Robot Harvesting Machine Is Tip Of The Agri-Tech Iceberg

July 9, 2019 by Pat Whetman 24 Comments

Harvesting delicate fruit and vegetables with robots is hard, and increasingly us humans no longer want to do these jobs. The pressure to find engineering solutions is intense and more and more machines of different shapes and sizes have recently been emerging in an attempt to alleviate the problem. Additionally, each crop is often quite different from one another and so, for example, a strawberry picking machine can not be used for harvesting lettuce.

A team from Cambridge university, UK, recently published the details of their lettuce picking machine, written in a nice easy-to-read style and packed full of useful practical information. Well worth a read!

The machine uses YOLO3 detection and classification networks to get localisation coordinates of the crop and then check if it’s ready for harvest, or diseased. A standard UR10 robotic arm then positions the harvesting mechanism over the lettuce, getting force feedback through the arm joints to detect when it hits the ground. A pneumatically actuated cutting blade then attempts to cut the lettuce at exactly the right height below the lettuce head in order to satisfy the very exacting requirements of the supermarkets.

Rather strangely, the main control hardware is just a standard laptop which handles 2 consumer grade USB cameras with overall combined detection and classification speeds of about 0.212 seconds. The software is ROS (Robot Operating System) with custom nodes written in Python by members of the team.

Although the machine is slow and under-powered, we were very impressed with the fact that it seemed to work quite well. This particular project has been ongoing for several years now and the machine rebuilt 16 times! These types of machines are currently (2019) very much in their infancy and we can expect to see many more attempts at cracking these difficult engineering tasks in the next few years.

We’ve covered some solutions before, including: Weedinator, an autonomous farming ‘bot, MoAgriS, an indoor farming rig, a laser-firing fish-lice remover, an Aussie farming robot, and of course the latest and greatest from FarmBot.

Video after the break:

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Safely Measuring Single And Three-Phase Power

July 6, 2019 by Maya Posch 7 Comments

There are many reasons why one would want to measure voltage and current in a project, some applications requiring one to measure mains and even three-phase voltage to analyze the characteristics of a device under test, or in a production environment. This led [Michael Klopfer] at the University of California, Irvine along with a group of students to develop a fully isolated board to analyze both single and three-phase mains systems.

Each of these boards consists out of two sections: one is the high-voltage side, with the single phase board using the Analog Devices ADE7953 and the three-phase board the ADE9708. The other side is the low-voltage, isolated side to which the microcontroller or equivalent connects to using either SPI or I2C. Each board type comes in either SPI or I2C flavor.

Each board can be used to measure line voltage and current, and the Analog Devices IC calculates active, reactive, and apparent energy, as well as instantaneous RMS voltage and current. All of this data can then be read out using the provided software for the Arduino platform.

The goal of this project is to make it easy for anyone to reproduce their efforts, with board schematics (in Eagle format) and the aforementioned software libraries provided. Here it is somewhat unfortunate that the documentation can be somewhat incomplete, with basic information such as input and measurement ranges missing. Hopefully this will improve over the coming months as it does seem like a genuinely useful project for the community.

We’ve covered the work coming out of [Michael]’s lab before, including this great rundown on Lattice FPGAs. They’re doing machine vision, work on RISC-Vchips, and more. A stroll through the lab’s GitHub is worth your time.

How Do You Get PCI-E On The Atomic Pi? Very Carefully.

June 26, 2019 by Tom Nardi 18 Comments

At this point, you’ve almost certainly heard about the Atomic Pi. The diminutive board that once served as the guts of a failed robot now lives on as a powerful x86 SBC available at a fire sale price. How long you’ll be able to buy them and what happens when the initial stock runs out is another story entirely, but there’s no denying that folks are already out there doing interesting things with them.

One of them is [Jason Gin], who recently completed an epic quest to add a PCI Express (PCI-E) slot to his Atomic Pi. Things didn’t exactly go according to plan and the story arguably has more lows than highs, but in the end he emerged victorious. He doesn’t necessarily recommend you try the same modification on your own Atomic Pi, but he does think this sets the stage for the development of a more refined upgrade down the line.

