With their multiple manipulator arms, array of finely tuned sensors and heavy-duty propulsion systems, there is no doubt that larger, work-class ROV’s have a wide variety of functions in the oil and gas sector. But there are a whole host of benefits and advantages that are unique to that of the modest but no less vital mini-ROV.

Mini-ROVs are a classification of remotely operated vehicle that weight less than 20kg. While lacking the raw power of the larger classifications of vehicles, their added manoeuvrability and smaller scale gives them a variety of important uses.

The advantages of these machines are capitalised on by skilled pilots, who use them to perform inspection and maintenance tasks on pipes and other installations that are located in the subsea environment. While inspection may sound insignificant, it is actually an important activity that is paramount to the safe functioning of the offshore energy sector, as this article will go on to explain.

The drive for safety

The oil and gas industry operates under perhaps some of the most strict and stringent safety regulations of any commercial sector. This is not without good reason as any accident that takes place offshore can have disastrous and wide-spread consequences for the well operators, the environment, and the local population.

As a result, in 2019, the energy sector is one of the safest and least accident-prone sectors in the world, with offshore oil and gas workers having a lower rate of personal injury than many other sectors including manufacturing and building construction.

However, at the same time, this drive for safety has to be balanced with ensuring that downtime on the installation is kept to an absolute minimum as even a short delay can have huge financial repercussions. While clearly safety is more important a priority than profit, using a small and expertly driven mini-ROV can enable both to be achieved.

Routine Inspection

It goes without saying that there are a staggering number of pipes, cables and connectors that sit below the water level on any offshore site. Every one of these assets serve a purpose and as such need to be regularly checked up on, to ensure that they are fit for purpose. This is where the mini-ROV comes into its own.

One of the main benefits that these vehicles offer is a cost-effective solution to quickly investigate a site which might be impractical, time-inefficient and sometimes impossible for a human diver to reach.

With offshore operators moving to deeper and deeper locations in search of oil, the advantage of being able to deploy a vehicle to inspect underwater assets, speaks for itself.

Moreover, these small-scale, lightweight mini-ROVs can inspect a wide variety of different underwater infrastructure including vessels and structures up to a depth of 300m without any downtime or additional support. This means that production doesn’t need to cease to accommodate the inspection process, resulting in a win-win situation for the offshore operators.

These lightweight vehicles can often fit inside confined underwater spaces with ease due to their small form-factor and are never at risk of damaging sensitive underwater equipment, or structures, making them an attract and viable alternative to utilising a human diver.

Fresh water and Ballast Tank’s

Ballast tanks obviously serve a crucial purpose both for vessels, semi-submersible rigs and more recently for floating wind turbines. Flooding the ballast tanks is vital to ensuring the stability and therefore safety of offshore structures. However, like any vital component, it is important to regularly inspect these tanks to ensure that they are functioning optimally.

In the past ballast tank inspection would involve pumping all the water out, and require a team of people with rope access to enter the tank and conduct a manual inspection, often using gas and oxygen monitoring devices.

However, by using a mini-ROV fitted, with suitable sensors, the same job can be done without emptying the tank, meaning that work is not disrupted, and the data is available instantly to the relevant staff. This in turn increases efficiency and reduces costs, making the ROV a valuable tool for tank inspection.

Cleaning Services

An ever-present problem for any structure, be it a vessel’s hull or a pipe that sits below the waterline, is marine biofouling. According to some reports over 1,700 different species comprising of 4,000 different organisms can latch onto submerged structures. These organisms form communities of ‘hard’ fouling organisms – barnacles, molluscs and mussels, and ‘soft’ fouling organisms – seaweed, algae and biofilm slime.

The development of marine growths such as these can lead to the rapid decline of asset integrity and additional loads and stresses due to drag loading in tidal and weather current. In the case of metal structures such as pipes, biocorrosion can occur, which will eventually lead to visible cracks, pitting and corrosion within assets, causing inefficiencies and ultimately repair costs for the operators.

Mini-ROV’s can yet again provide a viable solution to this never-ending problem. Vehicles can be outfitted with specially designed equipment created to clean underwater assets, cleansing them of biofilm and ensuring structural integrity is not compromised. Being able to rapidly deploy an ROV equipped with biofilm removing equipment constitutes a major advantage to offshore operators.


This article aimed to cover just a few of the many tasks that micro or mini-ROVs excel at. While they may not have the brawn of the bigger work class vehicles, mini-ROVs fitted with the right sensors and in the hands of a skilled pilot they can provide a range of high-value services that are critical to the offshore marine industry.

Being able to access restricted areas inspections by mini-ROVs, proves once and for all that bigger isn’t always better.

