Hackaday Prize Entry: Industrial Servo Control On The Cheap

[Oscar] wonders why hobby projects ignore all the powerful brushless motors available for far less than the equivalent stepper motors, especially with advanced techniques available to overcome their deficiencies.  He decided it must be because there is simply not a good, cheap, open source motor controller out there to drive them precisely. So, he made one.

Stepper motors are good for what they do, open-loop positioning along a grid, but as far as industrial motors go they’re really not the best technology available. Steppers win on the cost curve for being uncomplicated to manufacture and easy to control, but when it comes to higher-end automation it’s servo control all the way. The motors are more powerful and the closed-loop control can be more precise, but they require more control logic. [Oscar]’s board is designed to fill in this gap and take full advantage of this motor control technology.

The board can do some pretty impressive things for something with a price goal under $50 US dollars. It supports two motors at 24 volts with up to 150 amps peak current. It can take an encoder input for full closed loop control. It supports battery regeneration for braking. You can even augment a more modest power supply to allow for the occasional 1 KW peak movement with  the addition of a lithium battery. You can see the board showing off some of its features in the video after the break.

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Cyclists Use Tiny Motors to Cheat

Blood doping is so last decade! The modern cyclist has a motor and power supply hidden inside the bike’s frame.

We were first tipped off to the subject in this article in the New York Times. A Belgian cyclocross rider, Femke Van den Driessche, was caught with a motor hidden in her bike.

While we don’t condone sports cheating, we think that hiding a motor inside a standard bike is pretty cool. But it’s even more fun to think of how to catch the cheats. The Italian and French press have fixated on the idea of using thermal cameras to detect the heat. (Skip to 7:50 in the franceTVsport clip.) We suspect it’s because their reporters recently bought Flir cameras and are trying to justify the expense.

The UCI, cycling’s regulatory body, doesn’t like thermal. They instead use magnetic pulses and listen for the characteristic ringing of a motor coil inside the frame. Other possibilities include X-ray and ultrasonic testing. What do you think? How would you detect a motor inside a bike frame or gearset?

A Simple And Educational Brushless Motor

Sometimes there is no substitute for a real working model to tinker with when it comes to understanding how something works. Take a brushless motor for example. You may know how they work in principle, but what factors affect their operation and how do those factors interact? Inspired by some recent Hackaday posts on brushless motors, [Matt Venn] has built a simple breadboard motor designed for the curious to investigate these devices.

The rotor and motor bodies are laser-cut ply, and the rotor is designed to support multiple magnet configurations. There is only one solenoid, the position of which relative to the magnets on the rotor can be adjusted. The whole assembly is mounted on the edge of a breadboard, and can be rotated relative to the breadboard to vary the phase angle at which the drive circuit’s Hall-effect sensor is activated by the magnet. The drive circuit in turn can have its gain and time constants adjusted to study their effects on the motor’s running.

[Matt] has made all the design files available in his GitHub repository, and has recorded a comprehensive description of the motor’s operation in the YouTube video below the break. Continue reading “A Simple And Educational Brushless Motor”

An Open Source Two Stroke Diesel

With a welder and a bunch of scrap, you can build just about anything that moves. Want a dune buggy? That’s just some tube and a pipe bender. Need a water pump? You might need a grinder. A small tractor? Just find some big knobby tires in a junkyard. Of course, the one thing left out of all these builds is a small motor, preferably one that can run on everything from kerosene to used cooking oil. This is the problem [Shane] is tackling for his entry to the 2016 Hackaday Prize. It’s an Open Source Two-Stroke Diesel Engine that’s easy for anyone to build and has minimal moving parts.

[Shane]’s engine is based on the Junkers Jumo 205 motor, a highly successful aircraft engine first produced in the early 1930s and continued production through World War II. This is a weird engine, with two opposed pistons in one cylinder that come very close to slamming together. It’s a great design for aircraft engines due to it’s lightweight construction. And the simplicity of the system lends itself easily to wartime field maintenance.

