Fractional order modeling and control of a smart beam

Smart beams are one of the most frequently used means of studying vibrations in airplane wings. Their mathematical models have been so far solely based on classical approaches that ultimately involve integer order transfer functions. In this paper, a different approach towards modeling such smart beams is considered, an approach that is based on fractional calculus. In this way, a fractional order model of the smart beam is obtained, which is able to better capture the dynamics of the system. Based on this novel fractional order model, a fractional order PD mu controller is then tuned according to a set of three design constraints. This design leads to a closed loop system that exhibits a much smaller resonant peak compared to the uncompensated smart beam system. Experimental results are provided, considering both passive and active control responses of the smart beam, showing that a significant improvement of the closed loop behavior is obtained using the designed controller

High-performance control of dual-inertia servo-drive systems using low-cost integrated SAW torque transducers

Abstract—This paper provides a systematic comparative study of compensation schemes for the coordinated motion control of two-inertia mechanical systems. Specifically, classical proportional–integral (PI), proportional–integral–derivative (PID), and resonance ratio control (RRC) are considered, with an enhanced structure based on RRC, termed RRC+, being proposed. Motor-side and load-side dynamics for each control structure are identified, with the “integral of time multiplied by absolute error” performance index being employed as a benchmark metric. PID and RRC control schemes are shown to be identical from a closed-loop perspective, albeit employing different feedback sensing mechanisms. A qualitative study of the practical effects of employing each methodology shows that RRC-type structures provide preferred solutions if low-cost high-performance torque transducers can be employed, for instance, those based on surface acoustic wave tecnologies. Moreover, the extra degree of freedom afforded by both PID and RRC, as compared with the basic PI, is shown to be sufficient to simultaneously induce optimal closed-loop performance and independent selection of virtual inertia ratio. Furthermore, the proposed RRC+ scheme is subsequently shown to additionally facilitate independent assignment of closed-loop bandwidth. Summary attributes of the investigation are validated by both simulation studies and by realization of the methodologies for control of a custom-designed two-inertia system

Control and Automation

Control and automation systems are at the heart of our every day lives. This book is a collection of novel ideas and findings in these fields, published as part of the Special Issue on Control and Automation. The core focus of this issue was original ideas and potential contributions for both theory and practice. It received a total number of 21 submissions, out of which 7 were accepted. These published manuscripts tackle some novel approaches in control, including fractional order control systems, with applications in robotics, biomedical engineering, electrical engineering, vibratory systems, and wastewater treatment plants. This Special Issue has gathered a selection of novel research results regarding control systems in several distinct research areas. We hope that these papers will evoke new ideas, concepts, and further developments in the field

Vibration suppression of the horizontal flexible plate using proportional– integral–derivative controller tuned by particle swarm optimization

This paper presents the development of an active vibration control for vibration suppression of the horizontal flexible plate structure using proportional–integral–derivative controller tuned by a conventional method via Ziegler–Nichols and an intelligent method known as particle swarm optimization algorithm. Initially, the experimental rig was designed and fabricated with all edges clamped at the horizontal position of the flexible plate. Data acquisition and instrumentation systems were designed and integrated into the experimental rig to collect input–output vibration data of the flexible plate. The vibration data obtained through experimental study was used to model the system using system identification technique based on auto-regressive with exogenous input structure. The plate system was modeled using particle swarm optimization algorithm and validated using mean squared error, one-step ahead prediction, and correlation tests. The stability of the model was assessed using pole zero diagram stability. The fitness function of particle swarm optimization algorithm is defined as the mean squared error between the measured and estimated output of the horizontal flexible plate system. Next, the developed model was used in the development of an active vibration control for vibration suppression on the horizontal flexible plate system using a proportional–integral–derivative controller. The proportional–integral–derivative gains are optimally determined using two different ways, the conventional method tuned by Ziegler–Nichols tuning rules and the intelligent method tuned by particle swarm optimization algorithm. The performances of developed controllers were assessed and validated. Proportional–integral–derivative-particle swarm optimization controller achieved the highest attenuation value for first mode of vibration by achieving 47.28 dB attenuation as compared to proportional–integral–derivative-Ziegler–Nichols controller which only achieved 34.21 dB attenuation

Active vibration control of smart composite plates using optimized self-tuning fuzzy logic controller with optimization of placement, sizing and orientation of PFRC actuators

