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- เผยแพร่เมื่อ 19 ก.ย. 2017
- After working with stepper motors a few times I learned that this awesome bit of electronics has a big disadvantage. When pushing the stepper to its limits, the accuracy of the motor is not that good. In future projects I want to push the steppers to their max without any accuracy loss, that’s why I decided to build a Arduino Based Closed Loop Stepper.
Part 2 • Making an Arduino Clos...
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Steppers are accurate high torque direct current electro motors. You can find them in many devices, from 3D-Printers, actuator and even in transmissions of cars. The main difference from normal electro motor is the fact that they are control by electronic pulses. One pulse to the motor results in one step.
You can say that the stepper is blind. It has no way to check if the movement is has done is the same as the microcontroller has told it to do. The optical rotary encoder act as the eyes of the stepper. When the Arduino Based Closed Loop Stepper gets 200 pulses from the microcontroller but the rotary encoder detects that only 197 steps were mad, we can assume that we lost 3 steps. The system can now correct it’s mistake and give the 3 extra steps.
Building a Arduino Based Closed Loop Stepper can be seen as bit impractical. Why don’t you just buy a closed loop stepper… The answer is simple. Cost. This closed loop stepper can be built for less than 30 USD. Buying one, of this size, will cost you 3 to 5 times as much.
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A good 3D printer:
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A good 3D printer:
www.banggood.com/DIY-Creality-CR-10-3D-Printer-300300400mm-Printing-Size-1_75mm-0_4mm-Nozzle-p-1085645.html?p=CR190314405010201709
Just the kind of explanation video I have been looking for, really appreciate it.
I just made a bunch for a cnc conversion i did and this approach really shines when you put some variable load on the motor.
Good job! I've been toying with the idea of something like this for a 3d printer.
brilliantly constructed in my opinion
Very good explain why closed loop is better . Thanks!!!
Nice so far - and really needed, if you are driving the stepper without smooth acceleration!!!
That's, why you find in some slicer programs (i.e. Cura) those acceleration values. If you start the stepper with slow steps and make them faster until top speed, you will not loose steps too - and your candy sorting machine will be a lot smaller and cheaper.
By the way - someone mentioned a servo - for the wrong reason, but that will do the job too and servos are even smaller and cheaper than steppers. And the Arduino just needs one pin, to control a servo - two pins for a stepper.
If you're doing "smooth acceleration" you're losing speed. The entire point of a closed loop stepper like in this video would be to max out speed so velocity smoothing is not needed.
I can't be the only one that grimaced when you didn't clock that pulley in your chuck before boring it out xD
No you were not :-)
Aye, and looked like about 1mm of runout just to the naked eye... a shocker
Awesome, I'm glad I found your channel, Subbed!!
welcome aboard ;)
Noting the position after a move and correcting for lost steps with a retry is useful, but it is not always sufficient. If you were cutting a circle, for example, with two motors running simultaneously, correcting after the motion makes a different, imperfect motion when steps are lost on one motor and not the other. A true feedback system will correct in real time during the motion along the trajectory. This is why they are more complicated and costly.
I understand your point, but a complex cutter wouldn't likely be moving at the max speed of the stepper and knocking all around like this either; his design remains useful for specific applications, including tracking dual cutters; just not at break neck speeds.
@@geoffhubbard7815 Yes, but if the cut material provides resistance like in a cnc machine, which is typically where these closed loops are needed, then that problem can occur even at slow speeds.
Very good demonstration
well done and explained. :)
Magnifica ejecución y una interesante muestra, de las posibilidades infinitas del cnc. Gracias por compartir!
Is that possible to share the code for the control? I'm wondering how often does the encoder check the position? At the end point or periodically checking in the middle.
Very well explained ❤️❤️❤️
Awesome idea
My rotary encoder has an output of 250 mV. Yours probably to. How did you connect it with the arduino? Did you use a transistor or something similar? Looks cool.. thx
can you please post the code? and the encoder used
thanks!
Good job
Awesome.
How much does that encoder cost? Or what's the name of it?
Hi sir im having some problem with my timing pulley assembly can u guide me how to slove it
Amazing !
Nice, crispy, high quality audio! Cool project too. Source code please??
Hello, what kind of software do you use? Is it compatible with a step and direction signal
What I'm wondering now, is can you un-power the motor so you can read out the value on the encoder (like a digital read-out)? This would be great for instance for a CNC conversion on a lathe or something; you'd still be able to turn the handwheels manually, but also sometimes program and use CNC.
You definitely could.
also, is the hall effect sensor used to "home" the stepper motor?
how to increase the speed. would you share the code? is it the video, or is it the speed of full step? did u use the microstep on 8825?
can you please post a link to that encoder? thanks in advance
What is the purpose of the Hall Effect Sensor? The rotary encoder should do all the counting, and therefore know the location of the motor/encoder at each step.
I think it doesn't need it while the system is in operation, but if he turns the system off and then on he can use the hall effect sensor to re-adjust it to a 0. Even if he were to continuously save the position to some kind of long-term memory (e.g. the Arduino EEPROM), it would suck if someone turned the arrow while the system was off.
yared94 is correct. The hall effect sensor acts as the "home" position and tells the controller a given known position upon startup. Powering down the system or making mechanical repairs requires a re-home of the controller.
I guess that using a hall effect sensor would not be precise enough for steppers with many steps per revolution (or geared steppers, that is).
I was wondering about how to get a "zero position" working with my setup (600 steps per revolution stepper motor). At least the hall effect sensor is an idea I could not come up with.
What is the function of optical encoder? Just a bearing for magnet?
Is it possible to add feedback just by using Encoder instead of enoder motor
Hello,
Can you explain why you need a hall effect sensor ?
Isn't the rotary encoder has optical sensor internally to detect shaft movement ?
