Michael Ahlbeck-Fetch, Chenchao Jin, Thinh Tran, Bolong Zhang Lab 6: System Analysis 2

Group J – Instr. Kadri Parris, GTA Hossein Qarib February 25 th , 2015

Executive Summary Lab 6: System Analysis 2 was completed with the goal of building on the group’s understanding of the AEV’s energy consumption (as determined in Lab 5: System Analysis 1) by utilizing the propeller advance ratio to calculate the AEV’s propulsion efficiency. Specific goals and objectives included: writing out the code for the track test as specified in the Lab Guidelines, uploading and testing this code on the table track, pulling system data from the test run, and running analysis with the collected data.

The Arduino script file was written and executed as described in the Lab Guidelines, however 20% power to motors was not sufficient to keep the AEV in motion following the initial acceleration. To solve this, the code was rewritten with a 5% increase in power. With this adjustment the AEV performed as desired and without further issues. A copy of this code can be found in the appendix under Arduino Code. EEProm data was collected from Arduino and use to create an energy analysis plot. As well, a copy of this plot was marked with 7 phases to map data values to the commands utilized by the Arduino. Both plots and a table of the phase breakdown can be found in the appendix under Energy Analysis Plot, Phase Plot, and Table 1, respectively. On average, the propulsion efficiency was higher during Phase 5 than in Phase 2, where the only difference was an increase in power supplied to motors. This is an indication that the current design may be more efficient at higher power settings. However, greater efficiency does not necessarily imply less energy consumed. Even if the vehicle is extremely efficient, the chief concern is the total energy consumed during the scenario. The code that was run in Lab 6 constitutes 1/4th of the full scenario described in the Mission Concept Review, and yet we consumed 105.63 Joules. Competitive designs in the past have consumed approximately 41 Joules in completing the entire scenario.

Based on the results of Lab 6 two specific recommendations are made. Firstly, the current AEV design is far too heavy. By comparing energy consumption this became obvious and will need to be addressed before performance testing. Design revisions have already been made in Solid Works and, once finalized, the 3D printed design will facilitate reduction in weight. Secondly, the exact Arduino code used will be extremely important in minimizing energy consumption. Based on energy consumption seen in Table 1, avoiding calls to the brake and reverse functions when stopping the vehicle will inevitably end with less energy consumption. It is most efficient to use the friction of the track to stop the vehicle. The practicality of stopping with friction alone will need further investigation.

All goals and objectives of Lab 6: System Analysis 2 were completed as described in the Lab Manual. Primarily gained was an understanding of the AEV’s propulsion efficiency and a methodology to calculate this using the propeller advance ratio. In regards to future testing, mapping the propulsion efficiency to code segments and distance traveled will assist in maximizing physical design and Arduino software.

AppendixArduino Code // Reverse all motors due to motors orientation. reverse(4);

// Accel all motors from 0-30% in 2s celerate(4,0,35,2);

// Run all motors at 20 % for 8ft motorSpeed(4,25); goToAbsolutePosition(197); // Brake all motors for 1s brake(4); goFor(1);

// Accel all motors from 0-30 in 2s celerate(4,0,35,2);

// Run all motors at 20 % until reach 15ft motorSpeed(4,35); goToAbsolutePosition(369);

// Reverse all motors reverse(4);

// Run all motors at 30% for 1.5s motorSpeed(4,35); goFor(1.5);

Table 1

Phase Arduino CodeAbsolute Distance (Meters)

Time (Seconds)

Energy Used During Phase (Joules)

1 celerate(4,0,35,2); 0 0 8.466398

2motorSpeed(4,25); goToAbsolutePosition(197); 0.0496 2.102 41.1544

3 brake(4); goFor(1); 2.3188 8.223 04 celerate(4,0,35,2); 2.8892 9.363 5.32893

5motorSpeed(4,35); goToAbsolutePosition(369); 3.2612 11.463 37.06166

6 reverse(4); 4.612 14.96 1.840387 motorSpeed(4,35); goFor(1.5); 4.7368 15.123 11.68995

