New computational model for predicting the mechanical behavior of ionic polymer metal composite (IPMC) actuators

A new method to fabricate ionic polymer metal composite (IPMC) actuators with a 3-dimensional preshaped form by a simple thermal treatment process is demonstrated. The effects of the thermal treatment process on the properties of the actuator are analyzed and the characteristics of the actuator, such as stiffness, displacement and resonance, generating force, and repeated motions, are compared with those of unheated IPMC actuators. The experimental results show that thermal-treated IPMC actuators have improved generating force as well as preshaping of the 3-dimensional form.

Ionic polymer metal composite (IPMC) is a smart material with low driving voltage, high energy conversion, light weight and simple structure. It is suitable for driving the tail fin of small bionic fish. Actuators made of this material are quite flexible, and they are laborious to accurately describe the complex deformation of structures. Absolute nodal coordinate formulation (ANCF) has great merits in describing large deformation and large displacement problems. In this paper, the feasibility of ANCF in dynamic modeling of a fish tail actuated by IPMC actuator will be explored for the first time. The tail fin is simplified into two forms: a pure flexible IPMC beam and a hybrid beam that consists of an IPMC beam and a fixed rigid beam. The ANCF one-dimensional two-node beam element is adopted. Considering the influence of deformation curvature, the exact expression of generalized elastic force is obtained. The proposed dynamic model can describe the large deformation problem of the flexible beam. The dynamic responses of the pure IPMC beam tail fin and the hybrid tail fin driven by square wave voltage are calculated. The displacement changes of end nodes are compared, and the swing law under different driving voltage amplitude, frequency, and fluid resistance is analyzed. It is found that the driving efficiency of IPMC can be improved by increasing the driving voltage amplitude, reducing the voltage frequency, and reducing the fluid resistance in a certain range. This research would be beneficial to the study of the large swing motion mechanism of bionic robotic fish.

Compact structure, multifunction, and flexibility are normally considered as incompatible characteristics for legged microrobots. Most robots focused on complex structure of multi-joint legs to attain the multifunction and flexibility, while others had poor flexibility for miniaturization. In the field of underwater monitoring for applications such as pollution detection and video mapping in limited space, underwater microrobots are urgently demanded. To realize these purposes, we have developed several types of microrobots with both compact structure and flexible locomotion. However, they just realized walking, rotating, swimming, or floating motions. Without biomimetic fingers, they could not do some simple operations, such as grasping and carrying any objects to desired place. So, in this paper, we designed a novel type of biomimetic locomotion employing ionic polymer metal composite (IPMC) actuator as one-DOF leg. Then we proposed a new type of underwater microrobot using ten ionic polymer metal composite (IPMC) actuators as legs or fingers, which could realize walking, rotating, floating, and grasping motions. Also, we developed a prototype of this underwater microrobot and carried out some experiments to evaluate its walking and floating speeds. In addition, we used six IPMC actuators as fingers to grasp some small objects and float up. To realize the closed-loop control for the microrobot, we used three proximity sensors to detect and avoid the obstacle while walking.

Identification of an ionic polymer metal composite actuator employing Preisach type fuzzy NARX model and Particle Swarm Optimization

Mechanics and electrochemistry of ionic polymer metal composites

Underwater microrobots are in urgent demand for applications such as pollution detection and video mapping in limited space. Compact structure, multi-functionality, flexibility, and position precision are normally considered incompatible characteristics for underwater microrobots. To accomplish our objectives, we developed several novel bio-inspired biomimetic locomotions with ionic polymer metal composite (IPMC) actuators. IPMC actuator could implement a fast response and high bending deformation, which could be used as artificial muscles to propel robots backwards and forwards with a compact structure. To implement the position precision of IPMC actuator, we proposed an electromechanical model and analyzed the deformation and actuating force of the IPMC equivalent cantilever beam, which were used for the biomimetic locomotion. Then a conventional PID controller for IPMC actuators was designed from the identified model. Based on the IPMC equivalent cantilever beam model, we developed several kinds of underwater microrobots with the compact structure, multi-functionality, flexibility, and position precision.

