When Combat Robot Wheels Need To Be Nice And Cheap (But Mostly Cheap)

July 10, 2022 by Donald Papp 11 Comments

It started with [CHORL] making a promise to himself regarding constructing a new combat robot: no spending of money on the new robot.

That rule was violated (but only a little) by making his robot’s wheels out of EVA kneeling pads. EVA (Ethylene-Vinyl Acetate) is a closed-cell foam that makes for durable yoga mats, kneeling pads, and products of a similar nature. [CHORL] found a way to turn them into light but serviceable wheels for his robot: the Susquehanna Boxcar.

Nested hole saws create concentric holes. Perfect for wheels.

Here’s how the wheels were made: [CHORL] began with two hole saws. Nesting a smaller hole saw into a larger one by putting both on the same arbor created a saw with two holes, both of which were centered with respect to one another. The only problem was that this hole saw was not actually deep enough to cut completely through the thick foam. Luckily, cutting roughly halfway through on one side, then flipping the sheet over and cutting through from the other side was a good workaround. That took care of turning the thick foam sheet into round wheels.

A 3D-printed part served as a wheel hub as well as gear for the drivetrain. We want to call attention to the clever method of reinforcing the connection between the parts. [CHORL] didn’t want to just glue the geared hub directly to the surface of the foam wheel, because he suspected it might separate under stress. To address this, he designed six slots into the hub, cut matching slots into the foam wheel, and inserted six spline-like reinforcements in the form of some ABS strips he had on hand. Gluing it all together with E-6000 and leaving it to cure overnight under a weight resulted in a geared wheel assembly that [CHORL] judged to be about as round and rigid as a wheel should be, so the robot had a solution for nice light wheels that were, above all, cheap!

Lots of robots need wheels, and unsurprisingly, DIY solutions are common projects. [CHORL]’s approach here looks pretty scalable, as long as one can cut some accurate holes.

Interested in knowing more about the robot these wheels are destined for? [CHORL]’s still working on the Susquehanna Boxcar, but it’s almost done, and you can read a bit more about it (and see a few more pictures) here.

A Mostly Fair Deal For All With A Raspberry Pi

July 7, 2022 by Jenny List 3 Comments

To be a professional card dealer takes considerable skill, something that not everybody might even have the dexterity to acquire. Fortunately even for the most ham-fisted of dealers there’s a solution, in the form of the Dave-O-matic, [David Stern]’s automated card dealer using a Raspberry Pi 4 with a camera and pattern recognition.

It takes the form of a servo-controlled arm with a sucker on the end, which is able to pick up the cards and present them to the camera. They can then be recognized by value, and pre-determined hands can be dealt or alternatively a random hand. It seems that the predetermined hands aren’t an aid in poker cheating, but a part of the bridge player’s art. You can see it in action in the video below the break.

We like the project, but sadly at this point we must take [Dave] to task, because while tantalizing us with enough detail to get us interested he’s slammed the door in our faces by failing to show us the code. it would be nice to think that the clamor from disaffected Hackaday readers might spur him into throwing us a crumb or two.

It probably won’t surprise you to find that this isn’t the first Raspberry Pi to find itself dealing cards.

Continue reading “A Mostly Fair Deal For All With A Raspberry Pi” →

Hackaday Prize 2022: MasterPi Is A Capable Robot With Fancy Wheels

July 1, 2022 by Lewin Day 2 Comments

When it comes to building a mobile robot, often maneuverability is more important than outright speed. The MasterPi robot demonstrates this well, using fancy wheels to help it slide and skate in any direction needed.

Four DC gear-motors are fitted to a metal chassis, each one driving a mecanum wheel. These are special wheels with rollers fitted around their circumference at an angle that allows the robot to move in all directions and rotate in various ways depending on how each wheel is driven.

On top of this highly maneuverable chassis is placed a 5-degree-of-freedom robotic arm. The robot also gets a ultrasonic sensor for avoiding objects, as well as a camera for line-following duties. The camera also allows the robot to pick up blocks and identify their color, and it can then sort them into boxes. It’s all powered by a Raspberry Pi, running a bunch of Python code to make everything happen.

It’s a neat project that shows off just how capable a robot can be with some smart design choices and modern computing hardware on board. We’ve seen some other smart block sorters before, too. Continue reading “Hackaday Prize 2022: MasterPi Is A Capable Robot With Fancy Wheels” →

Design Your Next Robot Hand In Minutes

June 23, 2022 by Al Williams 1 Comment

MIT complains that designing a robot hand is time-consuming and takes a lot of iterations. They want to improve that using a unique approach by giving a modular hand tactile sensors. They claim this can reduce the design time down to minutes for many practical applications. For example, cutting paper. You can see a video about the paper below as well as read the text itself.

