Executive summary
The goal of this entire project is to build a green, energy efficient and cost effective AEV system as the assignment is to help rebel alliances transport their R2D2 units using the best monorail system on a remote planet. The system must follow the scenario given in the lab manual which includes of picking up and deliver the cargo (load) located on the other side of the track while in the same time satisfies the operational requirements, design constraints and minimizing the energy/mass ratio. To do that, the team must work together to build a creative design as well as perfect system of AEV. The task needed to complete this project needs the team to cooperate with each other throughout the whole process; start from the scratch.
For the first step, the team was introduced with the AEV system and build the basic design as stated in the lab manual. The team also tried and get familiarized with the coding for the same design on the inner side of the track. At the beginning the team encountered with some problem with the sensor but with the help of the TAs, the problem was solved within the class period; the team got new set of sensor. After the team get used with the coding for the inner track, the team also tried different coding to see which one is better for the project.
All the trials’ data were collected using EEPROM and MATLAB to see the AEV system performances. MATLAB will convert the data into excel files which make it easier for the team to access the data. Next, each team member sketched their own original design to be selected for the project team’s design. The design must be better than the reference design (the basic design); better stability, power consumption, turning and greener.
Among the four sketches, at first all team members decided to choose Ahmad’s design because of its simplicity to build, low cost, and great stability the design can offer. After discussed and considered every aspect, the team decided to only take certain features from everyone’ sketches and combined them into one design. At last, the team came up with the vertical design that use T-shaped board because the design offer greater stability than the Ahmad’s design and went well with the team’s previous coding.
After several times of trying, the team realized that the vertical design has problem to stop exactly at the point the team want it to stop (before the first gate) because the AEV kept gliding after the break command. Izzat came up with an idea to change the vertical design into horizontal design. The changes made did not take much times and gave the team the good result on the Concept Screening Scoresheet and Concept Scoring Matrix. The newest design score significantly better than the other previous design. The team decided to go on with this horizontal design since this design solved the gliding problem the previous design had.
Introduction
The overall goals for the assignment are for the team to cooperate with each other and making sure every team member participate in the whole process. Based on the Mission Concept Review(MCR), the team was assigned to build a green, energy efficient and cost effective AEV system to run on the track while follows the operational requirements, design constraints and minimizing the energy/mass ratio as the AEV has to pick up and send the cargo from the other side of the track to another. After comparing the score each design, the team had on the Concept Screening Scoresheet and Concept Scoring Matrix, the team finally decided the final design that has the highest score in the table. After trying several coding and made some alteration, the team finally came up with the most compatible coding for the latest design.
To accomplish the Mission Concept Review, the team need to produce an efficient AEV design with the ability to complete the task of the mission. Therefore, this preliminary design report is the documentation of our project progress from the beginning of the lab till the performance test 1.
Experiment Methodology
AEV Operational Requirements
The AEV is supposed to complete the following scenario while optimizing the criteria in the Mission Concept Review in order to complete the mission. The following scenario is listed below and in the figure 1 below show the AEV track layout.
- The AEV will start at the Drop-off area and it will stop at the first gate
- The AEV must not gets too close or too far from the gate to activate the sensor. It takes the gate 7.0 seconds to open when the sensor has been activated.
- After passing through the first gate, the AEV will navigate to the cargo area.
- The AEV must stop at the cargo area and pick up an R2-D2 and wait 5.0 seconds to verify cargo is all loaded.
- Then, the AEV need to travel back and stop at the previous gate.
- The AEV must not gets too close or too far from the gate to activate the sensor. It takes the gate 7.0 seconds to open when the sensor has been activated.
- Finally, the AEV navigate to the drop-off area after passing through the gate. Both wheels of the AEV must be between Mark 2 and the start point to successfully complete the mission objective. Lastly, the team must make sure that the AEV must complete the full cycle of the scenario within 2.5 minutes.
Figure 1: AEV Track Layout
Lab Equipment
In Figures 2,3,4 and 5 below shows the lab equipment that is being used in the lab to carry out the Mission Concept Review(MCR).
