Start Tracking Satellites with This Low-Cost Azimuth-Elevation Positioner

Tracking satellites and the ISS is pretty easy. All you really need is an SDR dongle or a handheld transceiver, a simple homebrew antenna, and a clear view of the sky. Point the antenna at the passing satellite and you’re ready to listen, or if you’re a licensed amateur, talk. But the tedious bit is the pointing. Standing in a field or on top of a tall building waving an antenna around gets tiring, and unless you’re looking for a good arm workout, limits the size of your antenna. Which is where this two-axis antenna positioner could come in handy.

While not quite up to the job it was originally intended for — positioning a 1.2-meter dish antenna — [Manuel] did manage to create a pretty capable azimuth-elevation positioner for lightweight antennas. What’s more, he did it on the cheap — only about €150. His design seemed like it was going in the right direction, with a sturdy aluminum extrusion frame and NEMA23 steppers. But the 3D-printed parts turned out to be the Achille’s heel. At the 1:40 mark in the video below (in German with English subtitles), the hefty dish antenna is putting way too much torque on the bearings, delaminating the bearing mount. But with a slender carbon-fiber Yagi, the positioner shines. The Arduino running the motion control talks GS232, so it can get tracking data directly from the web to control the antenna in real time.

Here’s hoping [Manuel] solves some of the mechanical issues with his build. Maybe he can check out this hefty dish positioner for weather satellite tracking for inspiration.

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Robotic Arm Rivals Industrial Counterparts

We’ve seen industrial robotic arms in real life. We’ve seen them in classrooms and factories. Before today, we’ve never mistaken a homemade robotic arm for one of the price-of-a-new-home robotic arms. Today, [Chris Annin] made us look twice when we watched the video of his six-axis robotic arm. Most of the DIY arms have a personal flare from their creator so we have to assume [Chris Annin] is either a robot himself or he intended to build a very clean-looking arm when he started.

He puts it through its paces in the video, available after the break, by starting with some stretches, weight-lifting, then following it up and a game of Jenga. After a hard day, we see the arm helping in the kitchen and even cracking open a cold one. At the ten-minute mark, [Chris Annin] walks us through the major components and talks about where to find many, many more details about the arm.

Many of the robotic arms on Hackaday are here by virtue of resourcefulness, creativity or unusual implementation but this one is here because of its similarity to the big boys.

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TeensyStep – Fast Stepper Library for Teensy

The Teensy platform is very popular with hackers — and rightly so. Teensys are available in 8-bit and 32-bit versions, the hardware has a bread-board friendly footprint, there are a ton of Teensy libraries available, and they can also run standard Arduino libraries. Want to blink a lot of LED’s? At very fast update rates? How about MIDI? Or USB-HID devices? The Teensy can handle just about anything you throw at it. Driving motors is easy using the standard Arduino libraries such as Stepper, AccelStepper or Arduino Stepper Library.

But if you want to move multiple motors at high micro-stepping speeds, either independently or synchronously and without step loss, these standard libraries become bottlenecks. [Lutz Niggl]’s new TeensyStep fast stepper control library offers a great improvement in performance when driving steppers at high speed. It works with all of the Teensy 3.x boards, and is able to handle accelerated synchronous and independent moves of multiple motors at the high pulse rates required for micro-stepping drivers.

The library can be used to turn motors at up to 300,000 steps/sec which works out to an incredible 5625 rpm at 1/16 th micro-stepping. In the demo video below, you can see him push two motors at 160,000 steps/sec — that’s 3000 rpm — without the two arms colliding. Motors can be moved either independently or synchronously. Synchronous movement uses Bresenham’s line algorithm to plan motor movements based on start and end positions. While doing a synchronous move, it can also run other motors independently. The TeensyStep library uses two class objects. The Stepper class does not require any system resources other than 56 bytes of memory. The StepControl class requires one IntervallTimer and two channels of a FTM  (FlexTimer Module) timer. Since all supported Teensys implement four PIT timers and a FTM0 module with eight timer channels, the usage is limited to four StepControl objects existing at the same time. Check out [Lutz]’s project page for some performance figures.

