Connectors

Bulgin IP68 six terminal connector mounted on the bottom plate of the pressure chamber bulkhead. Room for three more connectors is available.

Updated ROV

A view of the ROV updated with additional down propulsion motors (two pushing up & one beneath the chamber pulling down) and the new pressure chamber.

Pressure Chamber

Further progress with the pressure chamber now with the bottom ring/plate installed plus the cable/connector bulkhead section seen at the bottom of the assembly. I'm on a search now for sealed connectors for the interior wall and through hull cable seals for the outside surface of the cable bulkhead. This space will also support pressure and temperature sensors.

I'm working to adapt the original ROV frame to host this unit (12"x6" electronics + 3"x6" for the bulkhead). I'm also adding a more powerful down propulsion motor design (two motors pushing up on either side of the pressure chamber and one more powerful motor pulling down directly beneath the chamber).

Pressure Chamber Dome

The 6'' acrylic dome mounted on a flange fabricated from flat 1/4" PVC with a heavy gauge red rubber gasket. I have doubled the number of screws holes as early tests show small deformation of the acyclic between screws leading to possible leaks. I have replaced the philips head screws with stainless allen bolts (8-32) with nylon lock nuts.

Revised Pressure Chamber Design

Here's the revised design for the pressure chamber with a cable bulkhead. Cables will first enter the the cable bulkhead via a water proof seal. Connections to the pressure chamber will be via sealed connectors.

Proposed Dome Mount Design

This shows the current design to mate the acrylic dome to the body of the pressure chamber. A double seal would be formed with a gaskets (not shown) under the ring and under the flange of the dome.

Time Delay Water Switch

This is an earlier design David created. It is a normally-off switch. The delay is activated as the switch is submerged. Inside the chamber is a large spring compressing two copper contacts seperated by an Alka-Seltzer tablet. One possible application is to turn on the underwater camera lights after the craft has decended below the surface.

Underwater Video camera & Lamp

This was our first design for an underwater video camera and light source. These were used during our first test dive down the well.

First Dive Video

This is a video from our first test dive with our first underwater video camera design. This dive is in a residential fresh water well approximately 30 feet deep.

Pressure Chamber Model

This is the first draft of a design for a new pressure chamber rendered in SketchUp. We have an estimate from a local welding shop to fabricate the main body out of aluminum or stainless steel. The bottom section will be a double bulkhead chamber for connections to the surface cable and to sensors/actuators on the ROV.

Underwater Structures to Investigate

There are lots of interesting structures underwater that suggest investigation. This is an example in the channel fairly deep into the harbor. There are some remarkably large features in the sound that are also high on our target list.

Mini ROV Design

David recently created this design for a mini-ROV. The concept is for a small ROV with a four to five inch diameter pressure vessel (sketch not to scale) that can be launched from a larger ROV. The diagram shows a complete mini-ROV using a single motor for propulsion and a parallel up/down-right/left rudder system with linkage controlled by stepper motors. The mini-ROV has a video camera in the front dome with lighting and blue LED’s. In the middle, circuitry can be seen for the stepper motor controller, motor speed controller, video-to-fiber converter and at the top a fiber controller with a cable back to the main ROV (including power).

David's ROV Design First Sea Trial

This is a second ROV design David created and assembled. This image shows the first sea trial this weekend held off Misery Island. Two propulsion motors and the chum cannon are seen mounted on the frame.

Today we launched the original ROV design for the first time in Manchester Harbor. To reduce buoyancy, we drilled holes in the lower frame to let water in. We encountered a small water leak in two of the bulkhead cable seals. The lesson learned is that we must use a full length connector seal (including a silicone filled tube beyond the barb) and cannot get away with a short version!

We face a critical path challenge as we do not have a working match of ROV buoyancy to decent motor power. We will experiment with weights and likely a decent second motor.

Dive Throttle Arm

This is the throttle arm young David designed and constructed. Note the fine thread on the brass rod that supports the black handle. This was his first time using a tap & die set and he did a exceptional job threading the shafts and tapping the aluminum arm.

Depth Pressure Vessel

This is the completed depth pressure vessel. The fitting on the top will connect by tube to a pressure sensor (Honeywell) which has a linear voltage output of 15 mv/psi. At 33 feet, the volume of air will be half the total. We need to build an op amp circuit to drive the signal to the surface to a digital panel meter on the control console.

Video Camera Case

This is the newest underwater case design for our video cameras. I tested this today in 12 inches of water for 30 minutes (in the basement work sink) with no signs leaking. I used 2 inch acrylic tube with matching rubber washers found at the local hardware store. The next step is to build an internal support for the video camera and decide on the best option to seal the external wire feed.

FST

This view shows a nearly complete FST assembly with the plunger release mechanism (aluminum arm) and trigger solenoid (white cylinder on top). We made good progress today fabricating a housing for the trigger solenoid and initial mounting on the FST body.

Side View of ROV

This is a side view of the ROV. The starboard drive motor, blue instrumentation box and FST are seen in this image. Missing from this stage of assembly are the Chum Cannon, compressed air tank, depth pressure vessel, video cameras, and circuitry for motor control (with accelerometer stablilization), pressure sensors, temperature sensor, and more.

Chum Cannon Piston

This is a view of the o-ring assembly, piston lock nut and the plate attached to the end of the piston. The quarter inch holes that let water in as the piston pushes to the right are seen as well. The brass barb fitting is the piston air exhaust.

We're using a Humphrey solenoid pneumatic valve (model 310) to control the air piston.

Chum Cannon

In our first submersion test this evening, the chum cannon worked as expected. The piston moves more slowly than in air due to the limitation of only 4 quarter inch holes for water to flow through. We did experience a small leak in the chamber. The source appears to be a failure in the acrylic end seal. The use of PVC cement is not ideal for acrylic and has repeatedly shown poor strength. Now I have to figure out how to get the water out and re-seal the end.