Expectations
The robotic arm is expected be able to grab, hold, and release objects retrieved in a pool ranging in depths from zero to four meters. The arm must be able to open and close its claw with ease and precision. The second function is grabbing objects. It must be able to grab any type of objects, ranging from either a light lattice structure sphere to a heavy PVC pipe. It also must be able to pick objects such as rope and thread it through a metal ring or rounded object. The arm should be able to open and close its claw and move in any direction.
Procedure
Before the ROV arm can be tested a few things must be done. First the arm along with the ROV must be transported to a pool that meets the specifications and limits that the ROV is given, one such pool in the one at Monmouth University. Along with the ROV arm the ROV is needed to test the arm, along with a heavy PVC pipe, a small light ball much like a rock crab, a PVC pipe with velcroed rocks.
1. Attach arm to ROV in less than five minutes
2. Test arm while out of water: do this by performing all functions of arm detached from ROV and out of water. The arm should be able to open and close its claw and move in any direction.
3. Once the arm has performed the task above, place the vehicle in the pool and allow the ROV to reach the maximum depth before beginning the next phase of testing. The arm should be able to open and close its claw and move in any direction
4. After basic tests have been completed, the arm now has to perform the tasks which the MATES competition has set down. Set rock crabs at the bottom of the pool and allow the arm to try to grasp them off the bottom of the pool.
5. Place the PVC pipe (with attached rocks) at the bottom of the pool, and allow arm to grasp rocks off of it. Once the rocks are grasped move the vehicle in all directions to test how well the arm holds the object while in motion.
6. The final task for the arm is for it takes the temperature of the vent by being able to place the attached thermometer near the vent.
7. The final step is for the ROV and arm to return to the surface and purge all the water, and check for any signs of water leaking into the system.
Testing Results
On April 26th, 2008 team Autobots took part in the New England Regional ROV competition. The team’s pool time was scheduled for 1:30, and prior to that there was a fifteen minute safety check that was required to gain access to the pool. During the safety inspection the ROV and all its components passed with flying colors including the robotic arm, the only issue was the fuse for the ROV was 30 amps not 25, so that issue was corrected. After passing the safety check the team proceeded to the pool area where it waited until its turn. Soon after arriving the team was able to take its turn; the team was able to set up in less than the five minute time, however there was an issue. The control system for the ROV was not working, causing the ROV to stay out of the water much longer than anticipated. Once in the water the ROV had control of only two of its motors, the only reason it sank was because the robotic arm filled with water, which was not in its design. At the bottom of the pool the ROV was able to move slightly but the arm was not in use because the motor would not turn (figure 1). At the bottom of the pool a net was used as a substitute for the arm, but this method also failed which can be seen in figure 2 and 3. To see the final scores please see the end of the paper.
Prior to the competition the arm was tested a couple of times. The first was without the motor system in place and by turning the worm gear the two helical gears turned as they were designed to. After the success of the test the motor and wiring for the Arm was put into place and the motor was tested without the gear system and it worked both in the forward and reverse motions. After all the components worked the arm was put together and tested out of water to see if it would work. When tested the motor would turn the gears as planned, however it would seize up every couple of turns of the motor shaft. The day before the competition the arm was tested again and the same results were collected, the motor would not turn.
In conclusion the arm design worked when tested by hand and worked momentarily however when all the components were put together it did not function as it was designed to. However the arm was assembled in less than five minutes used less power than it needed, and passed a safety check, all of which were part of its specifications or limitations.
Final Standings
ENG CRABS VENT POSTER REPORT BONUS TEAM NAME TOTAL PRIZE(s)
80 100 100 25.5 50.5 2.1* Blue Hills 358.1 1st Place, 1st Mission
88 70 100 38 54.5 NYCHEA 350.5 2nd Place, 1st Poster
84 90 100 27.5 40.0 Milton 341.5 3rd Place
74 70 100 25 30.5 Diman 299.5 Judge's Choice
92 50 100 18.5 38.6 Rogers 299.1 1st Engineering Eval
82 20 95 23 46.2 MAST 1 Deception 266.2
71 0 100 24 40.0 CRLS 235.0 Sharkpedo
86 0 0 32.5 60.5** MATES 179.0 1st Tech Report
62 40 0 18.5 47.8 BMC Durfee 168.3
56 40 0 18 51.3 SE Vo-Tech 165.3
73 30 0 23 39.0 Bristol CC 165.0
84 0 0 22.5 46.7 MAST 2 Autobot 153.2 Guts & Glory
66 0 0 24 52.0 Sound School 142.0
69 0 0 18 39.9 Weaver 126.9 Team Spirit
100 100 100 40 60.0 10.0 410.0 (TOTAL POSSIBLE)
* 2.1 points for pool time bonus
** 0.5 bonus points after average
