3D Printing onto Moving Target

Summary: Conventional 3D printers print on a static baseplate or object in an open-loop control scheme, meaning there is no sensory feedback to the printer controller regarding the base plate's position or orientation. As a result, the baseplate must be stationary during printing to achieve acceptable print accuracy. By actively monitoring the position and orientation of the object being printed on, a controller can correct for movement of the target object, allowing for printing to occur on an object moving along an arbitrary, unknown planar path.

Two endoscope cameras were placed next to extruder nozzle of the printer to provide a composite image of the target that was unobscured by the nozzle. This composite video feed was processed to find the center of an identifying object on the print target with respect to the extruder nozzle. A position-based visual servoing controller combined the X and Y position of the target, desired print geometry data, and the extruder’s current position to generate the appropriate extruder velocity commands in the X and Y directions. These velocity command were passed to a microcontroller on the main print gantry, which was responsible for interpreting the velocity commands and running the low-level hardware components.

A physical prototype was constructed to validate the control strategy and computer vision tracking algorithms. The controller was validated by feeding in the current X and Y position of the target’s center from the path generator gantry, a device that moved the target through a random path. The system was found to print on a moving surface with a speed of 2 cm/s, with an accuracy of 1 mm of the desired geometry. The computer vision program was validated by following an identifying mark on the target as it moved along a random path. While both components were validated separately and found to work, further development is required to combine both the computer vision and controller aspects of the project into an integrated computer vision and control program.

Contributions: For this system, I designed many of the components using SolidWorks and used rapid prototyping techniques such as laser cutting and 3D printing to make them, such as the extrusion nozzles and moving target gantry. I, along with my partners, assisted in developing the control scheme to have the 3D printing gantry follow the moving target.

Year: 2017

Specifics:

Report: 3D_Printing_Moving_Target.pdf

Video: TBD