Preliminary R&D

Lab Progress Report Questions

Lab 01

Questions:

Comment on the performance of the electric motors (i.e., in scenario 1 line 1, did the propeller begin to rotate at the start of the program or was there resistance observed in the motor to rotate the propeller at low speeds?).

• The electric motors behaved exactly as the code told them to as far as the group could observe. They also started right away as soon as the “start” was initiated. As far as the group could observe, the motors behaved as expected.

• The commands could limit the success of the AEV in the completion of the scenario because the commands just account for how the motors behave. For example, if brake is applied, that doesn’t stop the AEV from continuing to roll on the track. Or another example, celerate doesn’t account for the speed in which the AEV is already travelling. These things could limit the success of the AEV to complete the task and therefore will require the team to observe and adjust to account for variables such as the ones listed above.

Discuss any potential errors made and how these were resolved during the lab.

• Potential errors for this lab could be incorrect coding, which could quickly be fixed by adjusting the code and re-uploading it to the Arduino.

• The team didn’t need any guidance on any of this lab material. Recommendations are to better organize and better emphasize what is expected to be done by when in terms of deliverables.

Lab 02

Image of the reflectance sensors attached to the AEV:

The reflectance sensors are way to measure the position of the AEV, and therefore are necessary for the AEV to function correctly.  It is important to accurately know when stop, slow down, reverse direction, or make any type of change in movement.  Ensuring that the sensors function correctly is crucial to completing the MCR in that if they are not working correctly, all the subsequent tests will be incorrect.

Code for Reflectance Sensor Test:

void {

motorSpeed(4, 25);

goFor(2);

motorSpeed(4, 20);

goToAbsolutePosition(300);

reverse(4);

motorSpeed(4, 30);

goFor(1.5);

brake(4);

}

Lab 03

See sketches and descriptions under the “Designs” tab.

The final concept sketch would be successful in completing the scenario because it is highly aerodynamic, with a rounded windshield covering the entire body. Further, it will have similar performance traveling both forwards and backwards, since the propellers are situated in the middle of the AEV, rather than on one end or the other.  Larger propeller blades are being used, as blades with a higher diameter have a higher power output, which will benefit acceleration and performance.  A “T” shaped base is being used for added space, since the motors can go on the “wings”, which leaves more space for the other components.  This shape will also promote greater balance and stability, since the weights are more evenly distributed over the entire machine.

Lab 04

Figure 1

Figure 2

In Fig. 1, the Power vs. Distance is shown. The test was performed on a straight track. As shown in the figure, the power output increases and decreases based on when the AEV accelerates or decelerates. There is also a large jump in power at about 1.3 meters, it is safe to assume that this power jump is due to the polarity shift in the motors. Fig. 2 shows the Power vs Time. The test performed was on a straight track so no outside factors affected the power output. As shown in the first four seconds, the AEV steadily accelerated, just as the code implies, and as such a steady increase in power was required. For the next second power decreased when the motors no longer needed to accelerate, but rather just ran at a constant speed. At about 5.5 seconds, a large power spike can be seen as the motors reverse and power back up to 25% power, then the power levels out before dropping when the motors cut off. This implies that power breaking may be very power consuming because of the power required to reverse and power up the motors again.

Code used for Lab 04 for reference:

celerate(4,0,25,3);  //accelerates all motors from 0% power to 25% in 3 seconds

goFor(1);  //sets all motors to run at 25% for 1 second

motorSpeed(4,20);  //sets all motors to 20% power

goFor(2);  //sets all motors to run at 20% power for 2 seconds

reverse(4);  //reverses all motors polarity

motorSpeed(4,25);  //sets all motors to 25% power

goFor(2);  //sets all motors to run at 25% power for 2 seconds

brake(4);  //brakes all motors

Lab 05