- Two electric motors
- AEV body structure and L-shaped arm
- Two diameter propellers
- Two reflective sensor
- AEV wheels
- AEV controller
- Lithium battery
Figure 2: Body Structure, AEV wheels and reflective sensor.
Figure 3: Electric motor and diameter propellers.
Figure 4: Lithium Battery. Figure 5: L-Shaped Arm
AEV Controller
In figure 6 shows the AEV controller is a custom made controller and performance recorder system with an Arduino Nano microcontroller and two motor chips. The Arduino Nano is the one that being used to control motor speed, the time or distance and for recording the system data. The Arduino programming language is required to operate the AEV by using “Functions calls”.
Figure 6: AEV controller with Arduino Nano.
Function Calls
- celerate(m,p1,p2,dt);
-
- Accelerates or decelerates motor(s) m from start speed (%) p1 to end speed (%) p2 over the duration of dt seconds.
▪ For example : celerate(4,0,20,2);
- Will accelerate all motors from 0% to 45% full power in 2 seconds.
▪ For example: celerate(2,20,0,4);
- Will decelerate motor 2 from 40% to 0% full power in 4 seconds.
-
- Four Arguments
▪ m: Motor number 1, 2, or 4 for all motors.
▪ p1: Start % speed (0% – 100%)
▪ p2: End % speed (0% – 100%)
▪ dt: Time span for celeration in seconds (1 – 10)
- motorSpeed(m,p);
-
- Initializes motor(s) m at percent power p.
▪ For example: motorSpeed(4,30);
- Sets all motors speed to 30% full power
-
- Two Arguments
▪ m: Motor number 1, 2, or 4 for all motors.
▪ p: % Speed (0 – 100)
- goFor(dt);
-
- Runs the motor(s) at their initialized state for dt seconds.
▪ Example: goFor(2);
- Runs the motor(s) at their initialized state for 2 seconds
-
- One Argument
▪ dt: Time span in Seconds
- brake(m);
-
- Brakes motor(s) m. NOTE: This does not brake the AEV.
▪ Example: brake(4);
- Cuts the power from all motors.
-
- One Argument
▪ m: Motor number 1, 2, or 4 for all motors.
- reverse(m);
-
- Reverses the polarity of motor(s) m.
▪ Example: reverse(2);
- Reverse all motors;
-
- One Argument
▪ m: Motor number 1, 2, or 4 for all motors.
Results and Discussion
In the performance test lab one, the team was required to come out with two design and analyze the performance of both design. The performance of the both AEV design is analyzed based on the screening and scoring matrix. There are a few criterias highlighted such as the balanced in turns, the center of gravity, durability and environmental aspects. The team has made two designs (as shown in figure 7 and 8 below). The team has produced several design in the previous lab and shortlisted these two design as the selected design for the AEV project. In the figure 7 below show the design is like a vertical t-shaped spaceship while the design in figure 8 is actually the same shape but in horizontal orientation. Below is the discussion on how the team came up to the two prototype concepts used in Performance Test 1 by looking back on the previous lab.
Figure 7: Group Design 2
Figure 8: Group Design 4
In the previous lab 4, the group came up with four designs that had their own spin off of the AEV vehicle. Adam’s design was inspired by a picture of a random spaceship from Google image. The Star Wars theme in this AEV project makes him thinks of a spaceship design. The design is simple and easy to built. The wing makes the AEV more stable and adds the elegance look to it. Since there is a balancing issue that the team faced earlier when moving the AEV, Adam thought the wing is a right approach to solve the problem. The weight of the design (body) is pretty light in order to increase the efficiency rate and make it move easily. The accessory for the design is the additional dots at the front of the AEV that makes it looks like front light. Izzat’s design is pretty similar to Adam’s design because both of them look like spaceship or rocket design. The design has the propeller at the back so that the AEV can have more power to move faster since the team already dealt with the starting projection several times. The 3D printed body was designed to reduce the drag force because more speed will be generated when the drag force is less. John’s design looks like a cylinder from the back. The reason is he want to have the AEV gain more stability and to prevent all the wires and stuffs like battery and Arduino to look messy. Though it might be heavier than others’ design, it is the most stable than others. Ahmad’s design looks like a boat. He thinks that it will be much easier to set up the stuffs on the AEV design plus it gives more stability than the old one. The 3D print design used also make the design lighter which makes the AEV faster to move. While discussing the pros and cons of each design, the group came to a conclusion about the design of the AEV as the team have a problem regarding the stability of reference AEV. So, the group mostly focused on the efficiency, stability and environmental of the AEV while creating the orthographic designs, the team thought it would be best if a design used had both an efficient body as well as a large base. The group designed a fifth design that incorporated all of the necessary improvements for the AEV.
