g ro u p d ‐ a ﬃ ﬁ h u s s e n , g a r reĥ m a r l owe , te r r y n … · 2017. 12. 22. ·...

Group D ‐ Affifi Hussen, Garreĥ Marlowe, Terry Newsome, Pablo Torrico Progress Report Week 4 Instructor – Dr. Kecskemety, GTA – Rahel Beyene 2/5/2016

Week 3 Backwards looking summary Situation The objectives of last week’s lab were to learn two techniques used for creative design thinking, become familiar with the obstacles of creativity and to brainstorm AEV concept sketches in orthographic view. This lab was imperative to the AEV development; the key aspects that were being addressed in the lab were how to minimize energy usage and torque, handle variances on the track and to explain an initial conception of how certain components work. The team was allocated 1015 minutes to create an individual’s sketches, then, the team was allocated 1520 minutes to brainstorm and sketch a new design of the AEV. Upon the completion of this lab, the team then had a cogent idea of how the AEV will actually work, in the team’s own unique idea, in observation of the future labs. Results & Analysis The design of Concept Sketch #1 was inspired by the Thrust SSC (the fastest vehicle in the world) capabilities to minimize energy usage. To achieve the same feat, the Thrust SSC’s design was graphically reverse engineered and translated to fit the team’s Mission Concept. Two aspects were considered in this design: 1) reduce drag and 2) eliminate torque. Drag has been the central issues in determining the efficiency of the generated power by the motors. The contributing factors of drag are the overall surface area of an object (provided that the object is moving across a space); to reduce the overall surface area of the object, as much as possible, will be the main objective. The body of the AEV was designed with an aerodynamic property and with a small total surface area. The aerodynamic property will allow smooth airflow through the AEV and thus reducing drag from the air. The aerodynamic body will be 3Dprinted using a protopastacarbon fiber filament – since this is one of the lightest material available. Having an aerodynamic body isn’t enough, however, if the total surface area isn’t optimized. The shape of a pinnacle was chosen to be translated into the AEV design. Having needlelike ends (front and rear) will adopt the simplistic concept similar to the Thrust SSC and allows the AEV to dash through the airoccupied space. To allow the AEV to be able to traverse forward and backward, the AEV’s body will have aerodynamic shape from the front end to the rear end. Both of this design will reduce drag and optimize the power generated. A torque is created as a result of unbalanced force and causes the AEV to revolve about the axis, along which the arm is placed, making the AEV lopsided while hanging on the track. The AEV being not lying horizontally resulted in the force generated by the motor to be wasted (by orienting the force in the direction not parallel to the AEV’s motion). To counteract this phenomenon, the AEV must have a central mass concentrated below to where the arm is


placed. To achieve this, all of the components must be concentrated at one point or along a line perpendicular to the AEV’s line of motion. The Arduino and the battery are placed on top of each other while both of the motors are placed side by side to where the Arduino and the battery are placed a “tshaped” base is used. As a result, the resultant weight will be exerted at a point where τ ≈ 0 N.m. The design for Concept Sketch #2 was about low mass, simplicity and balance. The tshaped base place was selected in order to fit fit the battery and Arduino underneath the base. The battery was secured using zip ties rather than brackets. This allows for a reduction of drag, mass, and therefore, torque. The purpose of this design was to allow for easier manipulation of the center of mass. As previously discussed, the center of mass is a critical factor in the AEV’s performance and this design will allow flexibility in the placement of the heaviest components. The two propellers were placed further away from each other using brackets and trapezoidal plates in order to eliminate drag and avoid the cross cutting of each propeller’s respective air flow. While this design is simplistic in nature, the surface area in the front will provide unnecessary drag. The design for Concept Sketch #3 takes an unorthodox approach towards creating an AEV. This design relies directly on the motor and wheel for propulsion rather than using propellers. The motor will be directly wired to a custom wheel that has inner grooves containing a rubber band inside. This rubber band will provide the necessary friction for significant positive and negative acceleration to the AEV. One of the strengths of this design is it’s ability to brake significantly better than propeller based designs. The friction on the grooved wheel will allow the team to more effectively control where the AEV stops, reducing the amount of testing necessary later on. The wheel also contributes to this design’s biggest flaw. This component causes a significant amount of friction that normally isn’t present in propeller propelled designs. It is currently unknown how much this impacts the top speed but the team remains optimistic with its potential. This approach allows for a significantly lower energy consumption with minimal mass. The design for Concept Sketch #4 was an attempt to reduce drag and weight while increasing the efficiency of travel. The triangular shape towards the back of the AEV will decrease the surface area of air that will flow over the vehicle, thereby allowing the vehicle to cut through the air. The designs in the group differ for each group member, however the main goals of the design process is the same. With the operational constraints, creating the part that would reduce the most drag will help achieve the Mission Concept. Specifically, the techniques used for the brainstorming is creating individual sketches, and then getting together to describe them. The main materials used in the design of #4 AEV are there directly from the kit of the AEV, but the main feature is the 3D printed part to reduce drag. There is a section that is cut out in a triangle shape on both sides of the AEV main plastic board. This would allow for less material to be used, and an innovative way to mount the propellers. This would decrease the overall mass of the AEV thereby increasing the ratio of energy to mass. Ultimately the determination of the


