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ODrive - High performance motor control

Hobby brushless motors are incredibly cheap and powerful. However we need a way to make robots out of them. ODrive is that way.

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Stepper motors are ubiquitous in hobby robotics projects: If you make a robotics or automation project today, it is very likely you will use them. Almost all DIY projects from 3D printers and CNC mills, to air hockey and juggling robots use them. However in industrial automation, brushless servomotors have taken over, and it's clear why: They don't lose steps, are much more powerful, efficient, and silent.

However, brushless motors are not unique to expensive industrial automation equipment. In fact, you can get some very powerful and cheap motors at hobby shops. The electronics to drive these motors are also dirt cheap. So how come virtually no non-industrial automation systems use them?

To be honest, I have no idea. Seriously, a driver that allows this should clearly exist.
But since it didn't, I decided to make one.

And you are invited!
This project is open source, both in hardware and software, and I warmly welcome anyone who wants to join.

Alpha boards now sold out

Sign up here to be notified when the next batch is going.

Key specs:

  • 2 motor channels, designed for >100A peak current.
  • 1 DC-DC converter channel
    • For powering the system with an arbitrary voltage power supply, or
    • Use of a brake resistor
  • 24V bus voltage
  • USB, CAN, SPI, and step/dir interface (read more below)
  • Encoder feedback for arbitrarily precise movements
  • Supports power regeneration
  • Use of a high power density Li-Po battery means you can achieve >1kW peak power output with only a modest power supply.
  • It will feature various optimal control strategies and motion profiles.
  • Permissive licence on both hardware and software: You use this project in anything you like, even commercial products (as long as you attribute this project's contributors).

Demos

The design is based on two earlier prototypes.

Here are some very simple demos with v2. The peak power output in these tests were only about 60W. The new version (v3) will be able to deliver much more power.

Below is a demo with v1. The mass being moved is 3kg, and the peak power was about 200W. The noise is not from the motor, but from my poor mechanical design which means that the belt teeth rubs against the idler pulley edge.

Join the discussion!

Check out the ODrive Community.

Stay up to date


Motors

Check out the ODrive motor guide. You can also read this post about outrunner motors.

Interfaces

  • USB Serial port
    • G-code parser for interfacing with existing automation tools
  • CAN interface
    • Protocol TBD. One possibility is to support a subset of CiA 402.
    • Many types of command modes:
      • Motion profiled position commands
      • Velocity command
      • Torque command
  • Step/direction input
  • Some general purpose digital and analouge pins

Architecture

The drive is designed to be able to deliver incredibly high peak power, more than 1kW per motor channel. However, power supplies that can deliver this kind of power are expensive. Also, when the actuator is being decelerated, there is energy absorbed. Most power supplies do not like having energy dumped back into them.

The solution: Put high-power energy-storage on the DC bus. A battery like this one can deliver around 3kW. These types of batteries also have a fairly high charge rating, and if the regeneration is only over a couple of 100 milliseconds, they can probably handle a fair bit more than specified. Thus, they should be able to handle the full range of regeneration power in most robotics applications.

This means we have a variable voltage DC bus, that fluctuates with the battery's state of charge. So the way we power the system is via a DC-DC converter. There is another upside to this as well: we can use any voltage power supply and just convert it to the bus voltage. I expect most people will use an inexpensive ATX power supply (specifically the 12V rails). In many robotics applications the motion consists of several discrete movements, only some of which are high power. In this case, we can have access to a very high peak power, but only require a very modest power supply.

Another thing that's nice about using a battery for stabilising the DC bus, is that if multiple of these drives reside on the same bus, there is no fighting over the regulation of the bus voltage: a single board can have the DC-DC connected to a PSU, and the rest of the boards in the system can just use the bus. If fact, you can even skip populating the DC-DC on the slave boards.

The system is also capable of using a brake resistor to dump the regenerated energy instead of a battery to absorb it. This is a simpler and possibly safer setup, and is also what the project will use in the first instance, until the battery storage feature is ready.

Applications

So this project is good for some things, but not everything.

