Simulation Fitting Method for Setting Motion Parameters of Robotic ...

0.5
Fish curve
Link
0
Lateral Displacement
-0.5
-1
-1.5
-2
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Longitude Distance from Head
Figure 4 Result by JLM
and link and make the outcome minimum. However, there are even more problems in this method.
First of all, there is no obvious guide for adjustment in intermediate states. So there is only one
way to find the result, searching thoroughly. Then it causes another problem: high computational
complexity, especially when there are many segments in the link. So we need to figure out another
method.
4 Simulation Fitting Method
It is necessary to find a method which can compromise between computational complexity
and precision. Just as we borrow the structure of real fish to design robot fish, we can also borrow
ideas from physics to reach our goal.
4.1 Principle of the method
The basic thought of SFM is simple: view the fishcurve and link as real objects, imagine a
uniform force field between them and let physic laws do the rest.
As in Figure 5, a series of elastic ropes (shown as black lines) are attached between the link
and fish curve. Suppose the ropes always satisfy Hook Law and tend to contract. Then, in an
unstable state, rods are subjected to certain force and torque which drive them to translate and
rotate. Under such effect, link moves to its target position and finally stops in a stable state. Now,
the shape of the link is right for robot fish. All we need to do is to build a mathematic model,
simulate the process and record the result.
4.2 Physical modeling and analysis
With the set scene, it is easy to analyze the system.
4.2.1 Analyze single rod