[Jason] explains that the board’s Ethernet controller was already communicating with the Intel Atom x5-Z8350 SoC over PCI-E, so there was never a question about whether or not the modification was possible. In theory, all you needed to do was disable the Ethernet controller and tack on an external PCI-E socket so you could plug in whatever you want. The trick is pulling off the extremely fine-pitch soldering such a modification required, especially considering how picky the PCI Express standard is.

In practice, it took several attempts with different types of wire before [Jason] was able to get the Atomic Pi to actually recognize something plugged into it. Along the way, he managed to destroy the Ethernet controller somehow, but that wasn’t such a great loss as he planned on disabling it anyway. The final winning combination was 40 gauge magnet wire going between the PCB and a thin SATA cable that is mechanically secured to the board with a piece of metal to keep anything from flexing.

At this point, [Jason] has tested enough external devices connected to his hacked-on port to know the modification has promise. But the way he’s gone about it is obviously a bit temperamental, and far too difficult for most people to accomplish on their own anyway. He’s thinking the way forward might be with a custom PCB that could be aligned over the Ethernet controller and soldered into place, though admits such a project is currently above his comfort level. Any readers interested in a collaboration?

Like most of you, we had high hopes for the Atomic Pi when we first heard about it. But since it became clear the board is the product of another company’s liquidation, there’s been some understandable trepidation in the community. Nobody knows for sure what the future looks like for the Atomic Pi, but that’s clearly not stopping hackers from diving in.

Laser Cutting Wooden Pogo Pin Test Jigs

June 25, 2019 by Tom Nardi 10 Comments

Now as far as problems go, selling so many products on Tindie that you need to come up with a faster way to test them is a pretty good one to have. But it’s still a problem that needs solving. For [Eric Gunnerson] the solution involved finding a quick and easy way to produce wooden pogo test jigs on his laser cutter, and we have a feeling he’s not the only one who’ll benefit from it.

The first step was exporting the PCB design from KiCad into an SVG, which [Eric] then brought into Inkscape for editing. He deleted all of the traces that he wasn’t interested in, leaving behind just the ones he wanted to ultimately tap into with the pogo pins. He then used the Circle tool to put a 0.85 mm red dot in the center of each pad.

You’re probably wondering where those specific parameters came from. The color is easy enough to explain: his GlowForge laser cutter allows him to select by color, so [Eric] can easily tell the machine to cut out anything that’s red. As for the size, he did a test run on a scrap of wood and found that 0.85 mm was the perfect dimensions to hold onto a pogo pin with friction.

[Eric] ran off three identical pieces of birch plywood, plus one spacer. The pogo pins are inserted into the first piece, the wires get soldered around the back, and finally secured with the spacer. The whole thing is then capped off with the two remaining pieces, and wrapped up in tape to keep it together.

Whether you 3D print one of your own design or even modify a popular development board to do your bidding, the test jig is invaluable when you make the leap to small scale production.

Ditch The Switch: A Soft Latching Circuit Roundup

June 24, 2019 by Tom Nardi 32 Comments

For some of us, there are few sounds more satisfying than the deep resonant “thunk” of a high quality toggle switch slamming into position. There isn’t an overabundance of visceral experiences when working with electronics, so we like to savor them when we get the chance. But of course there’s no accounting for taste, and we suppose there are even situations where a heavy physical switch might not be the best solution. So what do you do?

Enter the latching power circuit, often referred to as a “soft” switch. [Chris Chimienti] has recently put together a fascinating video which walks the viewer through five different circuits which can be used to add one of these so-called soft power switches to your project. Each circuit is explained, diagramed, annotated, and eventually even demonstrated on a physical breadboard. The only thing you’ve got to do is pick which one you like the most.

There’s actually a number of very good reasons to abandon the classic toggle switch for one of these circuits. But the biggest one, somewhat counterintuitively, is cost. Even “cheap” toggle switches are likely to be one of the most expensive components in your bill of materials, especially at low volume. By comparison, the couple of transistors and a handful of passive components it will take to build out one of these latching circuits will only cost you a couple of cents.

