Meet The New Moteus BLDC Controller Board, The N1

March 18, 2023 by Chris Lott 4 Comments

[Josh] over at mjbots just released a new version of the moteus controller board, dubbed the moteus-n1. One change is that the volume and footprint size has been reduced. Considering many people, [Josh] included, use these controllers to operate robotic dogs, smaller is better. The previous moteus controller maxed out at 44 V, but the n1 can run at up to 54 V, allowing use of 48 V power supplies. And [Josh] improved the interface circuitry, making it much more flexible than before. This comes at an increased price, but he sells both versions — parts availability permitting. And like the previous versions of the moteus controller, this is an open source project and you’re free to build it yourself. You can check out the complete design package at the project’s GitHub repository.

One helpful point is that the firmware for the n1 is the same, it simply enables new features related to the I/O ports. This means a user could swap in a new controller with no impact to their system. Maintaining firmware compatibility was just one of the challenges [Josh] faced along the way. Squeezing additional functionality into the small number of user-exposed I/O pins was a chore, but dealing with supply chain issues was a big headache:

…make a revision that leveraged the parts I had, along with ensuring that the parts I needed were achievable to purchase in a reasonable time frame. Some parts orders for this batch were placed nearly a year ago.

Check out moteus if you need a brushless servo controller. We covered the previous major upgrade last year, which was primarily firmware and interface focused.

Moteus Open Source BLDC Controller Gets Major Upgrade

July 4, 2022 by Chris Lott 6 Comments

[Josh Pieper] of mjbots Robotic Systems just released a major revision to his moteus open sourced brushless DC (BLDC) electric motor controller. The update adds a flexible I/O subsystem which significantly expands the kinds of feedback encoders and peripherals the controller can accept. In the video below the break, [Josh] walks through eleven different example configurations. If you prefer, these examples are also presented in article form on his blog.

The moteus controller originally came about when [Josh] was developing the quad A0, an open source dynamic quadruped robot, along the lines of the MIT Mini Cheetah or Boston Dynamics robotic dogs, and wasn’t satisfied that existing controllers could do the trick. It’s a compact 50 mm square board based on an STM32G4, has an integrated magnetic encoder, and accepts external sensor connections. Interfacing with the board is via CAN-FD using a register-based scheme. A Python GUI tool provides name-based register access via a logical tree structure as well as real-time telemetry plotting capabilities for diagnostic and configuration tasks.

If you are using BLDC motors in your projects, definitely check this out. Even if you’re not using a moteus controller, [Josh]’s demonstrations of the various encoder feedback technologies is very interesting and educational. The entire project is open source, and both the hardware and software design files can be found on the project’s GitHub repository. For some users, this may be a major factor, considering that the latest ODrive BLDC controller offering has become closed source.

We wrote about the mjbots quad A0 in 2019, and you can follow the moteus project over on Hackaday.io. We also found this interesting video by [Skyentific] comparing three popular open source BLCD controllers including the moteus (second video below the break). There’s also the SimpleFOC project we covered last year if you want to dig in and learn more about field-oriented control of BLDC motors. Thanks to [Androiddrew] for the tip.

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Amazing Open Source Quadruped Capable Of Dynamic Motion

October 3, 2019 by Gerrit Coetzee 10 Comments

The more we read about [Josh Pieper]’s quadruped, the mjbots quad A0, the more blown away we are by his year of progress on the design. Each part of the robot deserves its own article: from the heavily modified brushless motors (with custom planetary gears) to the custom motor driver designed just for this project.

[Josh], realized early on that the off-the-shelf components like an ODrive just weren’t going to cut it for his application. So he designed his own board, took it through four revisions, and even did thermal and cycle testing on it. He ended up with the compact moteus board. It can pump out 400 Watts of peak power while its 3Mbit control protocol leaves plenty of bandwidth for real time dynamic control.

The motors and gearboxes are also impressive. It took thorough experimenting and taking inspiration from other projects before he arrived at a 8108 quad copter motor modified and upgraded so heavily its own mother wouldn’t recognize it. This is all packed into a leg unit with three degrees of freedom that puts even the fanciest servo based quadruped to shame.

Finally it’s all packed into a neat four-legged robot frame with batteries and a Pi. You can get a video summary of the robot here or after the break, and we recommend reading his blog for some more images and details.

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