This paper deals with optimization of the sizing, location and orientation of the piezo-fiber reinforced composite (PFRC) actuators and active vibration control of the smart composite plates using particle-swarm optimized self-tuning fuzzy logic controller. The optimization criteria for optimal sizing, location and orientation of the PFRC actuators is based on the Gramian controllability matrix and the optimization process is performed by involving the limitation of the plates masses increase. Optimal configurations of five PFRC actuators for active vibration control of the first six modes of cantilever symmetric ((90 degrees/0 degrees/90 degrees/0 degrees)s), antisymmetric cross-ply ((90 degrees/0 degrees/90 degrees/0 degrees/90 degrees/0 degrees/90 degrees/0 degrees)) and antisymmetric angle-ply ((45 degrees/-45 degrees/45 degrees/-45 degrees/45 degrees/-45 degrees/45 degrees/-45 degrees)) composite plates are found using the particle swarm optimization. The detailed analysis of influences of the PFRC layer orientation and position (top or bottom side of composite plates), as well as bending-extension coupling of antisymmetric laminates on controllabilities is also performed. The experimental study is performed in order to validate this behavior on controllabilities of antisymmetric laminates. The particle swarm-optimized self-tuning fuzzy logic controller (FLC) adapted for the multiple-input multiple-output (MIMO) control is implemented for active vibration suppression of the plates. The membership functions as well as output matrices are optimized using the particle swarm optimization. The Mamdani and the zero-order Takagi-Sugeno-Kang fuzzy inference methods are employed and their performances are examined and compared. In order to represent the efficiency of the proposed controller, results obtained using the proposed particle swarm optimized self-tuning FLC are compared with the corresponding results in the case of the linear quadratic regulator (LQR) optimal control strategy.This is the peer reviewed version of the article: Zorić, N.; Tomović, A.; Obradović, A.; Radulović, R.; Petrović, G. R. Active Vibration Control of Smart Composite Plates Using Optimized Self-Tuning Fuzzy Logic Controller with Optimization of Placement, Sizing and Orientation of PFRC Actuators. Journal of Sound and Vibration 2019, 456, 173–198. [https://doi.org/10.1016/j.jsv.2019.05.035

Improved performance of motor-drive systems by SAW shaft torque feedback

The paper describes the application of a non-contact, high bandwidth, low cost, SAW-based torque measuring system for improving the dynamic performance of industrial process motor-drive systems. Background to the SAW technology and its motor integration is discussed and a resonance ratio control (RRC) technique for the coordinated motion control of multi-inertia mechanical systems, based on the measurement of shaft torque via a SAW-based torque sensor is proposed. Furthermore, a new controller structure, RRC plus disturbance feedback is proposed, which enables the controller to be designed to independently satisfy tracking and regulation performance. A tuning method for the RRC structure is given based on the ITAE index, normalized as a function of the mechanical parameters enabling a direct performance comparison between a basic proportional and integral (PI) controller. The use of a reduced-order state observer is presented to provide a dynamic estimate of the load-side disturbance torque for a multi-inertia mechanical system, with an appraisal of the composite closed-loop dynamics. The control structures are experimentally validated and demonstrate significant improvement in dynamic tracking performance, whilst additionally rejecting periodic load side disturbances, a feature previously unrealisable except by other, high-gain control schemes that impose small stability margins

Controller Design for Active Vibration Damping with Inertial Actuators

In the machining industry, there is a constant need to improve productivity while maintaining required dimensional tolerances and surface quality. The self-excited vibration called chatter is one of the main factors limiting machining productivity. Chatter produces unstable cutting conditions during machining and unstable forces will damage and shorten the life of the machine tool. It can also damage the cutting tool, machining components as well as produce a poor surface finish on the workpiece. Researchers have developed various chatter suppression techniques such as changing process parameters, spindle speeds, and using passive dampers. However, many of these methods are not very robust to changing dynamics in the machine tool due to changing machine positioning, cutting setups, etc. Active vibration damping with a force actuator is a robust method of adding damping by due to its bandwidth and variable controller gains. However, the commissioning of the controller design for the actuators is not trivial and requires significant manual tuning to reach optimal productivity. The research presented in this thesis aims to simplify and automate the controller design process for force actuators. A frequency domain, sensitivity based automatic controller tuning method for force actuators has been developed. This method uses the measured actuator dynamics and open-loop system dynamics to develop a prediction tool for closed-loop responses without needing to have the complete system model (model free). By monitoring the predicted closed-loop response of various virtually designed controllers, an optimal controller is found amongst the candidate parameter values. The stability of the system and actuator is monitored during the search to ensure that the system is stable throughout its bandwidth that the actuator does not become saturated. The controller is then experimentally tested to ensure that the predicted output is the same as the real output. In cases where the system has several vibration modes that are in counter-phase and close in frequency, the model-free approach does not perform well. A more complex model-based control law has also been developed and implemented. The method automatically identifies a transfer function model for the measured open-loop system dynamics and synthesizes mixed-sensitivity optimization based controller to damp out the modes in counter-phase. In order to verify that the model-based controllers can reduce vibration modes in counter-phase, a small-scale experimental setup was developed to mimic machine tools with vibration modes in counter-phase. A flexure was designed and fabricated. A shaker from Modal Shop is used as an active damping actuator to reduce the flexure’s vibration modes. It was concluded that while the model-based controller synthesis techniques were able to damp the vibration modes in counter phase, the flexure was too simplistic and the model-free controller was able to achieve similar results

Proceedings of the Workshop on Computational Aspects in the Control of Flexible Systems, part 2

The Control/Structures Integration Program, a survey of available software for control of flexible structures, computational efficiency and capability, modeling and parameter estimation, and control synthesis and optimization software are discussed

Vibration Attenuation of the NASA Langley Evolutionary Structure Experiment Using H(infinity) and Structured Singular Value (mu) Robust Multivariable Control Techniques

This final report summarizes the research results under NASA Contract NAG-1-1254 from May, 1991 - April, 1995. The main contribution of this research are in the areas of control of flexible structures, model validation, optimal control analysis and synthesis techniques, and use of shape memory alloys for structural damping