- One of the first tasks our team worked on was buoy
- detection. Most of the navigation courses in Roboboat
- require us to identify buoys and then figure out how to
- navigate them. Using a ZED camera, we developed the
- following algorithmic steps to properly identify buoys
- on the course:
+ The purpose of a custom electronics box is to provide a lightweight, accessible, easily modifiable, cool (temperature-wise), splash-proof housing for Fish ‘N Ships’ electrical components.
-
Performs erosion with a segmentation kernel
-
- Performs dilation with the same segementation kernel
+
Design 1:
+
The initial design of the EE box focused on accessibility, modularity, and thermals. It consisted of an ⅛”
+ aluminum base, ⅛” acrylic walls, removable faceplates, a large “land” lid, and smaller “water” lids. This version of the box condensed the boat’s
+ sensors and electronics into a single sub-assembly--i.e., its “brains”--that could be removed and tested independent of the hulls. The electronics
+ were designed to mount to slightly elevated acrylic pegboards (elevated for subterranean wire management). Thermals were managed passively by aluminum
+ “sleeves” that wrapped completely around the hulls and made direct contact with the box’s aluminum base. Overall footprint was roughly 32”x16”x6.5”
+ (not counting the height of the sensor mast).
-
Converts the image to HSV
-
- Gets the mask for each color range we are looking
- at(red, green, yellow)
+ 
+
The second iteration of the box was driven by a single design requirement the first design failed to meet: weight.
+ The original design weighed ~13 lbs, roughly 12% of the team’s weight budget at the time. This egress prompted a spirited discussion of the
+ necessity of a custom EE box--off the shelf options are cheaper, require less manpower (from the team at least), are rated to depths well
+ beyond the design requirements of the box, and commonly used by RoboBoat teams. Modifying such boxes--while inelegant--is neither costly
+ nor difficult, though it does make the box’s original pressure rating irrelevant. The question thus became: can we manufacture a box that
+ offers a better weight to volume ratio than the leading alternative? And would it be worth the cost? We decided there was a high probability
+ we could--and that the cost was more than justified by the learning experience.
-
- Generates a bounding box for each disjoint blob in the
- color range mask
+
Design 2:
+
Design two features the elevated peg boards and removable faceplates of the first design, only this time they’re
+ compressed into a footprint roughly a third the size (12”x16”x8”). To account for this compressed footprint the pegboards were elevated ~4” off
+ the base (enough room to rotate the average human hand comfortably)--opening up a second layer for mounting components. The focus on weight reduction
+ meant the old aluminum base with its heat finned cooling system was a non starter.. Fabric--engineered by a fashion industry focused on breathability,
+ water resistance, and weight--was the obvious replacement. The new box was constructed almost entirely out of an ⅛” plywood frame, and the lid draped
+ in PolyUrethane Laminate--a lightweight, durable, water resistant cloth commonly used for DIY diapers. Finally, fans, protected by 3D printed shrouds,
+ were added for increased airflow.
+
+
+
Current Design:
+
The current design retains many of the core innovations of the previous two--including the elevated peg boards,
+ fabric lid, and removable faceplates. The primary driver of this iteration was usability feedback from the EE team: a self locating pin was added
+ to make aligning the lid easier when latching the box shut and to prevent water from pooling during rainy tests; the number of mounting screws per
+ faceplate was doubled to prevent water from entering the box when rogue waves swept over the deck; 1/32” aluminum L brackets were fastened to the edges
+ of the acrylic pegboards to prevent the previous bowing/flexing/swaying behavior that made mounting components to the pegboards difficult; compliant hooks
+ were added to keep the latches in the “upright” position while lowering the lid; and the Jetson was mounted on L-bracket stand-offs to allow for rapid
+ insertion and removal from the box. Once the wooden seams of the base were caulked with a polyether adhesive the box proved watertight to 16cm (at which
+ point water entered via the fan out take), well above design spec.
