Open Source Autopilot For Cheap Trolling Motors

September 24, 2021 by Danie Conradie 14 Comments

Quiet electric trolling motors are great for gliding into your favorite fishing spot but require constant correction if wind and water currents are at play. As an alternative to expensive commercial GPS-guided trolling motors, [AlexAsplund] created Vanchor, an open source system for adding autopilot to a cheap trolling motor.

To autonomously control an off-the-shelf trolling motor, [Alex] designed a 3D printed steering unit powered by a stepper motor to attach to the original transom mount over the motor’s vertical shaft. A collar screwed to the shaft locks the motor into the steering unit when the motor is lowered. The main controller is a Raspberry Pi, which hosts a WiFi hotspot and web server for control and configuration using a smartphone. Using navigation data from an e-compass sensor and a marine GPS chart plotter, it can hold position, travel in a specified direction, or follow a defined route. [Alex] is also planning to add the option of using a GPS module instead of a commercial plotter.

For an estimated total of $300, including the motor, this seems like a viable alternative to commercial systems. Of course, it might be possible to add even more features by integrating the open source ArduRover autopilot, as we’ve seen [rctestflight] do on multiple autonomous vessels. You can also build your own open source chart plotter using OpenCPN, which rivals commercial offerings.

Download From NFC Datalogger, No App Required

September 23, 2021 by Danie Conradie 14 Comments

The plethora of wireless technologies has made internet-connected devices the norm, but it’s not always necessary if you don’t need real-time updates. Whether it’s due to battery life, or location and range constraints, downloading data directly from the device whenever possible might be a viable solution. [Malcolm Mackay] demonstrates an elegant solution on the open source cuplTag temperature/humidity logger, using any NFC-enabled smartphone, without requiring a custom app.

The cuplTag utilizes the feature on NFC-enabled smartphones to automatically open a URL provided by the cuplTag. It encodes the sensor data from the sensor unit as a circular buffer in a ~1 kB URL, which automatically uploads to a web frontend that plots the data. (You can use their server or run your own.)

This means that data can be collected by anyone with the appropriate phone with zero setup. The data is displayed on the web app and can be downloaded as a CSV. To deter spoofing, each tag ships with a secret key which is used to generate a unique HMAC every time the circular buffer changes.

Battery life is a priority on the cuplTag, and it’s theoretically capable of running seven years on a single CR1220 coin cell using the current-sipping Texas Instruments MSP430 microcontroller. The hardware, firmware, and server-side frontend and backend code are all open source and available on GitHub.

Earlier this year, we held a data logging contest, and featured submissions that monitored everything from your garden’s moisture levels to your caffeine intake.

Electric “Radial” RC Aircraft Motor

September 19, 2021 by Danie Conradie 23 Comments

For a long time radial aircraft engines, with their distinctive cylinder housings arranged in a circle, were a common sight on aircraft. As an experiment, [KendinYap], wanted to see if he could combine 3 small DC motors into a usable RC aircraft motor, effectively creating an electric radial engine.

The assembly consists of three “180” type brushed DC motors, mounted radially in a 3D printed casing. A 3D printed conical gear is attached to each motor shaft, which drives a single output gear and shaft mounted in the center with two bearings. The gear ratio is 3:1. A variety of propellers can be mounted using 3D printed adaptors. As a baseline, [KendinYap] tested a single motor on a scale with a 4.25-inch propeller on a scale, which produced 170 g of thrust at 21500 RPM. Once integrated into the engine housing, the three motors produced 490 g of thrust at 5700 RPM, with a larger propeller. Three independent motors and propellers should theoretically provide 510 g of thrust, so there are some mechanical losses when combining 3 of them in a single assembly. However, it should still be capable of powering a small RC plane. It’s also not impossible that a different propeller could yield better results.

While there is no doubt that it’s no match for a brushless RC motor, testing random ideas just to see if it’s possible is usually fun and an excellent learning experience. We’ve seen some crazy flyable RC power plants, including a cordless drill, a squirrel-cage blower, and a leaf blower.

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Solar Powered Autonomous Tugboat For Rescuing Autonomous Vessels

September 18, 2021 by Danie Conradie No comments

[rctestflight] has built several autonomous boats, and with missions becoming longer and more challenging, he bought an inflatable kayak to serve as a dedicated rescue vessel. Instead of relying on outdated manual paddling, he built an autonomous solar-powered tugboat.

Towing test with kayak — ♪ “Rum, treasure, ArduRover, Pixhawk 4 and so much solar, break of dawn till the day is over, the ship will surely go…” ♪

The tugboat uses a pair of molded fiberglass hulls in a catamaran configuration. The wide platform allows a pair of 100W solar panels to be mounted on top. It was [rctestflight]’s first time molding anything out of fiberglass, so there was quite a bit of trial and error going on. The mold was 3D printed in sections, aligned with dowel pins, and glued together. After the epoxy had cured, the mold halves could be split apart for easier removal of the hull.

