September 11, 2020, 07:52:37 pm
content: Expensive to implement but air cylinders are great for force feed back. You still have the position sensing issues but liner pots might be a cheap alternative. To get variable force feedback you wold need a servo pressure regulator which would blow out the costs. The neat thing here is the compress ability of the air which gives a very analog feel.

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 11, 2020, 08:11:56 pm
content: Quote from: james_s on September 11, 2020, 06:41:07 pmyup! unless you want to simulate car's ABS.Quote from: james_s on September 11, 2020, 06:41:07 pmmaybe like this onehttps://www.ebay.com.my/itm/1x-25GA370-DC12V-400RMP-Gear-Motor-With-Encoder-Electric-Speed-Reduce-Motor/233691576935?hash=item36691a7a67:g:dCcAAOSwrF1fRHzv, its fun to play with. get the high rpm (low gear reduction) if the motion is sudden, less resistance to force and less chance to break the gearing, without gearing (direct drive to motor's shaft) you can barely feel the feedback unless you go with bigger motor. some experience playing with it may helps. another drawback is you need to program yourself to keep track of motion/position. but maybe built-in FW, absolute positional encoder or I2C serial interface are out there, but i guess much more expensive. and err, dont forget to order few thick arse mosfets too... ymmv.

author: EverydayMuffin
author_rank: Regular Contributor
timestamp: September 11, 2020, 09:48:11 pm
content: There are two methods that come to my mind:Monolithic Power Systems (MPS) MagAlpha Position Sensors:https://www.monolithicpower.com/en/introduction-to-the-magalpha-magnetic-angle-sensor-familyhttps://www.monolithicpower.com/en/products/sensors/position-sensors.htmlPixart Imaging have an optical sensor for measuring the rotation of a shaft, the PAT9125:https://www.pixart.com/products-detail/72/PAT9125EL-TKIT___TKMThttps://www.pixart.com/_getfs.php?tb=product&id=72&fs=ck2_fs_enNot sure if they'll meet your requirements, but definitely worth looking at.

author: james_s
author_rank: Super Contributor
timestamp: September 12, 2020, 05:43:08 pm
content: One of the best force feedback systems I've seen is in the Atari Race Drivin' and Hard Drivin' arcade games. These use a huge brushed permanent magnet DC motor coupled to the steering with a toothed belt and an optical encoder to sense the position of the wheel.