This paper describes the design, construction, and testing of a biomimetic pectoral (side) fin with actively controlled curvature for UUV propulsion. First, a 3D unsteady computational fluid dynamics (CFD) analysis tool has been adapted to computationally optimize any fin design, followed by a full parametric study based on our findings. Second, this said fin has been constructed, and our working optimized mechanical design is offered. Lastly, we make an experimental vs. computational result comparison for thrust, lift, and flapping moment data -showing that a UUV with this technology can have dramatic improvements in low-speed propulsion and control over traditional thruster methods.

No abstract

This paper describes the modeling, simulation, and control of a UUV in six degree-of-freedom (6-DOF) motion using two NRL actively controlled-curvature fins. Computational fluid dynamic (CFD) analysis and experimental results are used in modeling the fin as part of the 6-DOF vehicle model. A fuzzy logic proportional-integral-derivative (PID) based control system has been developed to smoothly transition between preprogrammed sets of fin kinematics in order to create a stable and highly maneuverable UUV. Two different approaches to a fuzzy logic PID controller are analyzed: weighted gait combination (WGC), and modification of mean bulk angle bias (MBAB). Advantages and disadvantages of both methods at the vehicle level are discussed. Simulation results show desirable system performance over a wide range of maneuvers.

A method was devised to vector propulsion of a robotic pectoral fin by means of actively controlling fin surface curvature. Separate flapping fin gaits were designed to maximize thrust for each of three different thrust vectors: forward, reverse, and lift. By using weighted combinations of these three pre-determined main gaits, new intermediate hybrid gaits for any desired propulsion vector can be created with smooth transitioning between these gaits. This weighted gait combination (WGC) method is applicable to other difficult-to-model actuators. Both 3D unsteady computational fluid dynamics (CFD) and experimental results are presented.

No abstract

This paper describes the modeling and control development of a bio-inspired unmanned underwater vehicle (UUV) propelled by four pectoral fins. Based on both computational fluid dynamics (CFD) and experimental fin data, we develop a UUV model that focuses on an accurate representation of the fin-generated forces. Models of these forces span a range of controllable fin parameters, as well as take into account leading-trailing fin interactions and free stream flow speeds. The vehicle model is validated by comparing open-loop simulated responses with experimentally measured responses to identical fin inputs. Closed-loop control algorithms, which command changes in fin kinematics, are tested on the vehicle. Comparison of experimental and simulation results for various maneuvers validates the fin and vehicle models, and demonstrates the precise maneuvering capabilities enabled by the actively controlled curvature pectoral fins.

No abstract

Summary. This paper describes the design, construction, and testing of a biomimetic pectoral (side) fin with actively controlled curvature for UUV propulsion. It also describes the development of a test UUV and the design of a fin control system for vertical plane motion. A 3D unsteady computational fluid dynamics (CFD) analysis has been carried out to computationally optimize the fin design including a full study of the primary design parameters. The fin has been constructed and it can reproduce any specified deformation time-history. The full dynamics of the proposed vehicle have been modeled and the forces produced by the flapping fins computed. Finally, the stability of motion in the vertical plane has been analyzed and a control system has been designed.