High-Style Ball Balancing Platform

February 2, 2019 by Dan Maloney 14 Comments

If IKEA made ball-balancing PID robots, they’d probably look like this one.

This [Johan Link] build isn’t just about style. A look under the hood reveals not the standard, off-the-shelf microcontroller development board you might expect. Instead, [Johan] designed and built his own board with an ATmega32 to run the three servos that control the platform. The entire apparatus is made from a dozen or so 3D-printed parts that interlock to form the base, the platform, and the housing for the USB webcam that’s perched on an aluminum tube. From that vantage point, the camera’s images are analyzed with OpenCV and the center of the ball is located. A PID loop controls the three servos to center the ball on the platform, or razzle-dazzle it a little by moving the ball in a controlled circle. It’s quite a build, and the video below shows it in action.

We’ve seen a few balancing platforms before, but few with such style. This Stewart platform comes close, and this juggling platform gets extra points for closing the control loop with audio feedback. And for juggling, of course.

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Homebrew Linear Actuators Put The Moves On This Motion Simulator

October 4, 2018 by Dan Maloney 32 Comments

Breaking into the world of auto racing is easy. Step 1: Buy an expensive car. Step 2: Learn how to drive it without crashing. If you’re stuck at step 1, and things aren’t looking great for step 2 either, you might want to consider going with a virtual Porsche or Ferrari and spending your evenings driving virtual laps rather than real ones.

The trouble is, that can get a bit boring after a while, which is what this DIY motion simulator platform is meant to address. In a long series of posts with a load of build details, [pmvcda] goes through what he’s come up with so far on this work in progress. He’s building a Stewart platform, of the type we’ve seen before but on a much grander scale. This one will be large enough to hold a race car cockpit mockup, which explains the welded aluminum frame. We were most interested in the six custom-made linear actuators, though. Aluminum extrusions form the frame holding BLDC motor, and guide the nut of a long ball screw. There are a bunch of 3D-printed parts in the actuators, each of which is anchored to the frame and to the platform by simple universal joints. The actuators are a little on the loud side, but they’re fast and powerful, and they’ve got a great industrial look.

If car racing is not your thing and you’d rather build a full-motion flight simulator, here’s one that also uses DIY actuators.

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Hackaday Prize Entry: DIY 6-Axis Micro Manipulator

July 4, 2017 by Donald Papp 18 Comments

[David Brown]’s entry for The Hackaday Prize is a design for a tool that normally exists only as an expensive piece of industrial equipment; out of the reach of normal experimenters, in other words. That tool is a 6-axis micro manipulator and is essentially a small robotic actuator that is capable of very small, very precise movements. It uses 3D printed parts and low-cost components.

SLS Nylon Actuator Frame. Motor anchors to top right, moves the central pivot up and down to deflect the endpoints.

The manipulator consists of six identical actuators, each consisting of a single piece of SLS 3D printed nylon with a custom PCB to control a motor and read positional feedback. The motor moves the central pivot point of the 3D printed assembly, which in turn deflects the entire piece by a small amount. By anchoring one point and attaching the other, a small amount of highly controllable movement can be achieved. Six actuators in total form a Gough-Stewart Platform for moving the toolhead.

Interestingly, this 6-Axis Micro Manipulator is a sort of side project. [David] is interested in creating his own digital UV exposer, which requires using UV laser diodes with fiber optic pig tails attached. In an industrial setting these are created by empirically determining the optimal position of a fiber optic with regards to the laser diode by manipulating it with a micro manipulator, then holding it steady while it is cemented in place. Seeing a distinct lack of micro manipulators in anything outside of lab or industrial settings, and recognizing that there would be applications outside of his own needs, [David] resolved to build one.

Animatronic Head Responds With Animated GIFs

December 10, 2016 by Dan Maloney 6 Comments

[Abhishek] describes Peeqo as a “personal desktop robotic assistant” that looks like “the love child of an Amazon Echo and a Disney character.” We’re not sure about that last part — we’re pretty sure [Bender Bending Rodriquez] would fail a paternity suit on this one. Just look at that resemblance.

Whatever Peeqo’s parentage may be, it’s a pretty awesome build, and from the look of [Abhishek]’s design notes, he put a lot of thought into it, and a lot of work too. The build log reveals 3D-printed parts galore, custom-etched PC boards, and a hacked Raspberry Pi to both listen for voice commands and play responses in the form of animated GIFs on Peeqo’s ‘face’. The base has six modified RC servos to run the Gough-Stewart platform that lets Peeqo emote, and the head contains pretty much all the electronics. Beyond the hardware, a ton of programming went into giving Peeqo the ability to communicate through head gestures and GIFs that make sense for the required response.

Whether it’s bopping along to the tunes on your playlist or motivating you to lay off the social media with [Will Ferrell]’s flaming angry eyes, Peeqo looks like a ton of fun to build and use. Conveniently enough, [Abhishek] has shared all his files so you can build one too.

