Self-Assembling Modular Systems: Enhancing Efficiency and Accuracy in Robotic Lattice Assembly

Abstract

This thesis introduces a robotic system designed to progress the concept of modular ’industrial Legos,’ aiming to harness the advantages of modularity in new environments, such as CNC machines and factory automation. This vision intersects with the domain of modular self-reconfigurable robotics and robotically-assembled structures. The work presented here extends from existing research and is particularly focused on three key areas: (1) the development of improved modular connectors between system elements, (2) the advancement of modular linear actuator designs that not only facilitate component rearrangement but also contribute to task performance, and (3) improved performance and efficiency of lattice-assembler robots. All topics are examined in depth, and their relevance to prior work is carefully outlined. Central to any modular system is the design of connectors, which enable the modules to assemble into various configurations. Although extensive research has been conducted in this area, existing connector solutions often fall short in terms of repeatability, affordability, and mechanical strength. This thesis addresses these shortcomings by introducing a new connector that utilizes a kinematic coupling for high-repeatability and incorporates a simple, screw-based latching mechanism for strong mechanical connections. Detailed design specifications for these connectors are provided; these designs are both relatively simple to implement and robust enough to withstand the harsh conditions encountered in industrial settings. In CNC and industrial automation, linear actuators often pair with structural elements to form gantry systems, allowing for precise 3D-positioning of tools and end effectors. While there are self-contained linear actuators that offer some level of modularity—often termed ’superficial modularity’—traditional designs generally lack the capacity for what might be called ’deep modularity.’ This refers to the unique ability to seamlessly join two actuators of length L to create a single actuator of length 2L. To address this, the thesis presents a high-strength, extensible modular linear actuator built on magnetic lead screws, capable of general linear motion and of cooperating with other modular elements to rearrange modules. Lastly, this thesis introduces an assembly robot named Belty, equipped with proprioceptive actuators that feature large-diameter, high-torque-density brushless motors and minimal gearing. These actuators offer several advantages, such as efficient motion, back-drivability, force sensing, and impact resilience. These features are especially valuable for assembly tasks within constrained spaces, as they enable simplified assembly algorithms through contact-rich motion primitives (e.g., dragging parts, bumping into objects). Following the hardware discussion, assembly algorithms are detailed to demonstrate the system’s ability to construct a diverse array of structures quickly and energy-efficiently.