Stabilization system to make offshore maintenance robots resistant to currents

A team of engineers from the University of Edinburgh has developed a system that can keep robots, which are supposed to autonomously maintain offshore wind farms and tidal turbines at sea, stable in the water even in heavy seas. The system, which can predict wave movements, works almost in real time.

Underwater and above-water robots, which are designed to carry out maintenance work on offshore installations independently, have to contend with a number of adversities during their work. The sometimes high swell and underwater currents can repeatedly move the robots out of position so that they have to correct them autonomously. The corrections must be made as quickly as possible in order to continue working effectively. The aim is for such autonomous robots to be stationed off the coast and carry out routine work independently – without the help of humans, who have so far carried out these often dangerous tasks from boats and helicopters.

The scientists have now found an approach that enables robots to react to different external influences, as they explain in the study "Nonlinear model predictive dynamic positioning of a remotely operated vehicle with wave disturbance preview", published in The International Journal of Robotics Research. To this end, the researchers developed a model that uses measurement data from wave measuring devices on the seabed to predict and compensate for water movements that affect a maintenance robot.

Predictive response to currents

To do this, the scientists first measure the direction and height of the incoming waves and then pass this information on to the robot in real time. The robot uses a model to predict possible currents that will affect the robot. The robot can then counteract these immediately, even before it is exposed to them and could perceive them itself.

Existing systems struggle with this late perception. They can only react very slowly to changing currents in the sea, which makes them unreliable and can have dangerous consequences for a maintenance robot.

The engineers have already tested their model in a simulation using wave data from a FloWave test tank. The data was used to carry out corrections to maintenance robots in a simulation under real conditions.

The researchers now want to integrate the prediction of wave disturbances into the control system of maintenance robots. In principle, this is possible with any robot on the market with little or no changes to the hardware.

(olb)