Baby’s First Hands-Free Stroller

So you’ve had your first child. Congratulations; your life will never be the same again. [Dusan] was noticing how the introduction of his children into his life altered it by giving him less time for his hobbies in his home laboratory, and decided to incorporate his children into his hacks. The first one to roll out of his lab is a remote-controlled baby stroller.

After some engineering-style measurements (lots of rounding and estimating), [Dusan] found two motors to drive each of the back wheels on a custom stroller frame. He created a set of wooden gears to transfer power from the specialized motors to the wheels. After some batteries and an Arduino were installed, the stroller was ready to get on the road. At this point, though, [Dusan] had a problem. He had failed to consider the fact that children grow, and the added weight of the child was now too much for his stroller. After some adjustments were made (using a lighter stroller frame), the stroller was eventually able to push his kid around without any problems.

This is an interesting hack that we’re not sure has much utility other than the enjoyment that came from creating it. Although [Dusan]’s kid certainly seems to enjoy cruising around in it within a close distance to its operator. Be sure to check out the video of it in operation below, and don’t forget that babies are a great way to persuade your significant other that you need more tools in your work bench, like a CNC machine for example.

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This Miniscule IR to HID Keyboard Hides in a Key Cap

Shards of silicon these days, they’re systematically taking what used to be rather complicated and making it dead simple in terms of both hardware and software. Take, for instance, this IR to HID Keyboard module. Plug it into a USB port, point your remote control at it, and you’re sending keyboard commands from across the room.

To do this cheaply and with a small footprint used to be the territory of bit-banging software hacks like V-USB, but recently the low-cost lines of microcontrollers that are anything but low-end have started speaking USB in hardware. It’s a brave new world.

In this case we’re talking about the PIC18F25J50 which is going to ring in at around three bucks in single quantity. The other silicon invited to the party is an IR receiver (which demodulates the 38 kHz carrier signal used by most IR remotes) with a regulator and four passives to round out the circuit. the board is completely single-sided with one jumper (although the IR receiver is through-hole so you don’t quite get out of it without drilling). All of this is squeezed into a space small enough to be covered by a single key cap — a nice touch to finish off the project.

[Suraj] built this as a FLIRC clone — a way to control your home-built HTPC from the sofa. Although we’re still rocking our own HTPC, it hasn’t been used as a front-end for many years. This project caught our attention for a different reason. We want to lay down a challenge for anyone who is attending SuperCon (or not attending and just want to show off their chops).

This is nearly the same chip as you’ll find on the SuperCon badge. That one is a PIC18LF25K50, and the board already has an IR receiver on it. Bring your PIC programmer and port this code from MikroC over to MPLAB X for the sibling that’s on the badge and you’ll get the hacking cred you’ve long deserved.

[via Embedded Lab]

A Real Turn Off

[Newbrain] had a small problem. He’d turn off the TV, but would leave the sound system turned on. Admittedly, not a big problem, but an annoyance, none the less. He realized the TV had a USB port that went off when it did, so he decided to build something that would sense when the USB port died and fake a button press into the amplifier.

He posted a few ideas online and, honestly, the discussion was at least as interesting as the final project. The common thread was to use an optoisolator to sense the 5 V from the USB port. After that, everyone considered a variety of ICs and discretes and even did some Spice modeling.

In the end, though, [Newbrain] took the easy way out. An ATtiny 84 is probably overkill, but it easy enough to press into service. With only three other components, he built the whole thing into a narrow 24-pin socket and taped it to the back of the audio unit’s wired remote control.

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Open Hardware RC Radios

A decade ago, RC transmitters were clunky, expensive and PCM. A decade before that, everything was analog. Now, RC transmitters are completely digital, allowing for hundreds of aircraft to take to the sky. They’re also cheap, thanks to engineers in China. Now, they’re open hardware, too.

An old Futaba radio outfitted with AR Uni electronics. Image source: vikar
An old Futaba radio outfitted with AR Uni electronics. Image source: vikar

An exceptionally long thread over on the RCGroups forums has been going on for a few months, extolling the virtues of the ‘AR Uni’ board that turns old transmitters into full featured digital radios. This board runs everything, from two analog sticks, a directional keyboard, pots galore, switches everywhere, and a fancy LCD that makes programming easy. The joys of Open Hardware, brought to RC geeks. It’s a thing of beauty. Continue reading “Open Hardware RC Radios”

Kansas City Maker Faire: Lawn da Vinci is the Droid You’re Looking For

Summer is now in full swing, which means that mowing the lawn once a week is starting to get old. So why not build a robot do it for you? That’s what [Blake Hodgson] did, and he’s never been happier. It only took him a couple of weeks of quality time at one of the local makerspaces.