You should use this drive in your project if:

  • You need high power: >1kW peak power per channel!
  • You need high precision: Encoder feedback control means that the precision is as high as your encoder's precision, which can be very...
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  • Maker Faire and Alpha Shipping Update

    Oskar Weigla day ago 3 comments

    Maker Faire

    Last week I was at the 2017 Bay Area Maker Faire. It was really fantastic to meet other people who are into building cool stuff. Thank you for all the praise, suggestions, interesting discussions and ideas!

    Also, Juha Kuusama, the man behind the Liteplacer, flew over from Finland to hang out, and to help man the booth. Thank you!

    Below are some pictures of the booth we managed to put together with a very last minute effort. Huge thanks to my girlfriend for all the help!

    ODrive booth, shared with an unrelated exhibitor.

    Left to Right: Hardware showcase (see next picture), newsletter signup laptop, handcrusher5000 (seriously, several people didn't take the hint from the acrylic shields).

    Hardware showcase, top to bottom: Motors and encoder, with prices from Hobbyking/aliexpress (many people were very impressed with the kW/$), old versions of ODrive, and finally the last of the ODrive alpha stock for sale. I marked up the price from the nominal price of $120 because they were selling too fast, and I still sold out on Sunday morning ;D

    Handcrusher5000 in action. You can see the ODrive to the right of the laptop dancing to the accelerations.

    Handcrusher5000.

    Brakeresistor heatsinking on extrusion. It was cool to feel the heat gradient along the extrusion ;D.

    Alpha Shipping

    The first batch of Alpha boards were shipped out on Tuesday. Here are some pictures.

    Boards in boxes.

    Accessory bags.

    Some standoffs.

    29/30 boxes ready to go. The last one I filled after I realised it was missing, after I took the picture.

    30/30 boxes ready to go!

    EU orders

    The shipment of 21 ODrives going to Sweden to be resent from there, due to the exquisite dance of following VAT regulations, has been stuck in customs for a week. I supplied them with the additional information they needed on Friday (two days ago), so hopefully it will be released ASAP. I will keep you posted on any updates.

    Kits

    The order of 40 motors from Hobbyking is still on backorder, with no estimate when they will have additional stock. All they tell me is that "we usually get new stock every 30 days".

    In any case, knowing that shipments from China likely has problems, I made a backup order of 40 similar motors from Aliexpress. They also took forever to get here, but they actually came in the end. Specifically, they are the EMP C4250 - 500kv. The motor has very similar dimensions, it is a slightly faster motor (slightly higher kv), and it seems to have a bit more cogging torque.

    Finally, motors!

    EMP C4250 - 500kv.

    EMP C4250 - 500kv with the included accessories.

  • LitePlacer - First Tests and Build

    Oskar Weigl05/09/2017 at 06:45 3 comments

    The first test of the LitePlacer retrofitted with ODrive motors was a success!

    Running at 40% speed limit and 25% current limit, reaching a top speed of 1.75 m/s. The motor that is currently on the LitePlacer was picked for a system running on 24V, but this test was run on 12V, hence the low speed limit. I have ordered a 24V power supply, so hopefully we can see it go twice as fast soon!


    It should be noted that it is possible to pick a motor with twice the kv rating to run on a 12V system, and it would perform respectably.


    LitePlacer build

    The LitePlacer comes in a kit, which took about 2 days to build. Below follows the build in pictures.

    Here is an empty table; this is where we start. It is where the LitePlacer will be bolted. I chose to get a sturdy table but it still wobbles with the very high accelerations.

    A box full of goodies!

    Here is everything in the kit, splayed out on the floor, and somewhat organised by type of part. If you are building the kit, I would recommend also sorting the bolts by size, which I did later on.

    The build instructions are very well done, with everything detailed in bite sized build steps. A significant time of the build is spent collecting the components for each step. So if you have an assistant, have them help you collect parts for the build steps. Above is our assembly line at one point.

    Here is the z-axis (with the lead screw and rails), rotation axis, and the pick mechanism.

    Here is the x-axis finished.

    Retrofitting the y-transmission with a Turnigy Aerodrive SK3 - 5065-275kv. Calculations show that it is vastly overpowered for this application. Just the way a demo should be.

    Mechanical parts semi-finished.

    Tasty kilowatts, aluminium and steel.

  • ODrive v3.2 Have Arrived!