Since its inception in the early 1950’s Remotely Operated Vehicles (ROV’s) have become hugely important in many industries such as offshore renewables, oil and gas, defence and underwater exploration. This started in 1953 with the first un-manned vehicle, produced by Dimitri Rebikoff.  It was used for the location and documentation of sites which would have been far too harsh an environment for divers to reach. Since then innovation has helped to make the world of ROV’s far safer and much more efficient.

ROV Classification
Since their development in the early 1950’s there has been a range of technological developments in these vehicles, which has led to the following categorisation:

First Stages of Innovation
During the late 1950’s and early 1960’s the American navy became interested in the subsea world and diverted additional resources to investigating the advantage of ROV’s. This began with the development of the Cable-controlled Undersea Recovery Vehicle (CURV) in the early 1960’s. The first of these was the XN-3 and was used for inspecting the seafloor with the aim of retrieving torpedoes which had been used in tests and training. One of the more notable achievements of these original systems was the retrieval of one of the Mk28 hydrogen bombs that was dropped during the 1966 Palomares B-52 crash.  This alone took almost 90 days from finding the hydrogen bomb underwater to retrieving it and bringing it to the surface. The military still use many of these systems for a range of practices such as mine hunting and mine breaking.

Oil and Gas Use
Usage in the military world aside, remotely operated vehicles have become synonymous with the oil and gas sector. The need for these vehicles has since become integral to the industry with many of the offshore oil fields now too deep for human divers to access. As the years have progressed, ROV’s have become more and more advanced with each new model of ROV that is brought out. For example, many companies have developed technology which allow for the vehicles to manoeuvring around subsea installations and check for faults in pipelines and subsea structures or perform tasks like turning valves on and off. As will be explored later on, the future of ROV and its technology is rapidly changing, and innovation is still constantly occurring, allowing for further developments in the subsea sector.  

Scientific Use
As ROV’s allow exploration in areas of the ocean where a diver cannot go, they have tremendous value to the scientific community. ROV’s have been used for the inspection of the ocean floor and submerged archaeological sites. Their main purpose is for capturing and transmitting data from the vehicle to the surface. This will allow for scientists to explore underwater areas that previously they were unable to and allow for more of the subsea world to become known mid ocean ridges and black smokers spring to mind.

One of the most famous examples of ROV aiding the scientific world is the use of the machine, Argo in the discovery of shipwrecks.  Dr Robert Ballard used an underwater video camera to document the exploration of both the Titanic and Bismarck shipwrecks. An autonomous vehicle located U Boat 166 in the Gulf of Mexico in 2003 during.  More recently the Mardis Gras shipwreck was discovered by using this technology to explore some 4,000 feet underwater.  This wreck was untouched for over 200 years and its 2007 discovery was a breakthrough for historians and proved an innovative use for ROV’s. This was the deepest underwater archaeological project that was ever attempted in the Gulf of Mexico.  

Moving Forward
As has been noted, the world of ROV technology is constantly changing so it comes as no surprise that many of the recent developments are pioneering in the field. The new standard of vehicles allows for a range of tasks to be undertaken and seemingly there is no project that can be considered too advanced.   was previously mentioned AUV’s are ground-breaking in terms of the subsea world, allowing for far bigger and longer-term tasks to be carried out, due to the lack of human control needed. For example, underwater vehicles have been developed which allows for large-scale mapping of the subsea world.  A team in Norway have recently developed an autonomous robot which has mapped over 120,000km of the seabed!  The advancement in this technology means that the need for human control is negated, allowing for better allocation of human resources to projects that require a skilled ROV operator.

To conclude, this article has shown that the world of ROV has had a long and interesting story to the present day.  With the world of subsea technology constantly improving there is seemingly no limit to the potential innovation for this technology.

In the 1980’s, remotely operated vehicles (ROVs) were revolutionised with the introduction of fibre optic cables to replace the old and outmoded copper ones. This allowed a far greater quantity of data and video content to be transmitted from the ROV back to the surface. In addition, it paved the way for ROV’s to function at greater depths than was ever previously possible.

Since then there have been plenty of incremental advances and iterative improvements in the ROV sector but there hasn’t been one single identifiable revolutionary shift, until now.

Thanks to a perfect combination of advances in automation control, machine vision technology and the development of new algorithms for artificial intelligence, the whole industry is on the precipice of a major step-change.

Control Programs

At this stage it would be virtually impossible to create a fully automated ROV, that was guided by artificial intelligence that could pre-empt and react to changes in the underwater environment without human interaction.

However, whilst a fully automated, reactive and self-aware ROV is not feasible, it is possible to automate many of the day to day ROV tasks to reduce the strain on the pilot.

