Drone Boat Sails Seattle

March 11, 2021 by Lewin Day 11 Comments

Thanks to the availability of cheap, powerful autopilot modules, building small autonomous vehicles is now well within the reach of the average maker. [rctestflight] has long been an enthusiast working in this space, and has been attempting long range autonomous missions on the lakes of Washington for some time now. His latest attempt proved to be a great success. (Video, embedded below.)

The build follows on from earlier attempts to do a 13 km mission with an airboat, itself chosen to avoid problems in early testing with seaweed becoming wrapped around propellers. For this attempt, [Daniel] chose to build a custom boat hull out of fiberglass, and combine both underwater propellers and a fan as well. The aim was to provide plenty of thrust, while also aiming for redundancy. As a bonus, the fan swivels with the boat’s rudder, helping provide greater turn authority.

After much tuning of the ArduPilot control system, the aptly-named SS Banana Slug was ready for its long range mission. Despite some early concerns about low battery voltages due to the cold, the boat completed its long 13 km haul across the lake for a total mission length of over three hours. Later efficiency calculations suggests that the boat’s onboard batteries could potentially handle missions over 100 km before running out.

It goes to show that, even with an off-the-shelf autopilot and mapping solution, there’s still a huge amount of engineering that goes into any successful long-range mission, whether land, sea or air.

Continue reading “Drone Boat Sails Seattle” →

Six Degrees Of Freedom Omnicopter With Ardupilot

January 9, 2021 by Danie Conradie 12 Comments

Modern multirotors are very maneuverable but are mostly limited to hovering in a single orientation. [Peter Hall] has gotten around this by building an omnicopter drone with six motors mounted in different orientations on a collapsed tetrahedron frame.

The shape of the frame consists of six tetrahedrons all joined together at a single point. With a motor in each frame, the drone can produce a thrust vector in any direction, to achieve six degrees of freedom. The control system is the challenging part of this project, but fortunately [Peter] is one of the Ardupilot developers. Unlike a standard multirotor, it doesn’t need to tilt to move around laterally but can keep its orientation constant. One of the limiting factors is that the motors need to stop and reverse rotation for direction changes, which takes time. At slow maneuvering speeds this isn’t a major problem, but at higher speeds rotation is noticeably less smooth.

Because the drone is symmetrical all around, keeping track of orientation is challenging for a human pilot, but it’s perfect for an autopilot system like Ardupilot. In the video after the break, [Peter] demonstrates this by flying the drone around while the autopilot rotates it randomly. The 6DoF control system is open source and a pull request is live to integrate it into the official version of Ardupilot. The obvious application for this sort of drone is for inspection in and around structures.

This omnicopter is an entry into the Lynchpin drone competition by the celebrity [Terrence Howard]. We’re not quite following his claims regarding the scientific significance of this shape, which he named the “Lynchpin”, but it works for drones. Continue reading “Six Degrees Of Freedom Omnicopter With Ardupilot” →

Analyzing Water Quality With A Pair Of Robots

August 14, 2020 by Tom Nardi 2 Comments

To adequately study a body of water such as a lake, readings and samples need to be taken from an array of depths and locations. Traditionally this is done by a few researchers on a small boat with an assortment of tools that can be lowered to the desired depth, which is naturally a very slow and expensive process. As the demand for ever more granular water quality analysis has grown, various robotic approaches have been suggested to help automate the process.

A group of students from Northeastern University in Boston have been working on Project Albatross, a unique combination of semi-autonomous vehicles that work together to provide nearly instantaneous data from above and below the water’s surface. By utilizing open source software and off-the-shelf components, their system promises to be affordable enough even for citizen scientists conducting their own environmental research.

The surface vehicle, assembled from five gallon buckets and aluminum extrusion, uses a Pixhawk autopilot module to control a set of modified bilge pumps acting as thrusters. With ArduPilot, the team is able to command the vehicle to follow pre-planned routes or hold itself in one position as needed. Towed behind this craft is a sensor laden submersible inspired by the Open-Source Underwater Glider (OSUG) that won the 2017 Hackaday Prize.

Using an array of syringes operated by a NEMA 23 stepper motor, the glider is able to control its depth in the water by adjusting its buoyancy. The aluminum “wings” on the side of the PVC pipe body prevent the vehicle from rolling will moving through the water. As with the surface vehicle, many of the glider components were sourced from the hardware store to reduce its overall cost to build and maintain.

The tether from the surface vehicle provides power for the submersible, greatly increasing the amount of time it can spend underwater compared to internal batteries. It also allows readings from sensors in the tail of the glider to be transmitted to researchers in real-time rather than having to wait for it to surface. While the team says there’s still work to be done on the PID tuning which will give the glider more finely-grained control over its depth, the results from a recent test run already look very promising.

A Hackable Drone Without All The Wiring

May 2, 2020 by Danie Conradie 13 Comments

Drones have come a long way in the past decade, and a lot of the pioneering work that made them mainstream was done by individual hackers and small teams. This often involves cobbling together components into flying crow’s nests of wiring. To streamline things a bit for hackers, the team at Luminous Bees are working on Ardubee, a small 3″ drone designed from the ground up for hacking.

The Ardubee is built around a single PCB that also acts as the frame of the drone. Onboard is an STM32F427 microcontroller, IMU, barometer and compass, ESCs, ESP8266 for telemetry, and a downward-facing range finder. It’s ready to connect to an SBUS RC receiver and a range of pluggable modules are in development to expand the drone’s capabilities. It’s designed to run the open-source Ardupilot software, which we’ve seen in so many DIY autonomous vehicles. Power is provided by a single 18650, which will probably limit higher speed maneuverability a bit but should be fine for the slower precision flight that such a drone is likely to be used for.

The team already has a swarm of larger 5″ drones that they developed for light shows. In the process they developed their own Ultrawide-band indoor positioning system, which will also be available for the Ardubee. They hope to launch a Kickstarter campaign soon and are asking for input from the community, so they can know what features need to be prioritized. We look forward to seeing where this project goes!

Autonomous vehicles are a popular topic around here for air, land, and water, and we have no doubt there will be many more.

Thanks for the tip [Andreas]!

DIY Autonomous Mower In The Wild

January 10, 2020 by Danie Conradie 35 Comments

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

December 21, 2019 by Danie Conradie 7 Comments

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

November 6, 2019 by Danie Conradie 9 Comments

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” →