Design, Dynamics, and Control of Mobile Robotic Systems
Mobile robotic systems are increasingly prevalent in several fields of academia, industry, and everyday life. This dissertation outlines the development of several means of locomotion for such systems and the tools created and used to design them. Novel mechanical designs with minimal actuators are combined with advanced control systems to create dynamic locomotion behavior. A single, unified Lagrangian dynamics architecture is used to represent a variety of robotic systems, derived from first principles and applied programmatically. Model-based control methods are heavily used to take advantage of the known dynamics and are also applied programmatically for the automatic generation of control laws and gain scheduling lookup tables. Improvements to encoder velocity estimation across a wide velocity range are described in detail. A number of key hardware advances in different fields are exploited to create low-cost, but capable, mobile robotic systems: additive manufacturing (3D printing), powerful embedded microprocessors (Arduino, ARM, FPGA), solid state sensors (MEMS accelerometers and gyroscopes), and inexpensive brushed DC motors. This dissertation presents both notable results and tactical details of implementation that will be useful to those designing similar systems.
Several novel robotic systems are presented in this dissertation. First, two incarnations of a mobile balancing platform with two coaxial wheels with the center of mass above the center of rotation are presented. Active feedback control is required to stabilize the system. Next, Switchblade is a patent pending treaded inverted pendulum designed for maximum mobility over a wide range of terrain including tight spaces and significant obstacles (e.g. stairs). Multiple variants of the design are explored, which shows that the vehicle concept is broadly applicable across different length scales and use cases. SkySweeper is an under-actuated robotic system designed for multimodal locomotion along wires and cables. Finally, RAPID is a reconfigurable, automated dynamometer for characterizing small DC motors, the primary purpose of which is identifying the operating parameters of motors used in vehicles with model-based control and estimation algorithms.