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The Project:
I am going to design and build a small rig to use for iPhone hyperlapse video-making. It will use gearing to slowly ride along a cable and will also have the ability to slowly rotate to pan while moving.
Goals of the Project:
Project Goals
- Create something that is of personal interest
Learning Goals
- Apply all the knowledge and skills learned to a self directed project
- Strengthen time management skills
First Phase - Prototyping
For this project, most of the work was on the computer using SolidWorks to design the framework of the rig, but before I started to do this CAD work, I wanted to do some rough prototyping out of cardboard and other materials. First I took inventory of what parts were necessary:
Two servos for forward movement and pan movement, a small battery pack, a breadboard, an Arduino board, a drive wheel, gears, a phone holding clip, and my iPhone. With this, I started to design a rough prototype out of cardboard to try to visualize in 3 dimensions how all the parts could fit together.
(Pictures of prototypes here)
Second Phase - Design
After I had decided on a broad design idea, I started to use solidworks and other programs to design the parts for the robot. For the hyperlapse robot, there were some specific parts I had to design from scratch. The parts were:
- Main frame(SolidWorks)
- Connection for iPhone(SolidWorks)
- Gears(Gearotic and Inkscape)
Gears
To slow down the rotation of the camera, I needed to use gearing. To fabricate these gears, I couldn't use a 3-d printer because the resolution isn't high enough to create the teeth. However, a laser cutter could cut the gears out of thin wood. Creating a gear file to print requires multiple steps. First, the gears are designed on a program called Gearotic. The Gearotic file is then opened in Inkscape, where the line thickness is changed to .001 in, the thickness that the laser cutter recognizes as a cut line. Finally, the Inkscape file is saved as a PDF and printed on the Laser cutter. These gears are extremely accurate and work perfectly with a 200mm 3d printer belt.
Connection to iPhone
Since I already had a JOBY iPhone Grip-tight mount, which adjusts to all sizes of iPhones, all I needed to do was design a piece to connect this product to a servo or other drive shaft. This design came together in about 30 minutes.
The Main Frame
The main frame was the most complex design aspect of this project. At first, I designed it as one large piece, but I quickly realized that I needed to split it into two sections because of the 3d printer size limitations(4 inches by 4 inches by 4 inches).
This original design turned out to be mostly reflective of the final version except its split into two pieces. Along with the split, room for the gears was added at the bottom for a more complete design.
The final design was printed and all the components fit as expected.
Third Phase - Programming
The next phase, which I worked on at the same time as the design aspect, but didn't finalize until fabrication had occurred, was one of the more simple parts of the whole robot. The drive-wheel, which rides on cable or string and provides longitudinal movement, was simply set to rotate counterclockwise at the slowest rate possible(about 1 revolution per 17.5 seconds).
The servo in control of the panning movement of the camera needed to move even slower. For this, I set the servo to rotate 1 degree every 7500 milliseconds(7.5 seconds), and for each of these 1 degree intervals the camera moves about 1/5 to 1/6 of a degree. In total, in an hour of filming the camera should rotate about 70 to 90 degrees.
Final Phase - Tweaking and Testing
Once the program and robot had been successfully completed, I moved onto testing the whole apparatus. The first test showed some flaws, but was for the most part successful.
The only issues were stability and lack of rotation, but hopefully using cable instead of string will take away a lot of the stability issues, and only filming for about 15 minutes explains the lack of visible rotation.
In conclusion, this was a very successful project, as I tackled an ambitious design challenge but ended up with a great looking and functioning final project.
Reflection on the Project
Informal Lessons:
1) Don't get too attached to one idea or design, because changes are going to need to be made.
2) Always remember possible constraints(printer size, material limitations) when designing.
If I were to start over, the only change I would make would be to use more gears so that continuous servos could be used for both systems. This could help with stability.
This was a very difficult and challenging but highly rewarding project. I enjoyed each day of work because I had to think critically but it wasn't too difficult that I felt stuck.
I do not have any suggestions for changes to this project, as it is a great project for this level of engineering students. It provides free choice, but for self-driven students it also provides an opportunity to really push towards higher achievement.
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