Pushing The Boundaries Of Tiny Mechanical Devices With Compliant Mechanisms

October 8, 2023 by Maya Posch 12 Comments

Mechanical actions underlie much of what makes modern day society function, whether it’s electric motors, combustion engines, switches, levers, or the springs inside a toy blaster gun that propel foam darts at unsuspecting siblings. Yet as useful as it would be to scale such mechanisms down to microscopic levels, this comes with previously minor issues on a macroscopic scale, such as friction and mechanical strength, becoming quickly insurmountable. Or to put in more simple terms, how to make a functioning toy blaster gun small enough to be handled by ants? This is the topic which [Mark Rober] explores in a recent video.

Continue reading “Pushing The Boundaries Of Tiny Mechanical Devices With Compliant Mechanisms” →

Physical Neural Network Can Be Trained Like A Digital One

July 20, 2023 by Donald Papp 11 Comments

Here’s an unusual concept: a computer-guided mechanical neural network (video, embedded below.) Why would one want a mechanical neural network? It’s essentially a tool to explore what it would take to make physical materials work in nonstandard ways. The main part is a lattice of interlinked mechanical components. When one applies a certain force in a certain direction on one end, it causes the lattice to deform in a non-intuitive way on the other end.

To make this happen, individual mechanical elements in the lattice need to have their compliance carefully tuned under the guidance of a computer system. The mechanisms shown can be adjusted on demand while force is applied and cameras monitor the results.

This feedback loop allows researchers to use the same techniques for training neural networks that are used in machine learning applications. Ultimately, a lattice can be configured in such a way that when side A is pressed like this, side B moves like that.

We’ve seen compliant structures that move in unexpected ways before, and they are always fascinating. One example is this 3D-printed door latch that translates a twisting motion into a linear one. Research into physical neural networks seems like it might open the door to more complex systems, or provide insights into metamaterial design.

You can watch the video below just under the page break, or if you prefer, skip the intro and jump straight into How It Works at [2:32].

Continue reading “Physical Neural Network Can Be Trained Like A Digital One” →

Electromagnetic Mechanism Makes Reconfigurable Antenna

February 22, 2023 by Al Williams 10 Comments

Antennas are a key component to any RF gadget. But antennas often only perform well over a narrow band of frequencies. For some applications, this is acceptable, but often you would like to reconfigure an antenna for different bands. Researchers at Penn State say they’ve developed a tunable antenna using compliant mechanisms and electromagnets. The new scalable design could work in small areas to provide frequency agility or beamforming.

The prototype is a circular patch antenna made with 3D printing. If you want to read the actual paper, you can find it on Nature Communications.

A compliant mechanism is one that achieves force and motion through elastic body deformation. Think of a binder clip. There’s no hinge or bearing. Yet the part moves in a useful way, using its own deformation to open up or grip papers tightly. That’s an example of a compliant mechanism. This isn’t a new idea — the bow and arrow are another example. However, because 3D printing offers many opportunities to build and refine devices like this, interest in them have increased in recent years.

We couldn’t help but notice that the antenna is a variation of a “compliant iris” like the one in the video below. You can find designs for these online for 3D printing, so if you wanted to experiment, you might think about starting there.

We’ve looked at compliant mechanisms before. Why would you want better chip-scale antennas? Why, indeed.

Continue reading “Electromagnetic Mechanism Makes Reconfigurable Antenna” →

Flexures Make This Six-DOF Positioner Accurate To The Micron Level

May 6, 2022 by Dan Maloney 26 Comments

It’s no secret that we think flexures are pretty cool, and we’ve featured a number of projects that leverage these compliant mechanisms to great effect. But when we saw flexures used in a six-DOF positioner with micron accuracy, we just had to dig a little deeper.

The device is known as the Hexblade, and it comes to us from the lab of [Jonathan Hopkins] at UCLA. We have to admit that at times, the video below feels a little like the “Turbo Encabulator” schtick — “three identical decoupled actuation limbs arranged in an axisymmetric configuration” may be perfectly descriptive, but it does not flow trippingly from the tongue. Hats off to [Professor Hopkins] for nailing the narration, though, and really, once you get a handle on the jargon, it all makes perfect sense. The platform is supported by a total of six flexures, which look like bent pieces of sheet metal but are actually cut from a solid block of material using wire EDM. Three of the flexures are oriented in the plane of the platform, while the other three are perpendicular to it. The far end of each flexure is connected to a voice-coil actuator that is surrounded by another flexure, this one in a parallelogram arrangement. The six actuators can move the platform smoothly through three linear translations (X, Y, and Z) and three rotations (roll, pitch, and yaw).

