(Mis)use This Part To Attach 3D Printed Stuff To A Shaft

September 2, 2019 by Donald Papp 16 Comments

Interfacing a shaft to a 3D printed gear doesn’t have to be tricky. [Tlalexander] demonstrated a solution that uses one half of a spider coupling (or jaw coupling) to create an effective modular attachment. The picture above (and this older link) shows everything you need to know: the bottom of the coupling is mounted to the shaft, and a corresponding opening is modeled into the the 3D printed part. Slide the two together, and the result is a far sturdier solution than trying to mate a 3D printed gear directly to a motor shaft with a friction fit or a screw. This solution isn’t necessarily limited to attaching gears either, any suitable 3D printed part could be interfaced to a shaft in this way.

These couplings are readily available, and fortunately for hobbyists, come in sizes specifically designed for common stepper motors like NEMA 17 and NEMA 23. Ironically, these couplings are often used when building custom 3D printers for those same reasons. With this method interfacing anything at all to a motor shaft becomes mostly a matter of modeling a matching hole out of the part to be 3D printed. One coupling even provides two such attachments, since only one of the two sides is used.

The image up top is from [Tlalexander]’s Rover image gallery, which contains a ton of fantastic pictures of the work that went into the gearboxes, a major part of the Rover’s design that we’ve seen in the past.

Double 3: Your Instant Physical Presence Anywhere, No Matter Where You Are

August 31, 2019 by Maya Posch 18 Comments

Telepresence is one of those futuristic buzzwords that’s popped up a few times over the decades; promising the ability to attend a meeting in New York City and another in Tokyo an hour later, all without having to leave the comfort of your home or office. This is the premise of Double Robotics’ Double 3, its most recent entry in this market segment, as the commercial counterpoint to more DIY offerings.

More than just a glorified tablet screen.

Looking like a tablet perched on top of a Segway, the built-in dual 13 megapixel cameras allow the controller to get a good look at their surroundings, while the 6 beamforming microphones should theoretically allow one to pick up any conversation in a meeting or on the work floor.

Battery life is limited to 4 hours, and it takes 2 hours to recharge the built-in battery. Fortunately one can just hop over to another, freshly charged Double 3 if the battery runs out. Assuming the $3,999 price tag doesn’t get in the way of building up a fleet of them, anyway.

Probably the most interesting aspect of the product is its self-driving feature, which has resulted in a whole range of sensors and cameras (Intel RealSense D430 stereo vision depth sensors) being installed. To handle the processing of this sensor data, the system is equipped with an NVidia Jetson TX2 ARM board, running Ubuntu Linux, which also renders the mixed-reality UI for the user with way points and other information.

Currently Double Robotics accepts sign-ups for the private beta of the Double 3 API, which would give developers access to the sensor data and various autonomous features of Double 3’s hardware. Co-founder of Double Robotics, [Marc DeVidts] stated to Hackaday that he is looking forward to seeing what people can build with it. Hopefully this time people will not simply take the thing for a joyride, like what happened with a predecessor of the Double 3.

Building A Robot Rover For Those Tough Indoor Missions

August 30, 2019 by Maya Posch 4 Comments

Making an outdoor rover is easy stuff, with lots of folk having them doing their roving activities on beaches and alien worlds. Clearly the new frontier is indoor environments, a frontier which is helpfully being conquered by [Andreas Hoelldorfer]’s Mantis Rover.

OK, we’re kidding. This project started out life as a base for [Andreas]’s exquisite 3D printable robotic arm, but it’s even capable of carrying people around, as the embedded video after the break makes abundantly clear. The most eye-catching feature of the Mantis Rover are its Mecanum wheels, which allow it to move in any direction, and is perfect for those tight spots where getting stuck would be really awkward.

The Mecanum wheels are 3D printed, making the motors and the associated controllers the more complicated part of this package. Plans for the wheels involve casting some kind of rubber, to make the wheels more gentle on the floors it has to drive on. The electronics include TMC 5160 motor drivers and an STM32F407VET6 MCU, as well as a W5500-equipped custom ‘Robot Shield’.

It seems that there are still a lot of tweaks underway to make the project even more interesting. Maybe it’s the perfect foundation for your next indoor roving sessions at the office or local hackerspace?

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A Handy Way To Cheaply Print A Robotic Arm

August 29, 2019 by Maya Posch 5 Comments

There’s something fascinating about humanoid robotic hands, if only because of how they are such close approximations of our own hands. One could almost picture them with tendons and skin covering them. Sadly, making your own is quite prohibitive because in addition to being complex bits of machinery, making one of these marvels of engineering is usually rather expensive.