As with most of [rctestflights] autonomous vehicles, control is handled by a Pixhawk 4 running ArduPilot/ArduRover. A pair of 76 mm brass propellers powered by brushless motors provide propulsion and differential steering. The motors get power from six LiFePO4 batteries, which charge from the solar panels via MPPT charge controllers. The hulls are covered with plywood decks with removable hatches and inspection windows. After a bit of tuning, he took the boat for a few test runs, the longest being 5.1 km with himself in tow in the kayak. At less than 5 km/h (3 mph) it’s no speedboat, but certainly looks like a relaxing ride. Many of [rctestflight]’s previous vessels were airboats to avoid getting underwater propellers tangled in weeds. It was less of an issue this time since he could just haul the tugboat close to the kayak and clear the propellers.

[rctestflights] are always entertaining and educational to watch, and this one certainly sets the standard for sea-shanty soundtracks at 13:32 in part two.

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Triple Monitor Luggable PC Is An All In One Powerhouse

September 17, 2021 by Danie Conradie 11 Comments

[Matt] from [DIY Perks] has made a name for himself building nice custom computing machines, and his latest triple-monitor luggable PC (video after the break) is sure to give most high-performance desktop machines a run for their money.

The large central monitor folding laptop monitors mounted vertically on either size look impressive, but only just scratches the surface of this build. Hidden behind aluminum panels are Ryzen 5950X CPU and RTX 3080 GPU with water cooling, 64 GB of RAM, and two 8 TB SSDs. A set of high-quality speaker drivers, subwoofer, and audio amps is also included. All this hardware pulls about 600 W of power from a large DC-DC converter block, which in turn receives power from either a pair of onboard AC-DC converters or a 16 V – 63 V DC source, like a battery system.

To mount everything to the back of the main monitor, [Matt] created 3D printed adaptor blocks with threaded inserts which slide under existing hooks on the back of the monitor. Aluminum angles screw to these blocks to cover the edges of the display panel, together with a large mounting plate with pre-drilled holes to mount all the components on standoffs. A set of adjustable and removable legs mount to the side of the PC. A hinged door in the back cover allows storage space for a keyboard and mouse during transport. When folded, the laptop monitors don’t fully cover the main monitor, so [Matt] created a leather cover that doubles as a cable and accessory organizer.

Whether its dual screens and an integrated SDR, or a rotating-folding screen, there is no shortage of ways to build a portable powerhouse. Continue reading “Triple Monitor Luggable PC Is An All In One Powerhouse” →

Tiny ESP32 Strider Walks The Walk

September 6, 2021 by Danie Conradie 3 Comments

Wheels might be the simplest method of locomotion for robots, but walkers are infinitely more satisfying to watch. This is certainly the case for [Chen Liang’s] tiny Strider walker controlled by a ESP32 camera board.

The Strider mechanism might look similar to Strandbeest walkers, but it lifts its feet higher, allowing it to traverse rougher terrain. [Chen]’s little 3D printed version is driven by a pair of geared N20 motors, with three legs on each side. The ESP32 camera board allows for control and an FPV video feed using WiFi, with power coming from a 14500 LiFePO4 battery. The width required by the motors, leg mechanisms, and bearings means the robot is quite wide, to the point that it could get stuck on something that’s outside the camera’s field of view. [Chen] is working to make it narrower by using continuous rotation servos and a wire drive shaft.

We’ve seen no shortage or riffs on the many-legged walkers, like the TrotBot and Strider mechanism developed by [Wade] and [Ben Vagle], and their website is an excellent resource for prospective builders.

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Small Scale Mad Max: Danny Huynh’s Dystopian Animatronics

September 6, 2021 by Danie Conradie 11 Comments

The hacker spirit is always alive and well in post-apocalyptic fiction, as characters throw together contraptions from whatever junk they can find. While these might not always be practical or possible in reality, their primary purpose is usually to look the part. This is definitely the case for [Danny Huynh]’s post-apocalyptic animatronic creations, which look like they can slot straight into Mad Max or Fallout.

[Danny] is an avid RC enthusiast, so many of the models are highly customized off-the-shelf RC cars. However, it’s the lifelike moving characters in these models that really catch the eye. Their hands and feet move with the steering and throttle, and in the motorcycle builds they will often lean with the turns. Other notable builds include a hexapedal taxi and a couple of animatronic bands.

All the vehicle builds are electric, but it looks like [Danny] often includes an audio module to simulate a roaring engine. He makes extensive use of servos and linkages for character movement, with wiring and electronics carefully hidden by paint or bodywork.

With all the CGI technology available today, great animatronic builds like an eerily lifelike heart, or a talking Nikola Tesla are all the more impressive to see.

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