Each style of manipulator has an associated graph. Predefined elements let you assemble a palm and specialized fingers. You deform the fingers to match the use of the hand. Then a sensor that looks like a mitten provides feedback fo the task.

Continue reading “Design Your Next Robot Hand In Minutes” →

many revisions of the ball and socket robot

Practice Makes Perfect For This Ball And Socket Robot

May 20, 2022 by Anne Ogborn 3 Comments

Ball and socket joints are useful, but making a part slide over the surface of a sphere, held by magnets, requires a lot of fiddling to get right. We admire persistence and nailing all the details. [Matthew Finlay] has been doing just that with his ball and socket robot. He’s on version six, a testament to his desire to do the idea justice. Luckily for us, he’s documented each version as he went.

Version one, made from a DIY Christmas ornament ball, had no stability around the radial axis, and oscillated badly. Version two demonstrated the problem of centering the mechanism in the ball. Version 3 fixed this problem (it’s covered in the same video). Then version four fixed many of the assembly issues and replaced the servo controllers with an Arduino, but the ‘arm’ piece was too small and mechanically iffy.

Version five used a fabricated bearing. Matthew used airsoft rounds as the balls. Not a good idea. And assembly was a nightmare. So all this progress up to version six shows his improving technique. Artists say ‘work on your process, not on your pieces’. He’s become much more analytic about what’s needed. He’s started measuring the strength of the robot, and handled issues like adding limit switches so it doesn’t crash at the limits of travel.

Fun build, reminds us of [Stephen Dufresne]’s BB-8.

Continue reading “Practice Makes Perfect For This Ball And Socket Robot” →

Verbot Goes To The Dark Side

May 9, 2022 by Adam Fabio 14 Comments

What happens to old, neglected 1980s toy robots? According to the [Randi Rain], they turn to the dark side! Way back in the ’80s, Tomy had an entire line of robots — from keychain wind-up toys to rolling, talking machines almost 2 feet tall. Tucked into the middle of this line was Verbot. Verbot’s claim to fame is that it is a voice-controlled robot. More than that, it was speaker-dependent. Train the robot with commands like “go forward” and then watch as it responds to your every command.

As you might guess, the speech recognition wasn’t great by today’s standards. Recognition was handled by a Microcontroller — a Mitsubishi product that was possibly a mask programmed 8051 variant. Pretty novel for an 80s toy — in fact, there’s a patent for it.

Continue reading “Verbot Goes To The Dark Side” →

This 3D Printed Robot Can Actually Pick Locks

May 1, 2022 by Robin Kearey 8 Comments

Lockpicking is more of an art than a science: it’s probably 10% knowledge and 90% feeling. Only practice will teach you how much torque to apply to the cylinder, how to sense when you’ve pushed a pin far enough, or what it feels like when a pin springs back. Surely a robot would never be able to replicate such a delicate process, wouldn’t it?

Well, not according to [Lance] over at [Sparks and Code], who thought that building a lock picking robot would be an interesting challenge. He started out with a frame to hold a padlock and a servo motor to apply torque. A load cell measures the amount of force applied. This helps to keep the lock under a constant amount of tension as each pin is picked in succession. Although slow, this method seemed to work when moving the pick manually.

The difficult part was automating the pick movement. [Lance] built a clever system driven by two motors that would keep the pick perfectly straight while moving it horizontally and vertically. This was hard enough to get working correctly, but after adding a few additional clamps to remove wobble in the leadscrew, the robot was able to start picking. A second load cell inside the pick arm would detect the amount of force on each pin and work its way across the lock, pin by pin.

At least, that was the idea: as it turned out, simply dragging the pick across all pins in one go was enough to open the lock. A much simpler design could have achieved that, but no matter: designing a robot for all these intricate motions was a great learning experience anyway. It also gave [Lance] a good platform to start working on a more advanced robot that can pick higher-quality locks in which the dragging technique doesn’t work.

We haven’t come across lockpicking robots before; perhaps the closest equivalent would be this 3D-printed Snap Gun. If you’re interested in all aspects of locks and how to apply them, check out our Physical Security Hack Chat with Deviant Ollam.

Continue reading “This 3D Printed Robot Can Actually Pick Locks” →