Title :
Modeling the dynamics of spring-driven oscillating-foil propulsion
Author :
Harper, Karen A. ; Berkemeier, Matthew D. ; Grace, Sheryl
Author_Institution :
Charles River Anal., Cambridge, MA, USA
fDate :
7/1/1998 12:00:00 AM
Abstract :
In this paper we present a model for oscillating-foil propulsion in which springs are used to transmit forces from the actuators to the foil. The expressions for hydrodynamic force and moment on the foil come from classical, linear, unsteady aerodynamics, and these are coupled to linearized rigid-body mechanics to obtain the complete model for swimming. The model is presented as a low-order set of ordinary differential equations, which makes it suitable for the application of techniques from systems and control theory. The springs serve to reduce energy costs, and we derive explicit expressions for spring constants which are optimal in this sense. However, the use of springs can potentially lead to unstable dynamics. Therefore, we also derive a set of necessary and sufficient conditions for stability. A detailed example is presented in which energy costs for one actuator are reduced by 33%
Keywords :
cost optimal control; drag; feedback; hydrodynamics; marine systems; mechanical stability; mobile robots; modelling; motion control; propulsion; robot dynamics; robust control; stability criteria; actuator; autonomous underwater vehicle; classical linear unsteady aerodynamics; drag; dynamics modeling; energy costs; feedback; forward motion; hydrodynamic force; linearized rigid-body mechanics; low-order set; moment on foil; ordinary differential equations; robotic fish; spring constants; spring-driven oscillating-foil propulsion; stability conditions; swimming model; tail dynamics; unstable dynamics; Actuators; Aerodynamics; Control theory; Cost function; Differential equations; Hydrodynamics; Propulsion; Springs; Stability; Sufficient conditions;
Journal_Title :
Oceanic Engineering, IEEE Journal of
