8.24.2015

Front Assembly – Camera and Sensor Mounts

After designing our front camera and sensor mounts in SolidWorks, we moved onto prototyping and assembling the pieces. We designed all of the mounts to be 3D printed using the same Makerbot Replicator we used to print the thruster curtains and rear cone.

Camer Mount

Printing:


Our first couple of prints were test prints. We wanted to see if the printer could handle the complex camera mount and test the orientation of each of the side mounts. After a few re-designs we were able to print the final camera mount, but the side mounts continued to gives us problems. Due to their large footprint, the filament continued to peel off of the print plate.

After more than four unsuccessful attempts at printing the front camera mount we switched over to a different 3D printer. We used a Dremel 3D Printer with PLA. The printed turned out well, although getting the software to work was another story (lets just say it needed some persuasion).

Right Cover
Left Cover

Cover Pair



Assembly:


There are a few different aspects to the assembly of the Camera Mount. The assembly consisted of adding threaded inserts, painting the printed plastic, fitting the polycarbonate shield, and finally epoxy the camera and mounting it in the front. 


Threaded Inserts:

Similar to our posts about the through hole thrusters and the large rear thruster we used threaded inserts to mount many of our front pieces. The entire front assembly consisted of ten threaded inserts. Two M3 inserts were used to mount the servo on the right cover. Two M4 inserts were used in the camera cast to hold the camera cover on the camera. Two more M4s were used for the sensor mount. The last four M6 inserts on the left and right side coverts to hold them on the aluminum frame. To get a better understanding of the location of the inserts refer to the images at the bottom of this post. The holes colored red are where the inserts will be used. Below is a CAD drawing of the right cover:

Front Right w/ Threaded Inserts



Epoxying the Camera:

Similar to last year we decided to epoxy our camera. We epoxied the camera in order to waterproof it without having to design a watertight space in the front of the submersible. To epoxy the camera we mounted it to the camera cover using M2 bolts.


DUO w/o Epoxy

We then covered it in two layers of epoxy. The first layer was black heat-sink epoxy. We used this to ensure that the electronics on the camera board did not overheat. The second layer was optically clear epoxy. We used this to put some finishing touches on our first coat and to cover the built in LEDs  on the board.

Epoxying Camera


Mounting the Camera:

In order to mount the camera after it had dried we needed to do a few small things. First we mounted the servo to the right side cover using the M3 threaded inserts. We then used the servo horn that comes with the the servo and screwed it to the camera mount. Next we screwed the LED packages onto the camera cover and mounted all of that to the camera cover. We added a 1/4" Delrin rod to support the side of the camera opposite the servo. We did this by screwing it into the camera mount closest to the servo and sliding it through the entire mount.

Servo w/ Horn and Delrin Shaft

We also mounted the LiDAR to the top half of the camera mount. We use this for measuring distances in order to detect any objects in front of the submersible.

Mounted LiDAR

Sensor Mount

The sensor mount was a little less involved than the camera mount. After printing the mount (pictured below) we epoxied the LiDARs PCB and tested it.

Empty Sensor Mount

We then wired the MS5803 Pressure sensor and the Razor IMU. After finishing the with the wiring we used heat-sink epoxy to mount the electronics in the mount. We also added M4 threaded inserts to the mount in order to mount the LiDAR. Below is a picture of the finished sensor pack. You can see our down facing LiDAR as well as where the IMU and pressure sensor are epoxied in place.

Finished Sensor Pack

Assembly

After finishing both the sensor mouth and the camera mount we assembled it on the front of the sub. To assemble the front we first mounted the camera/servo combination to the right side cover. In the picture you can also see our LED units we will use for lighting.




Camera Mounted on Right Cover

Next we bent a piece of polycarbonate to fit in the slot in the printed plastic and pressed the left cover on. we then slid it inside our frame. The finished assembly is pictured below:

Finished Front Assembly

1 comment:

  1. During the camera assembly travel, is the incidence angle constant between the focal plane and the polycarbonate outside shell? If it is not, then the breaking index of the outside shell will vary and distort the optics. You could post-process that out, but then you would have to model the breaking index transfer function of your camera positions.

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