By breaking down a routine operation that an ROV may perform into little steps, and automating each of these steps, you can gradually build up an ROV’s automatic capability. the pilot can simply set the ROV to this task, instead of having to manually pilot the ROV the entire time.

Whilst the ROV is not completely self-aware, the automation program can tell when one of the steps it has to perform to complete a task has been interrupted, by unforeseeable circumstance, and can immediately alert the human pilot who can re-assert control of the ROV and guide it out of trouble.

By allowing the pilot to simply oversee and manage the ROV as it completes quotidian tasks by itself, it reduces the stress of the pilot and allows them a greater degree of focus for more critical tasks, thus increasing safety and reducing the likelihood of incidents.

Vision Control

Some of the most difficult ROV tasks require extreme precision, manoeuvring the ROV to a very specific distance away from an object, and maintaining that distance. These delicate tasks can be made more straightforward when the ROV is fitted with an automated navigation and control system. This allows the ROV to maintain its position in the water by ‘seeing’ where it is in relation to other objects, enabling it to remain in a stable position, even in turbulent offshore environments.

These types of automated navigation systems utilise a ground-breaking combination of both Vision Technology and ROV motion dynamics. Whilst Vision Technology uses a camera to track the relative position of the ROV in relation to subsea objects, ROV motion dynamics uses a wide variety of motion sensors that allow the ROV to understand and anticipate how it needs to move. Applying the brakes when it approaches a target position for example.

By setting an ROV to automatically maintain a certain distance from an object, the ROV pilot can focus on the task at hand, rather than have to divert half their attention on keeping the ROV stable.

Manipulator Advances

In a typical ROV manipulator, there are six degrees of movement that can be achieved. The three cartesian motions (the x, y and z axis) and the three angular motions (pitch, roll and yaw). Whilst it can be advantageous to be able to control all six of these degrees of motion at the same time, it is not always desirable.

Manipulator control methods rely extremely heavily on the skill of the operator, therefore a system where some of the process can be automated reduces the level of operational stress on the ROV pilot. This in turn contributes to a safer and less incident prone work site.  

Recent developments in the sector allow for exactly that, ROV operators can now select which of the six degrees of movement he/she want to control, and let the software handle the others. This means that the human pilot can still control the most critical movements specific to that job, whilst the software can ensure that the less important motions are taken care of, thus increasing productivity and efficiency.

Computer Diagnostics

Up until now the foundation of fault detection in ROVs have been based upon sensors that test for low, high or band range limits. Whilst the advent of digital control systems has allowed for these sensors and their limits to be adjusted in real time, the system is still too rigid and inflexible to keep up with the spiralling level of complexity associated with modern ROVs.

With each additional function that is added to an ROV, more of these sensors must be added to monitor each of these functions. Based on this it can easily be seen how a model of a single sensor to detect a single fault can quickly become unworkable.

A better alternative to the conventional sensor system is an Intelligent Diagnostic System. These systems use basic equations of electrical power flow through the ROV, and combine it with telemetry from sensors to create a virtual model of the system. It can then use this to more accurately diagnose faults in an ROV, by pulling all the salient information into one central place.

Using a system like this, multiple simultaneous failures can be more easily distinguished from each other and the root cause, that may have caused multiple failures can be identified much more easily.

Satellite Control

With the introduction of low-earth to orbit satellites, offshore sites can now access high-bandwidth, low-latency networks, worldwide. Combining this with the latest computer programs that aid with the control of an ROV, means that ROV’s can be operated remotely, in real time, with the pilot not even required to be in the same country as the ROV.  

This creates obvious cost saving opportunities, due to the fact that the pilots no longer have to be in close proximity to the ROV that they are controlling. It also allows for experts in specific fields of ROV piloting to be rapidly deployed during incidents or in times where high skill are critical to operational needs.  

This development means that ROV’s are one step closer to being truly remote operated, with the range of the pilot extending from a nearby vessel, to anywhere with a secure internet connection.

Looking to the future

As this article covers, there is tremendous potential for innovation by the incorporation of AI technology into the world of ROVs.

Moreover, all of these separate innovations are starting to converge and mesh together into something greater, an artificial intelligence revolution.

In the future there is further scope to create fully autonomous ROV control programs that can pilot themselves to underwater coordinates, follow pipelines with machine vision, and even avoid objects on their route.

Since the 1980’s ROV’s have become an increasingly staple asset to the Oil and Gas Sector, providing a safe way to remotely inspect, maintain and replace critical underwater assets.