The Jumo 205 was a monstrous 12-piston, 6-cylinder engine, but for [Shane]’s first attempt, he’s scaling the design down to a 50cc motor with the intent of scaling the design up to 125cc and 250cc. So far, [Shane] has about 30 hours of simple CAD work behind him and a ton of high-level FEA work ahead of him. Then [Shane] will actually need to build a prototype.

This is actually [Shane]’s second entry to the Hackaday Prize with this idea. Last year, he threw his hat into the ring with the same idea, but building a working diesel power plant is a lot of work. Too much for one man-year, certainly, so we can’t wait to see the progress [Shane] makes this year.

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Automating RC Motor Efficiency Testing

Small brushless motors and LiPo batteries are one of the most impressive bits of technology popularized in recent years. Just a few years ago, RC aircraft were powered by either anemic brushed motors or gas. Quadcopters were rare. Now, with brushless motors, flying has never been easier, building electric longboards is simple, and electric bicycles are common.

Of course, if you’re going to make anything fly with a brushless motor, you’ll probably want to know the efficiency of your motor and prop setup. That’s the idea behind [Michal]’s Automated RC Motor Efficiency Tester, his entry to the 2016 Hackaday Prize.

[Michal]’s project is not a dynamometer, the device you should use if you’re measuring the torque or power of a motor. That’s not really what you want if you’re testing brushless motors and prop configurations, anyway; similarly sized props can have very different thrust profiles. Instead of building a dyno for a brushless motor, [Michal] is simply testing the thrust of a motor and prop combination.

The device is very similar to a device sold at Hobby King, and includes a motor mount, microcontroller and display, and a force sensor to graph the thrust generated by a motor and prop. Data can be saved to an SD card, and the device can be connected to a computer for automatic generation of pretty graphs.

Brushless motors are finding a lot of uses in everything from RC planes and quadcopters, to robotics and personal transportation devices. You usually don’t get much of a data sheet with these motors, so any device that can test these motors will be very useful.

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Home-Made Solenoid Motor

Want to really understand how something works? Make one yourself. That’s the approach that Reddit user [Oskarbjo] took with this neat electric motor build. He made the whole thing from scratch, using an Arduino, 3D printing, and ample quantities of wire to create a solenoid motor. This transforms the linear force of a solenoid, where a magnet is moved by a magnetic field, into rotary force. It’s rather like an internal combustion engine, but driven by electricity instead of explosions. Hopefully.

[Oskarbjo]’s engine seems to work, including a rather neat mechanism to detect the rotation of the shaft and relay that back to the controller. He hasn’t posted much detail in the build process, unfortunately, but did say that “If you’d want to build something similar I can probably help you out a bit, but half the fun is coming up with your own solutions.” Amen to that. We’ve seen a few neat solenoid motor builds, but this one wins points for starting from scratch. There is an Instagram video of the motor running after the break.

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Brushed DC Servo Drive

Brushless DC motors, and their associated drive electronics, tend to be expensive and complicated. [Ottoragam] was looking for a cheaper alternative and built this Brushed DC motor servo controller and the results look pretty promising. Check out the video after the break.

He needed a low cost, closed loop drive for his home-brew CNC. The servo drive is able to supply a brushed DC motor with up to 7 A continuous current at up to 36 V which works out to about 250 W or 1/3 HP. It does closed loop control with feedback from a quadrature encoder. The drive accepts simple STEP and DIRECTION signals making it easy to interface with micro controllers and use it as a replacement for stepper motors in positioning applications. All of the control is handled by an ATmega328P. It takes the input signals and encoder data, does PID control, and drives the motor via the DRV8701 full bridge MOSFET driver. There’s also some error detection for motor over-current and driver under-voltage. Four IRFH7545 MOSFETs in H-bridge configuration form the output power stage.

This is still work in progress, and [Ottoragam] has a few features pending in his wish list. The important ones include adding a serial interface to make it easy to adjust the PID parameters and creating a GUI to make the adjustment easier. The project is Open Source and all source files available at his Github repository. The board is mostly surface mount, but the passives are all 0805, so it ought to be easy to assemble. The QFN footprint for the micro controller could be the only tricky one. [Ottoragam] would love to have some beta testers for his boards, and maybe some helpful comments to improve his design.

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