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Misleading GPS, Philosophy of Maps, And You

10 Septiembre 2024 at 23:00

The oft-quoted saying “all models are wrong, but some are useful” is a tounge-in-cheek way of saying that at some level, tools we use to predict how the world behaves will differ from reality in some measurable way. This goes well beyond the statistics classroom it is most often quoted in, too, and is especially apparent to anyone who has used a GPS mapping device of any sort. While we might think that our technological age can save us from the approximations of maps and models, there are a number of limitations with this technology that appear in sometimes surprising ways. [Kyle] has an interesting writeup about how maps can be wrong yet still be incredibly useful especially in the modern GPS-enabled world.

[Kyle] is coming to us with a background in outdoor travel, involving all kinds of activities like hiking and backcountry skiing. When dealing with GPS tracking under these conditions, often the user’s actual position will deviate from their recorded position by a significant margin. Obvious causes like a loss of GPS signal are one thing, but there are some other reasons for this behavior. GPS can be off by tens of meters, so the question then becomes whether or not mapping software should record these errors or attempt to guess where it thinks the most likely location is, based on available data like barometric pressure, existing trails, elevation profiles, and other data. Especially in areas where the elevation changes rapidly, these errors can compound quickly and provide some truly mystifying data. Where mapping software draws these distinctions is a matter of active debate in these communities, with some taking more approximate routes that make more sense while sacrificing the raw data, and others letting the GPS pins fall where they may.

For anyone who’s been confused by Strava or Garmin data at the end of a run, hike, or bike ride, this is a fairly informative explanation of why the GPS data might differ from the actual distance of any of these activities. [Kyle] also notes that unless you’re out with a measuring wheel (and perhaps even then) any method to determine a true distance like this will have some amount of approximation or error. The closest technological solution to a problem like this we’ve seen is this GPS receiver which claims centimeter-level precision using some unique tricks.

Hackaday Links: September 8, 2024

8 Septiembre 2024 at 23:00
Hackaday Links Column Banner

OK, sit down, everyone — we don’t want you falling over and hurting yourself when you learn the news that actually yes, your phone has been listening to your conversations all along. Shocking, we know, but that certainly seems to be what an outfit called Cox Media Group (CMG) does with its “Active Listening” software, according to a leaked slide deck that was used to pitch potential investors. The gist is that the software uses a smartphone’s microphone to listen to conversations and pick out keywords that it feeds to its partners, namely Google, Facebook, and Amazon so that they can target you with directed advertisements. Ever have an IRL conversation about something totally random only to start seeing references to that subject pop up where they never did before? We sure have, and while “relationship mining” seemed like a more parsimonious explanation back in 2017, the state of tech makes eavesdropping far more plausible today. Then there’s the whole thing of basically being caught red-handed. The Big Three all huffed and puffed about how they were shocked, SHOCKED to learn that this was going on, with reactions ranging from outright denial of ever partnering with CMG to quietly severing their relationship with the company. So much for years of gaslighting on this.

In other dystopian news, the American Radio Relay League just wrote a $1 million check to end a ransomware attack. According to an ARRL statement, unidentified “threat actors” found their way into computer systems at the group’s Newington, Connecticut headquarters and related cloud-based systems, which allowed them to install encryption packages on laptops, desktops, and servers running a variety of operating systems. The ARRL’s crisis team managed to talk the cyberattackers down from their original demand of several million dollars to just a million, which all things considered was probably the path of least resistance and lowest cost. It’s a shame that things have come to that, but here we are.

