HEXATERRA · The development of a modular ‘stepping locomotion’ system for installation on subsea trenching machines used for subsea energy cable burial

Offshore wind and tidal energy generation is becoming an increasingly important component of the world’s energy mix with Europe at the forefront of this technological revolution. Continued strong growth is predicted. However, a growing problem is manifesting itself within the industry.The submarine cables that are an essential infrastructural component of offshore energy now account for 80% of insurance claims related offshore renewables. Unfortunately, current practice is to simply lay these cables on top of the seabed without burial or protection, as the traditional tracked trenching machines originally developed for deep sea oil and gas applications are inadequate for the harsh coastal terrain. Cables are therefore exposed to numerous risks such as tidal forces, rock abrasion, snagging from fishing nets etc. Furthermore, unburied HV cables present serious environmental concerns related to local habitat & water temperature.Existing technologies cannot address this growing problem. HexaTerra will develop a novel solution to the problem that builds upon recent advances made in ‘stepping’ locomotion systems for traversing undulated harsh terrain. This system will provide a robust solution for its environment, by achieving the following objectives: modular design suited to existing trenching machines; mechanical movement subsystem with <5% error in desired motion tracking & <1cm in actual tracking error; control subsystem capable of negotiating +/-0.5m 90° step in terrain & turn on-the-spot; complete simulated locomotion cycle in under 5mins, with <5% desired motion tracking error.Using this solution the project expects to comprehensively address the problem of damage to subsea energy cables, thereby maximising offshore energy reliability, maintain renewable energy affordability, & minimise the marine environmental impact of cables. In turn, we will deliver a profit of €10.95m & 100 new high skill jobs to the SME partners after 5 years.