ASSIGNMENT 4B: 2.5 AXIS MOTION SYSTEM

This project primarily operates on the principles of Long Exposure Photography where a stable camera is set up to take in light over a very long period of time and combines the images taken into 1 picture. The task of this project is to design a 2.5 Degree of Freedom system with which a certain action can be completed. The 2 degrees of freedom of this project is in the theta and phi directions (if using spherical coordinate system). The half degree of Freedom was achieved through the usage of a multi colored Neopixel LED Bulb which would either be a certain color or off. This project was designed so that it could be easily disassembled by removing the LED "Brush" Arm and unplugging the Data In wires from the Arduino. The controller joystick is also easily disconnected from the assembly by unplugging the attached ribbon cable. The main housing was designed to be compact, lightweight, and functional.

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To actuate the movements, a stepper motor was used for the theta direction due to it having a high degree of control in 360 degrees and a servo motor was used for the phi direction due to it having control across 180 degrees (since the table or supporting structure would prevent the arm to move past this physical constraint).

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The primary gearing structure was 3D printed to operate with the given drive belt and gears. The protective dome encasing the project was done using a thermoforming. Finally, the name and bottom plate of the project was fabricated using Laser Cutting and Engraving.

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The electronics and coding of this project were the more challenging areas of this project. A significant obstacle during fabrication was the restriction that the wires of the LED and Servo Motor gave. Since the entire device rotates about the Z axis, the wires would experience both tension and torsion after a few rotations causing them to unplug themselves from the Arduino. A few solutions were designed to prevent this but there was not enough time to test and implement them. Firstly, conductive paint was considered as a viable alternative to wires where the signal and power would be delivered through a brushed system (Similar to how brushed motors work). Another possible solution was to use strips of conductive material around the inside of the dome and a metal contact that would connect and power the required components. While the final product did not feature these solutions, it was still able to safely perform a maximum of 3 to 4 rotations before a hard stop prevented any further rotations.

Currently for controls, a 2 axis joystick with a button was used. The Y axis would control the Servo Motor, the X axis would control the Stepper Motor, and the button would operate the LED. The code implements a case system (Please download the ControlCode PDF for changelog) to control everything. It was also originally planned to be able to input a matrix of coordinates so that the apparatus could run autonomously however that requires a lot more calibrations than the time allotted for this project.

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If a second iteration of Das Brush^3D were to be made, it would be made with the aforementioned hardware improvements as well as a wireless controller so that the artist would not be constrained to an area around the apparatus. Other improvements could also be made with the use of multiple Arduinos as that would allow the bulb and motors to operate independently of each other resulting in a more flexible product.