Kategorie: Technology

What is an underwater ROV?

If you’re not sure what an underwater ROV is, the short answer is: a Remotely Operated Vehicle you chuck in the sea. But if you’re our favourite kind of geek and wish to feast on a much longer answer, Blue Robotics has shared a short history and explanation of how they work, including the excellent tidbit that the first ever ROV was called the Poodle.

BlueROV2 is billed as “the world’s most affordable high-performance underwater ROV.” While $3,950 seems like a lot, this ROV buying guide quotes prices up to $40,000. We like to think our affordable Raspberry Pi brain had a lot to do with bringing that cost down

What’s it made of?

The device measures 18 × 13.3 × 10 inches and can capture live 1080p HD video, thanks to a wide-angle low-light camera mounted to a tilt mechanism on the front. An on-board gyroscope, accelerometer, and magnetometer, along with pressure, depth, temperature, voltage, and leak detection sensors, make sure everything is functioning and navigating as it should.

If you choose a ROV with an acrylic enclosure, you can get to a depth of 100 metres, but splash out on the aluminium option and you’re safe to dive up to 300 metres. As far as we can tell, that’s deep enough to explore right down to the sea bed over much of the North Sea and almost all of the Irish Sea. Feel free to Google other bodies of water yourself.

What does its Raspberry Pi do?

The BlueROV2 is controlled by the Navigator Flight Controller, which is a HAT designed for Raspberry Pi 4. Raspberry Pi runs Blue Robotics’ bespoke BlueOS software and handles all of the processing and computing requirements inside the ROV.

All of those sensors are provided by the Navigator, and Raspberry Pi 4 communicates what’s happening back to base on dry land via BlueOS.

While we do think BlueROV2 is cool and all, we’re still too traumatised by the shark chase at the beginning of The Little Mermaid to watch any of the video it captures.

A sixth joint rotates the end of the head, to which you can attach various accessories using tiny LEGO connectors inserted into its grid of holes and those on the accessory, making them easy to fit and remove.

A similar LEGO connection system is used on the bottom of the robot to attach a base. Several options are available; we were supplied with the G-Base 2.0 (£58), which attaches the arm securely to the edge of a desk (so long as it’s not too thick).

Robot connections

With the robot arm secured to a desk, it’s time to power it up. A DC supply connects to a barrel jack on the base with a red power switch next to it. Raspberry Pi 4’s USB and Ethernet ports are exposed, along with its GPIO pins via a breakout header just above. On the opposite side of the base are a micro-HDMI port, headphone jack, USB-C port, and microSD card slot.

The inserted microSD card is pre-installed with a special version of Ubuntu MATE featuring a built-in development environment for MyCobot and several apps and tools. An extensive Python library enables you to quickly start positioning the arm by setting one or more joint angles or co‑ordinates – you can also read the current values. So you can manually move the arm into different positions and read the values to help you program it to shift between positions.

Another coding option is the myBlockly app in which you drag and drop Scratch-style blocks, including dedicated ones for MyCobot to set joint angles/co-ordinates and light up the RGB LED matrix on the head. Make sure you set the Baud value in the init block to 1000000, however, otherwise it won’t move. The arm also works with the commonly used ROS (Robot Operating System) 1 and 2.

The MyCobot written documentation could be clearer and better organised, but several videos help you to get to grips with it.

Attaching accessories

Our MyCobot arm was supplied with a couple of optional accessories: an adaptive gripper (£106) and a pen holder (£58). The gripper has a connector that plugs into a servo port on the head. It worked well and we soon had it picking up and dropping items on the desk with good repeated positioning precision.

The head also features a Grove connector, USB-C, and mini GPIO breakout, so there are plenty of connection options. You could even add a camera to give the arm computer vision.

While considerably more expensive than other Raspberry Pi robot arms we’ve tested, even without the addition of accessories, the MyCobot 280 is more robust and stylish. It has more powerful servos, while the joints have bearings for smoother movement and improved precision.

Verdict

9/10

It’s not cheap, but it does include a Raspberry Pi 4 and is a robust and stylish robotic arm with smooth and accurate movement.

Specs

Features: 6DOF, 330° rotation range, 280 mm radius, up to 250 g payload, LEGO interfaces on base and head, Raspberry Pi 4

Connections: 2 × USB 3.0, 2 × USB 2.0, Ethernet, micro-HDMI, GPIO breakout headers, USB-C, headphone jack, Grove and servo connectors

The two Toms continue to work together and are both members of Sheffield-based VolcanoTech. They aim to get more instruments onto volcanoes and acquire unprecedented long-term datasets that contribute to volcano research and monitoring. Designing and constructing low-cost scientific instrumentation is crucial for developing countries, where funding for equipment can be quite limited but where many of the world’s active volcanoes are located.

Tell-tale signs

A volcano’s degassing behaviour changes before an eruption, often increasing or decreasing. Since sulphur dioxide is the gas most prevalent at active volcano sites, Tom focused on monitoring this using a UV camera. There were already scientific-grade UV cameras in the field in some locations, but they cost tens of thousands of pounds, whereas Tom aimed to develop a UV camera “an order of magnitude cheaper” and much smaller, making it suitable for permanent installation and remote reporting. Monitoring volcanoes often involves tracking how sulphur dioxide diverges from a baseline and then investigating those changes. Tom’s system uses the Beer-Lambert law of absorption, comparing the optical depth of plume pixels in an image to the background sky radiance.

Tom and his colleagues didn’t know much about Raspberry Pi at the outset, “which made the detailed knowledge and wealth of experimentation by others invaluable when it came to asking specific questions or pulling ideas from pre-existing threads.” A particularly fruitful discovery was a YouTube video by Les Wright which simplified the process of removing the Bayer filter from the camera lens to enhance its sensitivity to ultraviolet light. This worked well for a Raspberry Pi Camera 1.3, but Tom reports that he was unable to remove the Bayer filter in the same way for the newer Raspberry Pi Camera Module. The process in any case requires a fume cupboard and dangerous chemicals (see ‘Warning’ box). Tom originally made use of the UV camera in a spectrometer he used for sulphur dioxide monitoring. Although this worked well, he subsequently decided to focus on the camera-based system.

How predictable

Having created an affordable alternative to the £10,000 scientific cameras, Tom has been working on modifying the camera design so they can be deployed permanently on volcanoes, without the need for human interaction. To date, only Stromboli in the Aeolian Islands, and Etna just to the south, have fixed monitoring. “We are now beginning to build high time-resolution sulphur dioxide emission rate datasets from several volcanoes, the likes of which are quite rare in volcanology,” he says.

Getting the cameras installed on hazardous volcanoes is no mean feat! Using a Starlink satellite connection has helped them overcome the major issue of handling and processing the terabytes of data each camera acquires each year, as well as partially solving issues relating to debugging camera installations remotely. With cameras in the Amazon rainforest as well as the Atacama desert, temperature extremes and huge amounts of rainfall add to the challenges. However, once in place, they’ll give volcanologists significantly improved monitoring capabilities that contribute to longer-term volcanological research – an increasingly critical aspect of their work “since a volcano can exhibit significant changes in activity over a wide range of time scales.