Additive manufacturing of robot components for a capstone senior design experience

Abstract

The University of North Carolina at Charlotte competed in the 5th Annual NASA Robotic Mining Competition with a robot that included several additively manufactured (AM) parts. The team used a design-build-test approach throughout their project and were drawn to additive manufacturing (or rapid prototyping) to help them to reduce the cycle time on each iteration of the design-build-test process. Two different technologies, fused deposition modeling (FDM) and film transfer imaging (FTI), were used to additively manufacture these parts, using a Stratasys Dimension and 3D Systems VFlash respectively. These technologies provided some significant advantages in producing complex parts for the robot, but it did come with some limitations as well. Several students started the project with the mainstream notion that additive manufacturing allowed effortless printing of any part you desired from a CAD file. Through both successes and failures, they came to realize both the limitations and appropriate application of both the FDM and FTI process and their associated materials. The AM parts that ultimately made it on to the robot included replacement aperture covers for a photomultiplier tube (PMT), a custom gimbal used to orient the PMT, a latch used to secure a deployed arm, enclosures to protect sensors mounted on the robot exterior, and custom enclosures for the laser beacon system used for navigation. Notable disappointments for the AM parts included issues with part warpage, inappropriate application of sparse internal structures, and restrictions related to discrete layer thicknesses. These setbacks were ultimately resolved by either redesigning the parts, additional post processing, or shifting to alternative manufacturing approaches. The key success for the AM parts included the desired reduction in cycle time, effective matching of existing complex geometry, efficient mass reduction, and increased productivity by allowing students to move on to other tasks while parts were being printed. Once final embodiments were settled on for the various AM parts, they performed their intended functions without incident throughout the testing and competition at Kennedy Space Center.