Josiah Myhre

Perhaps my largest contribution, other than management of the overall design process, was the design of the chassis. It was designed in parallel with the electronics enclosure and underwent many iterations before completion. It is constructed primarily of t-slot extrusion and phenolic panels. Other than the phenolic panels, which were waterjet cut by a sponsor, the frame was designed, machined, and assembled by me.

Requirement: Modularity

Solution: T-slot extrusion provides attachment points anywhere along its length. Phenolic panels are rigid yet easy to machine in place for additional mounting options.

Requirement: Six Degrees of Freedom

Solution: Thruster mounting positions were placed in a vectored configuration that allowed for translation and rotation about all axes.

Requirement: Safe and Ergonomic Handling

Solution: Two marine-grade handles secured to the structural frame provide easy-to-identify handling points, preventing damage to the vehicle and providing an ergonomic way to interact with it.

Requirement: One-Handed Retrieval

Solution: Two sleds on the bottom of the frame, machined from nylon, allow the vehicle to slide along the edge of a dock or pool for easy one-handed retrieval with minimal lifting.

Requirement: Tether Strain Relief

Solution: A stainless rope guide bolted to the rear of the t-slot frame provides an attachment point for the tether's strain-relief carabiner.

One of the tasks in the competition was to extract 50 mL of an unknown liquid sample from a container on the bottom of the pool that had a small opening covered in plastic film that needed to be punctured. The extraction tool was designed, printed, and assembled by me.

Requirement: Puncture Plastic Film for Extraction

Solution: A 4 mm diameter stainless steel tube that can be mounted vertically while in use or horizontally when stowed is attached to the bottom panel of the ROV near the front. The extraction tube can be quickly swapped between stowed and in-use positions by sliding it on and off of a rail. Magnets embedded in the printed material snap it in place, ensuring that it is secured in either position.

Requirement: Extraction of 50 mL of Fluid

Solution: A 60 mL syringe is mounted to the bottom frame of the ROV, where it attaches to the stainless tube with silicone hose and is actuated by a servo through a rack-and-pinion mechanism.

Throughout the competition tasks, props could appear in a number of different orientations. Some teams addressed this with multiple object manipulators; our team instead chose to develop a single manipulator capable of both rotation and tilt. Design, production, and assembly of the mechanism were done by me.

Requirement: The claw must rotate 90 degrees and tilt 90 degrees

Solution: A differential gear mechanism allows the claw to tilt by driving the gears in the same direction and rotate by driving them in opposite directions.

Requirement: Use 180-degree servos while allowing simultaneous 90-degree rotation and tilt

Solution: Brushless servos capable of greater than 180 degrees of rotation were prohibitively expensive for the club. Using a 3:4 gear ratio allows the claw to be both tilted and rotated 90 degrees with only 180 degrees of rotation from either servo.

Requirement: Electrical Simplicity

Solution: The differential gear mechanism uses only two servos that remain stationary relative to the chassis. Minimizing servo and cable movement reduces stress on waterproofed electrical connections and lowers the risk of manipulator failure during competition.

Several competition tasks required specialized tooling. Rather than permanently mounting single-purpose tools to the vehicle, we created attachments that could be quickly installed and removed from the object manipulator during a run. This reduced permanent weight, drag, and vehicle clutter. Both attachments were designed, printed in PETG, and assembled by me.

Requirement: Tool-less Installation and Removal

Solution: Each attachment is secured to one of the manipulator jaws with a custom printed thumbscrew. A large T-handle allows blind interaction for quick installation and removal.

Requirement: Capture and contain a "medusa jellyfish" without grabbing it

Solution: The medusa catcher uses the object manipulator's jaw actuation to open and close a container that can then be quickly removed topside for delivery to the judges. Magnets embedded in the lid and container hold it to the attachment while still allowing quick removal.

Requirement: Collect loops attached to a frame floating at the water's surface

Solution: A surface hook extends above the submerged ROV to collect loops located at the waterline. A barb at the end prevents collected loops from falling off while the vehicle maneuvers.

For an underwater vehicle like an ROV, neutral buoyancy is critical to maneuverability. While an ROV that is not neutrally buoyant can still operate, continuously compensating for vertical drift makes precise interaction with task props more difficult. The buoyancy panels are constructed from Formular 150, skinned in vinyl, and trimmed with PETG. They were designed, machined, and assembled by me.

Requirement: Neutral Buoyancy

Solution: After the rest of the vehicle was complete, I measured the submerged weight of the ROV using a crane scale. Using the density of Formular 150 foam, I calculated the required panel thickness to compensate for the vehicle's submerged weight. The foam was cut to profile on a vertical bandsaw using a template and milled to final thickness on a manual mill.

