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.

Continue reading “LEGO Monowheel Corners Like It’s On Rails”

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.

Continue reading “R/C Bot Takes Your Strawberries Away”

RC Beer Crate Handles Rough Terrain like a Pro

[Niklas Roy] is at it again. Summer time means beer time and what better way for him to distribute beer at outdoor parties than a with an amazingly agile remote controlled beer crate capable of handling rough backyard terrain. With the controller firmly in hand he could even institute a leave-an-empty, take-a-beer policy to speed clean-ups.

We’ve seen awesome beer dispensing robots with all the bells and whistles in the past, from ones that are moving coolers, decapping the beer before handing it off, to BREWSTER the modified roomba who’ll fetch you a beer from a mini-fridge. [Niklas]’ RC beer crate sits at the simplicity end of the spectrum, reminding us of the no nonsense Star Wars mouse droid that wandered the Death Star’s corridors. The beer crate sits on a low wooden platform with a lip added to it to keep the crate from sliding off.  Under the platform are your basics: 2-channel RC receiver from a cheap toy car, H-bridges, two windscreen wiper motors and wheels, a LiPo battery, an on/off switch and two casters. For an arcade feel, the RC controller is a modified Competition Pro offering retro joystick steering.

As you can see from the video after the break (with a party-appropriate Metal soundtrack) it’s incredibly stable, moving rapidly over patio stones, from patios stones to dirt and lawn and even up messy inclines. This one’s sure to add excitement to many parties, while keeping party goers well served.

Continue reading “RC Beer Crate Handles Rough Terrain like a Pro”

DTMF Robot Makes Rube Goldberg Proud

Sometimes you start building, and the project evolves. Layers upon layers of functionality accrue, accrete, and otherwise just pile up. Or at least we’re guessing that’s what happened with [Varun Kumar]’s sweet “Surveillance Car Controlled by DTMF“.

In case you haven’t ever dug into not-so-ancient telephony, Dual-tone, multi-frequency signalling is what made old touch-tone phones work. DTMF, as you’d guess, encodes data in audio by playing two pitches at once. Eight tones are mapped to sixteen numbers by using a matrix that looks not coincidentally like the old phone keypad (but with an extra column). One pitch corresponds to a column, and one to a row. Figure out which tones are playing, and you’ve decoded the signal.

Anyway, you can get DTMF decoder chips for pennies on eBay, and they make a great remote-control interface for a simple robot, which is presumably how [Varun] got started. And then he decided that he needed a cell phone on the robot to send back video over WiFi, and realized that he could also use the phone as a remote controller. So he downloaded a DTMF-tone-generator app to the phone, which he then controls over VNC. Details on GitHub.

Continue reading “DTMF Robot Makes Rube Goldberg Proud”

Smartphone-based Robotic Rover Project goes Open Source

[Aldric Négrier] wrote in to let us know that his DriveMyPhone project has been open sourced. The project is a part telepresence, part remote-controlled vehicle, part robotic rover concept on which he says “I spent more time […] than I should have.” He has shared not just the CAD files, but every detail including tips on assembly. He admits that maybe a robotic chassis for a smartphone might not seem like a particularly new idea today, but it was “an idea with more potential” back in 2010 when he first started.

The chassis is made to cradle a smartphone. Fire up your favorite videoconferencing software and you have a way to see where you’re going as well as hear (and speak to) your surroundings. Bluetooth communications between the phone and the chassis provides wireless control. That being said, this unit is clearly designed to be able to deal with far more challenging terrain than the average office environment, and has been designed to not only be attractive, but to be as accessible and open to repurposing and modification as possible.

Continue reading “Smartphone-based Robotic Rover Project goes Open Source”

Building a Sturdy Remote Control Mailbox

This DIY mailbox pretty much has it all. Not only is it waterproof and secure, it’s beautifully built and unlikely to arouse the suspicion of or induce fear in the mailman.

It’s made of 2mm thick sheet metal and features accents made of merri, a rather nice blood wood native to Western Australia. [George] of Make It Extreme built this mailbox primarily for remote control access, the idea being that each of his family members would have a key fob remote to open it. There’s an input panel under the lid in case someone loses or forgets their remote.

The setup is simple. That 12V solar panel under the address number is connected to a solar charge controller and charges a small battery. Pushing the A button on the key fob remote triggers the latch to slide over, unlocking the door. A push of the B button turns on an interior light for late-night mail collecting. The tube on the side is for leaflets and other postal miscellany. Now, the coolest feature: when mail passes through the slot, it lets [George] know by calling his cell phone. Check out the build/demo video after the break.

We’ve featured all kinds of mailboxen over the years. This wifi-enabled ‘box uses an Amazon Dash button and a Pi to play the AOL notification on the owner’s phone. The flag on this adorable mini mailbox goes up when there’s mail in the real one outside.

Continue reading “Building a Sturdy Remote Control Mailbox”

Solar FPV Plane Flies Forever

We love solar power. Not only is it environmentally friendly, but it’s relatively lightweight and involves fragile high technology. Just the sort of thing that we’d want to strap onto the wings of a large model aircraft.

Solar power on a remote-controlled plane would get you unlimited cruising range. Now, a normal land-and-swap-battery process might be good enough for some people, but judging from [Prometreus]’s YouTube channel, he’s a fan of long flights over the Alps, and of pushing long-distance FPV links to the breaking point. For him and his friends, the battery power is definitely the limiting factor in how far / long he can fly.

solar-powered-plane-_-drone-_-fpv-_-built-_-rc-aircraft-rmkpjbf6dnqmkv-shot0012

All of the information we have is in the video, but that’s plenty. [Prometreus] didn’t bother with maximum-power-point tracking, but instead wired up his solar cells to work just about right for the voltage of his batteries and the level of sun that he’s seeing. So it won’t work nearly as well on cloudy days. (Check out this MPPT build that was submitted for the Hackaday Prize.)

He could switch the solar cells in an out remotely, and it’s pretty gratifying to see the consumed current in the battery go down below zero. In the end, he lands with a full battery. How cool is that?

Continue reading “Solar FPV Plane Flies Forever”