Hi, i was looking at using the wiggle drive for a surfboard application - whereby two fins could be oscillating and a system will be in place to lock the fins in initial position once desired speed is achieved.

I am a final year mechanical engineering student, I am wondering which principle is used for the following: (ill try my best to explain)

The two fins will be Vertically mounted, they will flap from left to right and the pitch will be around +- 15 degrees.

It will be running off the same idea as this video

I am looking for some theory behind this?

Swashdrive™ Fin propulsion 2 (1 min 21 sec)

That's amazingly fast. Proves again how principles seen in nature are often quite ingenious.

It appears that the flappers are not only going left to right but are oscillating at the same time. It is hard to tell in the short period that they showed them out of water. Just my two cents, Mike.

First time I have seen this on the back of a boat. How about more video of it running out of the water, and info on who made the drive unit? Is this the same principle as on the fishing Kayaks?

Sorry for the confusion, this is the principle that i am running off - this is not my actual design.
The design, is inspired from nature - much research has gone into biomimetic devices, and there efficiencys. Many research reports suggest higher efficiency's can be achieved using "thunniform" motion. However, the purpose for my actual design - is for a surfboard. I want dual functionality. So my thought, use the fins already inherent in surfboard design - allow them to propel the surfboard. Once on the wave, the power is disengaged and a mechanism will lock the fins back into place.

Here is a video, of a sample mechanism that allows for "pitch" motion, aswell as "side to side" motion - similar to what you would see with a penguin.

Wiggle wing-drive (0 min 42 sec)

If anyone could help me to where to find parts of this nature, that would be great

You can probably source most of the gears from SDP-SI, WM Berg, or Amazon Supply(Small Parts inc).

http://www.sdp-si.com/
http://www.wmberg.com/
http://www.amazonsupply.com/b/163101...nk/ref=gw_c_pt

The drive mount you would have to manufacture yourself.
But it looks likeas simple bevel cut on a large diameter rod.
Ad you probably want some bearings in that cross mount on top of that bevel.

Festo makes a variety of bio-engineered robotics.
Air fish, air ray, air penguin, the Smart Bird, and the aquatic version of
the fish, ray and the penguin.

Festo - Bionic Learning Network 2009 (4 min 39 sec)

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Hi Umi, thanks for the quick reply
Since this device was clearly made to operate through air, i was concerned about the structural rigidity of a system like this running in a much denser fluid (the ocean)

I was considering using a cylindrical cam, with two individual cam profiles, with individial cam followers: This will be attached to a ball joint arm at two positions, with the ball joint being connected to the fin. One follower will be making the fins "side to side" motion, while the other will be "pitching" motion. However, machine a cam with two independant profiles in the one housing was going to be looking difficult.
Thats why i was hoping to use the above mechanism, for simplicity and was hoping to get mostly off the shelf parts - which you pointed out is feasible

By the way, i literally was just watching that video before you posted it haha.

Since you are a student, perhaps the school has CNC or 3d printing machines on campus.
If you can draw your design using CAD, and 3d model it, the machines can then create the
custom parts you require. If it has to be 3d printed, you can have a wax casting made, and
then invest the wax part and have it cast in metal.

As far as self centering, the Arduino technology, and some stepper motors should allow
the system to actively manage the location of the motor and drive fin.