[Blake] was showing off Lawn da Vinci at this year’s Kansas City Maker Faire. He had his own booth around the corner from Hammerspace, the shop where it all came together. [Blake] started with a standard push mower from a garage sale and designed a frame around it using OnShape. The frame is made from angle iron, so it’s strong enough that he can ride on the thing. To each his own, we say. The wheels and motors came from a mobility scooter and match the beefiness of the frame. These are powered by two 12v car batteries wired in series. He drives it around his yard with an R/C airplane controller.

lawnmower gutsLawn da Vinci’s brainpower comes from two Arduino Pro Minis and a Raspberry Pi. One Arduino controls the motors and the R/C signal from the remoteThe other runs some extra kill switches that keep the Lawn da Vinci out of trouble.

So what’s the Raspi for? Right now, it’s for streaming video from the webcam attached to a mast on the frame back to his phone. [Blake] says he has had some latency issues with the webcam, so there could be a pair of drone racing goggles in his future. He also plans to add a GPS logger and to automate part of the mowing.

Now, about those kill switches: there are several of them. You probably can’t have too many of these on a remote control spinning suburban death machine. Lawn da Vinci will stop grazing if it goes out of range of the remote or if the remote is turned off. [Blake] also wired up a dedicated kill switch to a button on the remote and a fourth one on a separate key fob.

The Lawn da Vinci is one of many example projects that [Blake] uses to showcase the possibilities of KC Proto, a company he started to help local businesses realize their ideas by offering design solutions and assistance with prototyping. Between mowings, [Blake] puts the batteries on a trickle charger. If you make your own robot lawn mower, you might consider building a gas and solar hybrid.

LEGO Monowheel Corners Like It’s On Rails

[Jason]’s at it again. This time the LEGO maestro is working on a LEGO BB-8 droid. As a first step he’s made a motorized monowheel that not only races along hallways and through living rooms at the peril of any passing people, but turns as well.

To drive it forward there’s an axle that runs across the center of the wheel and a motor that rotates that axle. He’s also included some weight bricks. Without the mass of those bricks for the rotation to work against, the motor and axle would just spin in place while the friction of the floor keeps the wheel from rotating. If you’ve seen the DIYer’s guide to making BB-8 drive systems, you’ll know that this is classified as an axle drive system.

LEGO monowheel interior shown while leaning to turn
LEGO monowheel interior shown while leaning to turn

For steering the monowheel left or right he has another mass located just above the axle. Shifting the mass to the left causes the monowheel to lean and move in that direction. Shifting the mass to the right makes the wheel move to the right in the same fashion. Being ever efficient, [Jason] has the motor that shifts the mass doubling as the mass itself.

As with any proof-of-concept, there are still some issues to work out. When turning the wheel left or right it can tip onto its side. Ridges on both sides of the wheel’s circumference reduce the chances of that happening but don’t eliminate it altogether. Also, the steering mass/motor doesn’t yet have a self-centering mechanism; after a turn it’s up to the person holding the remote control to find center. If the mass isn’t correctly centered after a turn, there tends to be some wobble.

As always, we’re looking forward to seeing how [Jason] solves those issues but first he’ll have to put it back together since, as you can see from the video below, it didn’t quite pass the stair test.

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R/C Bot Takes Your Strawberries Away

Don’t let the friendly smile on this RC cart fool you, it will take your strawberries away — though that’s kinda the point. It’s an RC car that [transistor-man] and a few friends modified for carrying freshly picked strawberries at strawberry fields so that you don’t have to.

RC strawberry carrying robot before putting on the cooler
RC strawberry carrying robot – WIP

They started with an older Traxxas Emaxx, a 4-wheel drive RC monster truck. The team also bought a suitable sized water cooler at a local hardware store. A quick load test showed that 5lbs collapsed the springs and shock absorbers, causing the chassis to sink close to the ground. The team had two options: switching to stronger springs or locking out the springs altogether. They decided to replace one set of shocks with metal plates effectively locking them. After that it was time for some CAD work, followed by the use of a water jet to cut some aluminum plate. They soon had a mounting plate for the water cooler to sit in. This mounting plate was attached to 4 posts which originally held the vehicle’s Lexan body. A bungee cord wrapped around the cooler and posts on the mounting plate holds the cooler in place.

Thermal image of bad MOSFET
Thermal image of bad MOSFET

Some initial testing showed that the vehicle moved too fast even in low gear and tended to tip over, as you can see in the first video below. Some practice helped but a 3:1 reduction planetary gearbox brought the vehicle down to walking speed, making a big difference. A trip was arranged to go to local strawberry picking field at Red Fire Farms, but not without some excitement first. At 1AM the UNIK 320A High Voltage Speed controller emitted some magic smoke. A quick check with a thermal-camera found the culprit, one of the MOSFETs had failed, and after swapping it with one that was close enough they were back in business.

As you can see in the second video below, testing in the strawberry field went very well, though it wasn’t without some tipping. Kids also found it a fun diversion from picking strawberries, alternating between mock fright and delight.

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