Even if you aren’t in the market for a new way to turn off your projects, this roundup of circuits is a fantastic reminder of how powerful discrete components can be. In an age where most projects seem assembled from pre-fabbed modules, it’s occasionally refreshing to get back to basics.

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Finally, An Open Source Multimeter

June 20, 2019 by Brian Benchoff 18 Comments

For his Hackaday Prize entry, [Martin] is building an Open Source Multimeter that can measure voltage, current, and power. It’s an amazing build, and you too can build one yourself.

The features for this multimeter consist of voltage mode with a range of +/-6V and +/-60V. There’s a current mode, basically the same as voltage, with a range of +/-60 mA and +/-500mA. Unlike our bright yellow Fluke, there’s also a power mode that measures voltage and current at the same time, with all four combinations of ranges available. There’s a continuity test that sounds a buzzer when the resistance is below 50 Ω, and a component test mode that measures resistors, caps, and diodes. There’s a fully isolated USB interface capable of receiving commands and transmitting data, a real-time clock, and in the future there might be frequency measurement.

This build is based on the STM32F103 microcontroller, uses an old Nokia phone screen, and unlike so many other multimeters, this thing is small. It’s very small. More than small enough to fit in your pocket and forget about it, unlike nearly every other multimeter available. There’s one thing about multimeters, and it’s that the best multimeter is the one that you have in your hands when you need it, and this one certainly fits the bill.

The entire project is being written up on hackaday.io, there’s a GitHub repo for all the hardware and software, and there’s also a video demo covering all the features (available below). This is a stand-out project, and something we desperately want to get our hands on.

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Homemade Magic Makes The Metcal Go

June 16, 2019 by Kerry Scharfglass 29 Comments

First soldering irons are often of the ~~Radioshack or Maplin~~ firestarter variety. They’re basically wall power shorted across a nichrome heater or similar with some inline resistance to make it harder to burn down the house. You plug them in, the current flows, and they get hot. Done.

If you stick with the hobby for a while, these eventually get replaced with something like the venerable HAKKO FX-888D or that one Weller everyone likes with the analog knob. These are much improved; having temperature control leads to a more consistently heated tip and much improved soldering experience.

Entering the electronics workplace one comes across the next level of quality soldering iron: high end HAKKOs, Metcals, JBCs, and the like. Using one of these irons is practically a religious experience; they heat in a flash and solder melts while you blink. They even turn off when you put the handpiece down! But they’re expensive to buy (hint: think used). What’s a hobbyist to do?

[SergeyMax] seems to have had this problem. He bit the bullet, figured out how the Metcal works, and made his own base. This is no mean feat as a Metcal might look like a regular iron but it’s significantly more complex than ye olde firestarter. The Metcal magic is based on a oscillating magnetic fields (notice the handpiece is connected via BNC?) interacting with a tip bearing a special coating. In the presence of the changing field the tip heats up until it hits its Curie temperature, at which point it stops interacting with the magnetic field and thus stops heating.

When the user solders, the tip cools by sinking its heat into the part and drops below the Curie temperature again, which starts the heating again. It’s like temperature control with the sensor placed absolutely as close to the part as possible and a nearly instant response time, without even a control loop! [SergeyMax] has a much more thorough description of how these irons work, which we definitely recommend reading.

So what’s the hack? Based on old schematics and some clever reverse engineering from photos [SergeyMax] built a new base station! The published schematic is as rich with capacitors and inductors as one could hope. He didn’t post source or fab files but we suspect the schematic and photos of the bare board combined with some tinkering are enough for the enterprising hacker to replicate.

The post contains a very thorough description of the reverse engineering process and related concerns in designing a cost efficient version of the RF circuitry. Hopefully this isn’t the last Metcal replacement build we see! Video “walkthrough” after the break.

Edit: I may have missed it, but eagle eyed commentor [Florian Maunier] noticed that [SergeyMax] posted the sources to this hack on GitHub!

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