servo

413 Articles

Useless Machine Is A Clock

September 14, 2021 by 15 Comments

Useless machines are a fun class of devices which typically turn themselves off once they are switched on, hence their name. Even though there’s no real point, they’re fun to build and to operate nonetheless. [Burke] has followed this idea in spirit by putting an old clock he had to use with his take on a useless machine of sorts. But instead of simply powering itself off when turned on, this useless machine dislodges itself from its wall mount and falls to the ground anytime anyone looks at it.

It’s difficult to tell if this clock was originally broken when he started this project, or if many rounds of checking the time have caused the clock to damage itself, but either way this project is an instant classic. Powered by a small battery driving a Raspberry Pi, the single-board computer runs OpenCV and is programmed to recognize any face pointed in its general direction. When it does, it activates a small servo which knocks it off of its wall, rendering it unarguably useless.

[Burke] doesn’t really know why he had this idea, but it’s goofy and fun. The duct tape that holds everything together is the ultimate finishing touch as well, and we can’t really justify spending too much on fit and finish for a project that tosses itself around one’s room. On the other hand, if you’re looking for a more refined useless machine, we have seen some that have an impressive level of intricacy.

Thanks to [alchemyx] for the tip!

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Smooth Servo Motion For Lifelike Animatronics

September 3, 2021 by 9 Comments

Building an animatronic robot is one thing, but animating it in a lifelike fashion is a completely different challenge. Hobby servos are cheap and popular for animatronics, but just letting it move at max speed isn’t particularly lifelike. In the video after the break, [James Bruton] demonstrates how to achieve natural motion with a simple animatronic head and a few extra lines of code.

Very little natural body movement happens at a constant speed, it’s always accelerating or decelerating. When we move our heads to look at something around us, our neck muscles accelerate our head sharply in the chosen direction and then slows down gradually as it reaches its endpoint. To do this in Arduino/C code, a new intermediate position for the servo is specified for each main loop until it reaches the final position. The intermediate value is the sum of 95% of the current position, and 5% of the target position. This gives the effect of the natural motion described above. The ratios can be changed to suit the desired speed.

The delay function is usually one of the first timing mechanisms that new Arduino programmers learn about, but it’s not suited for this application, especially when you’re controlling multiple servos simultaneously. Instead, the millis function is used to keep track of the system clock in the main loop, which fires the position update commands at the specified intervals. Adafruit wrote an excellent tutorial on this method of multitasking, which [James] based his code on. Of course, this should be old news to anyone who has been doing embedded programming for a while, but it’s an excellent introduction for newcomers.

Like most of [James]’s projects, all the code and CAD files are open source and available on GitHub. His projects make regular appearances here on Hackaday, like his mono-wheel balancing robot and mechanically multiplexed flip-dot display.

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Robot Pet Is A Chip Off The Old Logic Block

August 15, 2021 by 10 Comments

When [Ezra Thomas] needed inspiration for his senior design project, he only needed to look as far as his own robot. Built during his high school years from the classic 1979 Frank DaCosta book “How to Build Your Own Working Robot Pet”, [Ezra] had learned the hard way the many limitations and complexities of the wire wrapped 74xx series logic chips surrounding its 8085 processor.

[Ezra] embarked on a quest to recreate the monstrosity in miniature, calling it Pet on a Chip. Using a modern FPGA chip allows the electronics to shrink by an order of magnitude and provides flexibility for future expansion. Implementing an 8 bit CPU on the amply sized FPGA left plenty of room for a VGA GPU, motor controller, serial UART, and more. Programming the CPU is handled by a custom assembler written in Python.

The results? Twelve times less weight, thirteen times less power draw, better performance, and a lot of room for growth. [Ezra] hints at an I2C bus expansion as well as a higher level programming language to make software development less of a hurdle.

The Pet On A Chip is a wonderfully engineered project and we hope that we’ll be seeing more such from [Ezra] as time goes by. Watch his Pet On A Chip in action in the video below the break.

If [Ezra]’s FPGA escapades have you wondering how to get started, you can check out this introduction to FPGA from the 2019 Hackaday Superconference. And if you have your own FPGA creation to share, please let us know via the Tip Line!

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A Whole Lot Of Stepper Motors Make The Most Graceful 7-Segment Displays

August 11, 2021 by 22 Comments

Over the years we’ve seen many takes on the 7-segment display. Among the most interesting are the mechanical versions of what is most often an LED-based item. This week’s offering is from [John Burd], who published a very odd video showing off the clock he made. But look beyond YouTuber antics and you’ll see the stepper motors he used to turn the segments are dripping with graceful beauty. (Video, embedded below.)

Okay if you want to hear [Charlie Sheen] say “Raspberry P-eye”, this is the video for you. [John] used Cameo to get the (former?) star to talk about what was used to build the clock. Like we said, the video is weird. Let’s embrace that right away and then never talk about it again.

