Sundials, one of humanity’s oldest ways of telling time, are typically permanent installations. The very good reason for this is that telling time by the sun with any degree of accuracy requires two-dimensional calibration — once for cardinal direction, and the other for local latitude.
Switch it on, set it down, and the sundial spins around on a continuous-rotation servo until the HMC5883L compass module finds the north-south orientation. Then the GPS module determines the latitude, and a 180° servo pans the plate until it finds the ideal position. Everything is controlled with an Arduino Nano and runs on a 9V battery, although we’d love to see it run on solar power someday. Or would that be flying too close to the sun? Check out how fast this thing calibrates itself in the short demo after the break.
High Altitude Balloons (HAB) are a great way to get all kinds of data and shoot great photos and video, but what goes up must come down. Once the equipment has landed, one must track it down. GPS and LoRA, with its long wireless range and ease of use, are invaluable tools in tracking payloads that have returned to Earth. [Dave Akerman] has made handheld receivers to guide him to payloads, but wanted something even smaller; ideally something that could be worn on the wrist.
[Buttim] loses his car a lot, which might sound a little bit like the plot from an early-00s movie, but he assures us that it’s a common enough thing. In a big city, and after several days of not driving one’s car, it can be possible to at least forget where you parked. There are a lot of ways of solving this problem, but the solution almost fell right into his lap: repurposing a lock from a bike share bicycle. (The build is in three parts: Part 2 and Part 3.)
These locks are loaded with features, like GPS, a cellular modem, accelerometers, and in this case, an ARM processor. It took a huge amount of work for [Buttim] to get anything to work on the device, but after using a vulnerability to dump the firmware and load his own code on the device, spending an enormous amount of time trying to figure out where all the circuit traces went through layers of insulation intended to harden the lock from humidity, and building his own Python-based programmer for it, he has basically free reign over the device.
To that end, once he figured out how it all worked, he put it to use in his car. The device functions as a GPS tracker and reports its location over the cellular network so it can’t become lost again. As a bonus, he was able to use the accelerometers to alert him if his car was moving without him knowing, so it turned into a theft deterrent as well. Besides that, though, his ability to get into the device’s firmware reminded us of a recent attempt to get access to an ARM platform.
When you put a human driver behind the wheel, they will use primarily their eyes to navigate. Both to stay on the road and to use any navigation aids, such as maps and digital navigation assistants. For self-driving cars, tackling the latter is relatively easy, as the system would use the same information in a similar way: when to to change lanes, and when to take a left or right. The former task is a lot harder, with situational awareness even a challenge for human drivers.
In order to maintain this awareness, self-driving and driver-assistance systems use a combination of cameras, LIDAR, and other sensors. These can track stationary and moving objects and keep track of the lines and edges of the road. This allows the car to precisely follow the road and, at least in theory, not run into obstacles or other vehicles. But if the weather gets bad enough, such as when the road is covered with snow, these systems can have trouble coping.
Looking for ways to improve the performance of autonomous driving systems in poor visibility, engineers are currently experimenting with ground-penetrating radar. While it’s likely to be awhile before we start to see this hardware on production vehicles, the concept already shows promise. It turns out that if you can’t see whats on the road ahead of you, looking underneath it might be the next best thing. Continue reading “Navigating Self-Driving Cars By Looking At What’s Underneath The Road”→
[Jay Doscher] shares a quick GPS project he designed and completed over a weekend. The device is called the CLUE Tracker and has simple goals: it shows a user their current location, but also provides a compass heading and distance to a target point. The idea is a little like geocaching, in that a user is pointed to a destination but must find their own way there. There’s a 3D printed enclosure, and as a bonus, there is no soldering required.
[Jay] did a nice job of commenting and documenting the code, so this could make a great introductory CircuitPython project. No soldering is required, which makes it a little easier to re-use the parts in other projects later. This helps to offset costs for hackers on a budget.
The fact that a device like this can be an afternoon or weekend project is a testament to the fact that times have never been better for hobbyists when it comes to hardware. CircuitPython is also a fast-growing tool, and projects like this can help make it easy and fun to get started.
Keeping track of position is crucial in a lot of situations. On Earth, it’s usually relatively straight-forward, with systems having been developed over the centuries that would allow one to get at least a rough fix on one’s position on this planet. But for a satellite out in space, however, it’s harder. How do they keep their communications dishes pointed towards Earth?
The stars are an obvious orientation point. The Attitude and Articulation Control Subsystem (AACS) on the Voyager 1 and 2 space probes has the non-enviable task of keeping the spacecraft’s communication dish aligned precisely with a communications dish back on Earth, which from deep space is an incomprehensibly tiny target.
Back on Earth, the star tracker concept has become quite popular among photographers who try to image the night skies. Even in your living room, VR systems also rely on knowing the position of the user’s body and any peripherals in space. In this article we’ll take a look at the history and current applications of this type of position tracking. Continue reading “Star Trackers: Telling Up From Down In Any Space”→
Mowing the lawn is one of those repetitive tasks most of us really wish we had a robot for. [Kenny Trussell] mowing needs are a bit more strenuous than most backyards, so he hacked a ride-on mower to handle multi-acre fields all on it’s own.
The mower started out life as a standard zero turn ride on lawn mower. It’s brains consist of a PixHawk board running Ardurover, an Ardupilot derivative for ground vehicles. Navigation is provided by a RTK GPS module that gets error corrections from a fixed base station via an Adafruit LoRa feather board, to achieve centimetre level accuracy. To control the mower, [Kenny] replaced the pneumatic shocks that centred the control levers with linear actuators.
So far [Kenny] has been using the mower to cut large 5-18 acre fields, which would be a very time-consuming job for a human operator. A relay was added to the existing safety circuit that only allows the mower to function when there is weight on the seat. This relay is wired directly to the RC receiver and is controlled from the hand-held RC transmitter. It will also stop the mower if it loses signal to the transmitter. To set up mowing missions, [Kenny] uses the Ardupilot Mission Planner for which he wrote a custom command line utility to create a concentric route for the mower to follow to completely cover a defined area. He has made a whole series of videos on the process, which is very handy for anyone wanting to do the same. We’re looking forward to a new video with all the latest updates.
This mower has been going strong for two years, but in terms of hours logged it’s got nothing on this veteran robotic mower that’s been at it for more than two decades and still runs off an Intel 386 processor.