Engineering Experience 4: Design a Small Solar Vehicle/2014: Team PM12

Introduction
The main theme of Engineering Experience-4 is to design and develop a SSV (Small Solar Vehicle), which drives at high speed and can resist the impact of a collision. Team 'SolarBullet' is one of the teams that makes this vehicle come to life. With the team motto of cooperation and equal participation in every department of the project from each members, 'SolarBullet' is determined to construct THE innovative solar car, which:
 * is energy-efficient
 * can cover 10m distance in maximum 20 seconds
 * is strong enough to survive the collision against a pétanque ball
 * is able to push the pétanque ball as high as possible
 * and is cost-efficient

Design description
As you can see in the picture, our solar car contains three major parts. The base and the solar panel. The base is the main frame of our SSV. It is 23 cm wide, 35 cm length and 6 mm thick. For the moment, our does not have a controller and the most essential parts are build, but during testing the car does not drive in a straight line yet, this is due to fixation to the shaft and material type. In order to solve the problem of letting the car to drive straight, we attached side wheels on the base, but that would of course has a consequence in loss of energy. The height of the main frame is 77mm, we did this in order that air blows through the car more easily and less air pressure is present between the main frame and the ground. The more air pressure in between, the more the car would be held back while driving. On the base we fixate a 9V-motor and 2 gears, 2 shafts and 4 plexi glass wheels. First we took a gear ratio of 11 in our 2nd design. Now, in our 3rd and final design 2 gears were used, one gear has 80 teeth and the other one has 10. So that the gear ratio is 8. We decreased the gear ratio, because in Matlab the short circuit current of SSV that was used before was lower and after plugging in the real short circuit current we obtained a gear ratio between 8 and 9. The small gear is in contact with the motor, so when the motor start running, the small gear starts to rotate as well. The big gear is in contact the small gear, so when the small gear rotates, the big one will rotate. The front shaft is controls by the big gear, in that way when the shaft will rotate with the same speed as the big gear. At both ends of the front shaft, 2 wheels are fixed. We chose the wheels to be made from Plexi glass, because they have less friction with the rubber road of the race. In order the limit the friction in general, we also attached bearing to the front wheels. At the back of the car, we also have a shaft and 2 wheels. Their function to balance the car and to follow the front wheels. We choose the power and the rotation to be in the front wheels because then we create more speed and have a larger power, like in BMW cars. In order to kick the pétanque ball, we attached a metal to a lengthened part of the main frame. And as a support for the solar panel itself, we used a gps support.

Week 1
10-14/02/2014 Venue: cafetaria GroupT All the group members discussed about the first assignment work. We divided the work into five tasks and each task has been assigned to one member. We have set up a deadline to complete the tasks and upload the works on wikipage and in Dropbox. We decided to meet extra the day day before the deadline to solve problems if anyone has a one with their work. Target tasks are Work Break Down Structure, Gantt chart, Plan of Approach, Cooperation Contract and Meeting Report.

Week 2
17-21/02/2014 Venue: cafetaria GroupT The following discussion went on: Using values of U-I graph, we have derived the remaining unknown values by using maple and verified with manual calculations. After that we were able to analyze the graphs of P-U and P-I. The formula of the I-characteristic was decoded with the use of the motor information from the Internet. Errors are minimised by verifying the results. At the end of the meeting everyone clarified their doubts regarding project.

Week 3
25-28/02/2014 Venue: cafetaria GroupT We received small feedback from our coach about our previous report that we have handed in. The coach told us that we cannot use our average m for the whole calculation, instead we should use the average m coming from a calculate calculated current I (instead of the measured current). Therefore we find a new corresponding plot. Then we should search among our m values, which one is the closest. At the end, we use that m to calculate everything again. Due to week 5 we have a couple of assignments. First of all we have to calculate the Optimal Gear Ratio and Optimal Mass of our solar car and then we simulate that for at least 10 different gear ratios and 10 different masses using Matlab. To be more efficient we worked in pairs of two, so one pair would solve the problem we had with the last report and another pair would calculate the gear ratio and the last pair would spend time to calculate the optimal mass of the car. The pair that were doing the m problem, were having difficulties. Because the value that they found out was so different from our average m. So we showed on one the coaches and he said that our average m is just too big, so it should be some calculation problems. Then we searched for the problem, but we didn’t find out anything so we just decided to do it all over again in a new excel sheet. Then everything was alright. So we think we missed out on some dollar sign or something. The other pairs just went on with their calculations. We are still busy with finding the equations and calculating. The par that were busy with fixing the last report are now divided in the other two teams. So we are now working on teams of tree.

