A water-air amphibious cross-medium bio-robotic flying fish includes a body, pitching pectoral fins, variable-structure pectoral fins, a caudal propulsion module, a sensor module and a controller. The caudal propulsion module is controlled to achieve underwater fish-like body-caudal fin (BCF) propulsion, and the variable-structure pectoral fins is adjusted to achieve air gliding and fast splash-down diving motions of the bio-robotic flying fish. The coordination between the caudal propulsion module and the pitching pectoral fins is controlled to achieve the motion of leaping out of water during water-air cross-medium transition. The ambient environment is detected by the sensor module, and the motion mode of the bio-robotic flying fish is controlled by the controller.

A water-air amphibious cross-medium bio-robotic flying fish includes a body, pitching pectoral fins, variable-structure pectoral fins, a caudal propulsion module, a sensor module and a controller. The caudal propulsion module is controlled to achieve underwater fish-like body-caudal fin (BCF) propulsion, and the variable-structure pectoral fins is adjusted to achieve air gliding and fast splash-down diving motions of the bio-robotic flying fish. The coordination between the caudal propulsion module and the pitching pectoral fins is controlled to achieve the motion of leaping out of water during water-air cross-medium transition. The ambient environment is detected by the sensor module, and the motion mode of the bio-robotic flying fish is controlled by the controller.

Fluke drive system for a vessel (100), comprising a pivot element (114) having a forward end and an aft end, which pivot element (114) is pivotally connected at the forward end to a hull (101) of the vessel (100) and which pivot element (114) is connected at the aft end to a flexible fluke (125); a driving mechanism having a drive point (120), which driving mechanism is arranged to impart a reciprocal or rotary movement to the drive point (120); and a drive rod (121) having a first end and a second end, which drive rod (121) is connected at the first end to the drive point (120) and at the second end to the pivot element (114), which second end is connected to the pivot element (114) at a point (122) along the pivot element (114) between said forward and aft ends. The invention is characterized in that the driving mechanism comprises a carrier element (112) fastened to a propeller axle (111) of the vessel (100) and being arranged to rotate with the said propeller axle (111), and in that the said drive point (120) is excentrically arranged on the carrier element (112) so that a rotation of the propeller axle (111) will drive the drive rod (122) back and forth, in turn resulting in a reciprocal up and down motion of the flexible fluke (125). The invention also relates to a method.

A method including operating a vehicle in a medium. The vehicle is subject to advection due to movement of the medium. The method also includes measuring, using a navigation system, positions of a vehicle over time. The method also includes measuring, using a directional sensor, a course-through-medium over the time. The method also includes calculating, using the positions and the course-through-medium, a variation of a speed-over-ground of the vehicle over the time as a function of the course-through-medium over the time. The method also includes concurrently estimating, using the variation, 1) an average speed-through-medium for the vehicle over the time, and 2) an advection rate of the medium, and 3) an advection direction of the medium.

Disclosed herein are permanent magnetic AC machine direct-drive resonant flapper system for flapping wing micro air vehicles and flapping fin autonomous underwater vehicles.

Disclosed herein are permanent magnetic AC machine direct-drive resonant flapper system for flapping wing micro air vehicles and flapping fin autonomous underwater vehicles.

A passively controlled fluid foil has a span; and a rigid spar extending in the spanwise direction, a cellular material and a flexible outer surface defining a profile of the outer surface of the foil and encapsulating the cellular material and the spar.

A robotic fish includes a front body, a rear body that includes a first segment and a second segment, and a driving unit. The first segment has a front engaging portion projecting toward and pivotally connected to the front body, and a rear engaging portion formed with a recess that recedes toward the front body and pivotally connected to the second segment. The driving unit includes a motor disposed in the front engaging portion, and a shaft extending along a dorsoventral axis and connecting the motor and the rear connecting portion. A ratio of a distance between the shaft and a foremost edge of the front engaging portion to a distance between the foremost edge and an extreme point of the recess ranges from 0.075 to 0.75.

A robotic fish includes a front body, a rear body that includes a first segment and a second segment, and a driving unit. The first segment has a front engaging portion projecting toward and pivotally connected to the front body, and a rear engaging portion formed with a recess that recedes toward the front body and pivotally connected to the second segment. The driving unit includes a motor disposed in the front engaging portion, and a shaft extending along a dorsoventral axis and connecting the motor and the rear connecting portion. A ratio of a distance between the shaft and a foremost edge of the front engaging portion to a distance between the foremost edge and an extreme point of the recess ranges from 0.075 to 0.75.

A watercraft propulsion apparatus includes an eccentric crank assembly operatively connected to a pair of fins adapted to sweep back and forth in a generally transverse direction relative to a longitudinal axis of the watercraft. The fins may be rotatable about a longitudinal shaft fixedly secure to the bottom of the hull of the watercraft. A drive linkage assembly operatively connecting the eccentric crank assembly to the pair of fins imparts a torque force to oscillate the pair of fins. The oscillating fins provide a propulsive force to propel the watercraft longitudinally forward during both oscillating directions of the fins as they sweep back and forth.