In this work, flapping wings actuated by IPMCs are designed and simulated to mimick birds wing. In order for the wing to generate lift and thrust during flapping motion, the wing must be able to flap and twist at the same time. For design of such wings, shape of the IPMC actuator need to be designed such that the actuator can create bending and twisting motions during wing strokes. To determine the shape of the IPMC actuator, an equivalent bimorph beam model has been proposed based on the measured force-displacement data of an IPMC. The equivalent model and thermal analogy are used for numerical simulation of IPMC actuated wings to determine suitable shape of the IPMC actuator. In this way, we could select a best performing wing that can create the largest twist motion during flapping of the wing.

The ionic polymer metal composite (IPMC) actuator is one of the most promising smart actuators that possesses unique advantages and is suitable for underwater applications. However, there are challenges to employ it directly in such applications for precise tracking. The IPMC suffers from high nonlinearity due to the existence of inherent creep and hysteresis phenomena. Furthermore, the IPMC actuator is always subject to uncertainty and external disturbance due to the working environment. Therefore, to cope with the aforementioned restrictions and to make the IPMC applicable for real-life applications, designing a high-accuracy tracking control technique is an urgent demand. In this article, a new integral nonlinear hyperplane-based sliding mode controller is dedicated for an underwater IPMC actuator. The proposed controller employs an adaptive tuning law in the discontinuous part to overcome any prerequisite for knowing the upper bound of the model uncertainty and external disturbance. Extensive experiments have been carried out to verify practical effectiveness of the proposed controller in comparison with conventional nonsingular terminal sliding mode in terms of fast convergence, accurate tracking, and the robust performance.

For the first time, the ionic polymer metal composite (IPMC) actuator is integrated with a radio frequency identification (RFID) tag antenna for achieving frequency reconfiguration in the ultrahigh-frequency (UHF) band. Here, the IPMC movable flap serves as an actuator that can effectively tune the tag resonant frequency. By applying a two-layer-crenelated structure and employing a surface patterned electrode for restraining back relaxation, the deflection of the IPMC actuator can be significantly improved. The IPMC actuator can move in two directions, enabling two-degree frequency tuning. Numerical and experimental data confirm that the tip displacement of the IPMC actuator can be enhanced up to 266% with the use of the two-layer-crenelated structure. The IPMC actuator allows the resonant frequency of the tag antenna to be tuned back by as much as 35 MHz, after deviating due to placing on an unintended object. UHF RFID application is also performed using a portable commercial RFID reader. Good frequency reconfiguration and broad tuning range, along with far read distances, have been achieved with our tunable UHF RFID tag antenna.

Ionic Polymer Metal Composite (IPMC) actuators have shown promise as miniature underwater propulsors due to their high flexibility, reduced weight, and low activation voltage and power consumption. In this second of two papers, we discuss numerical simulations of the flow of a viscous fluid generated by a two-dimensional cantilever IPMC actuator vibrating along its fundamental mode shape. We compute the thrust produced by the actuator as a function of its oscillation frequency and maximum tip displacement and show that it is correlated to vortex shedding. We find that vorticity production is prominent at the IPMC tip and increases as the oscillation frequency increases. We analyze the lateral force and the moment exerted by the IPMC on the surrounding fluid. Further, we study the power transferred by the vibrating IPMC to the encompassing fluid. The findings are validated via comparison with the experimental results presented in part 1 of this series.

Bio-inspiration focuses on translating the evolutionary successes of natural species into engineering systems that mimic the geometry, function, and performance of the natural system. In this paper we present a latest comprehensive review of ionic polymer metal composite (IPMC) biomedical and biomimetic applications. IPMC is becoming an increasingly popular material among scholars, engineers and scientists due to its inherent properties of low activation voltage, large bending strain, flexibility, softness, suitable response time which make them a strong candidate to be applied as artificial muscle in biomimetic land and underwater applications. Among the diversity of electro active polymers (EAPs), recently developed IPMCs are good candidates for use in bio-related application because of their biocompatibility. Several recently reported IPMC biomimetic applications have been reported in this paper. The applications of IPMC have been growing due to progression in its manufacturing techniques, development of more accurate response models and control techniques, and recently more sophisticated IPMC actuator applications have been performed. This indicates that the IPMC actuators hold potential for more sophisticated and controlled applications in fields of biomedical and biomimetic. Extensive references are provided for more indepth explanation.

