What is an ROV Gripper?
An ROV gripper is a robotic ‘hand’ or ‘claw’ that attaches to an underwater remotely operated vehicle (ROV) to provide a means of interacting with the environment.
When ROVs were first invented, they were used to simply look at things underwater; that is, they were essentially a ‘flying camera’. Looking at things is very important but sometimes there is a need to do something in the environment. As technology developed, the ability to add a ‘hand’ to the underwater vehicle became achievable. Nowadays, even very small vehicles can be equipped with subsea ROV grippers (and more dexterous arms – but that’s another topic).
What are ROV Grippers used for?
ROV grippers enable intervention in a variety of applications including:
- Recovering objects from the bottom of the ocean, a lake, or other waterways (including victim recovery – take a look at some of our client’s HEART and Tethys)
- Untangling tethers and lines while conducting subsea operations
- Collecting samples from the seafloor including organisms, shells, and sediment for marine biology research (check out the marine biology of Boxfish)
- When augmented with a blade, use them as scissors to cut cables, rope, and other lines to untangle and recover objects. For example, rescuing trapped ROVs and AUVs
- Attaching and disconnecting carabiners and hooks from underwater infrastructure
- Turning valves and interacting with subsea control interfaces
Types Of ROV Grippers
ROV Grippers come in several sizes and are often built to different standards depending on the target industry. For example, there is lower cost grippers ideal for hobbyists wanting to conduct routine light work tasks and then there are more robust grippers specifically designed for the search and rescue and military community, for whom reliability is paramount and repeat, high-strain tasks are carried out. Besides that, there are two broad categories of grippers:
Fixed Grippers (or ‘Single Function’ Grippers)
These are ROV grippers that only have a single function: open/close. They are the most affordable types of grippers due to their simplicity. Actuation of the claw or ‘jaws’ is usually achieved by a motor and gearing that extends a linear pushrod in and out along the length of the gripper. This can be conceptualized as having your hand but not being able to rotate your wrist (so you need to move your whole body if you want to pick something up at a certain angle).
Rotating Grippers (or ‘Dual Function’ Grippers)
Rotating grippers are grippers that have two functions: rotate and open/close. They are more complex in their design as they have the same linear actuator as a fixed gripper as well as an additional actuator (‘actuator’ means a motor and gearbox combination) to achieve rotation of the gripper. This can be conceptualized as having your hand and your forearm so that you can rotate the grip angle. Rotating ROV grippers are more suitable for tasks such as turning valves or complex cutting or attachment tasks.
End-effectors for ROV Grippers
Depending on the use cases, the shape and design of the jaw (or ‘end effector’) of an ROV gripper may be significant. Some users will opt for a one-size-fits-all approach and need only a basic jaw attachment (such as the standard jaws shipped with all our Reach Alpha and Reach Bravo grippers). Other operators recognize a need to have a ‘tool kit’ of options for their ROV gripper to enable different tasks. An example of some of the different types of end-effectors are:
- Standard Jaws (non-parallel closing action)
- Parallel Jaws– closes evenly on the object being gripped
- Quad Jaws – wider grabbing surface area
- Soft Jaws – for picking up delicate organisms and samples
- Cutter Jaws – for cutting cables and lines
- Special Recovery Jaws – for achieving greater attachment force on the gripped object
- Needle Nose Jaws – for picking up very small objects
- Large-Opening Jaws – for picking up larger objects such as pipes or rocks
Some of these jaws are best used on manipulator arms that have more functions than a fixed or rotating robot gripper. For example, soft jaws are usually used to pick up very small samples from the seafloor. Having the ability to ‘sit’ the ROV on the seabed to prevent turbidity and then move the soft jaws into position can only be achieved with more dexterous ROV manipulators.
So…is it ‘Gripper’ or ‘Grabber’?
Some of our clients use ‘grabber’, some say ‘gripper’, internally we say ‘grabber’, Google tells us that ‘gripper’ is more common…good luck!