Table 1: Concept Screening From Lab 5
| Concept Screening | ||
| Success Criteria | Reference | Group Design |
| Balanced In Turns | 0 | + |
| Center-of-gravity | 0 | + |
| Maintenance | 0 | 0 |
| Durability | 0 | 0 |
| Cost | 0 | – |
| Environmental | 0 | – |
| Sum +’s | 0 | 2 |
| Sum 0’s | 6 | 2 |
| Sum -‘s | 0 | 2 |
| Net Score | 0 | 0 |
| Continue? | For Now |
Table 2: Concept Scoring From Lab 5
| Concept Scoring Matrix | |||||
| Reference | Group Design | ||||
| Success Criteria | Weight | Rating | Weighted Score | Rating | Weighted Score |
| Balanced In Turns | 20% | 3 | 0.6 | 4 | 0.8 |
| Center-of-gravity | 20% | 3 | 0.6 | 5 | 1 |
| Maintenance | 15% | 3 | 0.45 | 3 | 0.45 |
| Durability | 15% | 3 | 0.45 | 4 | 0.6 |
| Cost | 10% | 3 | 0.3 | 1 | 0.1 |
| Environmental | 20% | 3 | 0.6 | 2 | 0.4 |
| Total Score | 3 | 3.35 | |||
| Continue? | Reference | Yes | |||
In the concept screening and scoring matrices above, the team observed that the group AEV design has smooth turn and does not seems to fall off when making the turn. The team noticed that the group AEV design have a good centre of gravity rather than the reference AEV design in which has the higher possibility to fall off from the AEV track. However, the team found out that the group AEV design have a lack of efficiency and less environmental. Due to the wide body and unused part in the group AEV design, it makes the group AEV design more heavier and need more power to move it. The team decided to cut off the unused part and create a new design that satisfy the Mission Concept Review(MCR). Thus, the two design prototype concept in Performance Test 1 ( in figure 7 and 8) emphasize the team mission on going forward; well-balanced AEV, more environmental and efficiency with less cost.
These success criterias was made based on the run of the AEV on the track as shown in the concept scoring and screening( in the appendix). For the first design (Design 2 in figure 7), the team designed a “cross” shape AEV with vertical orientation. On the other hand, the team created the second design using the “cross” shape but the team change the orientation to a horizontal AEV design(Design 4 in figure 8). The team found out that both of the design have a good centre of gravity in which allowed the AEV to have a good balance when turning; the AEV did not leaning to one side or swaying. One of the factors that lead to this situation is because the speed of the AEV is set up at a moderate level. So, both of the design shows a good stability when turning. The thing that really separated both of the design is the Design 4 have more efficiency and environmental than the Design 2. It is because the team notice that the Design 4 tend to give more thrust when using the same Arduino code. This is because the Design 4 stops further than the location recorded by the Design 2. This also shows that the energy consumption by the Design 4 is lesser compared to Design 2. In terms of the environmental aspects, the Design 4 recorded a higher score than the Design 2 due to the higher efficiency of energy usage. A design that satisfy the environmental aspects is the design that is capable of reducing the total energy usage as shown by the Design 4. For the maintenance aspect, the team take account of the material needed, the possibility of the damage and the time to set up the design. Moreover, the cost of the project remain the same because both of the design are made up of the same parts. The team has tried to minimize the usage of any parts to make sure that the weight of the AEV is at optimum level. This also helps the team to satisfy the cost aspects because the minimum parts used will reduce the total cost of the project.
