stepper motor and RC

Hi everybody

I used 2 stepper motors to run robot like RC (car). these steppers are connecting directly to wheels , holding torque of each steppers is 80N.cm.
when robot is moving directly, max load can be 16 kg (for better efficiency 15 kg) and everything is working well , but when robot is moving in curve, max load can not exceed of 8 kg. in fact, in the curve moving, robot is jumping a little in some positions and i don't know what is the problem !!
 
Hi everybody

I used 2 stepper motors to run robot like RC (car). these steppers are connecting directly to wheels , holding torque of each steppers is 80N.cm.
when robot is moving directly, max load can be 16 kg (for better efficiency 15 kg) and everything is working well , but when robot is moving in curve, max load can not exceed of 8 kg. in fact, in the curve moving, robot is jumping a little in some positions and i don't know what is the problem !!
Hi

Can we get a short description of the mentionned system, like a draft or drawing of the configuration ..

Also What kind of controls system is used , (OEM motors, drives, encoder, ...)

So we can have a better overview of your problem...

James
 
every Nema 17 steppers (Primopal PHB42S63‐403) have one driver (s109 with tushiba IC "tb67s109AFTG") that can give up to 4A,
and i used arduino mega 2560 to control these drivers.
I think, when left wheels move faster than right wheels (for turning the robot to right) , so left motor must withstand more torque than right motor. this is correct?
 
Is that what the Differential gearbox is for? ....sounds like your project just got a whole lot more complicated.
Maybe you can adjust wheel speed according to load.....that might be a bit tricky with a stepper motor
 
I've not used diff gearbox for this project, steppers are connected directly to wheels by long shaft.
I want to use another wheel instead of pulley in these images.

20210314_103823222.jpg
20210314_103830222.jpg
 
I would suggest you take a video of the problem...
Then slow it down...I'm not sure if you can post vids on this forum
But regardless it might give you a clue...
Are you saying that one of the wheels is "skipping"
Sounds like a nice project
How are you synchronizing the motor...one step is how much mm in movement?
I would hazard a guess that it is out of sync on a curve ,,,on a straight line the rotational speed would be 1:1 on a curve it would be 1:whatever...
If you are using those cogs for wheels,,, then the traction is going to be different on a turn.....
 
Hello,

To test youtube:

@Carl As you can see youtube videos can be embeded.
@smsebna , you could make a video and post it on youtube.
When a link to the youtube video is entered in the post, it will be embedded as shown.

Bertus
 
I would suggest you take a video of the problem..
the stepper motor who running faster, turning abnormally. you can assume that second hand in clock is turning normally , but at moment, turn back 1 second!! and then turn normally.
robot work also in curve mode and unfortunately lower than 8 kg (in straight mode , load can be max 16 kg) . but i have 2 steppers that can handle 160 N.cm (both of them)
 
ok..now I see
Well, it can be mechanical or software, those are your two big pictures of the problem...
Can you explain that action mechanically...(is there an elastic force being built up that springs it back like that?)...
If it can't be explained mechanically then something is going on in the software..
Put an oscilloscope on your power device and monitor the firing....if you don't have an oscilloscope...then monitor it via the software( maybe that has a graphing function )
 
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