    Oskar Weigl05/04/2017 at 19:25 0 comments

    ODrive v3.2

    I just received a huge box from the factory today, full of ODrives (mango for scale).

    ODrive v3.2 looking good!

    Now I will be testing to make sure the design works as expected. Once that is done, we are looking good for shipping ahead of schedule!

    At the time of writing there are still 10 ODrive v3.2 left in the batch. Get one here.

    Kits

    A huge pile of encdoers have arrived.

    Also the first batch of motors for testing have arrived.

    Turnigy Aerodrive SK3 4250-410kv looking good!

    For the kits we are still waiting on the large order of motors from hobbyking, and the jigs have yet to be 3D printed. The 3D printing should be okay for making the expected delivery date, but the motor order may cause delays. I will make sure to keep you up to date with how that goes.

    Cheers!

  • ODrive Community and New Website

    Oskar Weigl04/28/2017 at 22:04 0 comments

    I'm very excited to announce that the ODrive community forums are up and running. This is the place for all kinds of discussions, comments, ideas, feature requests and queries. It also serves as the main place to get help with your ODrive; where I, and others who will be gaining experience with the board, can all help you and each other. We'd also love to hear about your project: what you wish to do when kilowatts and micrometers meet in an affordable package.

    The ODrive website has moved to https://odriverobotics.com. It has also been updated and now has some basic content on it. Progressively more information and resources will be added, and soon enough it will become a fully featured place to find information about ODrive.

  • ODrive and LitePlacer at Maker Faire

    Oskar Weigl04/25/2017 at 19:58 7 comments

    For a long time now, the main ODrive demo has been the pen plotter from more than a year ago:

    This is about to change! Through a close collaboration with Juha Kuusama, the guy behind LitePlacer, I am excited to announce that there is a demo ODrive/LitePlacer demo brewing. This consists of a LitePlacer retrofitted with the vastly overpowered SK3-5065; able to put out 300N of force on the belts, and hence a theoretical acceleration of the head at 50g. This virtually unlimited power capability should be a good platform to test the actual performance of the full setup, with the ability to emulate the power capabilities of other motors by simply applying software limits.

    So if you are in the area, or maybe even if you are not, please do come see the demo at the Bay Area Maker Faire on Sat/Sun the 20th/21st of May.

  • Alpha Preorders Finished

    Oskar Weigl04/19/2017 at 21:48 0 comments

    The preorder period of ODrive v3.2 and the corresponding getting started kits has now concluded. To those who joined the project, thank you for your support, and welcome to the alpha stage team! The batch of v3.2's have now gone to manufacture and we are slightly ahead of schedule for shipping things out by the 15th of May.

    I anticipate that there are some people who will want to join mid-way through the alpha stage, so I made sure to order some extra stock. At the time of writing there are 8 kits left and 17 ODrives. They will continue to be available on the ODrive Shop page until stock runs out.

    Again thank you for your support!

  • ODrive v3.2 and Alpha Release

    Oskar Weigl03/27/2017 at 20:31 2 comments

    I am excited to let you know that the time has finally come for the alpha stage of the ODrive project. This consists of two components, the alpha software release and the manufacturing run for ODrive v3.2.

    TL;DR: Get your v3.2 alpha board Here.

    ODrive v3.2

    The new design is ready, and can be reviewed here. The design will go to production on Monday the 17th of April. As a one man team, I would greatly appreciate any and all feedback in from your review. Feel free to leave comments on this post, or write a private message.

    Changes from v3.1

    • Fix current sensor filter capacitor values
    • Break out the SPI port
    • Consolidate all 0.1" headers into two long rows
    • Remove the confusing EV (Encoder Voltage) rail.
    • Add test-points for most interesting analogue signals
    • Add precision LDO for AVCC (analog VCC)
    • Change MOSFETs to a slightly better Rdson version (30% better)
    • Adjust heatsink holes
    • Add fiducials
    • Improve labling

    ODrive v3.2 production run

    You can buy a board in this run on the shop: https://odrive.xyz/shop. The expected shipping date is expected to be the 15th of May, and the pre-orders will close on Monday the 17th of April, though some extra stock may be left after that. This is the board revision designed to be delivered simultaneous to the alpha firmware release.

