MEMS the word

Norwegian universities have a great habit of directing their students towards research that quite often results in a new technology – and new businesses. Elaine Maslin reports on a new business bringing micro-electronic mechanical systems to the subsea business.

Photos from Norwegian Subsea.

Norwegian Subsea is a great example of how research in Norway can drive industry innovation. The company was founded in 2014, with the help of the Research Council of Norway, by three graduates of the Norwegian University of Science and Technology (NTNU).

One undertook a PhD in inertial navigation, the result of which is the foundation of the company and its first product – MEMS (micro-electromechanical systems) based motion sensors. MEMS technology, which has seen rapid development in other areas in the past decade, could help both increase accuracy, reduce power consumption and weight, according to Norwegian Subsea.

“We were all at the university, two of us finished master’s degrees some years ago and were working in the maritime industry. Then we all came together,” says Lars Gaarder Torgersen, CEO at Norwegian Subsea, who studied marine engineering and worked at Marine Cybernetics, since bought by DNV GL, before co-founding Norwegian Subsea.

“We saw that there was a gap in the market for MEMS-based motion sensors with high accuracy and low power consumption. By implementing the latest and best state-of-the-art MEMS sensors and combining them with our own algorithms, we could come up with motion sensors less costly and more accurate than those on the market.”

A MEMS-based subsea motion sensor from Norwegian Subsea.

The firm’s products include the NORSUB 6000 subsea motion sensor, which offers roll and pitch (both to 0.01°), heading (0.5°), at 0-2000 Hz frequency, in a 1.5kg unit measuring 14.6cm by 7cm. It’s been designed for use in water up to 6000m water depth. Existing alternatives include fiber optic gyros, which are expensive, consume more power, and are large and heavy, Torgersen says. Norwegian Subsea also has the NORSUB AHRS 1, for use on small-medium sized ROVs and NORSUB AHRS 2 for auto heading and motion control on ROVs, with both providing measurements without time lag and designed to work down to 6000m. Alternatives used on ROVs include fluxgate compasses.

MEMS are miniaturized mechanical and electro-mechanical elements made using the techniques of microfabrication. The functional elements of MEMS are miniaturized structures, sensors, actuators, and microelectronics, the most notable elements are the microsensors and microactuators, which convert energy from one form to another, i.e. from a measured mechanic signal into an electrical signal.

MEMS were developed for the defense space but for the past 10 years they have been adapted for more commercial uses. With a lot of research carried out in to MEMS technology, and subsequent commercialization, production costs have decreased. “The technology has been moving at a very fast pace and becoming quite cheap, smaller and smaller, and more accurate, because the manufacturing techniques have improved. Today, you can buy quite high performance MEMS at affordable prices,” Torgersen says.

Lars Gaarder Torgersen

But, the MEMs is actually not the clever bit. Norwegian Subsea has taken MEMs technology and added its core competence – designing smart, efficient algorithms. “Our algorithms allow us to combine data from many sensors – gyro, accelerometer, etc., – and then fuse them together to increase frequency and therefore accuracy of the calculations, at the same time reducing the amount of power used to do those calculations,” Torgersen says. “That allows us to run an algorithm on a microprocessor, which is key to reducing the size and cost of the units.”

Other methods, such as Kalman filtering, a type of algorithm which requires a lot of computing power, can be used, but subsea the computing power required is an issue and reduces the frequency of the calculations, Torgersen says.

The motion sensors are intended to be used for asset integrity, measuring BOPs for fatigue, survey work, ROV heading and control, and a myriad of other uses. The young company’s first deployments, in late summer 2015, saw the firm initially loaning out a unit in order to get industry feedback, with one or two clients. Sales are expected to start and increase in 2016-17, Torgensen says.

Norwegian Subsea has also moved into marine motion reference units (MRUs), which it thinks could offer a larger market and where costs could be significantly reduced compared to existing solutions. The MRUs use the same technology but it is used on ships in DP or to measure motion compensation on offshore cranes, for example.

The company, which has five staff in Oslo, currently assembles the units, using off-the-shelf MEMS units, with its own programmed algorithms.