Introduction
The final solution of the tether operated vehicle must function in a number of ways. The vehicle must be able to drive in a controlled manner over both land and water, including traversing a sand dune. The vehicle must then be able to pick up objects off of the bottom of a pool, off of land, and off of a floating ship. This can be done in any manner we as a group decide, provided that the vehicle and all components comply with the rules set forth in the challenge. The components of the vehicle cannot utilize any materials banned by the rules of the challenge. The hull must be able to resist water, maintain buoyancy, and provide a place to mount the propulsion system, crane style arm, and location to place objects retrieved from the course. The propulsion system must be able to allow the vehicle to traverse a sand dune, travel over water, and be able to be driven in a controlled manner. The hull will be tested to make sure that the tether operated vehicle is able to resist water and stay afloat with the projected weight of the propulsion system and crane components. The propulsion system will be tested to make sure that all wheels and the propeller work. They will then be mounted together and be tested as a single cohesive unit. The tests will be administered by both me and my partner. The test will take place at both my home and school depending on the component being tested. The unit will be both dry and wet when tested, and will be powered on for testing. In these procedures, the unit/craft refers to the Tether Operated Vehicle. Full unit refers to unit comprised of propulsion system and final hull securely mounted together. The testing tank refers to a tank similar to the one picture below. The dune refers to the green area on the image, the sand referring to the tan areas both in front and behind the dune. The terms, “the water” and “the pool” refer to the blue area in the image.
Testing Stages
Exploratory testing is the preliminary testing in all designs. The design of the unit was built using K’nex© by JB. This was an exploratory test because this stage comprised of evaluating the design on a mock up of the final product. In this manner, the steering and propelling concepts were proven to work.
The preliminary stage of testing on the hull must be done before the hull is even cut and shaped. The hull material must be tested to make sure the material will float, or to make sure that there is a suitable method of making the material float. The testing of the hull is an assessment test because of what is being tested. In this stage we are testing to prove the concept of a floating material. The only tool to be used in this test is a container. The test will be performed by JB. The steps involved in this test are as follows.
1. Fill small container with water.
2. Cut out small piece of material to be used for hull.
3. Place material in the water.
4. Observe if material floats.
The secondary stage of testing of the hull is to be done after the hull is cut and shaped. This stage of the test is to be assured that the hull design can work in the shape that is created, and that water will not cause the hull to submerge. The procedure to be used to test this piece will also be an assessment test because the item is being tested to prove that the hull design will work as originally thought. The only tool required for this test is a container that can be filled with water. This test will be performed by JB. The procedure is as follows.
1. Fill large container with water.
2. Cut out small piece of material to be used for hull.
3. Place material in the water.
4. Observe if material floats.
The tertiary stage of testing of the hull is to be done after proving that the final shaped hull does indeed float properly without taking on water or submerging. This test is a validation test because the test is going to prove that the final design of the hull can support the projected weight of the arm, propulsion system, and payload. This test is necessary for completion of this project because if this test is not performed properly, and the hull cannot support the weight of all of the items to be mounted on/in the hull. The hull must be able to have all items mounted in or on the unit, and still be able to not take on water or submerge. The steps involved in this test are as follows.
1. Fill large container with water.
2. Place projected final weight inside the completed hull design securely.
3. Place the hull with all weight inside of the container, floating the unit gently on top of the water.
4. Observe if the final hull floats with all possible weight placed within the unit.
5. Remove unit from the testing tank and continue work on the final product.
The testing of the propulsion system must be done in a series of stages, testing each wheel to make sure that they can freely spin when necessary, and spin in a controlled manner when required, then moving on to test all other components of the propulsion setup. The preliminary stage of testing on the propulsion system will take place after the system has been mostly built. Mostly built in this instance means that the basic structure of the system will have been put together, and all wheels and propellers are mounted. Testing in this stage is considered validation testing because the test is to see if the design is correct, and that all items to be used on the final product will work. This stage will test to make sure that the front wheels can pivot properly along the rack and pinion system, being moved by hand. This stage will also test to make sure that the rear wheels turn along the rear axle at the same time, and are able to be turned at the same time as the propeller in the rear of the unit. This test will be performed by JB. The procedures for this test are as follows.