    Firmware alpha release

    You can check which features will be included in the release here. The alpha release will include all the core features of the board, and allow go-to commands sent over USB, as well as step/direction interfacing.

    Proper documentation, setup and tuning instructions will be ready for you by the time that the board ships.

    ODrive is for real

    As I mentioned in the previous post, I finish my day job on Friday, and I will be taking up developing ODrive full time.

    ODrive is a serious product and deserves a website, so I bought the domain odrive.xyz, and set up a Squarespace website. As of the time of writing, I have only added the shop page: the reason for putting up that first is to be able to take the payments for this v3.2 pre-order. I've been focusing on getting the v3.2 board ready, and I haven't had time to put the rest up just yet. It will be up soon :)

    The reason I'm sharing this with you now, is because some people astutely pointed out that a website with no content, and only a shop page, looks very suspicious. Rest assured that the site at odrive.xyz is mine, and communication from oskar.weigl@odrive.xyz is legitimate. Any payments should go to ODrive SWE, and the address of the business is in Stockholm, Sweden. The VAT number of the business is SE901114035801.

    ODrive forums

    I am deeply impressed with the projects, ideas, skills and contributions that all of you have conveyed to me through various channels. I am really excited to talk to you about your application, how we can build the ODrive community and advance the project. In the next couple of weeks, I will set up an online forum for ODrive, and I hope you will join the community there!

    This will be the place for all kinds of discussions, comments, ideas, feature requests and queries. It will also serve as the main place to get help with your ODrive; where I, and others who will be gaining experience with the board, can all help you and each other. We'd also love to hear about your project: what you wish to do when kilowatts and micrometers meet in an affordable package.

  • Someone please build a parallel cable robot

    Oskar Weigl03/23/2017 at 11:44 7 comments

    I think the ODrive could provide plenty of power to make some really cool high dynamics.

    I was inspired by the Hangprinter discussions over on the RepRap forums.

  • Progress Update

    Oskar Weigl03/10/2017 at 01:48 6 comments

    It's time for an update.

    There has been some significant progress on the software including two major new features. The v3.1 hardware that I wrote about in the previous post has been further tested, this time not only by myself, but by several early developers. We managed to find only one serious hardware bug so far, which is fixed by replacing four capacitors. With the fixes to those bugs, the alpha testing stage is around the corner.

    New Features

    Two new major features are ready: USB Serial and brake resistor control.

    USB CDC - The main way for the ODrive to communicate with a PC or embedded computer (such as the RaspberryPI) is via USB Serial (aka USB CDC). This interface will be used both for sending configuration and commissioning commands, and interfacing with existing tools that have G-Code style output. With further extension, it can also support binary, and various application specific, protocols. Yay for open source.
    With significant help and contribution from @nickaknudson we now have a working USB CDC interface, which runs in a task parallel to the motor control tasks. The current implementation is very basic, it parses the commands and relays position commands directly to the motor control task. Going forward we will add trajectory generation to support coherent movement between multiple axes. Then we can handle the basic G0 and G1 G-Code "go-to" commands.


    Brake resistor - Software support for a brake resistor is now in place. This means that we can safely dissipate the energy absorbed when decelerating. This is important since many power supplies cannot handle reverse energy flow. The implementation has the two motor controllers estimate their power draw, and then calculates the net power draw from the power rail. If it is negative in total, the pulse width of the brake resistor control is set to exactly dissipate and hence cancel this power.

    Demo - In the above video you can see a demo of both features.

    Hardware bug found

    Everyone knows that voltage amplifiers have high input impedance, and low output impedance. Right? Well, apparently not.

    Above is a figure from the DRV8301 datasheet. 100 ohm output impedance doesn't qualify as low output impedance in my book... So this extra output impedance is causing a way too large "R" in the RC filter that filters the current sensor output. Hence the current sensing is way too slow, and barely usable.

    The fix involves replacing the capacitors highlighted in green painted labels with 2.2nF capacitors.

    Replacing 0603 capacitors on lots of boards gets quite tedious. Nevertheless, I don't want to ship out any of the remaining ODrive 3.1 boards with known errors on them. As you can see, I have 8 left, and they should all work now. If you are interested in claiming one of them, sign up for an Initial Development board on this form.

