For performance test two, the objective is added to the objective of performance test one. The AEV must still be able to get to through the gate but now must also retrieve the caboose. The AEV has to be able to get to, and connect to, the caboose and then move a slight distance back towards the gate with the caboose to prove it can run while connected.
Figure: AEV Design for Performance Test 2
The code used for this test was found to have power efficiency problems as the amount of coasting and braking was not optimally implemented. This leads to the motor being used more than necessary and causing an increase in braking to be necessary to achieve the same stopping distance. Possible error in our testing and coding could be due to the battery’s varying in strength for the run. Although the code was changed from time commands to distance commands, the battery still has a reduced effect on how the AEV performs requiring small alterations in the code for each new battery.
No results were collected for this performance test as it was an intermediary step to finishing the final performance test and did not require data collection. During the run, the AEV did not require breaking before connecting with the caboose but instead needed a reduced absolute distance to reduce its speed. This conserved energy and allowed for a smoother braking and connection with the caboose.
The only error that could have been observed during these runs is that the battery power at the beginning will get the AEV to a higher speed than later on when there is less power and this will always cause the later on runs to reach a slightly smaller distance than the first runs.
As performance test two was completed, a big focus of the team was to refine the code and increase power efficiency as they worked. One of the major power savers that was found in the second performance test is the elimination of the brake while the AEV is on its way to the caboose. It was noticed that the caboose itself acted as its own brake and therefore the AEV would coast up to the caboose and the connection would be a natural break. Other refinements to the code were also carried out while performing this second task by reducing AEV power output and changing the absolute position to make up for the less power. The only negative observation form the second performance test is that the battery still had a slight effect on the AEV’s run even while using position commands. This had to be taken into account for the final testing.
Code: Performance Test 2
reverse (2);
motorSpeed(2,60);
goToAbsolutePosition(246);
brake(2);
reverse(1);
motorSpeed(1,65);
goFor(1.5);
motorSpeed(4,0);\
goFor(7);
motorSpeed(2,55);
goToAbsolutePosition(425);
brake(2);
motorSpeed(4,0);
goFor(10);
goToAbsolutePosition(400);
brake(1);
motorSpeed(2,65);
goFor(1.5);