Robotically assembled aerospace structures: Digital material assembly using a gantry-type assembler

Abstract

This paper evaluates the development of automated assembly techniques for discrete lattice structures using a multiaxis gantry type CNC machine. These lattices are made of discrete components called "digital materials." We present the development of a specialized end effector that works in conjunction with the CNC machine to assemble these lattices. With this configuration we are able to place voxels at a rate of 1.5 per minute.The scalability of digital material structures due to the incremental modular assembly is one of its key traits and an important metric of interest. We investigate the build times of a 5x5 beam structure on the scale of 1 meter (325 parts), 10 meters (3,250 parts), and 30 meters (9,750 parts). Utilizing the current configuration with a single end effector, performing serial assembly with a globally fixed feed station at the edge of the build volume, the build time increases according to a scaling law of n 4 , where n is the build scale. Build times can be reduced significantly by integrating feed systems into the gantry itself, resulting in a scaling law of n 3 . A completely serial assembly process will encounter time limitations as build scale increases.Automated assembly for digital materials can assemble high performance structures from discrete parts, and techniques such as built in feed systems, parallelization, and optimization of the fastening process will yield much higher throughput.

Discretely assembled mechanical metamaterials

“…Scaling to part counts above 10 3 will benefit greatly from assembly automation. Stationary gantry platforms have been fitted with end effectors for voxel transport and bolting operations (36), and mobile robots have been implemented to perform similar operations while locomoting on the lattice as they construct it (37). Stationary systems promise high throughput for a bounded work envelope, while mobile robots can be parallelized and require no global positioning due to local alignment features, offering benefits of autonomy and reliability.…”

Analytical Comparison between the Speed of Screw and Crank-Rocker BasedPick and Place Mechanisms for Seedling Tray Seeding Machine

“…The estimation of the pick and place time in a pick and placement operation is vital in efficient assembly plant design process. Such time was studied by Ellis et al (2001); Trinh et al(2017) and Bharadwaj, et al(2018). It is based on this time analysis that the mechanism will be adopted for detail design or another option will be considered in the event of longer operational circle period.…”

Elastic shape morphing of ultralight structures by programmable assembly

“…Comparison to 3D printing, automated carbon fiber layup [40], filament winding [41], or anisogrid fabrication [42], shows that automation is extremely important. Development of automated robotic assembly of discrete lattice material systems is in its infancy, on relatively small (<1m) scale structures, but has already demonstrated a rate of 40 seconds per building block [43], or nearly 40,000 (cm 3 /hr), as shown in table 2. We see that even mass throughput is on par with current low-cost 3D printers.…”

“…The tip set is first fit to lines in the y-z and x-y plane and the endpoints of each fit lines are used to calculate the distance between the leading edge and trailing edge identifiers of the set, d x , d y , d z for the x distance, y distance, and z distance respectively. The rotation matrix about the z-axis between the tunnel reference plane and the motion capture system is: [46] <60 <65 >1 Polyjet (photopolymer) [47] <80 <95 <1 Discrete lattice material manual assembly (this work) ≈5000 ≈27 >1 Discrete lattice material robotic assembly [43] ≈39821 ≈220 <1…”