Labs

EXERCISE ONE

celerate(m,p1,p2,t);

accelerates or decelerates motor(s) m from start speed p1 to end speed p2 over time period t

motorSpeed(m,p);

sets motor(s) m at percent power p

goFor(t);

runs motor(s) at initialized state set for time t (in seconds)

brake(m);

brakes motor(s) m (stops motors from spinning)

reverse(m);

reverses the spin/polarity of motor(s) m

goToRelativePosition(n);

continues previous command for n marks from the AEV’s current position (positive=vehicle is moving forward, negative=moving backward, 1 mark = 0.4875 inches)

goToAbsolutePosition(n);

continues the previous command for n marks relative to staring position of the AEV

 

EXERCISE TWO

AEV Reflectance Sensors:

The function of these reflectance sensors is to record the distance that the vehicle travels using marks and the reflectance tape. The sensors could potentially provide significant data for the Mission Concept Review if our team chooses to use distance as our main unit of measurement, rather than time.

Code for the Reflectance Sensors:

motorSpeed(4,25); goFor(2);
motorSpeed(4,20); goToAbsolutePosition(295);
reverse(4);
motorSpeed(4,30); goFor(1.5);
brake(4);

 

EXERCISE THREE

Individual concept sketches:

 

 

 

 

 

 

 

Design 1

The aerodynamic shield will improve weight distribution, increase speed, and improve energy efficiency. It will cover haphazard parts like the wires and battery to reduce air resistance. Two motors provide more potential speed and the AEV is properly balanced fro safety.

Design 2

One motor may result in better energy efficiency while still maintain balance. The shield may provide aerodynamic advantage although the AEV is not moving terribly fast isn’t the testing conditions so it likely has little affect.

 

Straight Track Code Graphs:

Energy vs. Time plot:

Energy vs. Time plot analysis:

The AEV from 0 to 3.11 seconds rose to about 6.11 watts in power, which means there had to be an acceleration code segment there, then it was at constant power for about a three quarters of a second, which means it must have been the constant motorspeed function. Then it suddenly dropped to a lower constant motor speed, before spiking suddenly at 6.22 seconds. The spike is likely due to reversing the motors. Then, it stayed at constant energy for a bit, before going to a lower constant energy, then braking completely.

Energy vs. Distance plot:

Energy vs. Distance plot analysis:

For the energy vs distance plot, this seems to follow a similar trend with the energy vs time plot. Whenever there are high amounts of power, the AEV seem to cover more distance in a shorter amount of time. For the first 0.17 or so meters, the power seems to be at 6.11 watts, before dropping to 4 watts over a distance of .3 meters. The watts suddenly spike, presumably when the motors are reversed, before dropping again to a constant level of power for about half a meter. Then when the power drops again to a constant level, the AEV travels far enough for about .2 meters before finally braking.

Codes used so far:

Exercise One Test Run Code

celerate(1,0,15,2.5);

motorSpeed(1,15);goFor(1);

brake(1);

celerate(2,0,27,4);

motorSpeed(2,27);goFor(2.7);

celerate(2,27,15,1);

brake(2);

reverse(2);

celerate(4,0,31,2);

motorSpeed(4,35);goFor(1);

brake(2);

motorSpeed(1,35);goFor(3);

brake(4);goFor(1);

reverse(1);

celerate(1,0,19,2);

motorSpeed(2,35);goFor(2);

motorSpeed(1,19);goFor(2);

motorSpeed(4,19);goFor(2);

celerate(4,19,0,3);

brake(4);

Exercise One Code Explanation

The code first accelerates the first motor from 0 to 15 percent power in 2.5 seconds. Then motor one runs at 15 percent power for one second before braking. Next, the second motor accelerates from 0 to 27 percent power in 4 seconds. Then motor 2 runs at 27 percent power for 2.7 seconds. Then motor 2 decelerates from 27 percent power to 15 percent power in one second before braking. Next, motor two is reversed. Both motors are then accelerated from 0 to 31 percent in 2 seconds. Both motors will then run at 35 percent power for one second before braking motor two. Then motor one will run at 35 percent power for 3 seconds before braking both motors for one second. Motor one is then reversed before accelerating from 0 to 19 percent power in 2 seconds. The second motor then runs at 35 percent power for 2 seconds. The first motor runs at 19 percent power for 2 seconds. Then, both motors run at 19 percent power for 2 seconds. Finally, both of the motors decelerate from 19 percent power to 0 percent power over three seconds before braking.

