|
|
Nose Cone
Robot Pike's nose cone is made out of rigid fiberglass.
Pectoral Fins
-
A wooden laminate provides the form, with
a surface of epoxy and fiberglass to give it strength. There is an
acetal plate, to give it a centerline, and a mounting plate. This is
the same method by which the caudal fin was created.
Caudal Fin
As with the pectoral fins, a wooden laminate provides the
form, while a surfaceof epocxy and fiberglass give it strength. Again,
there is an acetal plate to give it centerline and a mounting plate.
Anal and Dorsal Fins
These fins are constructed using stainless steel wire and Skin
Flex(TM). Skin Flex(TM) is a castable rubber, which will allow the
fins to bend during turning and swimming.
Main Body Servo
The main servo, not having to flex the body very much, was
implemented with a scotch yoke and linkage to the two main bulkheads
of the fish. One side of the linkage, going to the tail bulkhead is
attached to the servo shaft. The other side of the linkage, going to
the nose bulkhead, is attached to the servo housing. The motion of the
servo results in the linear movement of the servo shaft, and a change
in the length of the linkage. This change results in a bend of the
spline, which runs betwiin the two main bulkheads. this servo can bend
the body 30 degrees.
Tail Servo
The tail servo is driving a section of the body which needs to
bend a lot. The tail must be able to bend at least 90 degrees. This
requirement means that a direct linkage between a spline is
infeasible. Thus, we chose to use a sequence of pulley driven
links. Due to the high power transmission efficiency and the large
degree of curvature, this section of the fish is extremely complex.
Tail Fin Servo
- The caudal tail fin is the main source of propulsion in a
fish. It provides thrust by having an angle of attack with the
oncoming water. This pitch angle is very important, and is controlled
seperately by its own servo. This means that the tail fin servo
controls a hinge which the caudal tail fin is attached to. Since it is
impossible to fit our cheap submersible servos near the tail, we use a
cable transmission to drive the tail fin. By converting a single
scotch yoke servo system, used for the main body section, into a
double scotch yoke, a pull-pull cable system can be driven. Since the
forces on this system are low, and space is at a premium, a cable
housing to transmit the cable tension was chosen.
Pectoral Fin Servo
The pectoral fins are controlled by miniature model airplane
servos. These servos are mounted to a waterproof mitre box, which
redirects the axis of movement outside the hull of the fish. The fins
are mounted on the output shaft of the servo.
Batteries
- Nickel Metal Hydride batteries supply medium amounts of current
(peak 9A), and provide large power densities (1.5h for AA sized) in a
rechargeable package. They have a large self discharge rate (50 mA),
but this is fine for experimental runs in the tank.
| | |
|
