Designing Tiny Motors Right Into The Robot’s Circuit Board

Motors are not overly complex, but this one is downright simple. Carl Bujega has been working on a motor design that heavily relies on the capabilities of the printed circuit board (PCB) fabrication processes. His talk at the 2018 Hackaday Superconference covers how he built a brushless DC motor and speed controller into a PCB. You can watch the newly published video after the break.

There are two main parts of an electric motor; the stator is stationary while the rotor spins on bearings. Electromagnetic forces are used to cause that spinning action. In this case, Carl has built the electromagnets as coils on a 4-layer circuit board (six coils on each layer). When electrified, a magnetic field is generated that pushes against the rare-earth magnets housed in the rotor.

A couple of things are really interesting here. First, those coils are usually made of “magnet wire” (enamel covered wire that is very thin) wrapped around an iron core. Using the circuit board instead saves both physical space, and the time and expense of wrapping coils of wire in the traditional way. Second, Carl has been designing with manufacture in mind; you can see in the image show that his motor design is dead-simple to assemble by inserting a 3mm bearing in the PCB, inserting magnets into the plastic rotor and snapping it into place. The end goal is to make robot actuators that are part of the circuit board itself.

The genesis of this idea came from Carl’s interest in drone design, in fact, he jumped right into a drone startup immediately after finishing his EE. The company didn’t last, but his thirst for interesting designs is ongoing. When looking at reducing the total parts necessary to build a quadcopter he happened on the idea of PCB-based coils and he’s followed it to this motor design, and beyond to some very interesting flexible-PCB robot design work which you can check out on his Hackaday.io page, YouTube, and Twitter.

There are of course some trade-offs to this. The motor is low torque since it uses an air core and not an iron core. And he’s had trouble implementing a sensor-less Electronic Speed Controller (ESC) as the back-EMF from the coils appears to be too weak. Not to fret, he added a hall sensor and has succeeded in designing an ESC that measures just 14mm by 8mm. In fact, he’s holding up the ESC and motor in the image at the top of this article!

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Putting a Motor Inside a Speed Controller

One of the more interesting hacks we’ve seen this year is [Carl]’s experimentations with making motors out of PCBs. Honestly, it’s surprising no one has done this before — a brushless motor is just some coils of wire and a few magnets; anyone can turn some coils into traces and make a 3D print that will hold a few magnets. This latest advancement is something else entirely. It’s a motor and an electronic speed controller all in one.

This project is a continuation of [Carl]’s PCB motor project, which started with him routing coils for a brushless motor as traces in a circuit board. Previously, we’ve seen [Carl]’s motor spinning on its own with the help of a small hobby ESC / motor controller meant for model planes and drones. This time, we’ve got something different. It’s an entire controller and motor, integrated into one single PCB.

This is a very, very small motor and ESC combo. The motor driver is a 3x3mm QFN package, and most of the other components are 0201. The main parts are a very tiny triple half-bridge motor driver and a PIC16F microcontroller. This PIC reads a hall sensor to detect the speed of the motor, and with just three pins — power, ground, and a PWM pin — this motor can spin at a set speed.

The future goals of this project are to make it work just like any other hobby ESC — just plug it into a servo controller and let ‘er rip. Since this motor with an integrated PCB requires only three connections, we’re looking at a great tool to add motion and rotation to any project. It’s fantastic, and we can’t wait to see something like this in robots, toys, and other home goods.

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Friday Hack Chat: Motors Made Out Of PCBs

One of the most amazing technological advances found in this year’s Hackaday Prize is the careful application of copper traces turned into coils. We’ve seen this before for RFID tags and scanners, but we’ve never seen anything like what Carl is doing. He’s building brushless motors on PCBs.

All you need to build a brushless motor is a rotor loaded up with super powerful and very cheap magnets, and a few coils of wire. Now that PCBs are so cheap, the coils of wire are easily taken care of. A 3D printer and some eBay magnets finish off the rest. For this week’s Hack Chat, we’re talking with Carl about PCB motors.

Carl Bugeja is a 23-year old electronics engineer who is trying to design new robotics technology. His PCB Motor design won the Open Hardware Design Challenge and will be going to the Finals of the Hackaday Prize. This open-source PCB motor is a smaller, cheaper, and easier to assemble micro-brushless motor.

[Carl]’s main project, the PCB Motor is a stator that is printed on a 4-layer PCB board. The six stator poles are spiral traces wound in a star configuration. Although these coils produce less torque compared to an iron core stator, the motor is still suitable for high-speed applications. [Carl]’s been working on other PCB motor designs, like the Linear PCB motor which is a monorail on a PCB and the Flexible PCB actuator where the coils of wire are tucked inside Kapton.

During this Hack Chat, we’re going to be discussing:

  • The design and construction of brushless motors
  • How to drive these motors
  • PCB applications beyond standard circuitry
  • Building accessible robotics technology

You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the Hack Chat Event Page and we’ll put that in the queue for the Hack Chat discussion.join-hack-chat

Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. This week is just like any other, and we’ll be gathering ’round our video terminals at noon, Pacific, on Friday, August 10th. Need a countdown timer? You wouldn’t if we switched to universal metric time.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io.

You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.