The long saga of Starliner’s first crewed test flight is finally over, as the beleaguered spacecraft pushed back from the International Space Station and headed back to a midnight landing in New Mexico on Saturday. The return was sans crew, of course, with NASA being unwilling to risk the lives of astronauts Suni Williams and Butch Wilmore in a spacecraft that hadn’t really performed up to snuff on the way up to the ISS. As if the leaky thrusters weren’t enough, just before the hatches were closed Wilmore reported weird noises coming from a speaker in Starliner. He managed to capture the sounds on his mic for Mission Control, which for all the world sounded like someone repeatedly banging on a pipe in the distance. The weird thing about the sound is the regularity, which sounded a little faster than one per second. We’re keen to see if NASA shares any in-depth engineering information on this and all the other Starliner anomalies now that the craft is back on the ground.

If you’ve ever had to do extensive overhead work, such as sanding or painting ceilings, or working under a car on a lift, you know the burn that starts to set in after just a short while of holding your arms over your head. Up to now, the only way to fix that was either hit the gym and work on upper body strength, or find another way to make a living. But now that we’re living in the future, you can just strap on your own exoskeleton backpack and take a load off the robotic way. Perhaps unsurprisingly, the ExoActive exoskeleton comes from Festool, best known for its wonderfully well-engineered premium tools that often command a premium price. The ExoActive is battery-powered and straps on like a backpack with extensions that support the upper arms. It can be set to different work heights and provides a boost in lifting power, taking some of the weight off your shoulder girdle and transmitting it to your lower back. Unlike other exoskeletons we’ve seen breathless press releases for, this one seems like something you can buy right now. Sure, it’s expensive, but it’s a fraction of the cost of shoulder surgery.

And finally, Animagraffs is back with an incredibly detailed look inside the inner workings of a 16th-century sailing vessel. The video really captures what it took to build vessels that could (just barely) sail around the world for the first time. We loved the explanation of the rigging, especially the differences between the standing rigging and the running rigging. If you don’t know your clewline from your backstay, this Blender tour de force will set you straight.

Browse AI

Por: EasyWithAI
26 Enero 2023 at 18:46
Browse AI is an easy-to-use tool that allows you to extract and monitor data from any website, without coding. The prebuilt robots can be trained in 2 minutes and can extract specific data from various websites such as LinkedIn, Indeed, ProductHunt, Eventbrite, Google, Upwork, and more. You can also set up monitoring and get notified […]

Source

3D Printering: Switch and Klip(per)

4 Septiembre 2024 at 14:00
Art of 3D printer in the middle of printing a Hackaday Jolly Wrencher logo

Last time I tried to convince you that, if you haven’t already, you should try running your 3D printer with Klipper. There are several ways to actually make it work.

The first thing you need is something to run the Klipper host. Most people use a Raspberry Pi and if you already have one that runs OctoPrint, for example, you might well use it. Just tuck your SD card away in case you give up and install a fresh Linux system on a new card.

The Creality Sonic Pad has issues, but it does work.

However, a Pi isn’t your only option. You should be able to make it work on nearly anything that runs Linux. We’ve even seen it running on Windows under WSL. If you have an old laptop that can run Linux, that would work, too. We’ve even heard it works on a Chromebook.

The other option is to get a “pad.” Several vendors make touchscreens with some Linux single-board computer bundled together with Klipper preinstalled. For example, there is the Creality Sonic Pad, along with similar devices from other 3D printing companies.

If you decide to go that route, you might want to make sure it is easy to install your own software easily. Some pads, like the Creality unit, are notorious for having so much customization that they don’t lend themselves to upgrades unless they come from the manufacturer. In some cases, you can wipe out the stock firmware and install a normal operating system, but at that point, you could probably just buy a Pi and a touchscreen, right?

Installation

If you use something like a pad, it probably has a menu option to provide prebuilt firmware for your printer. Typically, you let it save the code to an SD card or a USB stick and then you are expected to flash it to your printer which, of course, depends on what kind of printer you have.

If you are rolling your own, you use a menu configuration program something like building a Linux kernel. If you have a pre-built configuration file, it will probably tell you in its comments what things you should pick. You need to know, for example, the type of CPU your board has, the bootloader offset, and if you are connecting via USB or serial. You can find details on the Klipper project pages.

