In this paper, we present a method of locomotion control for underwater vehicles that are propelled by a periodic deformation of the vehicle body, which is similar to the way a fish moves. We have developed control laws employing ldquoextremum seekingrdquo for two different ldquofishrdquo models. The first model consists of three rigid body links and relies on a 2-degree-of-freedom (DOF) movement that propels the fish without relying on vortices. The second fish model uses a Joukowski airfoil that has only 1 DOF in its movement and, thus, relies on vortex shedding for propulsion. We achieve model-free and position-free ldquosource seeking,rdquo and, if position is available, navigation along a predetermined path.

Our past work introduced source seeking methods for GPS-denied autonomous vehicles using only local signal measurement and operating in two dimensions. In this paper, we extend these results to three dimensions. The 3D extensions introduce many interesting challenges, including the choice of vehicle models in 3D, sensor placement to allow probing-based gradient estimation of an unknown signal field in 3D, the question of what type of pattern of vehicle motion can be produced in an underactuated 3D vehicle to allow tuning by single-loop or multiloop extremum seeking, and the shape of attractors, which become very complex in 3D. We present two control schemes that address these questions. The first scheme focuses on vehicles with a constant forward velocity and the ability to actuate pitch and yaw velocities. The second scheme employs vehicles with constant forward and pitch velocities and actuate only the roll velocity. Our results include convergence analysis and simulation results.

Extremum seeking has been successfully applied to source seeking for autonomous vehicles operating in two dimensions. In this paper we extend these results to vehicles operating in three dimensions. The extension is interesting for several reasons. First, there is the choice of vehicle models to consider, and second there is the question of what type of vehicle movement can be actuated. We present two control schemes which address these questions. The first scheme focuses on vehicles with a constant forward velocity and the ability to actuate pitch and yaw velocities. The second scheme explores vehicles which operate with a constant forward velocity and a constant pitch velocity and which are capable of actuating only the roll velocity. We present the vehicle models, details of the control schemes, and simulation results.

Summary form only given. Recent results from the ethological literature challenge some widely held views about the development of animal behavior and offer new directions for research into the organization of synthetic behavior systems. The process of development is often seen as one of continual refinement, with infantile behaviors representing the primitive precursors of adult behavior. While this notion is intuitively pleasing, there are two ways in which it may be incorrect. First, Coppinger (Coppinger and Smith 1990) argues that infantile behaviors are just as well adapted as adult behaviors, but adapted to the challenges that the organism faces during its early life and early social context. In his view, development is best understood as a process of, 'swapping' elements in the behavioral repertoire rather than refining them; the adult version of a behavior, in other words, is a distinct replacement for its juvenile counterpart, not an outgrowth of it. The second problem with the traditional view of behavioral development is that infantile behaviors are often expressed in an entirely different motivational context than their adult counterparts. Indeed, infantile behaviors that satisfy a particular motivational system such as hunger may be controlled by entirely different motivational systems. Hall and Willams have shown, for example, that during the first several weeks of life, a rat pup's suckling rate is independent of how hungry it is. That is, rat pups suckle because they are innately motivated to do so, not because they are hungry. Similarly, Hogan (Hogan 1999) suggests that during the first 48 hours of a chick's life, the amount that it pecks has nothing to do with its level of hunger. Leyhausen (Lorenz and Leyhausen 1973) has shown that the behaviors that make up the sequence of predatory behaviors in cats are refined through play, often well before the cat ever makes 'the connection' between the acquisition of prey and a subsequent reduction in hunger. What is going on here? In the first two cases, the juvenile behaviors act as 'fail-safe' mechanisms to ensure that the creature's needs are met without needing an innate or learned connection between the behaviors and the critical motivational systems that they act to satisfy. In the latter case, behaviors that will be critically important in adulthood are initially expressed and refined in a context in which the costs of failure are low, i.e. the creature's life doesn't depend on how well they perform the behavior at that given moment. Both of these concerns suggest that by re-examining our assumptions about development in animals, we may be able to glean generally useful organizing principles for the design of adaptive computational systems.