1. Remove any chocks from the wheels to allow them to spin as designed.
2. Manually spin a single rear wheel, observing if the other wheel spins at the same rate.
3. While spinning a rear wheel observe if the propeller is spinning.
4. While unit is upside down and without resistance on the wheels, spin each of the front wheels.
5. Observe each front wheel spinning freely along the individual axes.
6. Move front support bar side to side, observing the wheels pivoting at similar angles, moving to the side as the rack moves.
The secondary stage of testing is another validation test. This test will take place after the system has been completely assembled, including all motors and other circuitry. This test will test to make sure that all wheels turn with the motors in a controlled manner. This test will require the unit to be fully assembled and be able to be driven while on land. This test will test the rack and pinion style steering setup, the rear wheel propulsion system, and make sure that the propeller works as designed. If assembled properly at the flick of a switch, the gear attached to the front mounted motor will rotate along the rack mounted to the front most support beam. Doing so will move the rack to the side, forcing the wheels to pivot to turn. Flicking the switch off should force the rack to stay in that position until the switch is once again turned on possibly in another direction. The rear wheels should be able to propel the entire unit at the flick of a switch. The switch turned in one direction should propel the craft forward, and in the other propel the craft in reverse. The same motor that is propelling the wheels of the craft is also rotating the propeller. This propeller is to move the unit while on the water. This test will be performed by JB. The procedures for testing the unit at this point are as follows.
1. Remove wheel chocks.
2. Place unit upside-down to reduce resistance.
3. One by one turn on all switches in all possible directions, observing the wheels and propeller moving.
4. Turn on rear motor to make propeller and wheels rotate.
5. Turn on front motor to steer, making sure that both motors work at the same time.
6. Turn all motors off.
7. Place craft right-side-up.
8. Turn on rear motor, observing craft move forward and propeller spin.
9. Flip rear motor switch, observing craft move in reverse and propeller spin in opposite direction.
10. Turn off rear motor.
11. Turn on front motor, observing the front wheels pivot in a single direction.
12. Flip front motor switch, observing front wheels pivot in opposite direction.
13. Turn off all power.
14. Turn on rear motor to propel craft forward.
15. Turn on front motor switch, observing craft turn.
16. Flip front motor switch, observing craft turn the opposite direction.
17. Remove all power from the unit.
18. Replace chocks to all wheels.
19. Continue to work on final product.
The testing of the individual components is now complete. The two units must be now mounted together. The hull and propulsion system must be secured together in a manner that allows the propulsion to have all wheels and propeller below the hull, so that wheels can make contact with the ground, and that the propeller can be in the water. At this point the unit can be tested to make sure that it floats, and that all motors, wheels, and the propeller, all move while both on land and in water. This test will involve placing the unit on the ground outside a small pool, driving the unit into the water, then turning in the water to drive out of the water, turning around to then perform this test multiple times. This test is also a validation test because the test is proving that the final product will in fact work as designed. At this point the craft contains the hull and the propulsion system. The procedures to test the unit complete apart from the arm that will later be secured to the craft are as follows.
1. Remove wheel chocks.
2. Place unit in test tank complete with dune and water.
3. Turn on rear motor to propel craft forward.
4. Observe craft moving forward.
5. Flip rear motor switch, observing craft move in reverse and propeller spin in opposite direction.
6. Turn off rear motor.
7. Turn on front motor, observing the front wheels pivot in a single direction.
8. Flip front motor switch, observing front wheels pivot in opposite direction.
9. Turn on rear motor to propel craft forward.
10. Turn on front motor switch, observing craft turn.
11. Flip front motor switch, observing craft turn the opposite direction.
12. Drive unit toward the sand dune, observing craft successfully traverse the dune.
13. Drive craft toward the water, observing craft float and move through the water, propelled by the propeller.
14. Turn on front motor switch, observing craft turning in the water.
15. Drive craft around the water and out of the water onto the sand.
16. Drive toward and traverse the sand dune.
17. Remove craft from the testing tank.
18. Replace chocks to all wheels.
19. Continue to work on final product.