KIAUH makes installing Klipper and supporting programs painless.

Installing the Linux side is easy because there is a nice script called KIHUH. The easiest thing to do is clone the Git repository and run it. From there, you can install Klipper, Moonraker, Fluidd, Mainsail, and some other things, too.

The real trick isn’t installing the software. The challenge is creating a proper configuration file for your printer. If you have a totally stock and popular printer, you’ll probably be in luck. But, how many of us can say that?

Start with the GitHub list to see if your printer or board is there. Even if it isn’t an exact match for your hardware, it will give you a start. For example, my custom printer is a Fysetc Spider, but the canned configuration is for a core XY machine, which means I have to make changes.

Even if you get a pad that claims to be “plug and play,” don’t count on it. For example, a Creality Sonic Pad’s instructions for installing with a Creality Ender 3 first asks you to take the printer apart to determine the type of motherboard you have. That’s not really plug and play! Any deviation from the stock machine is likely to require you to change the default profile.

Ch…Ch…Ch…Changes

In addition to just setting things up to match my exact hardware, I also needed to adjust the extruder step count. That has to be simple, right? Most firmware requires you to plug in the number of steps per millimeter of filament.

Klipper, on the other hand, wants to know how many millimeters extrude from a full rotation of the stepper. If you know how many steps (and microsteps) your printer uses, you can easily calculate either number from the other. For example, if you have 200 steps per rotation and 16 microsteps, that’s 3200 steps total. If your current steps per millimeter is 100, then your Klipper “rotation distance” is 3200/100=32.

Configuration Example

I had another major change to make. My printers have a non-standard filament sensor that detects the filament moving. That way, it can detect not only broken filaments but jammed filaments, too.

To install it, I had to add a few lines to my printer.cfg file and restart Klipper. Since I have more than one printer with the same sensor, I put all the lines in a single file and then included it in each printer. So the printer.cfg change was very simple:

[include sfs.cfg]

Then the real work is in sfs.cfg:

[filament_motion_sensor SFS_T0]
detection_length: 10.00 
extruder: extruder
switch_pin: ^PA4 
pause_on_runout: True 
event_delay: 3.0
pause_delay: 0.5
runout_gcode:
  M117 Runout Detected!

[delayed_gcode DISABLEFILAMENTSENSOR] 
initial_duration: 1
gcode:
 SET_FILAMENT_SENSOR SENSOR=SFS_T0 ENABLE=0

[gcode_macro SFS_ENABLE] ; Add this to PRINT_START
description: Enable smart filament sensor
gcode:
  M117 ENABLING the Smart Filament Sensor
  G92 E0
  SET_FILAMENT_SENSOR SENSOR=SFS_T0 ENABLE=1

[gcode_macro SFS_DISABLE] ; Add this to PRINT_END and PRINT_CANCEL
description: Disable smart filament sensor
gcode:
  M117 DISABLING the Smart Filament Sensor
  G92 E0
  SET_FILAMENT_SENSOR SENSOR=SFS_T0 ENABLE=0

This defines a few macros you can use elsewhere. Like Python, the indentation matters. You can organize your files using [include], and that’s especially useful if you have multiple printers that can share files.

Reference

So, how do you know what’s available? The Klipper reference. It will show you all the configuration sections you can use and what can possibly go in them. Don’t forget that some features — like print status notifications — will be in the Moonraker configuration which is a separate document.

Since the system is in Python, you can hack on it to your heart’s content. Just back up first. For example, you can add some custom Python scripts in the klipper/extras directory, like the one that can run arbitrary system commands from G-code.

Tinkering is what most of us like the best, and there’s plenty of opportunity to tinker with here. Klipper is also a good way to put new life in a very old printer since what runs on the printer is very simple, and all the heavy lifting is done elsewhere.

Klipper can easily do adaptive bed leveling, for example. If you can work in Python, it is also easy to experiment with things like exotic sensors.

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