Code Used:
Exercise 1 (1/10/19) – Testing out various code for the Nano
celerate(1,0,15,2.5); //Accelerates motor 1 to 15% in 2.5 seconds
goFor(1); //Maintains the current system for one second
brake(1); //brakes motor one
celerate(2,0,27,4); //Accelerates motor 2 to 27% in 4 seconds
goFor(2.7); //Maintains the current system for 2.7 seconds
celerate(2,27,15,1); //Decelerates motor 2 from 27% to 15% in 1 second
brake(2); //Brakes motor 2
reverse(2); //reverse motor 2
celerate(4,0,31,2); Accelerates all motors to 31%
motorSpeed(4,35); //Initializes the all the motors at 35%
goFor(1); //Maintains the current system for 1 second
brake(2); //Brakes motor 2
goFor(3); //Maintains the current system for 3 seconds
brake(4); //Brakes all motors
goFor(1); //Maintains the current system for 1 second
reverse(1); //Reverse motor 1
celerate(1,0,19,2); //Accelerates motor 1 to 19% in 2 seconds
motorSpeed(2,35); //Initializes motor 2 at 35%
goFor(2); //Maintains the current system for 2 seconds
motorSpeed(4,19); //Initializes all motors at 19%
goFor(2); //Maintains the current system for 2 seconds
celerate(4,19,0,2); //Decelerates all motors from 19% to 0% in 2 seconds
brake(4); //Brakes all motors
Exercise 2 (1/17/19) – Reflectance sensor test
reflectanceSensorTest(); //Test to ensure sensors are working properly
Exercise 3 (1/31/19) – Code used for data extraction tool
celerate(4,0,25,3); //Accelerates all motors to 25% in 3 seconds
goFor(1); //Maintains the current system for 1 second
motorSpeed(4,20); //Initializes all motors at 20%
goFor(2); //Maintains the current system for 2 seconds
reverse(4); //Reverses all motors
motorSpeed(4,25); //Initializes all motors at 25%
goFor(2); //Maintains the current system for 2 seconds
brake(4); //Brakes all motors
Graphs:
Power v Time:
Shows the power in watts of the AEV over the time is seconds across a certain distance.
Power v Distance:
Shows the power in watts vs the distance in meters over a certain time.
Designs:
Original AEV Design:
Original AEV design given to the team at the beginning of the semester all further designs have evolved from this original design.
Ryan’s Design:
Group I team member Ryan created an individual AEV design, that is focused on energy efficienicy.
Mike’s Design:
Group I team member Mike created an individual AEV design, that incorporates an O-shape, with the idea in mind to keep the center of mass centered.
Camille’s Design:
Group I, team member Camille, created an individual design that incorporates a design with the focus of keeping a stable low center of mass.
Observations about design:
The current design is acceptable, however, it can be improved. Ultimately, Group I wants a design that is energy efficient, in order to accomplish this the design must be as aerodynamic as possible. While this design incorporates a triangle shape it is not very aerodynamic in the backwards direction. It is very important that the design is aerodynamic in a forward and backward direction. A design that is aerodynamic will be more efficient because it will use less energy because there will be less wind resistance to fight against. This design has a good center of mass as the battery and Audrino are in the center of the design.
Maddie’s Design:
Group I, team member Maddie, created an individual design with the main focus of aerodynamics.
Observations about design:
The current design is satisfactory, however, if we want our AEV to have better acceleration and deceleration, we need a machine with a center of mass closer to the wheels as well as a lower moment of inertia so it doesn’t drag as long when meant to brake. The propellers can work better when closer to the base (wheels) as well.
Current sample AEV:
The current AEV works fine, however with the pieces in our kit, the design doesn’t work as fluently as we’d like it to, therefore the next design should have better methods of holding the battery, wire control, and stability.
The current AEV works well, however it does not have a good aerodynamic design in the forward and backwards directions. This can be improved upon in the final design.
The current AEV, has a T-shaped structure, this T-shape does not take up that much surface area, therefore this AEV is relatively light weight.
Advanced R&D:
As we began testing our AEV for Advanced R&D, we noticed a few things about our design and methodologies that led us to our key priorities.
Our Key Priorities are: Stable center of mass, low mass design, aerodynamic shape, efficiency.
These priorities all play together and enabled us to create the design we currently. We are only using one medium rectangle with one motor facing each direction to keep mass low and be more aerodynamic. The Arduino on the front and the battery on the back of the wheel holder allows for a stable center of mass as well as a more aerodynamic shape. This new aerodynamic shape allows the AEV to run more smoothly and therefore be more efficient than it previously was. In order to determine how to best run the AEV with this design, we looked to aR&D to help determine which propeller and how many motors running and where would produce the best outcome.