    Crowdsourced Testing

    I'm incredibly grateful for the people who were brave enough to pay for a board that was completely untested and with missing core features, and generous to spend their time helping to test those features as the were being brought up. You know who you are: Thank you!

    Below are some videos of some ODrives out there ;D


    ODrive v3.2 and Alpha Testing

    Already almost 200 of you have signed up for a board and at the same time shared with me the amazingly diverse projects that you want to use ODrive for. There were many projects that I expected like 3D printers, CNC mills, and Pick and Place machines. However there were so many cool and diverse projects I didn't expect. Here are some examples that was mentioned by more than one person each:

    • polargraphs
    • robot arms
    • walking robots
    • exosuits
    • motion simulation platform
    • heavy duty camera gimbals
    • camera dolly/slide
    • under water robots
    • mobile ground robots
    • various art projects

    I aim to have a quote ready for the manufacture of ODrive v3.2 at the beginning of April, and with that, I will open pre-orders for the Alpha release. I will send an email to everyone signed up on the google form. It will also be possible for anyone else...

    Read more »

  • The Boards Have Arrived!

    Oskar Weigl01/20/2017 at 17:39 4 comments

    Check this out, a box full of goodies:

    Inside each of the 5 packets, are 6 ODrive v3.1. And they are in lovely black and gold. The manufacturing quality of CircuitHub is really top notch ;D

    Here is a picture of the new boards on the testbed. Actually I never used the test bed in the end, since the manufacturing quality was so good. I don't expect any defects, and with such a small batch I don't mind replacing a board if it was indeed a DoA.

    ODrive v3.0 next to v3.1. Black looks great ;D

    Preparing some kits to go out with the first round of pre-alpha board orders.

    With the help of the early developers who will be helping, hopefully Alpha release will occur soon. If you want to get notified when that happens, make sure to sign up for the board manufacturing run: Link.

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Discussions

fabien.bruning wrote 2 hours ago point

Super cool project, do you have any estimate on when new boards can be ordered?

Thanks!

  Are you sure? yes | no

Guilhem Saurel wrote 05/23/2017 at 08:54 point

Hi !

I've ordered a v3.2 from my research lab in EU, and for some paperwork, my staff would need an invoice… It is possible ? If not, at least the VAT ref from Sweden, or a postal address in US would be nice :)

Thanks !

  Are you sure? yes | no

Oskar Weigl wrote 4 days ago point

Hi Guilhem, please email info@odriverobotics.com.

Cheers!

  Are you sure? yes | no

eduardo calegari wrote 05/07/2017 at 19:30 point

Some software suggestions compatible with the odriver

  Are you sure? yes | no

O4karitO wrote 05/05/2017 at 00:35 point

hi there. I've been monitoring this project for quite a while, amazing job. Are you planning to make a 1 or 3 motor version? For use in 3axis applications.
Thx

  Are you sure? yes | no

Oskar Weigl wrote 05/05/2017 at 00:35 point

Thanks!

Yes it is planned that ODrive v4 will be 3-axis.

  Are you sure? yes | no

O4karitO wrote 05/05/2017 at 00:37 point

wow, that was fast!
Any eta on that? I mean very roughly, like end of 2017, mid 2018, etc.

  Are you sure? yes | no

Oskar Weigl wrote 05/05/2017 at 02:18 point

@O4karitO I expect end of 2017.

  Are you sure? yes | no

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Oskar Weigl wrote 05/04/2017 at 17:58 point

You can sign up to the forum with existing Google, Facebook or Github logins. You can also just make a new user on the forum with any new username using just any email of your choice for verification.

  Are you sure? yes | no

Johannes wrote 04/27/2017 at 08:59 point

I like the lightplacer a lot...Hope this will work out soon! I'd like to come to MakerFair in SanMateo, but the flight is too long just to see this in action. Please keep us posted and upload a video. This looks similar to our NanoPlace machine, which runs on direct drive linear BLDCs with optical feedback encoder. 

Do you use a optical, linear encoder, too? If not, try it! it is definitely worth the effort. Precision rises a lot compared to just using the rotary encoder. Or, even better, use a camera atteched to the tool as a motion feedback sensor! I saw the ADNS 3080 chip has great performance and is quite affordable. It is an optical mouse flowcam with up to 6400fps at 6bit grey sclace depth and 30x30 pixels. Something i want to give a try.