The platform’s range of motion is limited, but the advantages of using flexures as bearings are clear — there’s no backlash or hysteresis, and the voice coils can control the position of the stage to micron accuracy. Something like the Hexblade would be an ideal positioner for microscopy, and we can imagine an even smaller version, perhaps even a MEMS-fabricated one for nanomanufacturing applications. The original concept of the Hexblade serving as the print head for a fabrication robot for space applications is pretty cool, too, and we’d venture to say that a homebrew version of this probably isn’t out of reach either.

Continue reading “Flexures Make This Six-DOF Positioner Accurate To The Micron Level” →

3D-Printing Complex Sensors And Controls With Metamaterials

September 17, 2021 by Dan Maloney 4 Comments

If you’ve got a mechatronic project in mind, a 3D printer can be a big help. Gears, levers, adapters, enclosures — if you can dream it up, a 3D printer can probably churn out a useful part for you. But what about more complicated parts, like sensors and user-input devices? Surely you’ll always be stuck buying stuff like that from a commercial supplier. Right?

Maybe not, if a new 3D-printed metamaterial method out of MIT gets any traction. The project is called “MetaSense” and seeks to make 3D-printed compliant structures that have built-in elements to sense their deformation. According to [Cedric Honnet], MetaSense structures are based on a grid of shear cells, printed from flexible filament. Some of the shear cells are simply structural, but some have opposing walls printed from a conductive filament material. These form a capacitor whose value changes as the distance between the plates and their orientation to each other change when the structure is deformed.

The video below shows some simple examples of monolithic MetaSense structures, like switches, accelerometers, and even a complete joystick, all printed with a multimaterial printer. Designing these structures is made easier by software that the MetaSense team developed which models the deformation of a structure and automatically selects the best location for conductive cells to be added. The full documentation for the project has some interesting future directions, including monolithic printed actuators.

Continue reading “3D-Printing Complex Sensors And Controls With Metamaterials” →

Xbox Flexure Joystick Puts You In The Pilot’s Seat

August 11, 2021 by Tom Nardi 6 Comments

With the recent release of Microsoft Flight Simulator on the Xbox Series X|S there’s never been a better time to get a flight stick for the console, and as you might imagine, there are a number of third party manufacturers who would love to sell you one. But where’s the fun in that?

If you’ve got a fairly well tuned 3D printer, you can print out and assemble this joystick by [Akaki Kuumeri] that snaps right onto the Xbox’s controller. Brilliantly designed to leverage the ability of 3D printers to produce compliant mechanisms, or flextures, you don’t even need any springs or fasteners to complete assembly.

The flexture gimbal works without traditional springs.

The free version of Thingiverse only lets you move the controller’s right analog stick, but if you’re willing to drop $30 USD on the complete version, the joystick includes additional levers that connect to the controller’s face and shoulder buttons for more immersive control. There’s even a throttle that snaps onto the left side of the controller, though it’s optional if you’d rather save the print time.

If you want to learn more about the idea behind the joystick, [Akaki] is all too happy to walk you through the finer parts of the design in the video below. But the short version is the use of a flextures in the base of the joystick opened up the space he needed to run the mechanical linkages for all the other buttons.

This isn’t the first time [Akaki] has used 3D printed parts to adapt a console controller for flight simulator use. A simplified version of this concept used ball-and-socket joints to move the Xbox’s analog sticks, and he even turned a PlayStation DualShock into an impressive flight yoke you could clamp to your desk.

Continue reading “Xbox Flexure Joystick Puts You In The Pilot’s Seat” →

3D Printed Joystick Using Spherical Flexure Joint

May 25, 2021 by Danie Conradie 19 Comments

One of the many advancements brought about by 3D printing is the rapid development of compliant mechanisms and flexure joints. One such example is [jicerr]’s joystick, which uses a pair of spherical flexure joints recently developed by researchers from Delft University of Technology in the Netherlands, See the videos after the break.

Both flexure joint designs make use of tetrahedron-shaped elements, allowing an object to pivot around a fixed point in space like a ball-and-socket joint. One of the joints, named Tetra 2, is perfect for printing on a standard FDM printer, and the 3D files were uploaded to Thingiverse by [Jelle_Rommers], one of the researchers. [jicerr] took the design and created a base to mount an HMC5883 3-axis magnetometer a short distance from the focal point, which senses the rotation of a small magnet at the focal point. An Arduino takes the output from the magnetometer, does the necessary calculation, and interfaces to a PC as a joystick. Demonstrates this by using it to rotate and pan the design in Solidworks. One thing to keep in mind with this design is that it needs a fixed base to prevent it from moving around. It should also be possible to integrate the design directly into the housing of a controller.

Another amusing application is to turn it into a pen holder with a chicken head on the front, as demonstrated by [50Pro]. If you have any ideas for other applications, drop them in the comments.

Compliant mechanisms have a number of interesting applications, including harmonic drives, dial indicators and thrust vectoring mounts.

Continue reading “3D Printed Joystick Using Spherical Flexure Joint” →