[Klaus Halbach] gets his name attached to these clever arrangements of permanent magnets but the effect was discovered by [John C. Mallinson]. Mallinson array sounds good too, but what’s in a name? A Halbach array consists of permanent magnets with their poles rotated relative to each other. Depending on how they’re rotated, you can create some useful patterns in the overall magnetic field.
Over at the K&J Magnetics blog, they dig into the effects and power of these arrays in the linear form and the circular form. The Halbach effect may not be a common topic over dinner, but the arrays are appearing in some of the best tech including maglev trains, hoverboards (that don’t ride on rubber wheels), and the particle accelerators they were designed for.
Once aligned, these arrays sculpt a magnetic field. The field can be one-sided, neutralized at one point, and metal filings are used to demonstrate the shape of these fields in a quick video. In the video after the break, a powerful magnetic field is built but when a rare earth magnet is placed in the center, rather than blasting into one of the nearby magnets, it wobbles lazily.
Be careful when working with powerful magnets, they can pinch and crush, but go ahead and build your own levitating flyer or if you came for hoverboards, check out this hoverboard built with gardening tools.
Continue reading “Step the Halbach from My Magnets”
A traditional quadcopter is designed to achieve 6 degrees of freedom — three translational and three rotational — and piloting these manually can prove to be a challenge for beginners. Hexacopters offer better stability and flight speed at a higher price but the flight controller gets a bit more complex.
Taking this to a whole new level, the teams at the Swiss Federal Institute of Technology (ETH Zürich) and Zurich University of the Arts (ZHDK) have come together to present a hexacopter with 6 individually tiltable axes. The 360-degree tilt in rotors allows for a whopping 12-degrees of freedom in flight and allows the UAV to fly in essentially any direction including parallel to walls.
In addition to the acrobatic capabilities of the design, the team has done some testing with autonomous control using external cameras. Their blog contains videos of their testing at various stages and it interesting to see the project evolve over a short span of nine months. Check out the video below of the prototype in action.
With Amazon delivering packages via drone and getting patents for parachute labels, UAV design is evolving faster now than ever. We can’t wait to see where this 12 DOF takes the state of the art. Continue reading “Harrier-like Tilt Thrust in Multirotor Aircraft”
Some scrap wood, a few pieces of sheet metal, a quartet of old gear motors, and a few basic hand tools. That’s all it takes to build an omni-bot with Mecanum wheels, if you’ve got a little know-how too.
For the uninitiated, Mecanum wheels can rotate in any direction thanks to a series of tapered rollers around the circumference that are canted 45° relative to the main axle. [Navin Khambhala]’s approach to Mecanum wheel construction is decidedly low tech and very labor intensive, but results in working wheels and a pretty agile bot. The supports for the rollers are cut from sheet steel and bent manually to hold the wooden rollers, each cut with a hole saw and tapered to a barrel shape on a makeshift lathe. Each wheel is connected directly to a gear motor shaft, and everything is mounted to a sheet steel chassis. The controls are as rudimentary as the construction methods, but the video below shows what a Mecanum-wheeled bot can do.
There’s a lot of room here for improvement, but mainly in the manufacturing methods. The entire wheel could be 3D printed, for instance, or even laser cut from MDF with a few design changes. But [Navin] scores a win for making a working wheel and a working bot from almost nothing.
Continue reading “Scrap Wood and Metal Combined for DIY Mecanum Wheels”
Watching robots doing sports is pretty impressive from a technical viewpoint, although we secretly smile when we compare these robots’ humble attempts to our own motoric skills. Now, a new robot named Robomintoner seeks to challenge human players, and it’s already darn good at badminton.
Continue reading “Robomintoner Badminton Bot To Defeat Amateur Humans”
While studying acoustics in college (university for non-Americans), [Nick] had a great idea for an omnidirectional speaker. Some models available for purchase have a single speaker with a channel to route the sound in all directions, but [Nick] decided that a dodecahedron enclosure with 12 speakers would be a much more impressive route.
To accommodate the array of speakers, the enclosure needs twelve pentagons with a 58.3 degree bevel so that they fit together in a ball shape. After thinking about all of the complicated ways he could get this angle cut into the wood pentagons, he ended up using a simple circular saw!
Once the enclosure was painted [Nick] started wiring up the speakers. The equivalent impedance of the array of 8-ohm speakers works out to just around 10 ohms, which is easily driven by most amplifiers. The whole thing was hung from a custom-made galvanized pipe (all the weight adds up to about 15 kilograms, or 33 pounds for Americans, so the rig needed to be sturdy). We’ve featured other unique speaker builds, but this is the first 12-speaker omnidirectional speaker we’ve seen. [Nick] is happy to report that the speakers sound great, too!
For a number of children born of geek parents, the WowWee Tribot is sure to make an appearance underneath a Christmas tree this year. By New Year’s, though, this toy will surely make its way to the back of a closet to sit unused until spring cleaning. It’s a shame to let such an interesting robotics platform go to waste, so [haltux] sent in a nice guide to unlocking the motor controller of this talking robot.
The ‘legs’ of the WowWee Tribot have three omnidirectional wheels mounted 120 degrees apart. We’ve seen this drive system before, so getting a pre-built platform out of the toy box is pretty interesting.
[haltux] found three H-bridges inside the Tribot and connected the direction and enable pins for each motor directly to an Arduino. The build was a success, and the new robot platform scurried along the floor. There are also rotary encoders on the Tribot, but these run at 12 Volts. [haltux] said he’ll cover these in a future post, and we’re waiting to see it.
This is a four-wheeled robot chassis built by high school students over the summer. They were participating in workshops put on by xbot robotics in Seattle, Washington. The goal is to get them participating in events like FIRST Robotics and LEGO league, and eventually into science related careers.
At first glance we thought: oh, that’s a nice chassis build… on to the next tip. But then the difference in front and rear wheel types caught our eye. The problem with four-wheeled designs is that you need differential steering to overcome the skidding issue when turning. This usually means two independently powered rear wheels and one unpowered front wheel that can swivel. One way to overcome this is to use three omniwheels, each with their own motor. And more recently we have seen four-wheelers that use mechanum wheels to get around the issue… but that takes four motors.
The design seen above uses just two motors, each with a chain to drive both wheels on one side. The rear wheels have rubber grippers which give them great traction. The front wheels are omni-wheels which allow them to move side to side easily during turns while aiding in forward progress when not turning. This gives the robot enough grip to push object around, like you can see in the video after the break.
Continue reading “Student built robot chassis has something you can learn from”