Robotic Pectoral Fin Thrust Vectoring Using Weighted Gait Combinations

Abstract

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.

Swimming performance of a hybrid unmanned air-underwater vehicle

“…The design of the Flimmer vehicle built off previous studies. A number of changes to the underwater propulsion generating fins were required to achieve desired thrust generation and survivability for the mission [5] [10]. The result of this redesign process [8] led to a larger fin constructed of more robust materials (Figure 1).…”

“…Experimental measurements of heading angle and rate of change during a turn-in-place yaw maneuver were also performed ( Figure 8). By changing the curvature of the leftand right-side fins, a differential in thrust is achieved -one side producing forward thrust and the other side producing reverse thrust [5]. An open-loop yaw maneuver was achieved by running the left-side fins with 50% forward gait curvature and the right-side fins with 100% reverse gait curvature.…”

“…Several researchers have developed and adapted artificial pectoral fins onto UUVs due to their potential propulsion and control benefits in underwater environments where precise positioning is needed in the presence of changing currents and under waves. These fins have included rigid and passively deforming fins [1] [2][3] [4] as well as some actively controlled curvature fins [5] [6] [7].…”

Four-Fin Bio-Inspired UUV: Modeling and Control Solutions

“…The y-position of the center of pressure on the fins is denoted by y L for the left fins and y R for the right fins. The center of pressure defines the location of the fin generated forces which is needed to compute the fin generated moments, and was determined using CFD as described in [17].…”

Depth control of the biomimetic U-CAT turtle-like AUV with experiments in real operating conditions

“…Another line of development is represented by AQUA [6] and AQUA2 [7] four finned amphibian robots that are unique in the way the propulsors are used both for swimming and crawling in and out of water. [8] describes a four-finned robot with a controllable fin surface and the authors in particular focus on optimizing the performance of ribbed fins by actively changing the surface contour [9], [10]. Four finned propulsion is also realized by deploying a scaffold structure actively controlled by shape memory alloy (SME) wires [11].…”