The design in the image above, successfully completed performance test one. However, the team knew that the design would need to be adjusted in order for the AEV to successfully and efficiently complete upcoming performance tests. For example, the next design must include a metal arm to connect with the caboose, the team will need to rework the AEV design to incorporate the metal arm.
Motor configuration
What we found from testing different motor configurations was that two motors at full power (30%) produced the best outcome for us. We tested two motors at full speed, two motors at half speed, and one motor (front and back) at full speed. This can be supported by the data as two motors at full speed showed the lowest time for our constant test as well as only a marginally higher power requirement than the others. Our constant test we used was accelerating the motor to 30% then going to absolute position of 246 then coasting till it braked. This code can be seen here.
Part 1:
Trial 1: One motor on the front at full power
celerate(2,0,30,2);
goToAbsolutePosition(246);
Trial 2: Two motors at full power
reverse(1);
celerate(4,0,30,2);
goToAbsolutePosition(246);
Trial 3: two motors at half power
reverse(1);
celerate(4,0,15,2);
goToAbsolutePosition(246);
Trial 4: One motor on the back at full power
reverse(1);
celerate(1,0,30,2);
goToAbsolutePosition(246);
Data and Results:
| Trial | Method | Distance Travelled (total) (m) | Distance Travelled (Acceleration) (m) | Distance Travelled (constant velocity) (m) | Distance Travelled (braking) (m) | Time (total) (s) | Time (acceletration) (s) | Time (constant v) (s) | Time (braking) (s) | Total Input Power (W) |
| 1 | 1 motor (on front) (30%) | 4.7673 | 0.4705 | 2.6375 | 1.6593 | 13.2 | 4.98 | 5.28 | 2.94 | 615.4099 |
| 2 | 2 motors (30% each) | 6.0055 | 0.6191 | 2.5261 | 2.8603 | 9.482 | 3.722 | 2.82 | 2.94 | 626.2067 |
| 3 | 2 motors (15% each) | Data inconclusive for this trial | ||||||||
| 4 | 1 motor (on back) (30%) | 5.0521 | 0.3467 | 2.7613 | 1.9441 | 11.581 | 3.901 | 4.74 | 2.94 | 436.1789 |
This data supports our conclusion about two motors at full speed as it can be seen that this configuration produced the lowest time with only a slightly larger power usage.
Propeller configuration:
After conducting the motor configuration, the team wanted to identify which of the two propellers would be better. The propellers available are smaller flat propellers and curved longer propellers. The team had been using the latter up until this point. The test conducted was the same in motor configuration with both motors at full power. The code used can be seen here.
“Also, tapered blades are stronger and lighter than straight blades as the bending stress are reduced.” (Alternative Energy Tutorials, para. 16)
reverse(1);
celerate(4,0,30,2);
goToAbsolutePosition(246);
| Trial | Method | Distance Traveled (m) | Time (s) | Total Input Power (W) |
| 1 | 2 motors 30% big propellers | 6.0055 | 9.482 | 626.2067 |
| 2 | 2 motors 30% small propellers | 0 | n/a | n/a |
The data supports the conclusion as the smaller flat propellers produced zero motion for the AEV. This means that the team will continue to use the longer curved propellers going forward.
The Future:
As Performance test 1 and aR&D 1/2 are coming to a close, our key priorities moving forward are more precise and accurate movement and keeping costs low. Precise and accurate movements will allow the team’s AEV to be more exact with where it stops which allow an easier process for each performance test. With the overall goal of this project, the team has a budget to stay inside of and keeping the time and energy costs to a minimum will allow for more R&D as well as unforeseen problems.
Performance Test Two Design:
For performance test two the team needed to incorporate a metal arm to the AEV in order for the AEV to connect with the caboose. To do so, the team had to remove the front motor and put a a metal arm in its place for the second performance test. Any other arm tried added too much weight to the AEV. The design for performance test two was purely for performance test two, the team knew that this would not be a permanent fix because the AEV would need two motors to pull the heavy caboose for the final performance test. Using two motors to pull the caboose would also be the most efficient use of energy.
This depicts the solid works drawing of the design the team used for performance test. This design successfully completed performance test two. However moving forward the team decided that two motors would definitely be needed to pull the heavy caboose.
The following is the flowchart that the team followed for the previous 2 configurations tests and to determine what to move forward with:
Advanced R&D 3:
Servo Function, was the third and final methodology the team choose to take a closer look at. The reason the team wanted to take a closer look at how the servo could improve the AEV was due to how the only source of breaking for the first two performance tests where just cutting the motors and hoping the AEV would cost to the appropriate location. The team knew that costing would not be acceptable for the final performance test, because it is very unreliable. The servo would also increase the AEVs safety, by having the AEV come to a full stop at each location rather than costing to a stop.
