Engineering Experience 4: Design a Small Solar Vehicle/Nl/2014: Team AM5
We are team helios, one of the teams who are building a small solar vehicle. The main goal for this vehicle is to push a petanqueball as far as possible. We have 9 weeks to make and analyse the solar vehicle and to write a detailled report about it. We try to update this page every week and the content will contain things like a blog, the Work Breakdown Structure (WBS), the reports, the used sources and much more. So stay tuned! If you have any questions about certain topics on this project, feel free to contact a teammember. Our E-mail adress can be found in the coorporation contract.
In the following table all our team members and their functions are listed.
|Jonas De Broyer||Team leader / Matlab programmer|
|Yannick Michiels||Report supervisor|
|Bram Cludts||File administrator / Responsible of construction|
|Kristoff Fluyt||Simulink programmer / Responsible for wiki|
The groups were made and everyone had to write down what their skills are and in what they hope to improve during this project. Everyone starts mading an individual WBS and at the end they were put together to make a complete WBS. This was the starting point to make the Gantt Chart. Contact info was exchanged and by the end of the week, a coorporation report and Plan of Approach was submitted.
There was a seminar about the solar pannel and the used DC-motor. We had done a test with the solar pannel to calculate the maximum power it could deliver and to give a picture of the Volt-Ampère relation. Every member got the assignment to think of how the vehicle should be build.
The seminar of this week was about the gear ratio and how we should start with the analysis of the SSV. We did a small test that contained questions about the DC-motor and solar pannel. We have received feedback about the excel file (solar pannel calculations) and this was good enough. We started on our analysis of the SSV.
Mr Goethals gave us an introduction to Simulink and Matlab. We processed the data of the solar pannel and received important values (maximum power, ... ). We made a template for our technical report and process report. We started to fill in these reports with the data we already have.
We had an introduction of FabLab Leuven, this was given by the manager: mr. Lambaerts. He told us which machines there were and the location of FabLab. After this mr. Spaepen explained us what inkscape was and how to use it because we need it for the laser cutter in FabLab. While Bram, Jonas and Wout were doing some more calculations, Kristoff and Yannick started on the reports.
We are trying to finish the calculations and the reports about case SSV1 and case Simulink. These items must be handed over this friday (21/03/2014). We had some issues with these calculations but we solved it.
After finishing our calculations, we started brainstorming about the design, the materials, where to get it, ... . This week we also received feedback from mr. Hu about case simulink. This was rather positive, only a small problem with our part of matlab.
--> meeting report: the meeting was held in week eight for this week.
We made a test about case SSV1 and case simulink. This test was not easy but we did our best on it.
We started ordering our materials, this gave 1 problem: the gears were not in time. Jonas and Wout went to Fablab on 10/04 for making the frame. In the second week of the easter break, we started building and this went pretty good without problems. Communication was a bit of a problem during the break due to the delay of the question-awsner time.
Some photos of the progress:
We did a collision test, this was done in the GroupT building at -2. This test was done under supervision of the coaches.
--> meeting report: the meeting was held in week eleven for this week.
We started to finish the technical report, everybody has his task. The sankey diagrams, the collision analysis, strenght calculations, ... were started. We added sidewheels to the SSV to be sure that it will reach the ball.
We tested the SSV on the track with the sidewheels and with a ball. The results where pretty good, we reached the ball and hit it good. We had only 1 little problem, the holder for the item that hits the ball was breaking down a little bit, we are going to repare this. It's not a issue because it's only a small part that's breaking down.
We can't do the race because it's not the perfect weather for it. We have the possibility to show our SSV to the teachers and everybody else that's on GroupT, this happens from 12h till 13h in the Atrium. There they can vote for the most innovative and most beautifull SSV.
The purpose of this phase is mainly to get a good picture of what should be done, who should do it and when it should be done.
Plan of Approach
Work Breakdown Structure
We have divided the bigger parts into smaller parts, on this way we have a summary of what has to be done. This is the frame of our gantt chart.
This shows who is responsible for which task, when it has to be done and how many hours we expect to spend on it. When the project is proceeding, we fill in the ours we actually worked on it.