We haven’t seen anything like Peeqo before, but we have seen a lot of Amazon Echo hacks and even a few Stewart platform builds. But did we inadvertently feature a project starring Peeqo’s dad way back in 2009?

[Thanks to Aaron Cofield for the tip]

Palm Interface Has You Suggest Where Self Driving Car Should Go

October 30, 2015 by Sonya Vasquez 24 Comments

These days, our automobiles sport glittering consoles adorned with dials and digits to keep us up-to-date with our car’s vitals. In the future, though, perhaps we just wont need such vast amounts of information at our fingertips if our cars are driving themselves around. No information? How will we tell the car what to do? On that end, [Felix] has us covered with Stewart, a tactile gesture-input interface for the modern, self driving car.

Stewart is a 6-DOF “Stewart Interface” capable of both gesture input and haptic-output. Gesture input enables the car’s passenger to deliver driving suggestions to the car. The gentle twist of a wrist can signal an upcoming turn at the next intersection; pulling back on Stewart’s head “joystick style” signals a “whoa–slow down, there, bub!” Haptic output via 6 servos pushes around Stewart’s head in the car’s intended direction. If the passenger agrees with the car, she can let Stewart gesture itself in the desired direction; if she disagrees; she can veto the car’s choices by moving her hand directly against Stewart’s current output gesture. Overall, the interface unites the intentions of the car and the intentions of the passenger with a haptic device that makes the connection feel seamless!

We know we’re not supposed to comment on the “how” with art projects–but we’re engineers–and this one makes us giddy with delight. We’re imagining those rc car shock absorbers dramatically dampening the jittery servos and giving the user a nice resistive feel. Interconnects are laser cut acrylic, and the shell is a smoothly contoured 3d print. We’ve seen Stewart Interfaces before, but nothing with the look-and-feel of a sleek design feature on its way to being dropped into the cockpit of our future self-driving cars.

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Nothing’s As Vain As A Phone Taking A Selfie Of Itself… With Itself

November 12, 2014 by Sarah Petkus 13 Comments

The selfie: pop culture’s most frivolous form of self-expression is also probably one of the most human acts you could find yourself doing in a day. Everyone is guilty of snapping a quick pic from time to time with the expectation that it will leave an impression on those who see it. All of the implications surrounding why we do this support our deep-seated need to sculpt an identity for ourselves using others as the hammer and chisel. So, consider how upside-down the world would feel if you caught a robot posing for a shot in the mirror? What about one whose sole function was to take selfies and post them? If this breaks your mind a little, that was the intention. This #selfie robot by artists [Radamés Ajna] and [Thiago Hersan] is the first development in a larger body of work called “memememe”, which is meant to comment on our culture’s obsession with the trending, selfing nature of social media. This specific project explores the relationship between conversation and identity in a situation where there is no second party.

Hardware-wise, the #selfie bot is a Stewart platform made from six servo motors and a few pieces of carefully measured pushrod connected with swivel-ball-links. An android phone is mounted on the end effector which acts functionally as the robot’s face and eyes. To make it self-aware in a sense, [Ajna] and [Hersan] created their own recognition software with Open CV using a collection of sample images of various phones as reference points. As soon as the robot recognizes itself in the mirror as indicated by specific words flashing on its screen, it takes a picture, immediately uploading it to its own tumblr account. [Ajna] and [Hersan] have a nice description of their process on the project’s Instructable’s page which you can check out to see how they used Haar Cascades to create their custom object recognition. Additionally, if you’d fancy building your own robot to covertly place in your living room to snap pictures of other phones, you could check out their code on github.

Watch it selfie :

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Stewart Platform Ball Bearing Balancer

August 22, 2014 by Edward Becker 23 Comments

For their Mechanical Engineering senior design project at San Jose State University, [Tyler Kroymann] and [Robert Dee] designed and built a racing motion simulator. Which is slightly out of the budget of most hackers, so before they went full-scale, a more affordable Arduino powered Stewart platform proof of concept was built. Stewart platforms typically use six electric or hydraulic linear actuators to provide motion in six degrees of freedom (6 DOF), surge (X), sway (Y), heave (Z), pitch, roll, and yaw. With a simple software translation matrix, to account for the angular displacement of the servo arm, you can transform the needed linear motions into PWM signals for standard hobby servos.

The 6 DOF platform, with the addition of a resistive touch screen, also doubled as a side project for their mechatronic control systems class. However, in this configuration the platform was constrained to just pitch and roll. The Arduino reads the resistive touch screen and registers the ball bearing’s location. Then a PID compares this to the target location generating an error vector. The error vector is used to find an inverse kinematic solution which causes the actuators to move the ball towards the target location. This whole process is repeated 50 times a second. The target location can be a pre-programmed or controlled using the analog stick on a Wii nunchuck.

Watch the ball bearing seek the target location after the break.

Thanks to [Toby] for sending in this tip.

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