Which sequencer/automation software/realtime interface do you want to use for you projects? 

I saw the SmothStepper ESS with Xilinx Spartan FPGA supports driving BLDCs with feedback sensors and step/dir interface at max 4 Mhz for up to 6 axis using a Ethernet based real time interface along with the Mach4 automation software. Maybe this is an option for our projects. I am not sure about Mach4 abilities to drive robots though, maybe there is a better solution? I am new to this...the Software I use at work is much too expensive for hobby projects. 

  Are you sure? yes | no

Oskar Weigl wrote 05/04/2017 at 18:01 point

Yes I'm also excited for the LitePlacer demo! Working on making it a reality as we speak!

Currently there is no linear encoders. I think it could be a great upgrade for good precision even without extremely stiff mechanics.

  Are you sure? yes | no

Johannes wrote 04/26/2017 at 12:16 point

Nice, thx for clearing things up. Waiting keen for the the board to arrive. So I will now order 21pcs Sony VTC4 cells (best economical/quality/longlife cell for the purpose) and a 240W powersupply that can be tuned to 25.2 V or 3.6V per cell (7cells in series/3parallel with oz890 smartBMS as balancer/ I2C-bus-monitor w/o FETs) to run two SK3-6364 motors

  Are you sure? yes | no

Johannes wrote 04/23/2017 at 13:34 point

shipping date is Mai 15 if i rember right.

I dont get why there is a 12V input? Makes no sense to me. I want to use a 24V 10A powersupply from ebay, about $20 and no noisy fan sounds good to me, now that i payed over $100 for the V3.2 board. Using a PC powersupply is much too complicated and expensive for my purposes. 

Please throw out that 12V input and replace it by a simple 24V input, thanks!!

http://www.ebay.com/itm/DC-24V-10A-240W-Converter-Adapter-Power-Supply-for-LED-Light-CCTV-AC110V-220V-/291899181907?hash=item43f68c0b53:g:CnkAAOSwpLNX9DiH

  Are you sure? yes | no

Oskar Weigl wrote 04/23/2017 at 19:37 point

Yes, expected shipping date is the 15th of May.

I assume you are looking at the architecture diagram. That shows just one way to wire it up, where there is a battery on the DC bus, and an arbitrary voltage power supply (8 to 22V) on the AUX port.

The currently supported way to hook it up is to plug in a power supply (like your 24V supply) directly on the DC bus, and a brake resistor on the AUX port.

Cheers

  Are you sure? yes | no

Toon wrote 04/18/2017 at 07:24 point

Is the v3.2 send to production?
Starting to build my own controller, to learn more about it and understand the difficulties of controlling BLDC's.
Using a teensy, 8,5 bit magnetic encoder, and a 3phase bridge.
I'm currently implemented sinusoidal commutated control. No current feedback yet.
Can you recommend some good articles, studies, you use during development of the firmware?
How do you deal with cogging? The motor likes drop into a certain position. I have a turingy aerodrive 3542 800?

 

  Are you sure? yes | no

Oskar Weigl wrote 04/19/2017 at 06:33 point

Hey, yeah the v3.2 was just sent to production today, but I ordered some extra so there is still some up for grabs.

Cool! Best of luck. Here are some resources in the order of most basic to most in depth:

http://scolton.blogspot.co.uk/2009/11/everything-you-ever-wanted-to-know.html

http://www.drivetechinc.com/articles/IM97PM_Rev1forPDF.pdf

https://github.com/muffinator/fall-2011/raw/master/URGE/JamesMevey2009.pdf

The simple solution to the cogging is to just use encoder feedback to force the motor with high gain to the location you need, and just reject the cogging through the feedback. Otherwise I think it could be characterised, like so: http://hackaday.com/2016/02/23/anti-cogging-algorithm-brings-out-the-best-in-your-hobby-brushless-motors/

but I haven't looked into that myself yet.

  Are you sure? yes | no

Toon wrote 04/19/2017 at 08:52 point

I already ordered a V3.2 board :-).
The JamesMevey2009.pdf is going to be an interesting read.
Thanks for the resources.
I think I have to re-evaluate my code to compensate for the cogging. I created a methode that scales the gain in order to move the motor in position without pushing to much current through the motor. I'll make it a bit more aggressive and add some current sensing feedback. I scared that I might burn out my motor.