As a comparison, check out Better Stepping with 8-bit Micros — this approach uses DMA channels as high-speed counters, with each count sending a pulse to the motor.

Thanks to [Paul Stoffregen] for tipping us off about this new library. Continue reading “TeensyStep – Fast Stepper Library for Teensy”

BeamCNC: Computer-Controlled Construction System Mill

Need to make something quick and dirty out of wooden beams, and want to use elements you know will work together? BeamCNC is a mobile assembly of stepper-controlled rollers and a router that sucks a 2×2 through it and drills the holes in pre-programmed intervals. Currently being developed as part of an Indiegogo campaign currently in preview, its creator [Vladislav Lunachev] has declared it open source hardware. It’s essentially a CNC mill that makes Grid Beam, a classic DIY building set that resembles Meccano, Erector, and other classic sets, only made full-scale for larger projects. While BeamCNC is not affiliated with Grid Beam, it takes the same general idea and automates it.

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Fidget-Spinning Robot Out-Uselesses Other Useless Machines

When the [Director of Legal Evil] at Louisville’s LVL1 Hackerspace decided to demonstrate the uselessness of a 3D printer by printing a fidget spinner, another member at the space’s Tuesday meeting rose to the challenge and built a machine that whose sole purpose is to spin fidget spinners.

[Gary Flispart] used an Arduino clone and what appears to be a motor driver in conjunction with a stepper motor. The motor moves a belt that turns a series of metal scraps serving as a four-bar linkage. The linkage moves the dowel that turns the spinner and then gets out of the way so it doesn’t inhibit the toy’s rotation. The Digital Fidget Digit, as [Gary] calls it, looks like it was built out of scrap metal and random pieces of wood in the glorious tradition of hackerspace projects.

We at Hackaday love crazy projects that come out of hackerspaces, like the iris porthole at i3Detroit, another space’s ultimate fume extractor, and LVL1’s doomcano.

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Hackaday Prize Entry: 3D Printed Linear Actuator Does 2kg+

The rabbit hole of features and clever hacks in [chiprobot]’s NEMA17 3D Printed Linear Actuator is pretty deep. Not only can it lift 2kg+ of mass easily, it is mostly 3D printed, and uses commonplace hardware like a NEMA 17 stepper motor and a RAMPS board for motion control.

The main 3D printed leadscrew uses a plug-and-socket design so that the assembly can be extended easily to any length desired without needing to print the leadscrew as a single piece. The tip of the actuator even integrates a force sensor made from conductive foam, which changes resistance as it is compressed, allowing the actuator some degree of feedback. The force sensor is made from a 3M foam earplug which has been saturated with a conductive ink. [chiprobot] doesn’t go into many details about his specific method, but using conductive foam as a force sensor is a fairly well-known and effective hack. To top it all off, [chiprobot] added a web GUI served over WiFi with an ESP32. Watch the whole thing in action in the video embedded below.

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Hackaday Prize Entry: Modular Stepper Control

Stepper motors are a great solution for accurate motion control. You’ll see them on many 3D printer designs since they can precisely move each axis. Steppers find uses in many robotics projects since they provide high torque at low speeds.

Since steppers are used commonly used for multi-axis control systems, it’s nice to be able to wire multiple motors back to a single controller. We’ve seen a few stepper control modules in the past that take care of the control details and accept commands over SPI, I2C, and UART. The AnanasStepper 2.0 is a new stepper controller that uses CAN bus for communication, and an entry into the 2017 Hackaday Prize.

A CAN bus has some benefits in this application. Multiple motors can be connected to one controller via a single bus. At low bit rates, it can work on kilometer long busses. The wiring is simple and cheap: two wires twisted together with no shielding requirements. It’s also designed to be reliable in high noise environments such as cars and trucks.

The project aims to implement an API that will allow control from many types of controllers including Arduino, Linux CNC, several 3D printer controllers, and desktop operating systems. With a few AnanasSteppers one of these controllers, you’d be all set up for moving things on multiple axes.