Reasonably Priced 100A Motor Controllers

I don't think the motors are stalling or they are not powerful enough, they are 3 very big 750W 95 N.m motors. The lever is 130mm long and according to my calculations these three motors and levers combo can lift and stand 225 Kg and lift up 170 Kg at relatively fast acceleration (I don't remember now how much acc), so from my point of view the motion rig is oversized and should run well and unburdened.

The motors run well if I connect it directly to the PS.

Maybe the boards broke down in the first tests due to a bad configuration and now the boards are malfunctioning. In my previous 2DOF motion rig I broke some IBT-2 that does not stoped working but working bad so maybe I'm in that case now but with these boards. I don't know

Yeah in theory your motors a strong enough, but still reading the current that they are eating is a first diagnostic step to do imo.
Here is a video of my WIP rig with 2 of theses board. We can even be 2 people on the rig (not shown in this video) and no issues with the boards.

What is the gear ratio of your gearboxes ?

Yeaah that is amazing!!

The gear ratio is 50:1 (3000 to 60 rpm)

95NM with a 750 watt motor and a 50 ratio wormgearbox is verry optimistic
My advice use gazsprings to take the load off you need them probbebly to becauce of jithering what often happens with a 50 ratio wormgearbox. replacing the controller for a sabertooth 2x32 wont solve joure problem they are on te weak side when jou do the math. just my 2 cents regards Ad

I don't think so. I saw the Milani Fabio's 3DOF sim rig builded with 350W (69N.m torque) motors and that motors lift him very easy with a 100mm levers, mine is inspired in it and is 3x95/3x69=1,38 times stronger than his build. My motors are strong enough, they lift me very fast without signs of stress, the only thing is not working well at all is the boards

Good luck with youre project time will tell if you dont need them!

Thanks, I really wish don't will need any spring solution, the motivation to choose that motors was to be completely sure of that.

there should be plenty of power

try and measure the motors current to see if something is braking down

I strongly recommend you try them at 12v not 24v to start with

I already lowered the voltage to 12V but the problem is still there. Also I put a delay in the SMC Arduino code where I think it should be (in the move forward and backwards function, after each movement for each motor) but it does not result in a good solution, the movements starts to be erratics, even if the delay is 25ms. Without delay the movements are smooth but with delay does not.

Thanks!

Youre motors could by strong enuff but there is still a big chance you need them to take jithering out it often happens with big ratio wormgearboxes becauce they are sliding they can make little jumps

test one motor at a time and slowly add weight till you can find the problem - do you have a way to measure current ?

I'm uploading a video to Youtube showing the ammeter clamp reading the current of one of the motors moving a sine waveform. The current showed does not make any sense since it current is always under 5 ampers so I can deduce that the reading is not good. Maybe it is because the ammeter is configured in CA (not DC available) so tomorrow I'll test it again with another ammeter clamp with DC option.

That meter is only capable of measuring AC amperage via the clamp by the looks of it. You need one that can read DC.

Edit, I see you mentioned that in your message, sorry, I just went right for the video!

Well, today I measured the current again with an ammeter clamp able to read DC current and the changes in the readings are considerable.

The first measurement was taken between the board and the motor. The motor is eating up to 20 to 25 amps when it drives upwards and 10 to 14 amps when it drives downwards (only lifting the chair, about 15 to 20 Kg as most).

The second measurement was taken between the Power supply and the board and here is the weird thing. The board is eating 7 amps max when the motor drives upwards and les than 3 amps when it drives downwards.

There is A LOT of current running between the motor and the board.

If i put part of my weight to add resistance to the motor the board-motor curren shots up to 70 amps, too much IMHO. The PS-board current in this case is up to 20-30 amps.

The motor runs smooth and consume less than 10 amps when the levers are removed and runs freely.

What do you think? What is happening here? I'll gonna be crazy.

Here is the video:

That one is hard to explain. I'm not an electrician but energy is neither created nor destroyed so if you have 20amps going through the motor, you should have 20+ amps coming from the power supply (heat losses).

The only thing I can think of is that the voltage is somehow getting dropped going to the motor which would then increase the amperage.

I have 2 of these boards waiting to be put in use. I'll try to find time to measure mine and see if there is a difference. I'm using 12v though.

Hopefully somebody smarter than me has a better idea. Sorry.

Hi,

I redo the tests but now without load, the motor axis (the reducer axis instead) spining freely and there are the same behavior but with less current.

The board-motor current now is 5-6 amps and the PS-board is 0,3-0,5 amps.

The reduction is very noticeable and maybe I need to lower the load but again the current between the motor and the board is 8 to 10 times bigger than the "original" current wtf.

No reason to get crazy just do the math , 1 watt is 1 newton with a speed from 1 meter a second
Gearbox efficienty below 60% motor efficienty below 65% I told you a sabertooth 2x32 will be weak
With youre load regards Ad

Now i have more time and doing this out of my head motor 750watt rpm60 leverlengt 13 cm
60 rpm gives 1 round second 2x13x pi=80cm 750watt with 80cm gives 900N minus gearbox eff. 60% gives 540N so you need 750 watt to hold 540N and more to move it up. Now it comes youre gearbox is selflocking this means no current to hold the load its done mechanicly going down some current for moving the load is hold mechanicly but going up a big current spike hope this helps Ad

Thanks Ad!

Yes, you are right the motor and the gearbox have mechanical loses due multiple factors as friction (from there the efficiency) but even keeping in mind that, the motors are consuming a quantity of amps that is not normal. I'm testing the rig almost without load and the readings are really weird.

I'm convinced that even if I drill a hole at 90mm to the levers and use it the problem still will be there

The last test I done yesterday was change some SMC values while the motor was running with a sine wave and read constantly the amps and the result was that it does not matter what changes would I make, no matter what Kp or PWMmax value was configured, the speed and current always were the same, also testing with Ki, Kd and Ks, No changes.

Next days I'll drill a hole to 90mm to see what happens