  Are you sure? yes | no

Oskar Weigl wrote 04/19/2017 at 21:10 point

@Toon Cool, welcome to the alpha team!

Okay, best of luck!

FYI, cogging torque compensation is a planned feature for ODrive, though not the highest priority yet: https://github.com/madcowswe/ODriveFirmware/projects/1#card-2046258

  Are you sure? yes | no

Christopher McCloskey wrote 04/14/2017 at 19:10 point

What is the maximum encoder count/RPM that can be handled by the 2 axis system?

  Are you sure? yes | no

Oskar Weigl wrote 04/14/2017 at 19:13 point

Max encoder count is 2 billion, maximum encoder rate is around 10MHz, max rpm depends on the number of pole pairs of the motor. For a 7 pole pair motor, its around 18k rpm. 

  Are you sure? yes | no

eduardo calegari wrote 04/12/2017 at 02:26 point

Does your code identify the position of the motor rotor through the back emf and save this information through the encoder?
In which part of the code does this happen?
Is it automatic or does it have to be calibrated?
Which cnc software do you use?

Sorry so many questions, friend, it's the will to learn.
Hehe

  Are you sure? yes | no

Oskar Weigl wrote 04/12/2017 at 02:32 point

The encoder is calibrated against the rotor by driving a very strong current, and telling the user they may put no load on the motor. Then the rotor magnets will align to the magnetic field, and that is how you find where the rotor is in the first place. After that you just track the encoder.

I currently don't use any CNC software, but I will start trying some soon.

  Are you sure? yes | no

eduardo calegari wrote 04/11/2017 at 10:31 point

Congratulations on your cnc, the best project I've ever seen,

My names is eduardo calegari, I live in Brazil,
I've always been fond of cnc bldc its hardware and pid positioning codes,
If you could give me information on books and studies on pid and position codes bldc stm32f.
   I will be very grateful if you guide me in this learning because I am a little lay on this subject.

  Are you sure? yes | no

Oskar Weigl wrote 04/11/2017 at 17:03 point

Thank you!

Sure, I would recommend reading something like this: http://manuals.chudov.com/Servo-Tuning/PID-without-a-PhD.pdf

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Christopher McCloskey wrote 04/04/2017 at 19:39 point

Is the motion still precise/smooth at low/slow rpm? I am guessing commutation is done by back EMF, but I was under the impression that for precision at low speeds hall effect sensor commutation is generally necessary. Have you found a way around this? 

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Oskar Weigl wrote 04/11/2017 at 04:46 point

Yes the motion is precise and smooth at low speed. The commutation is done by encoder feedback, so even more precise than hall effect sensors.

Cheers!

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Christopher McCloskey wrote 04/11/2017 at 13:45 point

Wow, that's amazing. The only other encoder commutation system I've seen  costs $40 per cable, not including the actual encoders or drivers. Is there currently a feature to output one pulse per encoder revolution on one of the I/O? Equivalent to spindle indexing, which would allow tapping/threading operations with CNC via Mach3 or LInuxcnc. 

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Oskar Weigl wrote 04/11/2017 at 17:00 point

@Christopher McCloskey
It should be straightforward to set up one of the GPIO pins to send a pulse every revolution.

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Alexander Osika wrote 03/21/2017 at 09:08 point

Hi Oskar! Really cool project; cheap brushless motors with position control will be great for robotics :) I was wondering however if you have considered going in the direction of having a motor controller with integrated encoder, mounted at the motor itself, and connected on a bus? As reference I have been looking at the T-STorM32 project (http://www.olliw.eu/storm32bgc-wiki/What_is_T-STorM32_about?) and the commercial motors from SimplexMotion.
Greetings from Chalmers Robotics!

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Oskar Weigl wrote 04/11/2017 at 04:45 point

Hey! Thanks!

Yes I have thought about making an all-in-one package with motor/controller/encoder. The main limitation is cost. I will take it up seriously once the baseline controller is out and stable.

Cheers!

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EngineerAllen wrote 03/12/2017 at 10:30 point

looks complicated!

how many hours did it take? 1000?