Reflectance Sensors Test Code

motorSpeed(4,25); goFor(2);

motorSpeed(4,20); goToAbsolutePosition(295);

reverse(4);

motorSpeed(4,30); goFor(1.5);

brake(4);

Reflectance Sensors Test Code Explanation

For testing the reflectance sensors, the code first runs both of the motors at 25 percent power for 2 seconds. Then it runs the motors at 20 percent power when it goes to the absolute position of 295 marks, before reversing both motors. Then both motors will run at 30 percent power for 1.5 seconds before braking.

Straight Track Code

celerate(4,0,25,3);

motorSpeed(4,25);goFor(1);

motorSpeed(4,20);goFor(2);

reverse(4);

motorSpeed(4,25);goFor(2);

brake(4);

Straight Track Code Explanation

First, the AEV will accelerate both turbines from 0 to 25 percent power in 3 seconds. It will then run both motors at 25 percent power for one second, then run both of them at 20 percent power for two seconds. Both of the motors will then reverse and they will go 25 percent power for 2 seconds. Finally, they will brake.

 

Explanation of graphs (what the AEV is doing for each section of the plot):

When the graph displays a sharp, consistent increase or decrease in slope, the vehicle is accelerating or decelerating. At a constant motor speed for a certain amount of time or distance, the graph shows a fairly constant horizontal line because the amount of power isn’t really changing. The graphs of Power vs. Time and Power vs. Distance display similar overall features, but the different actions of the AEV are spread out a little differently because a certain amount of time doesn’t necessarily correspond with a certain amount of distance as speed changes.

 

EXERCISE FIVE

The attributes that seemed applicable were speed, energy efficiency, weight, safety, aerodynamics and balance. Although weight affects speed and energy efficiency and balance affects safety it is still necessary to include these over as they allow a better understanding of the many ways the AEV can be evaluated and improved.

Concept Screening

 

Attribute	Design 1	Design 2
Speed	X
Energy efficiency		X
Weight		X
Safety		X
Aerodynamics	X
Balance		X

 

Concept Scoring

 

Attribute	Design 1	Design 2
Speed	8	4
Energy efficiency	5	8
Weight	5	6
Safety	5	6
Aerodynamics	6	5
Balance	8	9

 

WEEK FIVE (Motor Quantity Testing)

Motor configurations tested: One motor and two motors

One motor AEV:

Two motor AEV:

Takeaways (which configuration we chose):

Four test runs with four different codes were ran for each of the two different motor configurations in question. The 4 codes tested were the same for each type of configuration and graphs of Power vs. Time and Power vs. Distance were created and compared for all eight trials. The center of comparison was the graphs of the one motor vehicle and two vehicle for each specific code individually. Based on the results of the tests, our group decided to use two motors. Using two motors is more energy efficient than using one motor, and this configuration will not compromise speed.

 

WEEK SEVEN (Coasting vs. Power Braking Testing)

Power braking

Pros: Safely stops the vehicle quickly, requires less distance to stop

Cons: Requires more energy

Data/results:

Start (in):	Reverse (in):	End (in):	Distance Motor Ran (in):	Distance After Reverse: (in):
155	184	210	29	26
	182	199	27	17
	183	199	28	16
	182	197	27	15
	182	199	27	17

Coasting
Pros: More energy efficient

Cons: Slower and more gradual

Data/results:

Start (in):	Motor Cut (in):	Coast End (in):	Distance Motor Ran (in):	Distance Coasted (in):
155	185	230	30	45
	182	238	27	56
	184	235	29	51
	182	234	27	52
	183	237	28	54

Decision/evidence:

According to the data, it turns out that the results for both of the data charts are extremely similar, with almost no difference. Although power coasting would take longer to calculate, it seems to be more safer and comfortable for the passengers. For the power braking, there is little calculation needed to brake the AEV properly, but it would probably be more dangerous for the passengers if the vehicle came to an abrupt stop. A combination of both methods will most likely be used in the final design.