Integrated Sensing for IPMC Actuators Using Strain Gages for Underwater Applications | IEEE Journals & Magazine | IEEE Xplore

Integrated Sensing for IPMC Actuators Using Strain Gages for Underwater Applications


Abstract:

Ionic polymer-metal composite (IPMC) actuators have many advantages, for instance, they: 1) can be driven with low voltages (<;5 V); 2) are soft, flexible, and easily sha...Show More

Abstract:

Ionic polymer-metal composite (IPMC) actuators have many advantages, for instance, they: 1) can be driven with low voltages (<;5 V); 2) are soft, flexible, and easily shaped; and 3) can operate in an aqueous environment (such as water). Important applications for IPMCs include active catheter devices for minimally invasive surgery, artificial muscles, and sensors and actuators for biorobotics. Due to inherent nonlinear behavior, dynamic effects, and external disturbances, sensing and feedback control are required for precision operation. A new method to sense the displacement of an IPMC actuator using resistive strain gages is proposed. The sensing scheme is low cost, practical, effective, and importantly, compact compared to existing methods such as lasers and charge-coupled device (CCD) cameras. The strain-to-displacement relationship is developed and experimental results are presented to demonstrate the effectiveness of the sensing scheme. Furthermore, the sensor signal is used as feedback information in a repetitive controller to improve the tracking of periodic motion. The stability condition for the controller is presented, and the sensing scheme and feedback control approach are applied to a fabricated perfluorinated ion-exchange-membrane-based IPMC actuator with lithium as its counterion. Experimental results show that the tracking error can be reduced by approximately 50% compared to PID control for tracking of periodic signals, including sinusoidal and triangular wave forms.
Published in: IEEE/ASME Transactions on Mechatronics ( Volume: 17, Issue: 2, April 2012)
Page(s): 345 - 355
Date of Publication: 14 February 2011

ISSN Information:


I. Introduction

Ionic polymer–metal composites (IPMCs) are innovative materials that can be exploited for emerging robotic, intelligent mechatronic, bioinpsired, and biomedical systems [1]–[5]. Due to their low driving voltage (<5 V), large strain, soft and flexible structure, and the ability to operate in an aqueous environment (such as water), IPMCs are suitable for many unique applications that include innovative propulsion systems in underwater autonomous systems [6]–[9]. Particularly, strips of IPMCs have been used to construct the legs (tentacles) of a jellyfish-like robot [10]. The walking speed of the jellyfish robot was controlled through the frequency of the input voltage applied to the IPMC-based legs. Likewise, the caudal fin to propel a robotic fish was created from an IPMC with an achievable peak swimming speed reported at 22 mm/s [11]. However, IPMC actuators can play a critical role in the development of highly-maneuverable biorobotic vehicles, e.g., the system described in [12].

References

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