Force control of a tri-layer conducting polymer actuator using optimized fuzzy logic control

Conducting polymers actuators (CPAs) are potential candidates for replacing conventional actuators in various fields, such as robotics and biomedical engineering, due to their advantageous properties, which includes their low cost, light weight, low actuation voltage and biocompatibility. As these actuators are very suitable for use in micro-nano manipulation and in injection devices in which the magnitude of the force applied to the target is of crucial importance, the force generated by CPAs needs to be accurately controlled. In this paper, a fuzzy logic (FL) controller with a Mamdani inference system is designed to control the blocking force of a trilayer CPA with polypyrrole electrodes, which operates in air. The particle swarm optimization (PSO) method is employed to optimize the controller\u27s membership function parameters and therefore enhance the performance of the FL controller. An adaptive neuro-fuzzy inference system model, which can capture the nonlinear dynamics of the actuator, is utilized in the optimization process. The optimized Mamdani FL controller is then implemented on the CPA experimentally, and its performance is compared with a non-optimized fuzzy controller as well as with those obtained from a conventional PID controller. The results presented indicate that the blocking force at the tip of the CPA can be effectively controlled by the optimized FL controller, which shows excellent transient and steady state characteristics but increases the control voltage compared to the non-optimized fuzzy controllers

Modeling and Control of a Flexible Ionic Polymer Metal Composite(IPMC) Actuator for Underwater Propulsion

The goal of this research is to model and control the underwater vehicle propelled by IPMC actuator. IPMC consists of an ionic membrane sandwiched between two metallic electrodes. When an external voltage is applied, IPMC undergoes large deformation due to transport of ions. Due to its ability to work in aqueous environments, it can be used for developing small scale underwater vehicles. First, Finite element approach is used to describe the dynamics of the both single and segmented IPMC actuator. In the approach presented, each element is attached with a local coordinate system that undergoes rigid body motion along with the element and the deformation of the element is expressed in local coordinate frame. This large deflection model is combines with Clumped RC model to model the dynamics of the IPMC. Next, hydrodynamic model for the IPMC driven vehicle is developed. Frictional resistive forces are considered for modeling the interaction with water. The hydrodynamic coefficients are identified using FLUENT CFD analysis. The developed hydrodynamic model is validated using the experimental data. An autonomous IPMC propelled vehicle is developed to overcome the limited applications tethered vehicle developed earlier. In this research, two kinds of control algorithms based on system identification are developed. A PI controller is designed using simulation data and implemented for controlling speed and orientation of the vehicle. Using the identified linear model, a decoupling control algorithm is developed to eliminate the interactions in tracking speed and orientation (heading angle) of the vehicle. The developed algorithm implemented on original non-linear plant. A path planning algorithm is presented to control the trajectory of the vehicle in the presence of obstacles. Obstacles are approximated by polygonal shapes that approximate their actual dimensions and the vehicle is approximated by a rectangle that encloses the largest deformation of the oscillating IPMC actuator. To simplify the problem of collision detection, vehicle is shrunk to a line while obstacles are expanded by a half width of the rectangle representing the vehicle. The path generated by the algorithm is discretized with respect to time and controlled simultaneously for the orientation angle and speed of the vehicle. A model reference adaptive controller (MRAC) is designed for underwater vehicle propelled by the Ionic polymer metal composite (IPMC) actuator. Trajectories of the vehicle are controlled by simultaneously controlling the bias and amplitude of the sinusoidal voltage applied to the IPMC actuator attached at the rear end of the vehicle. Using Lyapunov stability theory and factorization of the high frequency gain matrix, an adaptive output feedback control is designed for trajectory control of a heading angle and a speed of the vehicle. In the proposed approach, SDU (Square Diagonal and Upper triangular matrix) decomposition of the high frequency gain (HFG) matrix is used. Only signs of the leading principle minors of the HFG matrix are assumed to be known. Simulations results are presented to show that precise trajectory control of the heading and speed is achieved in spite of the coupling between controlled variables

Wearable exoskeleton systems based-on pneumatic soft actuators and controlled by parallel processing

Human assistance innovation is essential in an increasingly aging society and one technology that may be applicable is exoskeletons. However, traditional rigid exoskeletons have many drawbacks. This research includes the design and implementation of upper-limb power assist and rehabilitation exoskeletons based on pneumatic soft actuators. A novel extensor-contractor pneumatic muscle has been designed and constructed. This new actuator has bidirectional action, allowing it to both extend and contract, as well as create force in both directions. A mathematical model has been developed for the new novel actuator which depicts the output force of the actuator. Another new design has been used to create a novel bending pneumatic muscle, based on an extending McKibben muscle and modelled mathematically according to its geometric parameters. This novel bending muscle design has been used to create two versions of power augmentation gloves. These exoskeletons are controlled by adaptive controllers using human intention. For finger rehabilitation a glove has been developed to bend the fingers (full bending) by using our novel bending muscles. Inspired by the zero position (straight fingers) problem for post-stroke patients, a new controllable stiffness bending actuator has been developed with a novel prototype. To control this new rehabilitation exoskeleton, online and offline controller systems have been designed for the hand exoskeleton and the results have been assessed experimentally. Another new design of variable stiffness actuator, which controls the bending segment, has been developed to create a new version of hand exoskeletons in order to achieve more rehabilitation movements in the same single glove. For Forearm rehabilitation, a rehabilitation exoskeleton has been developed for pronation and supination movements by using the novel extensor-contractor pneumatic muscle. For the Elbow rehabilitation an elbow rehabilitation exoskeleton was designed which relies on novel two-directional bending actuators with online and offline feedback controllers. Lastly for upper-limb joint is the wrist, we designed a novel all-directional bending actuator by using the moulding bladder to develop the wrist rehabilitation exoskeleton by a single all-directional bending muscle. Finally, a totally portable, power assistive and rehabilitative prototype has been developed using a parallel processing intelligent control chip

Developing magnetic functionalized multi-walled carbon nanotubes-based buckypaper for the removal of Furazolid

Magnetic f-MWCNTs-based BP/PVA membrane was fabricated and utilized for the elimination of furazolidone (FZD) from aqueous solution. Characterisation and adsorption studies were performed to evaluate the performance and adsorptive efficiency, respectively of the membrane. Furthermore, statistical and machine learning technique were also applied to predict the removal efficiency of FZD on the membrane. The results revealed that magnetic f-MWCNTs-based BP/PVA membrane has the potential to be used as an efficient membrane for practical applications