DIY Autonomous Mower In The Wild

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.

Autonomous Boat For Awesome Video Hyperlapses

With the ever-increasing capabilities of smart phones, action cameras, and hand-held gimbals, the battle for the best shots is intensifying daily on platforms like YouTube and Instagram. Hyperlapse sequences are one of the popular weapons in the armoury, and [Daniel Riley] aka [rctestflight] realised that his autonomous boat could be an awesome hyperlapse platform.

This is the third version of his autonomous boat, with version 1 suffering from seaweed assaults and version 2 almost sleeping with the fishes. The new version is a flat bottomed craft was built almost completely from pink insulation foam, making it stable and unsinkable. It uses the same electronics and air boat propulsion as version 2, with addition of a GoPro mounted in smart phone gimbal to film the hyper lapses. It has a tendency to push the bow into the water at full throttle, due to the high mounted motors, but was corrected by adding a foam bulge beneath the bow, at the cost of some efficiency.

Getting the gimbal settings tuned to create hyperlapses without panning jumps turned out to be the most difficult part. On calm water the boat is stable enough to fool the IMU into believing that it’s is not turning, so the gimbal controller uses the motor encoders to keep position, which don’t allow it to absorb all the small heading corrections the boat is constantly making. Things improved after turning off the encoder integration, but it would still occasionally bump against the edges of the dead band inside which the gimbal does not turn with the boat. In the end [Daniel] settled for slowly panning the gimbal to the left, while plotting a path with carefully calculated left turns to keep the boat itself out of the shot. While not perfect, the sequences still beautifully captured the night time scenery of Lake Union, Seattle. Getting it to this level cost many hours of midnight testing, since [Daniel] was doing his best to avoid other boat traffic, and we believe it paid off.

We look forward to his next videos, including an update on his solar plane. Continue reading “Autonomous Boat For Awesome Video Hyperlapses”

Autonomous Air Boat Vs Lake Washington

Autonomous vehicles make a regular appearance around here, as does [Daniel Riley] aka [rctestflight]. His fascination with building long-endurance autonomous vehicles continues, and this time he built an autonomous air boat.

This craft incorporates a lot of the lessons learnt from his autonomous boat that used a plastic food container. One of the biggest issues was the submerged propellers kept getting tangled in weeds. This led [Daniel] to move his props above water, sacrificing some efficiency for reliability, and turning it into an air boat. The boat itself is catamaran design with separate 3D printed hulls connected by carbon fibre tubes. As with the tupperware boat, autonomous control is done by the open source Ardupilot software.

During testing [Daniel] had another run in with his old arch-nemesis, seaweed. It turns out the sharp vertical bow is a nice edge for weeds to hook on to, create drag, and screw up the craft’s control. [Daniel]’s workaround involved moving the big batteries to the rear, causing the bows lift almost completely out of the water.

With a long endurance in mind right from the start of the project, [Daniel] put it to the test with a 13 km mission on Lake Washington very early one morning. For most of the mission the boat was completely on its own, with [Daniel] stopping at various points along the lake shore to check on its progress. Everything went smoothly until 10 km into the mission when the telemetry showed it slowing down and angling off course, after which is started going in circles. Lucky for Daniel he was offered a kayak by a lakeside resident, and he managed to recover the half sunken vessel. He suspects the cause of the failure was a slowly leaking hull. [Daniel] is already working on the next version, and were looking forward to seeing what he comes up with. Check out the video after the break. Continue reading “Autonomous Air Boat Vs Lake Washington”

Skid Steer Mows Airport Grass Autonomously

Sure, mowing the lawn is a hassle. No one really wants to spend their time and money growing a crop that doesn’t produce food, but we do it anyway. If you’re taking care of a quarter acre in the suburbs it’s not that much of a time sink, but if you’re taking care of as much grass as [Roby], you’d probably build something similar to his autonomous skid-steer mower, too.

This thing isn’t a normal push mower outfitted with some random electronics, either. This is a serious mower that is essentially a tractor with blades attached to it. Since it’s a skid steer, it turns by means of two handles that control the speed of the left or right drive wheels. Fabricating up some servo linkages to attach them to specialized servos takes care of the steering portion, and the brain is ArduPilot hooked up to a host of radios, GPS, and a compass to allow it to drive all around the runways at the airport without interfering with any aircraft.

This is a serious build and goes into a lot of detail about how servos and linkages should behave, how all the software works, and the issues of actually mounting everything to the mower. The entire project is open source too, so even if you don’t have a whole airport runway to mow you might be able to find something in there to help with your little patch of grass.

Thanks to [Vincent] for the tip!

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Hackaday Podcast 032: Meteorite Snow Globes, Radioactive Ramjet Rockets, Autonomous Water Boxes, And Ball Reversers

Hackaday Editors Mike Szczys and Elliot Williams recorded this week’s podcast live from Chaos Communication Camp, discussing the most interesting hacks on offer over the past week. I novel locomotion news, there’s a quadcopter built around the coanda effect and an autonomous boat built into a plastic storage bin. The radiation spikes in Russia point to a nuclear-powered ramjet but the idea is far from new. Stardust (well… space rock dust) is falling from the sky and it’s surprisingly easy to collect. And 3D-printed gear boxes and hobby brushless DC motors have reached the critical threshold necessary to mangle 20/20 aluminum extrusion.

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

Direct download (41 MB)

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ArduRover Boat Uses Tub To Float

There’s nothing quite like the sight of a plastic box merrily sailing its way around a lake to symbolise how easy it is to get started in autonomous robotics. This isn’t a project we’re writing about because of technical excellence, but purely because watching an autonomous plastic box navigate a lake by itself is surprisingly compelling viewing. The reason that [rctestflight] built the vessel was to test out the capabilities of ArduRover. ArduRover is, of course, a flavour of the extremely popular open source ArduPilot, and in this case is running on a Pixhawk.

The hardware itself is deliberately as simple as possible: two small motors with RC car ESCs, a GPS, some power management and a telemetry module are all it takes. The telemetry module allows the course/mission to be updated on the fly, as well as sending diagnostic data back home. Initially, this setup performed poorly; low GPS accuracy combined with a high frequency control loop piloting a device with little inertia lead to a very erratic path. But after applying some filtering to the GPS this improved significantly.

Despite the simplicity of the setup, it wasn’t immune to flaws. Seaweed in the prop was a cause of some stressful viewing, not to mention the lack of power required to sail against the wind. After these problems caused the boat to drift off course past a nearby pontoon, public sightings ranged from an illegal police drone to a dog with lights on its head.

If you want to use your autonomous boat for other purposes than scaring the public, we’ve written about vessels that have been used to map the depth of the sea bed, track aircraft, and even cross the Atlantic.

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Gliding Back Home From 60,000ft

If you want to play around with high altitudes, weather balloons are the way to go. With a bit of latex and some helium, it’s possible to scrape up against the edge of space without having to start your own rocketry program. [Blake] was interested in doing just this, and decided to build a near space glider which could capture the journey.

There are certain challenges involved with this flight regime, which [Blake] worked to overcome. There was significant investment in the right antennas and radio hardware to enable communication and control of the aircraft at vast distances. Batteries were chosen for their ability to work at low temperatures in the high altitude environment, and excess heat from the transmitters was use to keep them warm.

The glider was also fitted with an Ardupilot Mega which would control the gliders’s flight after separation from the lift balloon. [Blake] had some success flying the aircraft at 60,000 feet, but found that due to communications issues, the autopilot was doing a better job. The initial flight was largely a success, with the glider landing just 9 miles off target due to headwinds.

We’ve seen glider builds on other autopilot platforms, too. Video after the break.

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