Evolution of Design

The initial design for the team’s AEV can be found in the Creative Design Thinking section of this division’s preliminary R&D pages.

Research, results, and decisions on the team’s approach during advanced R&D are located within battery and servo testing.

Regarding AEV design, the only change from the preliminary R&D design was the addition of a servo and servo apparatus for braking. Initially, multiple parts were intended for laser-cutting to use the servo as braking system correctly. Additionally, the servo arm was meant to come into contact with the rail for braking. However, since the apparatus could not be produced in time for servo testing, the servo was instead duct-taped directly to the AEV, in a position that allowed the arm to directly contact one of the wheels. Testing with this setup was extremely effective, with the AEV able to correct motor timing inconsistencies of up to 1 second and to stop within 3 inches of brake activation. Therefore, the servo mount was redesigned; the new design is a simpler apparatus that holds the servo in a location such that the arm comes in direct contact with the wheel, as was tested in the servo lab. No other changes were made to the design.

As seen in the specific aR&D reports, the battery’s effects on AEV performance are not significant enough to generate concern. The servo testing supported the effectiveness of a servo mechanism for braking. The team will be pursuing this feature, although in a different method than was originally planned, due to the effectiveness of the make-shift servo.

After advanced R&D, the team decided to scrap its original backup design and replace it with the current AEV design stripped of the servo apparatus. This new backup design can be a simpler alternative to the current design in the event that performance testing finds the servo to be inefficient.

During performance test 2, the team encountered a major problem involving insufficient thrust provided by the motors and propellers, so the team swapped out the smaller-pitch propellers for larger-pitch ones, which can be seen in the final design below.

After performance test 2, the team still used the same augmented design despite the motor and/or Arduino issues.

In terms of code, only minor changes were made to commands like power, time, and goToRelativePosition() values. These changes were lab-specific and test run specific to produce meaningful and reliable results during the advanced R&D labs and to accomplish the desired tasks for the performance tests and the final run. All changes in the code are documented in the respective code sections for each phase of the testing/R&D.