To zero the encoder, it's likely not an absolute encoder and even if it is, you have to calibrate it to somewhere.
Hi, i got a question for you. Is it necessary to convert a stepper motor into a closed loop one or is relying on its step/revolution enough to be accurate in tracking position?
In order to obtain a good precision you should use it..otherwise the stepper motor will memorize it's previous position as a reference...
you'll find more details in the link below:
phidgets.wordpress.com/2014/05/13/steppers-with-encoders-when-open-loop-control-isnt-enough/
hi
i have ac servo motors without drive
can you tel me please if i can used it without drive servo i mean convert it to just stepper motor that i can used stepper drive with it ?
anther thing i found in scrap ac servo without encoder in the back >> can i used it and how
thanks
AC servos are permanent magnet 3 phase AC motors with encoders attached. Totally different technologie than a stepper. You need an ac servo drive to control an AC servomotor.
Sail Junky thank you 🙏
can you plz help me to make a code for dmx stapper motor with encoder
This is a working but costly solution, rotary encoders aren't cheap and an extra mechanical part is needed. Usually, when we need speed and accuracy, we use only a hall sensor and decrease speed just after it's been active, not to lose any step. This works fine while movement implies a pass on the sensor, but software can manage this easily.
great
did u have an optical encoder? y didnt u use an absolute encoder better results m8?
how much does this absolute encoder cost?
I do believe that I am developing a nervous twitch in my eye after to many videos with *&^##@! music instead of dialog
What encoder has been used?
www.amazon.de/gp/product/B015GYY7XU/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
Thank you for this very nice tutorial.
How are you planning to use the stepper to actually drive something, since the pulley for the encoder belt takes all the shaft? Would it be possible to come up with a solution which doesn't imply having an extension shaft?
Buy a double shaft stepper motor. and directly mount the encoder on to the back of the stepper with a coupling.
@@nrml76 Hi again,
I managed to construct a belt drive, but it with a 4:1 stepper to encoder ratio.
However, I am having issues with the pulses generated by the encoder. They are not constant from one step of the motor to the other.
Do you have any idea what the reason might be? I 3D printed the pulleys, so maybe that has an effect. I can see that the belt is wobbling a bit as the pulleys rotate.
Maybe I am wrong on this one, but isn't this the same feature the TMC2130 stepper diver is supposed to accomplish?
Ben Müller how can anything know the actual position without an input? Unless that encoder also has a feedback input, it's guessing that it made it to the specified position.
I don't get the need of an encoder there, if all those tasks can be done with a stepper motor on it's own, or am I wrong?
@Ben Müller No. The TMC2130 can detect skipped steps and make corrections but...it still has no idea where it's positioned. The position is based on a calculation as opposed to reading an input from the actual position itself. The solution in this video is quite elegant in fact. The system will always know a given position of the belt and make corrections as necessary regardless if the stepper motor skips steps.
This optical encoder also don't "know" its position, it is incremental encoder so position is also based on calculation. It can lose "step" with high speeds. Whould be nice to see same test with TMC2130 without encoder
The hall effect sensor gives an absolute position.
Whre is the code?
Please give me your address, I'm gonna send you an assortment of washers!
Adrian Schwizgebel 😆️
you have bearings as well? If so, send me some as well :D!
Yeah same, i was like wtf u n use washers on plastic :D
Nice project !!!
do you share arduino code on public ? Or this is just for your use. Or maybe it's possible to ask you for code personally :)
Thanks Auryz! The public version will be posted in de video description somewhere in the next couple of weeks. I’ll give you a heads up!
Please show up your details about this project... Still more than 3 weeks since...
Some news about public version ?
Any news on about the public version of the code going out. My project currently is similar to this setup.
I am in as well for the arduino code .... a public release would GREAT !
Sir what difference closed loop stepper motor and hybrid servo motor
none
Your mean hybrid servo motor and closed loop stepper motor is same , only called different name
hybrid motor is another name for stepper motor
here if you want a deeper understaning: www.motioncontroltips.com/the-hybrid-servomotor-stepping-up-to-closed-loop/
where to buy this encoder?
Raja Haseeb ebay
public code to share? please
While interesting, it's not practical. Most application that require steppers, also require precision and correcting steps after they where lost is not precise. For fast and accurate control, DC motors equipped with encoders are typically used.
very compliment from Palermo :-) Francesco Pa
music name pls ? :)
Code?
You know, those closed loop steppers from Leadshine do not cost that much. No point in doing these yourself other than to learn about closed loop controls.
Love it, can you now retrofit it to a 3d printer :P?
That would be perfectly possible ;) But this one goes in a candy sorting machine!
the cheapest 3d printers run in 1/16th of full steps with pwm control, so can lose 1/16th, is the encoder that accurate? the newer drivers run 1/256 steath chop pwm or spread spectrum pwm, torque is reduced and chance of missed steps even higher. i thought 1/16th was voodoo but 256......
01:33 ma gemein ;-(
Oh well, another hollow promise to the people with no coding skills. I call it click bait.
I call stop nagging and get learning. Arduinos C is incredibly easy compared to other languages
daniel tabrizian, a little holding of hands and a little advice as well as something to start with comes a long way when someone is starting learning something new. I started using Arduinos about a year ago and without the help of others as well as sample-code I wouldn't be where I am today. Unless you're a stable genius, one is having a hard time learning steppers, rotary encoders and PID control all by himself.
So. Yes. Not providing the code here is somewhat comparable to clickbait.
Interesting, stationary drill, rotating part :D Steppers are not blind... check out Trinamic's stall guard: th-cam.com/video/Prw7wNa20Gk/w-d-xo.html
yeah its called a lathe
Can you please help me to make a code for dmx stapper motor with encoder
Please help me