Table 3 show the data of wind tunnel 2 in pull configuration with 3.0 inches of propeller diameter
| Power Input (Watts) | Power Output (Watts) | Propulsion Efficiency | Advance Ratio |
| 0 | 0 | 0 | 0 |
| 0.074 | -0.009031478 | -12.2047005 | 1.187890307 |
| 0.2442 | -0.006773609 | -2.77379558 | 0.736380898 |
| 0.4588 | -0.003386804 | -0.73818753 | 0.526061658 |
| 0.74 | 0.006773609 | 0.915352541 | 0.42325291 |
| 1.0878 | 0.018062957 | 1.660503475 | 0.347364804 |
| 1.5022 | 0.033868044 | 2.254562908 | 0.292248729 |
| 1.5096 | 0.080154371 | 5.309643005 | 0.225893894 |
| 2.2311 | 0.08241224 | 3.693794111 | 0.225893894 |
| 2.775 | 0.099346262 | 3.580045492 | 0.201197701 |
| 3.2153 | 0.109506676 | 3.405799633 | 0.183192722 |
| 3.6852 | 0.145632589 | 3.951823217 | 0.164372207 |
Figure 9: Graph Propulsion Efficiency Vs Advance Ratio
The figure 9 above show the propulsion efficiency against advance ratio It show that the lowest propulsion efficiency at power 10% which was -12%. On the other hand, it show the highest propulsion efficiency at power 40% which was 5.3%. This show that this configuration is not very suitable for the AEV because it decrease in the propulsion efficiency as the AEV maximized the power.
Table 4 show the data of wind tunnel 2 in pull configuration with 3.0 inches of propeller diameter
| Power Input (Watts) | Power Output (Watts) | Propulsion Efficiency | Advance Ratio |
| 0 | 0 | 0 | 0 |
| 0.1406 | 0.047415262 | 33.7235147 | 1.08340266 |
| 0.3108 | 0.065478218 | 21.0676378 | 0.72215015 |
| 0.5624 | 0.101604132 | 18.0661686 | 0.55787561 |
| 0.8695 | 0.139987915 | 16.0998177 | 0.4661151 |
| 1.2654 | 0.191918916 | 15.16666 | 0.40027676 |
| 1.7353 | 0.259655004 | 14.963119 | 0.35067988 |
| 2.2792 | 0.334164701 | 14.6614909 | 0.31473582 |
| 2.8305 | 0.399642919 | 14.1191634 | 0.28994272 |
| 3.478 | 0.476410486 | 13.6978288 | 0.2687705 |
| 4.2328 | 0.546404443 | 12.9088179 | 0.24878407 |
| 5.0172 | 0.640106032 | 12.7582323 | 0.2315887 |
Figure 10: Graph Propulsion Efficiency Vs Advance Ratio
As seen in figure 10 above, the lab team can concluded that increasing in percentage of arduino power makes the thrust scale reading increase too. The lowest propulsion efficiency at power 60% which was 12.7% while the highest propulsion efficiency at power 10% which was 33.7%. This configuration is suitable for the AEV because it increase the propulsion efficiency as the AEV used more power.
Figure 11: Power(Watts) vs Time(seconds)
The team has made a group design based on the four orthographic design by each team member and make a performance analysis to make sure it satisfy the energy efficiency aspect. Figure 11 and 12 below described the power consumption of the AEV correspond to the time taken during the run.
Figure 12: Supplied Power(Watts) vs Time(seconds)
In figure 12 above, the supplied power against time graph is classified into four phases. The phases were based on the arduino command. In the table 5 below shows the four phases of the AEV on going to the first gate.