This image shows the Total Energy vs. Time for the AEV Servo Test. This test was done to determine how much energy was used with the servo and how much energy was used with out the servo. Even though costing is a more energy efficient option for breaking it is unreliable and does not guarantee where and when the AEV will stop. The team decided that safety is the most important quality the AEV must have, therefore it was decided the Servo will be used moving forward because it will guarantee a safe stop. The image, Distance vs. Time for AEV Servo Test above shows the safer and quicker stop the servo provides when used on the AEV design.
Code used:
Precision test:
// The goal of this code is to check the precision of the servo by measuring stopping distance
motorSpeed(2,30);
goToAbsolutePosition(148); //motor 2 is set at 30% until absolute position 148 (6 feet)
brake(2);
goToAbsolutePosition(210); //brake of motor 2 goes until absolute position 210
rotateServo(90); //rotates servo
goFor(2); //holds servo in place for two seconds
rotateServo(-90); //unrotates servo
Trial 1: (No servo)
// Overall goal of this code is to test energy and time with coasting
motorSpeed(2,30); //sets motor 2 to 30%
goToAbsolutePosition(148); //motor goes until absolute position 148 (6 feet)
brake(2); //brakes motor 2
goFor(10); //time for coasting
Trial 2: (With Servo)
// The overall goal of this code is to test the servo’s efficiency of energy/time compared
// to not using the servo.
motorSpeed(2,30); //sets motor 2 to 30%
goToAbsolutePosition(276); //motor goes until absolute position 276 (11.3 feet)
brake(2);
goToAbsolutePosition(338); //brakes motor until absolute position 338 (13.7 feet)
rotateServo(90); //rotates servo
goFor(2); //holds servo in place for 2 seconds
rotateServo(-90); //unrotates servo
Final Design:
The final design, shown in the image above, incorporates two motors for the best use of energy, and it will be strong enough to tow the caboose back through the track. Two motors running is more energy efficient than one motor running at more power trying to compensate for not having two motors. The final design also incorporates the servo which will guarantee a stop in the right location and right away which improves the safety of the passengers on the AEV. The design is also light weight which keeps the overall costs relatively low, this ensures that the AEV is an affordable option for citizens.
Final Performance Test:
Code used:
//start to first gate check
motorSpeed(2,35);
goToAbsolutePosition(220); //initializes motor 2 at 35% and runs it until absolute position 220
brake(2);
goToAbsolutePosition(295); //brakes motor 2 until absolute position 295
rotateServo(135);
goFor(2);
rotateServo(-135); //rotates the servo, holds for 2 seconds and then rotates back to its starting position
brake(4);
goFor(7); //brakes the AEV for 7 seconds while waiting inside the first gate
//gate check to connection with caboose
motorSpeed(2,35);
goToAbsolutePosition(398); //initializes motor 2 at 35% and runs until absolute position 398
brake(2);
goFor(2); //brakes motor 2 for 2 seconds
motorSpeed(1,30);
goFor(1.5); //has motor 1 going at 30% in the opposite direction to help slow down for 1.5 seconds
brake(1);
goFor(8); //AEV has connected with the caboose here and is waiting to go back the other direction
//connection with caboose to second gate
reverse(2);
motorSpeed(4,50);
goToAbsolutePosition(420); //initializes both motors at 50% and goes backward until absolute position 420.
brake(4);
goToAbsolutePosition(370); //brakes both motors until absolute position 370
rotateServo(140);
goFor(2);
rotateServo(-140); //rotates the servo, holds it for 2 seconds and then rotates back to original position
brake(4);
goFor(7); //brakes the AEV for 7 seconds while waiting in the gate for the second time
//second gate to finish
motorSpeed(4,50);
goToAbsolutePosition(222); //Initializes both motors at 50% to accelerate the AEV and goes until absolute position 222
brake(4);
goToAbsolutePosition(200); //brakes both motors until absolute position 200
reverse(2);
motorSpeed(2,35);
goFor(2); //uses motor 2 at 35% power to help slow the AEV down
brake(2);
goToAbsolutePosition(20); //brakes the AEV until absolute position 20
rotateServo(130);
goFor(2);
rotateServo(-130); //rotates the servo, holds it for 2 seconds, then rotates back to the original spot in the ending position
Citations:
“Wind Turbine Blade Design, Flat Blades or Curved Blades.” Alternative Energy Tutorials, Apr. 2018, www.alternative-energy-tutorials.com/energy-articles/wind-turbine-blade-design.html.