[Gray Eldritch]’s Humanoid Robot Arm project seeks to fix both points, by providing a ready to print project. All it takes is about a kilogram of PLA filament, some TPU filament, five MG996r servos (or equivalent), an SG90 servo or similar, an Arduino Uno board and a few other bits and pieces. This should result in a robotic arm with hand as covered in the video of the Mark 3 version that is embedded after the break.

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Skid Steer Mows Airport Grass Autonomously

August 28, 2019 by Bryan Cockfield 32 Comments

Sure, mowing the lawn is a hassle. No one really wants to spend their time and money growing a crop that doesn’t produce food, but we do it anyway. If you’re taking care of a quarter acre in the suburbs it’s not that much of a time sink, but if you’re taking care of as much grass as [Roby], you’d probably build something similar to his autonomous skid-steer mower, too.

This thing isn’t a normal push mower outfitted with some random electronics, either. This is a serious mower that is essentially a tractor with blades attached to it. Since it’s a skid steer, it turns by means of two handles that control the speed of the left or right drive wheels. Fabricating up some servo linkages to attach them to specialized servos takes care of the steering portion, and the brain is ArduPilot hooked up to a host of radios, GPS, and a compass to allow it to drive all around the runways at the airport without interfering with any aircraft.

This is a serious build and goes into a lot of detail about how servos and linkages should behave, how all the software works, and the issues of actually mounting everything to the mower. The entire project is open source too, so even if you don’t have a whole airport runway to mow you might be able to find something in there to help with your little patch of grass.

Thanks to [Vincent] for the tip!

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A Car Phone — No, Not That Kind

August 27, 2019 by Erin Pinheiro 5 Comments

Autonomous vehicle development is a field of technology that remains relatively elusive to the average hacker, what with the needing a whole car and all. Instead of having to deal with such a large scale challenge, [Piotr Sokólski] has instead turned to implementing the same principles on the scale of a small radio-controlled car.

Wanting to lower the barrier of entry for developing software for self-driving cars, he based his design off of something you’re likely to have lying around already: a smartphone. He cites the Google Cardboard project for his inspiration, with how it made VR more accessible without needing expensive hardware. The phone is able to control the actuators and wheel motors through a custom board, which it talks to via a Bluetooth connection. And since the camera points up in the way the phone is mounted in the frame, [Piotr] came up with a really clever solution of using a mirror as a periscope so the car can see in front of itself.

The software here has two parts, though the phone app one does little more than just serve as an interface by sending off a video feed to be processed. The whole computer vision processing is done on the desktop part, and it allows [Piotr] to do some fun things like using reinforcement learning to keep the car driving as long as possible without crashing. This is achieved by making the algorithm observe the images coming from the phone and giving it negative reward whenever an accelerometer detects a collision. Another experiment he’s done is use a QR tag on top of the car, visible to a fixed overhead camera, to determine the car’s position in the room.

This might not be the first time someone’s made a scaled down model of a self-driving vehicle, though it’s one of the most cleverly-designed ones, and it’s certainly much simpler than trying to do it on a full-sized car in your garage.

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3D Printed Rover Enjoys Long Walks On The Beach

August 27, 2019 by Tom Nardi 13 Comments

More than a few hackers have put in the considerable time and effort required to build a rover inspired by NASA’s robotic Martian explorers, but unfortunately even the most well funded home tinkerer can’t afford the ticket to send their creation offworld. So most of these builds don’t journey through anything more exciting than a backyard sandbox. Not that we can blame their creators, we think a homebrew rover will look just as cool in your living room as it would traipsing through a rock quarry.

But the DIY rover status quo clearly wasn’t sufficient for [Jakob Krantz], who decided the best way to test his new Curiosity-inspired rover was to let it frolic around on the beach for an afternoon. But judging by the video after the break, his beefy 3D printed bot proved to be more than up to the task; powering through wildly uneven terrain with little difficulty.

Beyond a few “real” bearings here and there, all of the key components for the rover are 3D printed. [Jakob] did borrow a couple existing designs, like a printable bearing he found on Thingiverse, but for the most part he’s been toiling away at the design in Fusion 360 and using images of the real Curiosity rover as his guide.

Right now, he’s controlling the rover with a standard 6 channel RC receiver. Four channels are mapped to the steering servos, and a fifth to the single electronic speed control that commands the six wheel motors. But he’s recently added an Arduino to the rover which will eventually be in charge of interpreting the RC commands. This will allow more complex maneuvers with fewer channels, such as the ability to rotate in place.

We’re proud to count our very own [Roger Cheng] among the rover wrangling hackers of the world. An entire community has sprung up around his six-wheeled Sawppy, and the knowledge gained during its design and construction could be applicable to any number of other projects.

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