Week 4
4-7/03/2014 Venue: cafetaria GroupT Finding the Optimal Mass was our main purpose during this week. In order to not let only one person suffer of this, we have been brainstorming together. After some different insight from every individual, we finally we obtained the equation for our optimal mass. Therefore we found the mass of the car in function of the mass of the ball in a mathematical equation. One pair of the group has already began to see how Matlab works. Still, a lot of work should be done. Our next goal due to next week is to calculate the Gear with the help of Matlab. Therefore everyone has to introduce themselves on Matlab and Simulink.

Week 5
11-14/03/2014 Venue: cafetaria GroupT The mass relationship has been implemented in Matlab. At the beginning there were some difficulties in understanding the Matlab code posted on toledo. Although after asking the coach and colleagues their inputs, some clarifications came up. 2 people of the team were in the mean time starting on the Simulink part. Till now, no problems have been risen on that. We also already began with writing down the Report 2, case SSV Part I, that has to be hand in by next week Friday.

Week 6
17-21/03/2014 Venue: cafetaria GroupT This week we were trying to finish the report SSV part 1. Two people took care of Simulink and finished up their work. We also continued with matlab. We also did the bisection method. Some of the team members also began to collect information that was needed for the report. At the end we finalized the report.

Week 7
24-28/03/2014 Venue: cafetaria GroupT This week we got feedback about our report SSV part 1. There were some issues that need to be corrected, as we did. We also made a design drawing. But the most important part this week, was preparation for the test.

Week 8
31/03-04/04/2014 Venue: cafetaria GroupT To be on time, we scheduled for this week to finalize the decision of the design. In Fablab we did the main frame of our construction. We also started on writing some part of the next report that we have to hand in, some as finance calculation, enterprising, etc. We also are going to put our solar car together and see what are the new challenges that we have to overcome. During the holidays mainly we constructed the solar car.

Week 9
31/03-04/04/2014 Venue: cafetaria GroupT Improvement of constructed car. Following problems are tried to be solved: 1) reaching optimal weight of SSV; 2) driving in straight path, wheel problem; 3) solar panel positioning

Week 10
28-30/04/2014 Venue: cafetaria GroupT We start solving the questions of SSV part II. Therefore we managed to determine the losses and power flow with the Sankey Diagram; strength calculations were done to analyze whether the car will survive the impact; Lastly, the collision process was also studied and solved. At the same time, we rebuild our SSV in fablab in order to make the car more optimal for the collision.

Week 11
05-09/05/2014 Venue: cafetaria GroupT For the report of SSV part II we finish and check the problems we solved last week and solve the rest of the questions. The Education part now has also been taken in consideration.

Week 12
12-16/05/2014 Venue: cafetaria GroupT Feedback was given by our coach, and necessary corrections are done. A remodeling of the SSV was also done to improve the strength of our car. As a preparation for the upcoming 2nd test, we arranged a meeting for studying together.

Week 13
19-23/05/2014 Venue: Martelarenplein train station Leuven Preparation SSV for race.

Week 14
26-17/05/2014 Venue: GroupT Preparation for test 2.

Race Results
Round 1: AM3 / PM12 0.7cm AM1 2.5cm Round 2: PM7 5.8cm PM14 10.6cm PM12 9.5cm Round 3: PM12 / PM3 5.9cm AM6 4cm

Links
DropBox https://www.dropbox.com/home/EE4%20SolarBullet

Used References
Plexiglass: http://www.plexiglas.com/export/sites/plexiglas/.content/medias/downloads/sheet-docs/plexiglas-general-information-and-physical-properties.pdf Matlab Simulink Optimal mass Gear ratio wheels and gears body frame