Simple and highly efficient microvalve systems based on an ionic polymer-metal composite (IPMC) diaphragm actuator have been developed. The microvalve system that was fabricated in this work operates when open and close voltage is applied, due to the phenomena of lithium ion flux and the subsequent electro-osmotic drag of water to the cathode. IPMC was prepared by compositing with platinum nanoparticles on both sides of Nafion thin film. SEM images of the IPMC showed the high density and uniform size distribution of the Pt nanoparticles in the interpenetrating layer to ensure the proper performance of an IPMC actuator. The displacement of the IPMC for the microvalve was measured with a laser displacement meter. The application of open and close voltage made the operation of the valve faster. The fluorescence images of the flow in the fabricated IPMC-based microvalve system showed the successful operation of flow control in the microfluidic channel. The IPMC-based microvalve system shows a potential of IPMC for application as an actuator in microfluidic systems.

The paper presents a novel 3-dimensional arc-shaped ionic polymer metal composite (IPMC)/PVDF transducer. It not only can generate focused acoustic beam and electrically manipulate the focal range of the acoustic beam but possesses curvature self-detectable function. This transducer involves three major components: 1) IPMC actuator with arc-shaped arm which allows a large curvature change motion under electrical actuation; 2) an ultrasonic PVDF film transducer attached to the front surface of the arm of IPMC actuator, which can manipulate the ultrasonic beam profile via the control of IPMC actuator. 3) A pair of interdigital transducers (IDTs) made on the PVDF film which is attached to the back surface of IPMC actuator. The IDTs function as a curvature sensor to detect the arm of IPMC actuator curvature change via the input and output voltage difference of the IDT pair. Detailed fabrication process and associated device characterization are described in the text. The developed IPMC/PVDF actuator successfully demonstrates the wide-ranging acoustic beam tenability of 100%.

Ionic Polymer Composite Material (IPMC) is a flexible material and has revealed many advantages to encourage the scientists and researchers to investigate its characteristics for practical applications in various fields. The ongoing research can be divided into two branches. One deals with the improvement of the material properties to make it more useful and reliable while the other involves the exploration of new application areas. In this paper, Firstly, a new application of IPMC is suggested to actuate a rigid link that can mimic a bionic knee joint for a grass hopper manipulator. Secondly, forward kinematic model is proposed for the manipulator by employing geometric coordinate system method. Lastly, wolfram mathematica software is employed for the simulation of the model. The simulation results based on the model are found very encouraging to lure the article team to carry on the research idea for manufacturing and testing for the comparison of both types of results.

In this paper, model-based precision force and position control of an ionic polymer metal composite (IPMC) is presented. A 23.8 mm × 3.4 mm × 0.16 mm IPMC strip was used as an actuator in a cantilever configuration. Open-loop force and position responses of an IPMC are not repeatable, and hence closed-loop precision control is of critical importance to ensure proper functioning, repeat-ability and reliability. After feedback controllers were designed and implemented with empirically obtained fourth-order plant transfer functions, the overshoot decreased from 460 to 2.8 per cent and the settling time was reduced from 37.5 to 3.22 s in force control. In position control the overshoot decreased from 333 to 20.3 per cent and the settling time was reduced from 21.5 to 2.56 s. Microscale precision force and position control capabilities of the IPMC actuator were also demonstrated experimentally. An 8 μN force resolution was achieved with a force noise of 0.5μN r.m.s., and the position resolution was 6 μm with a position noise of 2.5 μm r.m.s. The maximum force and tip displacement achieved with the IPMC actuator under closed-loop control were 2 mN and 5 mm respectively. The IPMC actuator could follow various commanded force and position trajectories such as sinusoidal and trapezoidal position profiles, and a velocity profile with a 3 mm/s maximum velocity. A novel hybrid force and position control strategy demonstrated its utility in practical micromanipulalion applications where the actuator force must be limited to prevent damaging micro-objects. High-precision control of the IPMC at low force level proved its potential for micromanufacturing and micromanipulation applications such as robotic and biomedical microgrippers.