Nonlinear control and bioinspired underwater vehicle systems

Professor Kristi MorgansenUniversity of WashingtonDepartment of Aeronautics and AstronauticsUnderwater locomotion and propulsion for underwater vehicles provide rich applications for the development of control methods for nonlinear systems and underactuated mechanical systems. In the work here, the tasks of modeling and control for agile gait generation for robots built with fin propulsive and maneuvering surfaces are considered. Previous work for such bioinspired devices has shown that simplified models with quasistatic lift and drag can be used to construct trajectory tracking controls for forward and turning motions that strongly resemble biomimetic motions. Here we will evaluate the use of such models for agile maneuverability by comparing biomimetic fast start and snap turn data from experiment with simulation data from the model. Beyond single-vehicle applications, a number of current science applications indicate the need for operation of multivehicle groups composed of different types of vehicles operating in different media (air, water, space). Recent work in coordinated control of vehicle systems has shown that earlier studies in mathematics, physics, and chemistry with models of interconnected oscillators can be used to construct controls for coordinated vehicles. Additionally these oscillator models have been demonstrated to have direct connection to Frenet-Serret models of dynamics for nonholonomic systems (e.g. ground vehicles, fixed-wing aircraft, and underwater vehicles). The work presented here will address the construction of controls for oscilator-based analysis that allow a group of vehicles to track a moving target. Further, when these models are considered in a discrete time setting, effects of intermittent, dynamic and asynchronous communication can be incorporated into the dynamics. Stability bounds for particular group modes of behavior (identical heading or common point of rotation) can then be determined in the context of limited communication. Results are demonstrated in simulation and experiment with applications drawn from the engineering contexts of autonomous air and underwater vehicles as well as the biological context of schooling fish.Beyond single-vehicle applications, a number of current science applications indicate the need for operation of multivehicle groups composed of different types of vehicles operating in different media (air, water, space). Further, such systems are needed to operate with variable levels of autonomy and human interaction. Recent work in coordinated control of vehicle systems has shown that earlier studies in mathematics, physics, and chemistry with models of interconnected oscillators can be used to construct controls for coordinated vehicles. Additionally these oscillator models have been demonstrated to have direct connection to Frenet-Serret models of dynamics for nonholonomic systems (e.g. ground vehicles, fixed-wing aircraft, and underwater vehicles). The work presented here will address the construction of controls for oscillator-based analysis that allow a group of vehicles to track a moving target. Further, when these models are considered in a discrete time setting, effects of intermittent, dynamic and asynchronous communication can be incorporated into the dynamics. Stability bounds for particular group modes of behavior (identical heading or common point of rotation) can then be determined in the context of limited communication. Results are demonstrated in simulation and experiment with applications drawn from the engineering contexts of autonomous air and underwater vehicles as well as the biological context of schooling
fish.

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