- Email: [email protected]
Development of an oscillating fin type actuator for underwater robots
International Congress Series 1301 (2007) 214 – 217
www.ics-elsevier.com
Development of an oscillating fin type actuator for underwater robots Kimikazu Sugiyama ⁎, Kazuo Ishii, Keiichi Kaneto Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Japan
Abstract. We are focusing our attention on bio-inspired technologies and have been developing an oscillating fin type actuator for underwater robots using artificial muscles. Our research aims at the development of a fin type actuator imitating mechanisms of underwater creatures by using an electroconductive polymer as the driving source/s. We expect that this actuator takes the place of a screw propeller for missions that need precise and silent control. In this paper, we introduce the concept of the development of the actuator and the results of the performance evaluation test of the developed electroconductive polymer. © 2007 Elsevier B.V. All rights reserved. Keywords: Artificial muscle; Electroconductive polymer; Biomimetics; Fin type actuator
1. Introduction Generally, almost all ships and underwater vehicles use a screw propeller as their actuator. However, it is not easy to employ screw propeller type actuators for precise control without producing a large amount of noise. We have been approaching this technical problem by developing a new type of actuator. The actuators are expected to take the place of the screw propeller for the missions that need precise and silent control in future. In this research, we pay attention to the bio-mechanism of underwater creatures, especially ribbon-like fins using precise control. Bio-mechanisms of creatures are adapted to the environment as a result of evolution. If the motor control mechanism of the creatures can be introduced into underwater robots, it is possible that a high performance actuator will be developed. ⁎ Corresponding author. 2-4, Hibikino, Wakamatsu, Kitakyushu, Fukuoka, 808-0196, Japan. Tel./fax: +81 93 695 6102. E-mail address: [email protected] (K. Sugiyama). 0531-5131/ © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2006.12.017
K. Sugiyama et al. / International Congress Series 1301 (2007) 214–217
215
Fig. 1. Tree diagram of bio-inspired technology (e.g. underwater creatures) (A). Fish models for Biomimetics in this research. ((a): Thread-sail file fish, (b): cuttlefish, (c): ribbon fish), photo by http://fishing-forum.org/zukan/ index.htm (B).
We aim to develop an actuator by imitating functions of underwater creatures with the capability of precise and silent control. The first step of our research is the development of artificial muscles as the driving source. In this paper, the concept of the development of the actuator and the electroconductive polymer are described. We have carried out performance evaluation tests of the developed artificial muscles. 2. Fish fin Underwater technology has much potential to learn from underwater creatures. Fig. 1A shows bio-inspired technology from underwater creatures. We pay attention to precise control using ribbon-like fins that can induce impellent by wave propagation. For example, a Thread-sail file fish can hover like a helicopter even if there is a tidal current [1]. Fig. 1B shows some typical creatures which employ oscillating fins. They can swim precisely by switching wave propagation order. A forward (or backward) impellent is obtained by sending the wave backward (or forward). The direction of waves can be transferred to the other direction very quickly. If a new actuator can realize this ability, fin actuators could be controlled more smoothly. 3. An electroconductive polymer of artificial muscles Artificial muscles have smooth expansion and shrinkage motion like biological muscles. There are various materials used for artificial muscles, for example, IPMC (Ionic Polymer
Fig. 2. Principle of motion of electroconductive polymer as artificial muscles (A). One of the bending motion methods (B).
216
K. Sugiyama et al. / International Congress Series 1301 (2007) 214–217
Fig. 3. Developed film on the titanium electrode in electrolytic polymerization (A). Experimental setup for the performance evaluation test (B).
Metal Composite), conductive polymer, shape memory alloy, flexible micro actuator (air pressures) and electrostatic actuator, etc. [2]. We employed an electroconductive polymer as the artificial muscle material. Electroconductive polymers expand or shrink by the inward or outward dynamics of ion currents [3]. Fig. 2A shows the principle of polymer film motion. The bending motion is generated at bimorph type, which is shown in Fig. 2B [4]. The electroconductive polymer is produced by the electrolytic polymerization method. Materials of the produced polymer are Pyrrole, TBACF3SO3 (Trifluoromethansulfonic Acid Tetra-n-butyl ammonium Salt), and the methyl benzoate. This polymer film is called PPy/CF3SO3 (Polypyrrole/TBACF3SO3). Fig. 3A is the generated PPy/CF3SO3 film on the electrode surface of titanium. The thickness of the films is 10–15 μm. Thickness can be changed according to the polymerized time. In this experiment, the polymerized time is 15,000 s, where 0.2 mA/cm2 current is given continuously. 4. Performance evaluation The experiments for performance evaluation are carried out measuring displacement of expansion and shrinkage motion. Experimental setup is shown in Fig. 3B. The displacement of the test piece (5 mm in length, 2 mm in width and 10–15 μm in
Fig. 4. An experimental result of developed PPy/CF3SO3 film (A). Graph of the frequency response data (B).