Table 5 : The four phases of the AEV moving to the first gate.
| Phase | Code | Distance | Time | Total Energy |
| 1 | reverse(4);
motorSpeed(4,35); |
0 Meters | 0.06 Seconds | 1.0097 Joules |
| 4 | goToAbsolutePosition(245); | 3.137 Meters | 6.481 Seconds | 60.108 Joules |
| 3 | brake(4); | 0.0496 Meters | 0.06 Seconds | 0.2894 Joules |
| 4 | goFor(2); | 2.083 Meters | 4.98 Seconds | 0.66094 Joules |
| TOTAL | 5..2696 Meters | 11.581 Seconds | 62.06804 Joules |
Based on the phases above, there are two significant changes of power which is at the beginning of first phase and also the third phase. The supplied power is at its highest in phase one because the AEV require more power to move forward. As shown in the code above, the speed is set at 35% power. After the AEV starting to move, the power is decreasing. This is because the inertia gained from the phase 1 give enough power to move the AEV thus reducing the power supply. In phase 2, the power does not show any significant changes. At this point, the AEV is moving at same speed to the position before reaching the gate. In phase 3, the power shows a drastic decline due to brake command that cause the AEV to stop moving. In the phase 4, the AEV is still moving after the command for a few seconds and stop right before the gate. In the figure 11 and 12, the plot is based on the design in The team has came to a conclusion that the total energy of the AEV which is 62.07 J too high for this design. Although the code designated for the run is really simple and does not require any additional movement, the total of energy shows that it is not an efficient design. It is one of the reason why the team came up with the two design (Figure 7 and 8 above) to ensure the AEV does not only satisfy the stability aspect but also the energy efficiency aspect.
From the above system analysis 1 and 2 discussion, the team remarked that pull configuration provide the best efficiency for the AEV to move around the track. The team decided to use the push configuration from the start point which is the drop-off area to the cargo area. During this time, the AEV is lighter because it does not have any cargo or load, so it does not really required higher efficiency to navigate to the cargo area. On the other hand, the team decided to use the pull configuration from the cargo area back to the drop-off area. Because of the AEV have a load to carry over back to the drop-off area, the AEV will need higher and constant efficiency of the propeller. Therefore, the two concept design of Performance Test 1 is from the result of the analysis of the system analysis 1 and 2 in which both of the design used push configuration at the start point and pull configuration at the cargo area back to the start point in order to maximize the efficiency of the propellers.
Conclusion and recommendations
As discussed previously, all the labs leading up to the PDR presentation were a preparation for each of the Performance Test labs. The group worked out all of the kinks with the External Light Sensors, coding techniques, design building, and other facets of the AEV project. The team found what seemed to be more of an issue than other things, namely the sensors and battery inconsistencies. With the knowledge of the AEV functionality and a background of all of the equipment, the group was more ready to take on the project as it pertained more specifically to the Mission Concept Review. Throughout the Performance Test 1, the team designated the design as the independent variable, and held all other things about the code constant. The team created three different designs, but decided to compare the two that the team liked the most. These two designs were the HORIZONTAL and the VERTICAL designs. Moving on to Performance Test 2, the team decided on a single AEV design to test against an independent variable of coding.
Up to this point, the group had been testing with many different AEVs along with many different codes. Once the team reached Performance Test 2, a single AEV was required to be used in the continuation of the project. As shown in the results above, the two candidates for the job were the HORIZONTAL and VERTICAL designs. In the concept scoring charts, both AEV’s seemed to do the same in the overall performance of the design. Knowing this, the group consciously chose the HORIZONTAL design because it performed higher in the maintenance category of the concept scoring chart.
Currently, the group has reached Performance Test 2 and is testing the HORIZONTAL design with many different types of code to see which will perform the best. At this stage in the process, the group has done a nice job of completing everything in the designated time period, both documents and physical lab completion. However, the team is struggling to find a code that works consistently over many uses of the AEV. It is quite possible that the team does not find a code that works effectively and efficiently by the end of Performance Test 2. The reasons for this mostly lie within the errors of the External Light Sensors and the Battery. As the tests run, either the sensors struggle to count the marks in the same manner, or the battery slowly loses its power over time. In a lot of the tests so far, the group’s AEV stops shorter and shorter even if the marked distance is increased. Other than this single error, the group doesn’t have too much difficulty with completing tasks.
The link for PDR Slideshow