Requirement: Aesthetically Appealing

Solution: Because the buoyancy panels cover a significant portion of the vehicle, they also became a major visual element. The pink Formular 150 foam was covered with black adhesive-backed vinyl and finished with white 3D-printed PETG trim attached using marine-grade adhesive. The finished panels also provided space for sponsor logos.

Camera mounting was a crucial part of the ROV's design. Another team member designed a camera enclosure that allowed the camera to tilt so the operator could look down at tooling, straight ahead while maneuvering, or toward the surface when needed. Even with this articulation, determining the correct mounting location required testing. I created a two-piece adjustable bracket that allowed the camera to be repositioned during testing. Once the optimal position was established, I designed the final rigid bracket shown here. Mount design, printing, and assembly were done by me.

To reduce costs, we manufactured as much of the ROV ourselves as possible. I had access to a machine shop at my place of work and used it to manufacture several aluminum and acrylic components for the vehicle.

Junction Box

I machined the junction box on a manual mill from a solid block of 6061 aluminum. The O-ring gland radii were produced by calculating 16 points on each radius and plunging with an end mill. The gland was then hand-finished and the enclosure was pressure tested until a reliable seal was achieved.

Acrylic Enclosure Covers

The acrylic panels were cut to size on a vertical bandsaw and the hole patterns were drilled on a manual mill.

Electronics Enclosure

The object manipulator enables VESPA to grasp, move, and release PVC pipes and hooks during competition tasks. It uses three articulated fingers that close from multiple directions to center and securely hold objects. A pneumatic actuator drives all fingers through a linked mechanism, simplifying control and reducing electrical components.

Requirement: Securely grasp various sizes of PVC and other task objects

Solution: A three-finger design surrounds and centers objects, adapting to both cylindrical and irregular shapes. Features on the surface of the jaws were designed to interface with task props in the orientations that they would be interacted with.

Requirement: Waterproof for underwater operation

Solution: The pneumatic system is inherently suited for underwater use, with sealed components and air-driven actuation that prevent water intrusion into electrical actuators.

The spool tool was designed to retrieve competition props with vertical lifting hooks that rested on the bottom of the pool. Because pitching the ROV downward to engage these hooks directly was impractical, the tool used a retractable line to capture the hook while the vehicle remained level. Once engaged, the line was reeled in to lift the object off the pool floor, providing better control while maneuvering the vehicle.

Requirement: Retrieve objects with vertical lifting hooks while keeping the ROV level

Solution: A servo-driven spool extends a retrieval line beneath the vehicle, allowing the ROV to sweep across the pool floor until the line captures the hook.

Requirement: Prevent the retrieval line from tangling during operation

Solution: The spool features a helical groove that guides the line into evenly spaced wraps, ensuring controlled winding and reliable, tangle-free deployment and retraction.

Requirement: Ensure controlled unspooling of the retrieval line

Solution: Evenly spaced stainless steel beads are integrated along the line, providing consistent spacing and resistance that helps regulate the rate of deployment and prevents uncontrolled unwinding.

The rotator tool was designed to operate valve handles during competition tasks. Three curved prongs engage the outside of the valve, allowing the tool to accommodate minor misalignment while maintaining contact throughout rotation. A waterproofed servo drives the mechanism directly, enabling controlled valve operation without requiring the ROV to maintain a perfectly centered position.

Requirement: Rotate valve handles

Solution: A servo directly drives the rotating mechanism, providing controlled and repeatable valve actuation.

Requirement: Tolerate minor misalignment during engagement

Solution: Three curved prongs guide and center the valve within the tool, allowing successful engagement without requiring perfect positioning of the vehicle.

The topside control box served as the primary interface between the operator and the ROV. It distributed electrical power, supplied compressed air to the pneumatic systems, and housed the networking hardware that connected the pilot's laptop to the vehicle through the tether. In addition to consolidating these systems into a single enclosure, the control box incorporated safety features, thermal management, tether support, and service access to improve reliability during competition.

Requirement: Provide electrical power and compressed air to the ROV

Solution: The enclosure integrates power distribution and a pneumatic inlet, allowing both utilities to be supplied through a single tether connection.

Requirement: Establish communication between the ROV and the operator

Solution: An onboard network router provides a direct Ethernet connection between the pilot's laptop and the ROV for vehicle control and monitoring.

Requirement: Incorporate emergency shutoff

Solution: A circuit breaker disconnects electrical power while a manual shutoff valve isolates the compressed air supply.

Requirement: Protect the tether from mechanical loads

Solution: An integrated strain relief transfers cable loads to the enclosure, preventing tension from being applied directly to the electrical and pneumatic connections.

Requirement: Maintain safe operating temperatures for electrical components

Solution: A forced-air cooling system continuously circulates air through the enclosure to dissipate heat generated by the electronics.

Requirement: Allow internal components to be serviced or replaced

Solution: An internal access lid allows the enclosed components and connections to be reached without requiring the control box structure to be disassembled.