Smiling Robot Moves Without Wires

What could be cuter than a little robot that scuttles around its playpen and smiles all day? For the 2018 Hackaday prize [bobricius] is sharing his 2D Actuator for Micro Magnetic Robot. The name is not so cute, but it boasts a bill of materials under ten USD, so it should be perfect for educational use, which is why it is being created.

The double-layer circuit board hides six poles. Three poles run vertically, and three of them run horizontally. Each pole is analogous to a winding in a stepper motor. As the poles turn on, the magnetic shuttle moves to the nearest active pole. When the perpendicular windings activate, it becomes possible to lock that shuttle in place. As the windings activate in sequence, it becomes possible to move left/right and forward/back. The second video demonstrates this perfectly.

[bobricius] found inspiration from a scarier source, but wants us to know this is his creation, not a patent infringement. We are not lawyers.

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Scrapped Motors Don’t Care About Direction

Spinners built into games of chance like roulette or tabletop board games stop on a random number after being given a good spin. There is no trick, but they eventually rest because of friction, no matter how hard your siblings wind up for a game-winning turn. What if the spinning continued forever and there was no programming because there was no controller? [Ludic Science] shows us his method of making a perpetual spinner with nothing fancier than a scrapped hard disk drive motor and a transformer. His video can also be seen below the break.

Fair warning: this involves mains power. The brushless motor inside a hard disk drive relies on three-phase current of varying frequencies, but the power coming off a single transformer is going to be single-phase AC at fifty or sixty Hz. This simplifies things considerably, but we lose the self-starting ability of the motor and direction control, but we call those features in our perpetual spinner. With two missing phases, our brushless motor limps along in whatever direction we initiate, but the circuit couldn’t be much more straightforward.

This is just the latest skill on a scrapped HDD motor’s résumé (CV). They will run with a 9V battery, or work backwards and become an encoder. If you want to use it more like the manufacturer’s intent, consider this controller.

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Motor test bench talks the torque

Salvaging a beefy motor is one life’s greatest pleasures for a hacker, but, when it comes to using it in a new project, the lack of specs and documentation can be frustrating. [The Post Apocalyptic Inventor] has a seemingly endless stockpile of scavenged motors, and decided to do something about the problem.

Once again applying his talent for junk revival, [TPAI] has spent the last year collecting, reverse-engineering and repairing equipment built in the 1970s, to produce a complete electric motor test setup. Parameters such as stall torque, speed under no load, peak power, and more can all easily be found by use of the restored test equipment. Key operating graphs that would normally only be available in a datasheet can also be produced.

The test setup comprises of a number of magnetic particle brakes, combined power supply and control units, a trio of colossal three-phase dummy loads, and a gorgeously vintage power-factor meter.

Motors are coupled via a piece of rubber to a magnetic particle brake. The rubber contains six magnets spaced around its edge, which, combined with a hall sensor,  are used to calculate the motor’s rotational speed. When power is applied to the coil inside the brake, the now magnetised internal powder causes friction between the rotor and the stator, proportional to the current through the coil. In addition to this, the brake can also measure the torque that’s being applied to the motor shaft, which allows the control units to regulate the brake either by speed or torque. An Arduino slurps data from these control units, allowing characteristics to be easily graphed.

If you’re looking for more dynamometer action, last year we featured this neatly designed unit – made by some Cornell students with an impressive level of documentation.

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Pepper Mill Locks Your Door

Pepper! If you’ve ever tried to grind it, you’ve probably noticed it takes a bit of elbow grease. It’s actually possible to source electric pepper mills to grind it for you, in fact. It just so happens that [MarioM66] had one to hand, and a door lock that needed automating.

Seeing as grinding pepper requires at least as much torque as turning an average key in an average lock, the electric pepper mill makes perfect sense to use as a lock actuator. This build actually uses the electric pepper mill to directly turn the key in the lock, courtesy of an adapter to couple the square output shaft to the key. The adapter was crafted out of a moldable plastic called MultiMorph. The pepper mill is being used for its high-torque motor & gearbox, which makes it absolutely perfect for this application.

The rest of the project leans heavily on the hacker’s go-to, an Arduino and some off-the-shelf gesture recognition modules. Now, it’s possible to lock and unlock the door at the press of a button or the wave of a hand! Video after the break.

It’s great to see run-of-the-mill objects hacked into useful parts for new projects. In the same vein, check out this car that lets you fistbump to unlock.

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IQ Makes Smarter Motors

We think of motors typically as pretty dumb devices. Depending on the kind, you send them some current or some pulses, and they turn. No problem. Even an RC servo, which has some smarts on board, doesn’t have a lot of capability. However, there is a new generation of smart motors out that combine the mechanical motor mechanism with a built-in controller. [Bunnie] looks at one that isn’t even called a motor. It is the IQ position module.

Despite the name, these devices are just a brushless DC motor (BLDC) with a controller and an API. There’s no gearing, so backdriving the motor is permissible and it can even double as a motion sensor. The video below shows [Bunnie] making one module track the other using just a little bit of code.

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Here’s Why Hoverboard Motors Might Belong In Robots

[madcowswe] starts by pointing out that the entire premise of ODrive (an open-source brushless motor driver board) is to make use of inexpensive brushless motors in industrial-type applications. This usually means using hobby electric aircraft motors, but robotic applications sometimes need more torque than those motors can provide. Adding a gearbox is one option, but there is another: so-called “hoverboard” motors are common and offer a frankly outstanding torque-to-price ratio.

A teardown showed that the necessary mechanical and electrical interfacing look to be worth a try, so prototyping has begun. These motors are really designed for spinning a tire on the ground instead of driving other loads, but [madcowswe] believes that by adding an encoder and the right fixtures, these motors could form the basis of an excellent robot arm. The ODrive project was a contender for the 2016 Hackaday Prize and we can’t wait to see where this ends up.

Three Wires = One Motor

Here’s a quick build to show off fundamentals of electric current to new makers — or a cool party trick that might earn you a buck. [Jay] from the [Plasma Channel] shows off how you can make a simple motor with only three pieces of enameled wire in under five minutes.

Start with a roll of 26-guage — or thicker — magnet wire, and a pair of scissors or knife. For the base, wrap fifteen to twenty turns of wire around any spherical object about one and a half inches in diameter, leaving a few inches extra on both ends. Wrap those ends around your coil a few tines to secure it and straighten out the excess length — one will act as a support and the other will connect to your power source. Another piece of wire — similarly wrapped around the base coil — acts as the other support and the other terminal. Scrape off the wire coating from one side on both support wires and curl them into small loops. Halfway done!

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