+
diff --git a/Blogs/MechE/hulls.html b/Blogs/MechE/hulls.html
index 578ac45..15f4125 100644
--- a/Blogs/MechE/hulls.html
+++ b/Blogs/MechE/hulls.html
@@ -123,27 +123,22 @@
-->
-
- One of the first tasks our team worked on was buoy
- detection. Most of the navigation courses in Roboboat
- require us to identify buoys and then figure out how to
- navigate them. Using a ZED camera, we developed the
- following algorithmic steps to properly identify buoys
- on the course:
-
-
Performs erosion with a segmentation kernel
-
- Performs dilation with the same segementation kernel
-
-
Converts the image to HSV
-
- Gets the mask for each color range we are looking
- at(red, green, yellow)
-
-
- Generates a bounding box for each disjoint blob in the
- color range mask
-
+
Our new vehicle, Fish ‘N Ships, features a catamaran design due to its stability and low drag
+ characteristics. In the initial design, we placed the battery boxes within the hulls to lower the center of mass, decided on
+ ammo boxes to store the batteries for fireproofing, and used foam as the main material of the hulls since it would be less likely
+ to sink if the hulls were punctured. However, the final product turned out to be 36lbs, which was much higher than we expected,
+ since we were trying to keep the overall weight of the vehicle under 70lbs.
+
+
+
Thus, we began a new round of design with more specific design requirements and tried different
+ manufacturing techniques. While we still planned on using foam and sealing it with epoxy and fiberglass, we utilized vacuum
+ bagging technology instead of doing hand layups, since vacuum bagging can spread the epoxy more evenly across the surface, resulting
+ in less layers (and weight) than manual techniques. We also decided to shorten the hulls to make the boat smaller, which would also
+ help cut down the weight and make the boat easier to transport. Finally, instead of using ammo boxes, which contributed significantly
+ to the weight, we opted for tupperware, since they worked well in waterproofing the batteries and were also very lightweight. The current hulls
+ are only 12lbs total. They are four feet in length, and the entire boat can be easily carried by two people.
+
+
-->
-
- One of the first tasks our team worked on was buoy
- detection. Most of the navigation courses in Roboboat
- require us to identify buoys and then figure out how to
- navigate them. Using a ZED camera, we developed the
- following algorithmic steps to properly identify buoys
- on the course:
-
-
Performs erosion with a segmentation kernel
-
- Performs dilation with the same segementation kernel
-
-
Converts the image to HSV
-
- Gets the mask for each color range we are looking
- at(red, green, yellow)
-
-
- Generates a bounding box for each disjoint blob in the
- color range mask
+
Our previous vehicle only had two thrusters in the rear, which meant we didn’t have strafing or station
+ keeping abilities. Thus, for Fish ‘N Ships, it was very important to us to use an x-drive configuration (two thrusters in the front
+ and two thrusters in the back of the hulls). This allowed our new vehicle to strafe and station-keep with ease. However, we didn’t know
+ the best angle to mount the thrusters, and we wanted to keep it adjustable so that we can test out the best configuration. Therefore,
+ we designed an attachment on the bottom of the hulls that had holes in 22.5 degree increments, to allow us to easily attach the thrusters
+ in different positions.
+
+
+
Another design consideration we had in mind was to add some sort of protection to the thrusters. In the past,
+ we could not set the vehicle down without propping it on a platform since the thrusters protruded from the hulls. This made it difficult to
+ transport and test the boat. Therefore, our team decided to add some thruster cages to allow us to set the boat on the ground.
+
+
In our initial design, we mounted two U-bolts for each thruster, but we quickly realized that the U-bolts
+ were quite heavy, contributing to 10% of the overall vehicle weight. Therefore, we considered different materials and geometry to reduce
+ the weight. For material, we decided to SLA 3D print using Formlabs Tough 2K resin. As for geometry, two different designs were considered.
+ The first design weighed a total of 2.4 lbs, and the second design has a total weight of 4.15 lbs. We ended up choosing the first design in
+ consideration of weight restraints. However, we wanted to make sure that the first design can still withstand a reasonable amount of force,
+ so we verified with FEA performed on OnShape and physical tests. The results showed that each cage could support over 150lbs, which is more
+ than sufficient for our design, and now, the cages only contribute to 4% of the total weight.
+
+ 
Mechanical Engineering
Hulls
Propulsion/Thruster Cages