K. Sugiyama et al. / International Congress Series 1301 (2007) 214–217
217
Fig. 5. Bending motion of developed PPy/CF3SO3 film attaching a fixed length film with no expansion (1 frame per 1 s).
thickness) is measured using a laser displacement meter (Keyence Co. LB-040). The counter electrode is platinum, the working electrode is titanium and the reference electrode is AgCl. The condition parameters such as control voltage, waveform, frequency, electrolytic solutions, and load weights are changed and generated from a function generator (Yokogawa, FG110) and outputted from a Potentio/Galvanostat meter (Hokuto Denko, HA-501). Fig. 4A shows a time series of experimental results and Fig. 4B shows the frequency response. It is shown that the frequency response decreased rapidly with the increase in the input frequency. The response of the film can be expressed in the following equation. y ¼ ax−b
ð1Þ
where x is frequency and y is amplitude. Coefficients α and β are constant numbers obtained in these results. The coefficient α is 1.44 and the coefficient β is 1.08 in this test piece. As previously noted, a fixed length film with no expansion is attached to one side of the PPy/CF3SO3 film in order to realize the bending motion. The bending motion of the film can be realized as shown in Fig. 5. 5. Conclusion We have developed an oscillating fin type actuator using the PPy/CF3SO3 film (electroconductive polymer), which is one of the materials used to realize artificial muscles. The developed film can perform expansion and shrinkage by changing the control voltage and polarity switching, and can also realize the bending motion. We will develop a cation driven film and bimorph type actuator in the future. References [1] A. Azuma, Motion Dictionary of Creatures, Asakura, 1997 (in Japanese). [2] S. Dono, A. Saito, T. Kuwata, Knit structure SMA actuator for wearable artificial muscle systems, Technical Report, Matsushita Electric Works (Aug 2003) 59–63 (in Japanese). [3] Y. Nagata, Soft Actuators, NTS Inc., 2004. [4] W. Takashima, Shyam S. Pandey, K. Kaneto, Investigation of bi-ionic contribution for the enhancement of bending actuation in polypyrrole film, Sensors and Actuators B 89 (2003) 48–52.
www.ics-elsevier.com
Development of an oscillating fin type actuator for underwater robots Kimikazu Sugiyama ⁎, Kazuo Ishii, Keiichi Kaneto Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Japan
Abstract. We are focusing our attention on bio-inspired technologies and have been developing an oscillating fin type actuator for underwater robots using artificial muscles. Our research aims at the development of a fin type actuator imitating mechanisms of underwater creatures by using an electroconductive polymer as the driving source/s. We expect that this actuator takes the place of a screw propeller for missions that need precise and silent control. In this paper, we introduce the concept of the development of the actuator and the results of the performance evaluation test of the developed electroconductive polymer. © 2007 Elsevier B.V. All rights reserved. Keywords: Artificial muscle; Electroconductive polymer; Biomimetics; Fin type actuator
1. Introduction Generally, almost all ships and underwater vehicles use a screw propeller as their actuator. However, it is not easy to employ screw propeller type actuators for precise control without producing a large amount of noise. We have been approaching this technical problem by developing a new type of actuator. The actuators are expected to take the place of the screw propeller for the missions that need precise and silent control in future. In this research, we pay attention to the bio-mechanism of underwater creatures, especially ribbon-like fins using precise control. Bio-mechanisms of creatures are adapted to the environment as a result of evolution. If the motor control mechanism of the creatures can be introduced into underwater robots, it is possible that a high performance actuator will be developed. ⁎ Corresponding author. 2-4, Hibikino, Wakamatsu, Kitakyushu, Fukuoka, 808-0196, Japan. Tel./fax: +81 93 695 6102. E-mail address: [email protected] (K. Sugiyama). 0531-5131/ © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2006.12.017
K. Sugiyama et al. / International Congress Series 1301 (2007) 214–217
215
Fig. 1. Tree diagram of bio-inspired technology (e.g. underwater creatures) (A). Fish models for Biomimetics in this research. ((a): Thread-sail file fish, (b): cuttlefish, (c): ribbon fish), photo by http://fishing-forum.org/zukan/ index.htm (B).