Case SSV Part I
Below you can find the link to the calcalations we made for the Solar Cell and the DC-motor. Also the most important graphs to illustrate the experiments can be found here. https://www.dropbox.com/home/Engineering%20Experience%204%20-%20SSV/Calculations/Solar%20pannel
In the technical report a lot info can be found.
--> link techinical report: https://www.dropbox.com/s/idsetihhfi03pzl/Goede%20Technical%20Report.docx
Simulink is a programme that simulates (Suprising right?) all kind of things. We used it in combination with matlab for simulating the race and do several calclations with it. Again, in the technical report you can find a detailed explanation of it.$
-->link technical report: https://www.dropbox.com/s/idsetihhfi03pzl/Goede%20Technical%20Report.docx
Case SSV Part II
At the first meeting, we had a little brainstorm session where everyone could share his thoughts on how they wanted to build the SSV. We were thinking about a design that was aerodynamic, systems to absorb impact on the solar panel and on how to keep the SSV alive after collision. With this in mind, calculations on optimal gear ratio and mass were performed. Not the most easy calculations, neither the hardest, but they took some time. Once we had calculated these numbers, it quickly showed difficult to accomplish these requirements in real design. For starters, the optimal gear ratio was a decimal number: 12.9. Which is practically impossible to achieve. The closest, easy to build, solution was a gear ratio of 12. Secondly we had to keep the mass low, to approximately twice the mass of the ball. Which limited our design freedom significantly. The mass and gear ratio weren’t the only restricting factors to the design. First of all the SSV had to be able to hit the ball. Therefore it had to have a “ram” placed at the correct height.
As you can see in the picture, during the race, the center of the ball will be located at a height of 86mm. Furthermore the ram has to be able to go through the hole without hitting the panel. The last design specification needed to be kept in mind, was the solar pannel. The SSV has to be long enough to carry it. At the start of the building process, the design was too heavy. So one of the solutions was to take a smaller frame and add some extra round holes in the side of the SSV. Stylish, but also useful. They made the space between the vertical structures accessible for cables connecting the solar pannel and the engine. After all these weight reducing operations, the SSV was still a bit too heavy. But after testing it, it seemed to do well. So we didn’t change it anymore.
We did the collision test and we got some data with this:
We analyzed the losses together and made a sankey diagram with this, this was done for the SSV on full speed and on half the speed.
Check the techinical report! You won't be disappointed!
--> link technical report: https://www.dropbox.com/s/idsetihhfi03pzl/Goede%20Technical%20Report.docx
File:Sankey Full Speed.JPG|Sankey
After twelve hard weeks, the SSV was finally finished.
The whole car is made out of MDF. Except the motor, the gears, the pusher and the solar panel.
The body of the car consists of three plates. We used three of them to ensure that it is strong enough to stay in one piece after the collision.
At front there is a steel tube. This is the same material as the ball so it well have equeal hardness. This is important for an optimal ecolision. The shape of the car is such that it has a solid front. The back is thinner so we gain some weight which causes the SSV to move faster. The steel tube is made at a preceise height so it can fit through the whole where the ball lays at the end of the track.
The solar panel lays on the back of the "pusher". So it makes about a angle of 30 degrees with the ground. Unfortunately we didn't have enough time to implement a system that could turn the solar panel in the optimal direction for the sun.
There are holes drilled in the pusher its back. This is to lose some weight.
In the technical report there are some more pictures of and some more info about the SSV.
The two wheels in the back are placed at the center. This was done so we could make the back more thinner and thus lose some weight as mentioned above.
At the front there are four wheels. Two of them are normal wheels that drives the SSV forward. The other two wheels are there to let the car move in a straight line. They are placed horizontally and when the SSV begins to depart from it tracks. These wheels thouches the trakc and the SSV get pushed back to its course.
We also made a test-ride in the basement of Groep T at -2
When the time came to race, the weather wasn't too great. It was tuesday 20th and there were a lot of clouds. When the sun eventually (around 10am) showed itself we took the race. We ended up in the semi-finals with a top height of 18.7 cm. Everything went smoothly at the later races (in the beginning the height of the ball wasn't great), but the other teams were a bit better.