Robot Cat Takes Inspiration From Nature

September 30, 2020 by Lewin Day 3 Comments

Oftentimes, a project starts with a clean sheet of paper, and we set out wildly sketching towards the goal in our minds. However, it can pay to do your research first, as [Chen Liang] demonstrates with this great robotic cat build.

[Liang] began the project after being dissatisfied with existing robot animals they’d seen online. Rather than simply attempt to build a cat from memory, instead, [Liang] decided to first study a real cat to ensure the resulting robot would bear real resemblence to its biological inspiration. [Liang]’s focus was on the skeleton, as replicating the way the real skeleton worked would create a robot with more authentic movement.

Using 3D printed parts and many, many servos, we think [Liang] has done an admirable job at creating a basic robot cat platform. With an ESP32 running the show, the cat can be posed using a web interface to control the servo positions of its various joints. We look forward to future upgrades that enable fluid movement and other capabilities, particularly involving the onboard camera.

It’s not the first robot cat we’ve seen, and it’s likely it won’t be the last. If you’ve got one living in your own lab, drop us a note on the tipline. Video after the break.

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TI And Cadence Make PSpice Free

September 20, 2020 by Al Williams 29 Comments

We like simulation software. Texas Instruments long offered TINA, but recently they’ve joined with Cadence to make OrCAD PSpice available for free with some restrictions. You’ve probably heard of PSpice — it’s widely used in academia and industry, but is usually quite costly. You can see a promotional overview video below.

The program requires registration and an approval step to get a license key. The downloaded program has TI models along with other standard models. There seem to be few limits as long as you stick to the supplied library. According to the datasheet, there are no size or simulation complexity limitations in that case. If you want to use other models, you can, but that’s where the limitations hit you:

There is no limitation of how many 3rd party models can be imported into the design. However, if 3rd party models are imported, a user will be able to plot a maximum of 3 signals at a time of their choice when any 3rd party model is imported from web.

We aren’t completely sure what “from web” means there, but presumably they just mean from other sources. In any event, you still get AC, DC, and transient analysis with plenty of options like worst-case timing analysis. Mixed signal designs are supported and there is a wealth of data plotting options, as you would expect.

This is a great opportunity to drive some serious software that is widely used in the industry. The only thing that bummed us out? It runs under Windows. We couldn’t get it to work under Wine, but a Windows 10 VM handled it fine, although we really hate running a VM if we don’t have to.

Still, the price is right and it is a great piece of software. We also liked the recent Micro-Cap 12 release, but we don’t expect any updates for that. Of course, LTSpice is quite capable, too.

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A New Spin On A Medical Test

August 28, 2020 by Brian McEvoy 5 Comments

Most of us can say that we have taken an obsolete hard drive out of a computer and felt it was a waste to toss it in the e-waste pile. Some of us have children’s drawings hung on the fridge with actuator magnets, or maybe a vast spreadsheet suspended on a steel filing cabinet. Let us not forget that there is also a high-speed, low-noise motor in there. On some models it is separate from the PCB, so grab an Electronic Speed Controller (ESC), your microcontroller of choice, and make yourself a salvaged HDD centrifuge like [Cave Man] has. His build uses the tray as a chassis, but he modeled and printed a new face in the same style as the original.

On top, he has an OLED screen for displaying the requested speed, measured speed, and runtime. Next to the display is a four-button pad with a customized legend for setting parameters. The video after the break shows the machine running through its paces. This version accommodates the tiny capillary tubes, microhematocrit tubes, for processing raw blood. This test can calculate the packed cell volume, which professionals use to determine things from dehydration to anemia.

There are other builds out there where people have modified an old drive into the kind of centrifuge that accepts larger diameter tubes, but this was a shining example of what is possible. One good turn deserves another, so we recommend a desktop bio-lab companion, or enlist some LEGO Mindstorms to help out.

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Unique LED Display Inspired By Fighter Jet Dashboard

August 22, 2020 by Tom Nardi 6 Comments

Last year, [Mangy_Dog] was asked by a few friends to consult on a project they were working on. The goal was to build an authentic replica of an F-18 cockpit, apparently for the purposes of creating a film. The project never materialized, but it did inspire him to take a hard look at the 1970s era alphanumeric displays utilized in the real aircraft. One thing lead to another, and he ended up using his own take on the idea to build his own “starburst” digit display.