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davedarko wrote 03/12/2017 at 13:48 point

It's over 9000!!

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EngineerAllen wrote 03/12/2017 at 15:36 point

not you again

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Oskar Weigl wrote 03/12/2017 at 19:31 point

Yeah I's say around 1000 is about right. I haven't counted, but I know I've played 1000 hours of Dota 2, and I've worked on this project about the same ammount ^^

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EngineerAllen wrote 03/12/2017 at 20:24 point

haha thats a good balance =D

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Oskar Weigl wrote 03/12/2017 at 20:25 point

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Alain de Lamirande wrote 01/09/2017 at 14:51 point

Guten Tag Oskar ! Wie gehst ? Mein Name ist Alain. Ich bin von Kanada. Ich interessiere mich wirklich für Ihr Projekt. 

Do you have some boards, ready made to sell that I could test ? I know that this is open source, but I need a quick solution to test before I can make my own !

Danke für alles !



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Oskar Weigl wrote 03/07/2017 at 17:20 point

Sure, just sign up for a board here: http://goo.gl/forms/Y9aHMVqWyjW9WjHG2

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Toon wrote 11/25/2016 at 13:04 point

I just saw this : https://www.kickstarter.com/projects/919717340/the-user-friendly-servomotor-you-always-hoped-exis/comments
also on hackaday.iohttps://hackaday.io/project/6912-the-user-friendly-servomotor-you-hoped-existed
Price is a bit to much at $169 + shipping and I don't think they will reach the $75K goal.
I think ODrive can be cheaper with the same performance. 
Also they use a 14bit magnetic rotary position sensor from Austria Microsystems claiming accuracy of +/- 0.2°. I know we had a conversation before about this but I still think it could be a nice option compared to the "600P/R Incremental Rotary Encoders" which is bulkier and a bit more expensive.

Looking forward for news on the new test-PCB's. 

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Oskar Weigl wrote 11/26/2016 at 10:12 point

Thanks for sharing!

It looks like it is stepper motor based. In fact, it looks very similar to a Mechaduino, but with a web interfaced strapped on.

When it comes to performance, it depends on what you mean. But for sure in terms of power output, ODrive will be much higher.

Yeah I think the magnetic encoders are a good idea to support, and I intend to support it on ODrive v4.

I have some progress to share, I will do a writeup to share hopefully this weekend.

Cheers!

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Toon wrote 11/26/2016 at 17:08 point

The HDrive is a brushless direct drive based on a two phase hybrid stepper motor. They show a little movie where they spin it to 10.000 RPM. Impossible with a conventional stepper motor. Will be something between a BLDC and a stepper.

Mechaduino uses stepper motors. 

I like the idea of an webInterface and having a udp socket as an interface. 

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Maciej wrote 10/30/2016 at 19:08 point

Is it usable now? I'm thinking about testing it in big 3D printer, just want to know if step/dir input works? Than maybe I'll be able to help you guys developing it further ;)

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Oskar Weigl wrote 10/31/2016 at 10:38 point

Hey, sounds cool! Unfortunately the project is quite delayed, but it will get back on track in the next week, which is exciting!

If you want to be informed when you can buy a board at alpha testing stage, which is what it sounds like to me, please sign up here: http://goo.gl/forms/Y9aHMVqWyjW9WjHG2

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volatile666 wrote 11/09/2016 at 17:54 point

So, how's the status now? ;)

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Oskar Weigl wrote 11/10/2016 at 08:14 point

@volatile666 Last weekend I ordered some test-PCBs (bed of nails). So stuff is moving along again. Once the test-routines all work, we can start manufacture.

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volatile666 wrote 09/14/2016 at 15:10 point

Any news? :) No news is good news?

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Oskar Weigl wrote 09/15/2016 at 15:01 point

Currently the project is a bit stalled unfortunately. It should pick back up in full force around November (:

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PointyOintment wrote 09/01/2016 at 02:39 point

Could you do a writeup on how you arrived at your current design (i.e. what parts and configurations you're using and why)?

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Oskar Weigl wrote 09/01/2016 at 07:38 point

Yes I can do. Currently my priority is to the get the manufacturing and base functionality done. After that I can do a writeup.

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