As the energy sector shifts its focus more and more into deep-sea drilling projects in search of new opportunities, innovation across the ROV industry is being driven at an unprecedented rate. The latest models are equipped with highly advanced robotics and are armed with a wide variety of different sensors and instruments, able to collect data on anything from the temperature of the water, to the health of marine ecosystems!


An area of particular progress over the recent years has been in the area of robotic arms, with the latest models coming with seven different internal joints, to closely mimic the seven joints within the human arm. This allows for a far greater range of movements as well as greater dexterity, which in turn allows ROV pilots to successfully complete far more complicated tasks.

However, whilst the range of movements available within these robotic arms is important, equally significant is the sensitivity, giving ROV pilots a greater degree of understanding about what it is the arm is touching. One incredible development is ‘forced feedback’, a technological development that allows ROV pilots to physically feel things such as force resistance or ocean movement that the robotic arm or attachment is experiencing, as if it were an extension of their own body.

Advances in this technology have even lead to the ROV pilot being able to control the exact level of force that the robotic arm is exerting on an object, meaning these machines could pick up an egg without causing it to crack, or smash through thick concrete, all depending on the force the operator applies.

IT and Communication

Manoeuvrable and dexterous robotic arms are not the only key area of advancement in the field of ROV’s. Major developments have been taken in the area of communication, meaning that ROV’s can transmit high-quality video footage in real time, across a far greater distance than previously possible.

In a further attempt to reduce the margin for fault and ensure that safety is at the highest possible level, ROV’s can now be programmed to interpret CAD drawings of projects, enabling them to navigate themselves, thus reducing the occurrence of human error.

Data Collection

Perhaps the most important of all, data collection – a task that ROV’s excel at – has seen tremendous leaps in innovation in recent times. As project sites have become both more expansive, as well as being situated deeper in the ocean, they play host to more and more sensors, that monitor and produce reports on conditions such as production, asset health, as well as detection of potential irregular or abnormal situation.

With a single production field potentially having more than 40 underwater assets, and each of these individual assets having between 5-15 sensors mounted on them. With this sort of traditional sensors, offshore operators would be required to periodically lift these lines and manifolds in order to conduct maintenance. This would create a significant cost for the operator, due to both the

production of the asset being shut off, and the substantial cost of raising the asset to the surface, as well as the actual cost of repairs itself.

Instead of this, ROV’s can be fitted with sensor retrieval systems, which allows for both reading and maintaining these sensors to be done remotely, via the use of an ROV, providing both a time-efficient and cost-effective solution.

Power efficiency

A significant limitation on the effectiveness of ROVs has always been due to the fact that they are tethered by an umbilical cord, which in some cases can prove to be extremely thick and cumbersome, as well as providing a very concrete limit on their effective range.

Whilst batteries can provide a workable alternative to this, with advances both in weight and performance, a promising new area with serious implications for sustainability of power for ROVs is the study of underwater motion. This could enable ROV’s to create their own supply of power by moving on a dolphin like trajectory, thus removing the need for an external power supply all together.

Other applications of ROVs

Whilst ROVs are still a critical feature of the Oil and Gas sector, and will be for decades to come, there are other areas in which the use of ROVs can add significant value to a project.


A booming sector where ROVs can add value and make life both safer and more efficient for operators is renewables. The most recent trend in this sector is the installation of offshore windfarms. These windfarms are obviously a long-term investment and as such require frequent repair and maintenance, creating a new field of application for ROVs. Additionally, due to the environmental challenges such as high currents and low visibility, using ROVs instead of divers provides not only a reduction to operational cost, but also an increase in safety. Many of the advancements covered in this article already add to the high level of service that an ROV can provide.

Industrial Inspection

The importance of carrying out inspection on underwater assets isn’t uniquely valuable just to the Oil and Gas sector, any industrial facility or project that involves submerged assets is likely to benefit from an ROV.

For example, in many countries regularly effected badly by drought, such as Australia, where the government has invested in desalination facilities and infrastructure in order to try to mitigate the effects of droughts. The challenge with these installations is the monitoring and maintaining an extensive and extremely narrow network of pipes that is far too dangerous for divers to attempt.

The use of micro-ROVs in this particular example highlights the advantages that smaller, lightweight but efficient and high quality ROVs can bring to an industrial project.

Looking ahead

As the Oil and Gas sector drills ever deeper into the depths of the ocean in search of new prospects, it is expected that the ROV industry will continue to see innovation to continue to be able to meet those requirements.

With recent advances in the realms of artificial intelligence and machine vision technology, it is predicted that ROV’s will become more and more sophisticated, improving work-flow and increasing safety.

Craigmill, Pitcaple, Inverurie, Aberdeenshire, United Kingdom, AB51 5HP
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