The thing is, the build is such a good idea. [John] went with some stepper motors you can source relatively cheaply from Ali Express and the like. Typically they’re around a buck or two each and have a couple of wings for screw mounting brackets. This builds on the segment displays we’ve seen that use hobby servos by allowing you finer control of how the segments move. Sure, the 90° rotation isn’t all that much to work with, but it will be much smoother and you can get fancy with the kinematics you choose. The only place we see room for improvement is the alignment of the segments when they are turned “off” as you can see the center segment in the video thumbnail below is not quite level. Maybe a linkage mechanism would allow for a hing mechanism that aligns more accurately while hiding the servos themselves behind the mounting plate? It’s in your hands now!

In the demo video you’ll also find some interesting test rigs built to proof out the project. One just endurance tests the mechanism, but the other two envision water-actuated segments. One pumps a hollow, transparent segment with colored liquid. The other tried to use water droplets sprayed in the air to illuminate laser segments. Both are cool and we’d like to see more of the oddball approaches which remind us of the ferrofluid clock.

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Get Yourself A Pupper (For Education)

July 12, 2021 by 14 Comments

While the disquieting appearance of some of the robots coming out of DARPA and other labs might give us some reservations about how much intelligence we want to give to those robots, there’s a lot to be learned from them before their inevitable global takeover. This small quadruped called the Mini Pupper is just the robot for that job. With a low cost and familiar platform, it’s the ideal robot to learn some of the tricks of the trade.

For a quadruped so small, some unique changes had to be made to ensure the robot’s functionality. There have been a few developments since it was first shown over a year ago. The first was to design a custom servo that could handle the unique characteristics of this robot. From there, some other improvements were made to the robot chassis such as using threaded rods for ease of assembly and maintenance. Some other things have stayed the same though like using a Raspberry Pi to handle the control systems and self-navigation.

Of course everything needed to make this robot yourself is open source, from the code to the schematics. For experimenting with quadrupeds and even with automatic navigation, this would be a great way to get started, and the small size will also limit its ability for a Skynet-style takeover as well. That’s a nice bonus.

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Home Automation For Fans Of Quick-and-Dirty Solutions

July 9, 2021 by 25 Comments

At Hackaday, we celebrate all kinds of projects, but we’ll have to admit that the polished and professional-looking builds tend to catch our eye a lot more than perhaps they should. There’s plenty of love to be had for the rougher builds, though, of which this quick-and-dirty home automation system is a perfect example.

Before anyone rushes to state the obvious with, “Should have used some relays,” consider that [MAKE_IT_WITH_ME]’s stated goal was to get the basics of a home automation system built with pretty much nothing but what can be found in one of those Arduino starter kits. And further, consider that landlords might not look kindly on tenants who wire a bunch of SSRs or Sonoff switches into the walls of their building. So this minimalist build is perfect for certain use cases. Its interface to the building’s electrical system is 100% mechanical, via a servo that travels along the bank of switches on a stepper-driven leadscrew. The servo has a modified horn to properly flick the rocker-style switches, and although changing from switch to switch is a bit slow, it works surprisingly well. The video below shows it in action.

While we can see it possibly working as-is for Decora-style switches that are seen in some markets, we’d think some mods would be in order for the more standard toggle-style switch — perhaps a finger extending out from the horn, along with a second servo to tilt the whole assembly away from the wall to allow it to clear the switch bats.

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Compact M&M Sorter Goes Anywhere

June 20, 2021 by 12 Comments

Let’s face it — eating different colored candy like M&Ms or Skittles is just a little more fun if you sort your pile by color first. The not-fun part is having to do it by hand. [Jackofalltrades_] decided to tackle this time-worn problem for engineering class because it’s awesome and it satisfies the project’s requirement for sensing, actuation, and autonomous sequencing. We’d venture to guess that it satisfies [Jackofalltrades_]’ need for chocolate, too.

Here’s how it works: one by one, M&Ms are selected, pulled into a dark chamber for color inspection, and then dispensed into the proper cubby based on the result. [Jackofalltrades_] lived up to their handle and built a color-detecting setup out of an RGB LED and light-dependent resistor. The RGB LED shines red, then, green, then blue at full brightness, and takes a voltage reading from the photocell to figure out the candy’s color. At the beginning, the machine needs one of each color to read in and store as references. Then it can sort the whole bag, comparing each M&M to the reference values and updating them with each new M&M to create a sort of rolling average.

We love the beautiful and compact design of this machine, which was built to maximize the 3D printer as one of the few available tools. The mechanical design is particularly elegant. It cleverly uses stepper-driven rotation and only needs one part to do most of the entire process of isolating each one, passing it into the darkness chamber for color inspection, and then dispensing it into the right section of the jar below. Be sure to check out the demo after the break.

Need a next-level sorter? Here’s one that locates and separates the holy grail of candy-coated chocolate — peanut M&Ms that didn’t get a peanut.

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