Model Fish Robot, PPF-07i

Model Fish Robot, PPF-07i

Introduction

What happens when a school of fish robots swim with under certain conditions and rules?
It is thought that such 'group robots' can get high efficient operation and propulsion from dynamic effects of one robot upon another. We have started to discuss the group fish robots with Dr. Sugawara.
The model fish robot, PPF-07i was developed as the base model for group robots. It has an onboard microcomputer. The design aims at simple structure and small size.

Basic Structure of the PPF-07i

The PPF-07i is developed under the guidelines of simple structure, easy construction, small size and a small turning diameter.
In order to get the simple structure, a tail fin is moved by one R/C servomotor. The servomotor and battery pack are located in an acrylic case. Waterproofed seals are not needed, because the servomotor is connected to the tail fin over the case, above the waterline. The tail peduncle is made of aluminum and the tail fin is made of soft plastic.

Microcomputer

The right photograph shows an electric base for the microcomputer, PIC16F84/20P. Switches for the touch sensors are located on the base.
The detail of the electric parts, a circuit and program on the microcomputer is not given here because they yet ready for publication.

Conclusion

The model fish robot, PPF-07i was manufactured and run in a water tank. It was confirmed that the PPF-07i swam ahead, and turned to the left and right. However, the PPF-07i did not have a good performance. The problems are as follows.
(1) The PPF-07i has poor balance in the water. The center of gravity is too high, and the center of buoyancy is too low.
(2) The floating hull is large and cumbersome.
(3) It does not have so simple a structure.
(4) Turning diameter too large.
Based on the above problems, I went on to develop another fish robot for this research. The new fish robot -the PPF-08i- is working well!

Developmental Diary of the PPF-07i
Movie of PPF-07i (MPEG, 1.2 MB)

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