We aim to develop an actuator by imitating functions of underwater creatures with the capability of precise and silent control. The first step of our research is the development of artificial muscles as the driving source. In this paper, the concept of the development of the actuator and the electroconductive polymer are described. We have carried out performance evaluation tests of the developed artificial muscles. 2. Fish fin Underwater technology has much potential to learn from underwater creatures. Fig. 1A shows bio-inspired technology from underwater creatures. We pay attention to precise control using ribbon-like fins that can induce impellent by wave propagation. For example, a Thread-sail file fish can hover like a helicopter even if there is a tidal current [1]. Fig. 1B shows some typical creatures which employ oscillating fins. They can swim precisely by switching wave propagation order. A forward (or backward) impellent is obtained by sending the wave backward (or forward). The direction of waves can be transferred to the other direction very quickly. If a new actuator can realize this ability, fin actuators could be controlled more smoothly. 3. An electroconductive polymer of artificial muscles Artificial muscles have smooth expansion and shrinkage motion like biological muscles. There are various materials used for artificial muscles, for example, IPMC (Ionic Polymer
Fig. 2. Principle of motion of electroconductive polymer as artificial muscles (A). One of the bending motion methods (B).
216
K. Sugiyama et al. / International Congress Series 1301 (2007) 214–217
Fig. 3. Developed film on the titanium electrode in electrolytic polymerization (A). Experimental setup for the performance evaluation test (B).
Metal Composite), conductive polymer, shape memory alloy, flexible micro actuator (air pressures) and electrostatic actuator, etc. [2]. We employed an electroconductive polymer as the artificial muscle material. Electroconductive polymers expand or shrink by the inward or outward dynamics of ion currents [3]. Fig. 2A shows the principle of polymer film motion. The bending motion is generated at bimorph type, which is shown in Fig. 2B [4]. The electroconductive polymer is produced by the electrolytic polymerization method. Materials of the produced polymer are Pyrrole, TBACF3SO3 (Trifluoromethansulfonic Acid Tetra-n-butyl ammonium Salt), and the methyl benzoate. This polymer film is called PPy/CF3SO3 (Polypyrrole/TBACF3SO3). Fig. 3A is the generated PPy/CF3SO3 film on the electrode surface of titanium. The thickness of the films is 10–15 μm. Thickness can be changed according to the polymerized time. In this experiment, the polymerized time is 15,000 s, where 0.2 mA/cm2 current is given continuously. 4. Performance evaluation The experiments for performance evaluation are carried out measuring displacement of expansion and shrinkage motion. Experimental setup is shown in Fig. 3B. The displacement of the test piece (5 mm in length, 2 mm in width and 10–15 μm in
Fig. 4. An experimental result of developed PPy/CF3SO3 film (A). Graph of the frequency response data (B).
K. Sugiyama et al. / International Congress Series 1301 (2007) 214–217
217
Fig. 5. Bending motion of developed PPy/CF3SO3 film attaching a fixed length film with no expansion (1 frame per 1 s).
thickness) is measured using a laser displacement meter (Keyence Co. LB-040). The counter electrode is platinum, the working electrode is titanium and the reference electrode is AgCl. The condition parameters such as control voltage, waveform, frequency, electrolytic solutions, and load weights are changed and generated from a function generator (Yokogawa, FG110) and outputted from a Potentio/Galvanostat meter (Hokuto Denko, HA-501). Fig. 4A shows a time series of experimental results and Fig. 4B shows the frequency response. It is shown that the frequency response decreased rapidly with the increase in the input frequency. The response of the film can be expressed in the following equation. y ¼ ax−b
ð1Þ
where x is frequency and y is amplitude. Coefficients α and β are constant numbers obtained in these results. The coefficient α is 1.44 and the coefficient β is 1.08 in this test piece. As previously noted, a fixed length film with no expansion is attached to one side of the PPy/CF3SO3 film in order to realize the bending motion. The bending motion of the film can be realized as shown in Fig. 5. 5. Conclusion We have developed an oscillating fin type actuator using the PPy/CF3SO3 film (electroconductive polymer), which is one of the materials used to realize artificial muscles. The developed film can perform expansion and shrinkage by changing the control voltage and polarity switching, and can also realize the bending motion. We will develop a cation driven film and bimorph type actuator in the future. References [1] A. Azuma, Motion Dictionary of Creatures, Asakura, 1997 (in Japanese). [2] S. Dono, A. Saito, T. Kuwata, Knit structure SMA actuator for wearable artificial muscle systems, Technical Report, Matsushita Electric Works (Aug 2003) 59–63 (in Japanese). [3] Y. Nagata, Soft Actuators, NTS Inc., 2004. [4] W. Takashima, Shyam S. Pandey, K. Kaneto, Investigation of bi-ionic contribution for the enhancement of bending actuation in polypyrrole film, Sensors and Actuators B 89 (2003) 48–52.