Thus, by switching the polarity of the fingers, we are able to push the stepper one step. The four wires are wrapped to control two electromagnets, each of which powers every other opposing finger in the motor. Stepper motors have a magnetic core with protruding fingers of alternating polarity. To learn how to operate the stepper motors on a very low level, we referred to both the L298N datasheet and the Arduino library. Since our motor only had to step a certain extent without requiring control of speed, we opted for a simpler stepper motor driver module (L298N)-a module based on STMicroelectronics’ motor driver, which simply steps-up the control lines to feed into the motor’s inputs. The wiring hardware of this project was very simple, because the 3D scanner did not require too many peripherals.įIGURE 4 – Wiring diagram to the Raspberry Pi’s GPIO pins The main parts we used included the Raspberry Pi, the line laser, the stepper motor, a stepper motor driver, the PiCam, a metal push button, an LED and raw material for laser cutting and 3D printing. The device has two main layers-the electronics bed and the main bed, with holes for wires to run between the two layers. The device is a simple box, with a lid with laser-cut hinges. This lid minimizes the amount of light that leaks into the system, because external light can produce noise in the final scan.īefore we began laser cutting or 3D printing, we used Autodesk Fusion 360 to make a detailed 3D model of our design ( Figure 3). The electronics are hidden from sight in a bottom compartment, and the lid allows easy access for object placement on the rotating tray. These pieces were housed in a sleek, laser-cut box with a hinged lid, and held together with T-joint M3 machine screws. The third dimension, Θ (theta), is then achieved by rotating the object to a new slice. In radial coordinates, this picture would yield both the r and z components. In image processing, the distance between each segment of the line from the center of the object could be collected. This projection could be captured on the Pi Camera (PiCam), have its perspective corrected, and then filtered prior to image processing. The central component in this design is the line laser that projects upon a vertical slice of the objects. With our background in computer graphics, embedded systems and mechanical design, we decided that this was a feasible and interesting project for our team to take on. The cost of these scanners is often quite expensive. The ability to quickly scan existing objects can make them easy to reproduce, and facilitates designing other parts around them. The inspiration for this project came from our past experience with 3D printing and rapid prototyping. The object is spun on a rotating tray, and the process is repeated until the full object is scanned. The camera detects the slice’s distance from the center to give a mesh slice. The laser is positioned 45 degrees askew from the laser, and projects a bright red line on one vertical slice of the object. The device does this by utilizing a line laser and the Pi Camera to perform computer vision. obj mesh files for reproduction using 3D printing. Our Laser Scanner project is a Raspberry Pi-based embedded system device that’s able to digitize objects into.
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