A 3D-Printable Mecanum Wheeled Robot Platform

If your interest lies with robotics there are a multitude of different platforms for you to build. [Teemu Laurila] was frustrated with what was on offer, so designed his own with four-wheel double wishbone suspension and mecanum wheels for maximum flexibility.

It’s a design that has been through multiple revisions since its first iteration in 2015, and along the way it’s clear some thought has gone into it. That double wishbone suspension features an angle for a high ground clearance, and is fully sprung. Drive comes from small motor/gearboxes at each axle. The chassis meanwhile has plenty of space for a single-board computer, and has been specifically designed with the BeagleBone Black in mind.

This build isn’t fully DIY, as the mecanum wheels appear to be off-the-shelf items, but the rest of the project makes up for this. If you need to make your own, it’s hardly as though there aren’t any projects from which you can borrow components.

Russian EBike Goes Everywhere, Possibly Legal

Electric bikes may be taking the world by storm, but the world itself doesn’t have a single way of regulating ebikes’ use on public roads. Whether or not your ebike is legal to ride on the street or sidewalk where you live depends mostly on… where you live. If you’re lucky enough to live in a place where a bicycle is legally defined as having fewer than four wheels and capable of being powered by a human, though, this interesting bike from Russia might be the best homemade ebike we’ve ever seen. (Video embedded below the break.)

While some of the details of this build might be lost on those of us who do not know any Slavic languages, the video itself shows off the features of this electric vehicle build quite well. It has a custom built frame with two wheels up front, each with its own independent suspension, allowing it to traverse extremely rough terrain with ease even a mountain bike might not be able to achieve. It seems to be powered by a relatively simple rear hub in the single rear wheel, and can probably achieve speeds in the 20 km/h range while holding one passenger and possibly some cargo.

The impressive part of this build isn’t so much the electrification, but rather the suspension components. Anyone looking for an offroad vehicle may be able to take a bit of inspiration from this build. If you’re more interested in the drivetrain, there are plenty of other vehicles that use unique electric drivetrains to check out like this electric boat. And, if you happen to know Russian and see some other interesting details in this build that the native English speakers around here may have missed, leave them in the comments for us.

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Both Explanation And Build For This Artwork Are Beautiful

Sometimes you encounter projects that defy description, as is the case with this one. So perhaps it’s best to start with what this project is NOT. It is not a sphere. It is not a perpetual energy device. It has neither a sloppy build nor a slapdash video. This IS a motorized rhombicuboctahedron that is a well-explained with high-quality parts and loving attention to detail by [Wolfram Glatthar]. At its heart is an exercise in building a moving device with the barest minimum of friction. Without no grinding in the mechanism, the electronics will probably wear out first. Low friction also means low power consumption, and an hour of sunlight can run the device for two-and-a-half days. Take a look at the video below the break.

Along the sides are a balancing ring with threaded screw sockets and the load-bearing magnets which suspend the bulk of the rhombicuboctahedron using repulsion. Everything is stabilized by a ceramic sphere touching a sapphire glass plate for a single point of contact between some seriously tough materials. The clear sapphire furthers the illusion that everything is floating, but genuine magnetic suspension would require much more power.

Acoustic levitation cannot be forgotten as another powered source of floating or you can cheat and use strobe light trickery.

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3D Printed Tank Scores Suspension

Tanks are highly capable vehicles, with their tracks giving them the ability to traverse all manner of terrain at speed. An important part of a tank is its suspension setup, without which its treads are far less capable. When [Ivan]¬† began work on his 3D printed tank project, he couldn’t ignore the comments. His tank would need a suspension system.

The tank build itself is impressive, consisting almost entirely of 3D printed components held together with off-the-shelf bearings and threaded rod. [Ivan] retools the tank from the beginning to fit a pivoting suspension system which is surprisingly simple in its design, yet capable in operation. Particularly impressive are the 3D printed springs, which [Ivan] tunes the stiffness of to suit the weight of the vehicle.

It’s a build that shows just how far you can go when you master the basics of 3D printing and mechanical design. It doesn’t take a lot of advanced theory to design cool things, just a willingness to learn and experiment and the right set of tools behind you. [Ivan]’s tank treads are worth taking a look at, too.¬†Video after the break.

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Hovering Questions About Magnetic Levitation

Who doesn’t love magnets? They’re functional, mysterious, and at the heart of nearly every electric motor. They can make objects appear to defy gravity or move on their own. If you’re like us, when you first started grappling with the refrigerator magnets, you tried to make one hover motionlessly over another. We tried to position one magnet over another by pitting their repellent forces against each other but [K&J Magnetics] explains why this will never work and how levitation can be done with electromagnets. (YouTube, embedded below.)

In the video, there is a quick demonstration of their levitation rig and a brief explanation with some handy oscilloscope readings to show what’s happening on the control side. The most valuable part, is the explanation in the article where it walks us through the process, starting with the reason permanent magnets can’t be used which leads into why electromagnets can be successful.

[K&J Magnetics]’s posts about magnets are informative and well-written. They have a rich mix of high-level subjects without diluting them by glossing over the important parts. Of course, as a retailer, they want to sell their magnets but the knowledge they share can be used anywhere, possibly even the magnets you have in your home.

Simpler levitators can be built with a single electromagnet to get you on the fast-track to building your own levitation rig. Remember in the first paragraph when we said ‘nearly’ every electric motor used magnets, piezoelectric motors spin without magnets.

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Electronifying A Horror Fraught Hydraulic Press

[Josh] is replacing the springs in his car’s suspension. He wanted to know the travel rates of these springs, but apparently, this is a closely guarded trade secret in the industry. One company did manage to publish the spring rates, but they weren’t believable. Instead of taking this company’s word, [Josh] built a spring tester.

The theory behind a spring tester is pretty simple: apply a force to a spring, measure it, then measure how much the spring has traveled. Or compress a spring an inch or so, measure the force, and compress it some more. Either gets you the same data.

This spring tester is built around a Harbor Freight hydraulic press. Yes, the spring is completely captured and won’t fly out of the jig if you look at it wrong. The bottom of the press contains a few load cells, fed into an ATmega8, which displays a value on an LCD. For the displacement measurement, a ruler taped to the side of the press will suffice, but [Josh] used a Mitutoyo linear scale.

What were the results of these tests? You shouldn’t buy coils from Bilstein if these results are correct. The rates for these springs were off by 70%. Other springs fared better and won’t bind when going over bigger bumps. That’s great work, and an excellent application of Horror Fraught gear.

Tank Tread Robot Build Aims For A Smooth Ride

There’s all kinds of interesting things going into this tank robot build, but that beautiful suspension system immediately caught our eye. It helps to protect the body of the robot from being shaken apart when traveling over rough surfaces. Make sure to check out the four parts of the build log which are found on the left sidebar at the post linked above.

This a Master’s thesis project and has been built from common parts. The motors for the treads are pulled from a pair of cordless drills, with some capacitors added to help combat the draw when they start up. The treads themselves are each made from a pair of bicycle chains connected with numerous PVC pipe segments. The curved section of each PVC piece goes toward the chain, leaving the edges toward the ground for great traction. The tree wheels which support the middle of the tread each have a hinge and spring to absorb the shock of running full speed into concrete sidewalk corners like we see in the video after the break.

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