final design will be aided in the following lab when a concept scoring matrix is used to actually assess how the design will perform against a reference AEV. If the design performs better than the reference than the design will be kept, if not there may have to be additional changes to the final design of the AEV. The Final Concept Sketch took the defining attributes from both Concept Sketch #1 and Concept Sketch #3 to generate a more creative design. The final concept included the aerodynamic, 3D printed base from sketch #1 and the wheel based propulsion system from sketch #3. The group decided that the wheel based propulsion system had more potential than the propellers and with a decrease in drag, there’s a lower chance that the friction from the wheel would render the design unviable. To further reduce mass, the battery will be secured by store bought zip ties. This will free up space on the AEV and allow for the group to modify the design in order to alter the center of mass in order to reduce torque. Takeaways

1) The team have a better understanding of the trajectory of the AEV development in terms of design in observation to optimize energy efficiency.

2) The brainstorming sharpens the team’s critical thinking skills in the sense to apply prior physics, material science, and calculus knowledge to create the AEV design.

3) Each member in the team was able to embrace their creativity by engaging into the design considerations and to come up with an individual’s concept sketch.


Week 4 Situation In order to aid in the design process, the group will investigate how to effectively measure and evaluate the performance data of an AEV after its run. The team will measure the AEV’s performance by interpreting the EEPROM data with the aevDataRecorder function. The team will then calculate critical data such as total power consumed and incremental power consumption. This data will allow the group to better design the vehicle and optimize the code with respect to power consumption. After taking the given data into account multiple aspects of the AEV will be targeted for improvement. Weight and the distribution of it, wind resistance, and friction will all be reviewed. Possible part removal and streamlining will be some of the first attempts at perfecting the prototype, followed by possibly more drastic redesigns. Weekly goals 1) Learn how to download the EEPROM data from the Arduino 2) Learn how to convert the EEPROM data into a usable format 3) Understand the relationship between the AEV’s performance and the collected data 4) Improve time management and communication skills Weekly schedule

Table 1: Week 5 Schedule

Task Teammate(s) Start Time Due Date Time Needed

Data tables and figures Terry,Pablo 2/9 2/15 1 hour

Optimize Code Affifi 2/10 2/15 1 hour

Data Interpretation Garrett 2/7 2/15 1 hour

AEV Construction All 2/2 2/15 2 hours

Week 5 Progress Report All 2/8 2/15 3 hours


Appendices Team Meeting Notes 02032017 3:00pm4:30pm The objective of this meeting was to begin work on the progress report, as well as outline tasks for individual members, and set up a timeline for project completion and future meetings. Completed Objectives

Tasks were assigned to individual members Scheduled a future meeting for the team.

Objectives to be completed The progress report will still require some finishing touches.


Figure 1: Concept Sketch #1


Figure 4 : Concept Sketch 4


Figure 5: Final Concept Sketch

g ro u p d ‐ a ﬃ ﬁ h u s s e n , g a r reĥ m a r l owe , te r r y n … · 2017. 12. 22. ·...

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