Exploration of both the deep sea and of outer space share a lot in common. Both are extremely unforgiving environments where it is very expensive to create manned vehicles to carry out missions. As automation has become more capable, robotics and unmanned remote operated vehicles (ROVs) are used to execute much of this work. Underwater ROVs operate in challenging environments, which means that industrial-grade automation products are a natural fit to support these designs.

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Although, ROVs are controlled remotely by human operators, most have some degree of on-board automation, combining mechanical, automation, and other skillsets. To develop young talent to support this field, Monterey Peninsula College—via a grant from the U.S. National Science Foundation—has established a program called the Marine Advanced Technology Education (MATE) Center. MATE promotes marine engineering by inspiring and challenging students to learn and creatively apply STEM skills for solving real-world problems. Part of the program is the MATE ROV Competition, which offers five different contest classes, each based primarily on skill and not strictly by age group. 

At North Paulding High School in Dallas, GA, a number of students make up the “WhaleTech” team. Some of them have participated up to seven consecutive years, starting in middle school. Each year, the competition organizer publishes challenges and mock mission profiles simulating real-life conditions, with various restrictions. 

For example: dive to a pipeline simulation at a given depth, strategically remove a “bad” pipe segment, replace it with a new section, and bring the bad portion to the surface. The team builds a ROV to meet those challenges, and along the way they must act and present themselves as a professional company by developing technical documentation, conducting research, and selecting products. Throughout the process, the team must learn and follow safe practices, assemble and test the ROV and subcomponents, and even do a bit of marketing.

The Details

Many ROVs look a lot like aerial drones, with propellers arranged to provide thrust in various directions. Just as aerial drones use propellers to provide constant lift and control motion, an underwater ROV does the same, but it can also use an additional mechanism to adjust its buoyancy. Cameras and lights are common on ROVs, and many also have robotic arms and manipulators to perform tasks. Many of the monitoring and control needs mirror the types of functionalities needed by industrial automation control systems. AutomationDirect has a long history of supporting student STEM efforts, and this underwater ROV project exemplifies just how important it is for industry to support education.

For the 2024 competition, the WhaleTech team needed to develop a well-controlled ROV with an extensible gripper. The buoyancy mechanism, gripper, cameras, propellers, and other components would need to be supported and arranged in a chassis, which meant that some design effort would have to be in parallel and iterative to achieve the functionality and create an integrated form factor. As part of the process, the team used cardboard mockups and 3D printing, and then they created many structural elements cut out from high density polyethylene (HDPE).

The buoyancy engine is used to actively alter the buoyancy of the vehicle so the ROV can rise, descend, or stay at a fixed depth (Figure 1). A sealed cylinder compresses the fixed air volume, displacing it with water, which results in changing the overall density of the apparatus.

After selecting an industrial-grade cylinder, the team needed a powerful yet controllable way to actuate the piston portion via a linear screw drive mechanism. After some trial and error, and investigation of technologies readily available from AutomationDirect, the team found that a stepper motor could do the job admirably. A stepper motor can continuously turn in either direction and be commanded in increments as small as 1.8 degrees per step, driven by an AutomationDirect SureStep stepper drive commanded by an Arduino nano. 

A stepper motor draws no power when idle, it works well within the available power budget, and there is no rebound when the target position is achieved. The buoyancy engine is also outfitted with a pressure sensor used to store depth data into the on-board computer, and a wireless transmitter to communicate this information to the surface computer for a graph display when the ROV surfaces.

Similarly, the gripper assembly incorporates an AutomationDirect SureStep rotary stepper motor driving a screw shaft to provide the motion required to extend or retract a mechanism, which in turn opens or closes the gripper (Figure 2). Because this assembly must articulate, it is connected to the controller using a watertight flexible cable.

In previous competitions, the team had experienced issues with umbilical cables—running from the ROV to the surface—that were not flexible enough to allow precise movements in the water, or were insufficiently shielded and therefore susceptible to electromagnetic interference (EMI). To solve these issues, the team researched cables on the AutomationDirect website and found products with better flexibility and improved resistance to electrical noise. Further, the team occasionally used AutomationDirect’s phone support to iron out details. 

As a result of their design and execution efforts, the WhaleTech team won first place in the Ranger class of the 2024 MATE ROV Competition. While some members are graduating and moving on to new work and educational endeavors, a new crew will assemble next year and work to build upon their successes.

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