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Topic-icon 4 bldc-motors on 1 controller

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3 years 3 months ago #29532270 by Erik
I have an FBL2360 and 2 bldc motors from a balanceboard and use them in tanksteering mode.

Can i connect 2 more (same model) motors paralel to the other ones and not use the hallsensors of the 2nd pair of motors?

Will this configuration give any problems? The motors get 10 amps each so that's not an issue i guess.

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3 years 3 months ago #29532271 by roboteq
Replied by roboteq on topic 4 bldc-motors on 1 controller
You cannot connect 2 motors in parallel.

The second motor would have the rotor at the same angular position as the other.

The only way you could possibly is if the two motors where mechanically linked and their rotor at the same exact position vs the hall sensor of the one motor.

You need 2 controllers in order to have 4 motors

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3 years 3 months ago #29532302 by Erik
Replied by Erik on topic 4 bldc-motors on 1 controller
Forgive my ignorance please, but can i use any brandname controller to make it a 4wd as long as it has CAN ?? So the wheels will always run the same speed if i use closed loop? I might buy another pair of these wheels from a broken balanceboard with 10" wheels.

Is there a 4wd controller from Roboteq at all?

And i also need more wheelpower, i used a 10A fuse while my wheels each get Max. 10A from the controller and the fuse never broke.

How can i determine how many amps the wheels can stand? They don't have thick wires though but the fact that my 10A fuse never broke tells me i have never run on max. power right? I guess the wheels can stand 10A (the balanceboard was 700Watt at 36V).

And how should i adjust the amps-safety so i don't smoke my wheels? I just want to let them run on max. power now and see what they can do...

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3 years 3 months ago #29532303 by blake
Replied by blake on topic 4 bldc-motors on 1 controller
If you want to control four motors in closed loop and have all of the motors run the same speed you will need to be able to use hall or encoder feedback from all four motors. This means that the controller will need to have inputs for and be able to process the sensor feedback from all four motors. We do not have a four channel motor controller, I think you will be pressed to find a four channel brushless motor controller especially rated for the power that you need. The only way to accomplish this with our motor controllers is to connect two dual channel controllers (2 FBL2360) via RoboCAN which is our own proprietary CAN protocol to network our devices together. And again all four motors would have to have either hall sensors or encoders to measure speed.

To determine the current that your motors can handle you'll need to look at the datasheet, this is a spec that will be listed there.

Roborun+ enables you to adjust the amps limit and power output to the motors. This is done from the Configuration tab under motor output. See our User Manual for more details

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3 years 2 months ago #29532304 by Erik
Replied by Erik on topic 4 bldc-motors on 1 controller
On internet i see other controllers (from China) who claim to have 4-quadrant drive but only have connectors for 2 motors as far as i can see. So is 4wd the same as 4 quadrant?

To be sure, RoboCAN is not the same and not compatible with the CAN protocol other controllers use?
This text confuses me:

RoboCAN via Serial & USB
Important notice: On many controller models, CAN and USB cannot be operated at the same time. Please see product datasheet to verify if this is the case on the model used. In case USB is not available, this section only applies to RS232 connections.

So in this text they use the word CAN but they mean RoboCAN right? Which is not the same as CAN that other brands use on controllers?

If Roboteq controllers were cheaper i would buy a bunch to test it all out myself but in Europe they are not cheap at all so i better ask first.

I don't have manual from my motorwheels so have to try things out....My controller is set to give max. 10 A to each wheel but how can the mainfuse for the Whole controller never blow out? 2 wheels each at 10A means 20A so a 10A fuse should blow i would think.

Can i use higher amps untill the wires/motors get warm to find out how far i can go? All hubmotors come from China these days, i wished i could buy german or japanese ones but don't know where to find those. They will have good manuals i assume, chinese not.
And if i smoke out a motor will that damage my roboteq as well?

How would you guys figure out how far you can go with giving more amps?

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3 years 2 months ago #29532310 by Erik
Replied by Erik on topic 4 bldc-motors on 1 controller
I've got much more power now, just give each motor 20 Amp...I used 2x5 amp fuses this time and they won't blow and nothing gets warm.

The battery amps stay around 3 amp for each motor when i try to stall them. Guess i can also go to 30 amp but for now i'm happy.

I thought the controller always uses max. volts but it must lower the volts or i can't use 20 amp max. for each motor.

Yes i'm a noob and have my own ways to check things out. Still can't get the closed loop speed mode to work though.

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3 years 2 months ago #29532314 by blake
Replied by blake on topic 4 bldc-motors on 1 controller
I'm going to do my best to answer all of the questions you just proposed, please forgive me if I miss something:

4 quadrant drive does not mean 4 wheel drive. This refers to the conditions of a standard motor driving H-Bridge, each quadrant relating to the state of the motor acting as either a generator or as a motor. If you do a quick Google search of "4 quadrant drive" you'll see what I mean.

RoboCAN is not the same as the CAN protocol as other manufacturer controllers use, it is proprietary to our own products only. However, our motor controllers are capable of most industry standard CAN communication as well including CANOpen, RawCAN and MiniCAN.

That note you referenced regarding CAN operation and USB is true for all CAN modes when relevant, not just RoboCAN. However, if you are using the FBL2360 this note is not relevant to you as the FBL2360 is capable of using CAN and USB at the same time.