Sample Calculations (Attached behind)

Michael Ahlbeck-FetchLab 6: Sample CalculationsData Source: Phase 5

Distance:Formula: d=(0.0124) ∙Marks Sample: d= (0.0124 ) ∙ (271Marks )=3.604m

Velocity:

Formula: v=d2−d1t 2−t1

Sample: v=3.3604m−3.348m12.123 s−12.063 s

=0.206m /s

Kinetic Energy:

Formula: K=12M v2whereM=0.252 kg

Sample: K= (0.5 ) ∙ (0.252 kg ) ∙(0.206ms )2

=0.00535 Joules

Propeller RPM:Formula: RPM3−inch=−64.59 I 2+1927.25 I−84.58where I=current

Sample: RPM3−inch=−64.59 (1.3115 )2+1927.25 (1.3115 )−84.58=2332Revolutions per MinutePropeller Advance Ratio (dimensionless):

Formula: J= v

(RPM60 )DwhereD=0.0762meters

Sample: J= 0.206m /s

(2332 RPM60 )(0.0762m)=0.6978

Propulsion Efficiency:Formula: η=−454.37 J3+321.58 J 2+22.603 J

Sample: η=−454.37 (0.6978 )3+321.58 (0.6978 )2+22.603 (0.6978 )=17.97%

Sample Calculation Lab 6 System Analysis 2Bolong Zhang

Time(s) Marks Current (A) Voltage (V) Distance (m) Relative Position (m)

5.463 71 0.84406672 8.041992188 0.8804 0.8804

Supplied Power (W)

Incremental energy (J)

Total Energy (J) Velocity

(m/s/10)

Kinetic Energy (J/100)

Propeller RPM

6.787977992 0.410411592 30.37333 4.13333333 2.15246 1496.131379

Propeller Advance Ratio

Propulsion Efficiency

Propeller Diameter (m)

AEV Mass (kg)

0.15 9.09250125 0.0762 0.252

Distance :s = 0.0124 * Marks = 0.0124 * 71 = 0.8804 (m)

Velocity : v= (S2 - S1)/(t2 - t1) = (0.8804 - 0.8556)/(5.463 - 5.403) = 0.413333333 (m/s)=4.133333333 (m/s/10)

Kinetic Energy : Ek = 0.5 * m * v2 = 0.5 * 0.252 * (4.1333333333)2 = 2.15246 (J/100)

Propeller RPM :RPM3inch = -64.59I2 + 1927.25I - 84.58

= -64.59 * (0.84406672)2 +1927.25 * (0.84406672) - 84.58 = 1496.131379 Where I is the current.

Propeller Advance Ratio : J = v/(RPM * D / 60) = 4.133333333/(1496.131379 * 0.0762 / 60 ) = 0.15

Propulsion Efficiency : = -1205 *J3 + 1033 * J2 -179.4 * J + 17.91 = -1205 *(0.15)3 + 1033 * (0.15)2 -179.4 * 0.15 + 17.91 = 9.09250125 (%)

Chengchao Jin

DistanceS= 0.0124*MarksAt t=2.642 Marks=10S=0.0124*10=0.124 m

Velocity

v53= s53−s52t 53− t 52

Kinetic Energy

KE= m

KE= =0.00276 J

RPM

RPM=--64.59*I^2+1927.25*I-84.58

RPM=-64.5*0.818^2+1927.25*0.818-84.58=1799.45

Propulsion Efficiency

η=−1205∗J 3+1033∗J 2−179 .4∗J+17 .91J=0.0888

Propeller Advance Ratio

J= 0 .203(1799 .45 /60 )∗0.0762

=0 .0888

0.0888<=0.15 No power supply to motor

v53=0 .124−0 .11162 .642−2 .582

=0 .203m /s

η=−1205∗0.08883+1033∗0.08882−179 .4∗0 .0888+17 .91=9 .281%