Integrated Sensing for IPMC Actuators Using Strain Gages for Underwater Applications

Abstract

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.Index Terms-Ionic polymer-metal composite (IPMC) actuators, repetitive control, strain gage sensors.

Repetitive control of a trilayer conjugated polymer actuator

“…The laser displacement sensor limits the usage of feedback control in applications where the space is limited. However, recently published results on ionic metal composite polymer actuators with integrated feedback sensors [31,32] show promising results. More advanced feedback control methods can also be implemented to CPAs to improve their positioning performance by using integrated sensors.…”

Ionic electroactive polymer metal composites: Fabricating, modeling, and applications of postsilicon smart devices

“…231 the motion of IPMC actuators was sensed again by using resistive elements. Those elements anyway are not realized by patterning the IPMC electrodes but strain gages are used.…”

An error compensator based simplified adaptive inverse control method for IPMC actuators tuning

“…As actuators, IPMCs lend themselves well to robotics [4], micro manipulators [5], micro-pump [6,8], biomimetics [7] and other micro-electromechanical systems, due to their lightweight, flexibility, ability to tailor their geometry [8,9], work in water environment [1,2], as well as the capability to be miniaturized and implanted into MEMS devices. IPMC manipulator can also be used in the bio-structures operation [10] the Fig.1 shows the IPMC probe locates a bio-cell to the holder, the deformation of IPMC manipulators can be detected by a self sensing structures like a strain gage [11] or an outside laser displacement sensor, and Fig.2 shows the IPMC actuators can be integrated into a micro pump, when a sine signal is applied it, the micro-pump will be able to send out water steadily and continuously [6].…”