As [Mangy_Dog] explains, while the faces of these original displays might have been quite small, there was a lot going on behind the scenes. Due to the technical limitations of the time, each alphanumeric character was made up of an array of incandescent light bulbs and fiber optic cables. This worked well enough, but was bulky and complex to manufacture.

Today, we can do better, even on the hobbyist level. As it turns out, 0402 LEDs are just about the right size to recreate the segments of the original starburst displays. So [Mangy_Dog] came up with a simple PCB design to not only align the LEDs properly, but drive them with a 74HC595 shift register and an array of MOSFETs. While assembly wasn’t without its challenges, he made good use of his custom built reflow oven to get all the diminutive components in place.

He went through a few different ideas for the diffuser, but eventually settled on black plastic with tiny holes drilled through courtesy of his laser cutter. Behind each set of three holes is a small pocket that got filled from both sides with transparent UV resin, which was then sanded down after curing. The end result isn’t perfect as you can still tell the center dot is brighter than its peers, but the overall effect is still very nice and definitely has a sort of faux-retro appeal.

The military naturally has access to some incredible technology, though they have a tendency to hold onto it for decades. That an individual with a meager budget and homemade tools can improve upon a piece of hardware installed in a $60+ million airplane is a testament to just how fast things are moving.

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Miles The Spider Robot

August 6, 2020 by Orlando Hoilett 7 Comments

Who doesn’t love robotic spiders? Today’s biomimetic robot comes in the form of Miles, the quadruped spider robot from [_Robox].

Miles uses twelve servos to control its motion, three on each of its legs, and also includes a standard HC-SR04 ultrasonic distance sensor for some obstacle avoidance capabilities. Twelve servos can use quite a bit of power, so [_Robox_] had to power Miles with six LM7805 ICs to get sufficient current. [_Robox_] laser cut acrylic sheets for Miles’s body but mentions that 3D printing would work as well.

Miles uses inverse kinematics to get around, which we’ve seen in a previous project and is a pretty popular technique for controlling robotic motion. The Instructable is a little light on the details, but the source code is something to take a look at. In addition to simply moving around [_Robox_] developed code to make Miles dance, wave, and take a bow. That’s sure to be a hit at your next virtual show-and-tell.

By now you’re saying “wait, spiders have eight legs”, and of course you’re right. But that’s an awful lot of servos. Anyway, if you’d rather 3D print your four-legged spider, we have a suggestion.

Teardown: Orthofix SpinalStim

August 5, 2020 by Tom Nardi 55 Comments

If you’ve ever had a particularly nasty fracture, your doctor may have prescribed the use of an electronic bone growth stimulator. These wearable devices produce a pulsed electromagnetic field (PEMF) around the bone, which has been shown to speed up the natural healing process in a statistically significant number of patients. That’s not to say there isn’t a debate about how effective they actually are, but studies haven’t shown any downsides to the therapy, so it’s worth trying at least.

When you receive one of these devices, it will be programmed to only operate for a certain amount of time or number of sessions. Once you’ve “used up” the bone stimulator, it’s functionally worthless. As you might imagine, there’s no technical reason this has to be the case. The cynic would say the only reason these devices have an expiration date on them is because the manufacturer wants to keep them from hitting the second hand market, but such a debate is perhaps outside the scope of these pages.

The Orthofix SpinalStim you’re seeing here was given to me by a friend after their doctor said the therapy could be cut short. This provided a somewhat rare opportunity to observe the device before it deactivated itself, which I’d hoped would let me take a closer look at how it actually operated.

As you’ll soon see, things unfortunately didn’t work out that way. But that doesn’t mean the effort was fruitless, and there may yet be hope for hacking these devices should anyone feel like taking up the challenge.

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Hackaday Podcast 078: Happy B-Day MP3, Eavesdropping On A Mars Probe, Shadowcasting 7-Segments, And A Spicy Commodore 64

July 31, 2020 by Mike Szczys No comments

Hackaday editors Elliot Williams and Mike Szczys go down the rabbit hole of hacky hacks. A talented group of radio amateurs have been recording and decoding the messages from Tianwen-1, the Mars probe launched by the Chinese National Space Administration on July 23rd. We don’t know exactly how magnets work, but know they do a great job of protecting your plasma cutter. You can’t beat the retro-chic look of a Commodore 64’s menu system, even if it’s tasked with something mundane like running a meat smoker. And take a walk with us down MP3’s memory lane.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)