The motor controller should be okay as long as you stay within the maximum current and voltage ratings specified on the datasheet. If your motor is 700W/36V then according to ohms law it is theoretically capable of ~19A (when at 36V). Care should be taken when testing though if you don't know for sure. If the motor burns out then yes it is possible that residual voltage or current spikes can damage the controller as well.
The following user(s) said Thank You: Erik

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3 years 2 months ago #29532321 by Erik
Replied by Erik on topic 4 bldc-motors on 1 controller
Yes i just learned the difference between 4-quadrant and 4wd from another forum. It's like my new (well 6 years old allready) Makita powertools with BL-motors who also use that, they are much more powerfull than their old series.

But i don't think i'll buy another fbl-2360 to get my 4wd, those things cost 800 euro which is too much for a hobby-lawnmower gardenrobot. Also 4wd will ruin my lawn i guess, have to test it to be sure about that.

I'm not so happy about the tanksteering options though, it steers too direct and i can't change it. Tried all 3 modes, the inputcommand exp/log/linear modes, also my rc-transmitter has many options to adjust it but nothing is really perfect (which is the reason i bought the roboteq controller). For lawnmowing i need precise steering at low drivingspeed. Maybe it works better in closed loop speed mode but i can't get it to work...have to try more.

Maybe i'll change my robot into forklift-steering...one big fat drivewheel at the backside and 2 dumb frontwheels. The controller can power the big drivewheel and another steppermotor (or bl-motor) for steering.

Another option is to rewire my hubmotors to make them more powerfull, i found many shops who do rewiring for loudspeakers and motors. Is it possible to make a cheap hubmotor have more power?

What i also miss is that i can't (easy) use the D-out ports (with relays connected) to be controller by rc-signal (i have 10 channels). In the manual they tell it's also for using a weapon but still have to figure out how to program it.
So i bought an Arduino to see if that makes things easyier.

I'm not happy with the hall-cable though...why not make a heavy-duty shielded cable without that small print which even can't be boxed? Or just give us an (ebay) website where we can easy purchase that online.
My hall cable has issues which isn't so strange because of the very thin wiring and weak connections. They could at least have used hotglue to reinforce it.

It would also be nice if i didn't have to go buy me a relay to connect the controller properly, it should be onboard to make things easy for a customer. I don't have much space for loads of computers in my robot and also prefer to build things neat and tidy..
Also i bought a big heatsink for the controller, would be nice if we could buy it together with the roboteq and also a coolingfan on it. Maybe it's a bit overdone this way (for what i use it for) but i live in the warmest city of the world and yup it's hot here.

Also is it possible that my roboteq won't work at all with my hubmotors in closed loop? That would save me a lot of time/frustration. If it won't work than where can i buy good hubmotors who will guaranteed work with it? I choosed the hubmotors because i love how silent they are, didn't realise they can only be controlled by expensive controllers but that's allright. Now i just want to make it work flawless no matter how or at what price.

Another question is: If closed loop modes do work, can i let my robot mow my lawn by rc-control and at the same time the controller reads/stores all the data used to drive over my lawn so it can mow automatic the next week? I'm looking for a way how to easy learn the robot to do things, like first cut my lawn and than sweep the driveways all automatic.....That's my main goal for this robot, it will get many more functions though later in time.
I noticed that my hallsensors are not 100% precise....after letting both motors go forward/back a few times there is a small difference in the hallcounts, would that be a serious problem for what i want the robot to do? The motors have 15 poles each.

I also want to connect (waterproof) ultrasoon or infraredsensors to work with the controller, is there some info on the website how to do that easy? I can figure it all out myself but that will take much time. Would be nice if Roboteq helps the customers a little bit by that since we all will use sensors to drive it i guess..(not magnetic sensors though).

I know i have noob-questions but if the info was easy to find i guess more people would buy the same controller and build their own robots. BLDC hubmotors are great and get popular fast. I allready had many people asking me where to buy/build something like my own bot.

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3 years 2 months ago #29532322 by Erik
Replied by Erik on topic 4 bldc-motors on 1 controller
I'm trying to get closed loop speed mode working again.

It didn't work but when i touched the wheels (off the ground) they started running very fast and i can't stop them with the sliders on the run-page (they were at 0 anyway but the sliders didn't work at all). Only way to stop them is the emergency stop.

I set the max. speed at 10 rpm but it goes 650 rpm.

Another time i tried it the wheels wouldn't spin at all for some seconds and suddenly go full speed with much noise coming out of the motors.

I'm scared for this kind of behaviour, how come the sliders don't work? the motorcommand was also 0 on the charts. The pulsesommands were set off in the command settings so it's given by Roborun only but not with the sliders...

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3 years 2 months ago - 3 years 2 months ago #29532324 by Erik
Replied by Erik on topic 4 bldc-motors on 1 controller
Closed loop count mode works, that is it doesn't give any errors and keeps the motors at the same hallposition, even when i turn them manually they will go back.

also i can use sin-mode now without errors in closed loop but the motors don't react on motorcommands....when i turn them manually they won't go back to original position.

That's the progress for today...another 8 hours wasted.

I have no idea what i'm doing when i change the gains, can my issue be in those settings or is it the hall sensors? I never realised this would be so complicated...but i still have hope for a good ending.

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