Week of 3/26/12

This week again is pushing to get the sub in the pool to do some general maneuvering and perform some of the sub-tasks. Midway through the week we wired up the necessary circuitry(2x Arduino, 3x motor drivers, solenoid circuit, 2x VRB) to perform these task for the hardware demo. Checking each connection with a multimeter for added security. Upon wiring it was verified that with the two separate VRB's that we would not be able to utilize the kill switch to shut down the entire vehicle. For the time being we would just use the kill switch to shut down the motor drivers. It was later decided that a wire from the 32V VRB would power the 16V VRB, therefore the kill switch would shut down the entire system. Continuing with the setup, we placed the rack with circuits in place into the sub. We then sealed the sub and connected each wire to Seacon connectors and with the flip of the kill switch, there was an arc on the VRB. The reason for this is still unclear since multimeter showed all inputs/outputs were correct. We then decided to end on that note and prepare for the following days.
For the demo we decided to temporarily use the back-up VRB. Upon wiring the circuits the night before the demo, all four motor drivers(including 1 back-up) ceased working. It was then established that the utilization of only two wires controlling the thrusters from the motor drivers would not work and three wires would be used in the future.

Week of 3/19/12

This week served as another big week to prepare for a successful water demo. We spent a good amount of time wiring all the circuits exactly as the wiring diagram showed. In the end upon placing the electronics rack into the sub, the laptop was not able to communicate with the Arduino board controlling the thrusters. Initially we assumed a problem in the wire connecting to the Seacon, but after removing the rack and trying with a direct cable it was in fact the Arduino had acquired a problem. The only conclusion to be made was maybe the board had shorted due to the metal standoffs. This was a questionable concern with the motor drivers as well. In conclusion we will switch from the metal standoffs to nylon. This will remove any uncertainty with the standoffs. The hardware demo will be postponed for the upcoming week.

Week of 3/12/12

This week more circuitry had to be wired and tested. Hang completed his voltage regulation board and we tested two thrusters for proper performance. The circuits outputted the proper voltage needed to run the arduino board. It was established that one of the arduino boards had also failed during the hardware demo. The two new motor drivers were also placed on the electronics rack awaiting final wiring and testing.
The 3 colored buoys were purchased from a local marine store to optimize the obstacle course. The buoys are the same color and size as competition specs. Homemade anchors were constructed with buckets, I-bolts, and concrete. Buckets were used for safety to the pool liner when practicing and concrete due to its high density and low cost. The path segments are flat pvc boards purchased from a local hardware store. Each part of the course will be joined in the upcoming weeks for computer vision testing.

Week of 2/20/12

This week was aimed at waterproofing the servomotor to be used in the marker dropper mechanism as well as waterproofing the kill switch. We had two non working servos at our disposal to conduct waterproofing tests on so we tested a combination of methods on each. The servos are waterproof but only to a certain extent. Full submersion to the depths that are required for the competition are not plausible for the servo alone. We took the servos apart and filled the electronics section with a high viscosity mineral oil. We then filled the front gear reduction compartment with a silicon grease. The servo was then reassembled with an O-ring around the output shaft with added silicon grease. Screwing on the servo horn allowed for the O-ring to compress and form a water tight seal. The exterior was then cleaned and all of the seems were touched up with duco cement and the wires extruding out the rear of the servo were coated with plasti dip. The kill switch followed a similar method of waterproofing. The wires and terminals were dipped in plasti dip and the front seems were touched up with duco cement. The duco cement provides a clear barrier to inhibit water from entering. The kill switch was then mounted to a mounting plate with a rubber boot recovered from last years group to protect the front of the switch from water entry.

Week of 2/13/12

This week was devoted to the grasp/release mechanism. We have held off on this component due to it being a subsystem that did not prevent the vehicle from progressing to the final stages. We purchased two double acting air cylinders for the initial design, recently this has changed to only utilizing one double acting air cylinder. After redesigning the grasp release mechanism with a different geometry for the claws and knowing the displacement of the air cylinder to be two inches. It was deemed that the width of the mechanism would have to be too great to allow for proper rotation about the pivot point. The dimensions would not physically work and the air cylinder would prematurely halt created unnecessary stress on the mechanism. The conclusion was to see if we can return the two previously purchased air cylinders and utilize an air cylinder with only one inch of displacement. 

Week of 2/6/12

The majority of the beginning of this week was spent on the presentation. The seacon connectors finally came in towards the end of the week so we spent much time prepping wires for soldering. The thrusters were removed from the vehicle where we then removed the previous internal wires and inserted the new wires that were supplied with the seacon connectors. We then soldered and shrink wrapped the four remaining thrusters since the two new thrusters came pre-potted. After soldering the thrusters need to be potted with epoxy before they are completed and watertight. The upcoming week will focus more on finishing and installing all the seacon connectors with the exterior components.

Week of 1/30/12

This week we finished assembling the compressed air system and integrated it with the torpedo launcher. We had difficulties at first with attaching the low pressure regulator to the high pressure regulator. The sealing of the two together created some losses of the compressed air. After learning the proper order of operation for the compressed air system we fired both torpedo launchers which proved to be a success. The torpedo fired around 6-8ft @ 100psi. This was in the lab and future test underwater will be required to fine tune the system. The torpedo flew straight as expected so the test passed. The learning from these test was necessary and meanwhile we consumed majority of the compressed gas in the bottle. Future tests will require the bottle to be refilled.