Adaptive frequency domain identification for ANC systems using non-stationary signals

The problem of identification of secondary path in active noise control applications is dealt with fundamentally using time-domain adaptive filters. The use of adaptive frequency domain subband identification as an alternative has some significant advantages which are overlooked in such applications. In this paper two different delayless subband adaptive algorithms for identification of an unknown secondary path in an ANC framework are utilized and compared. Despite of reduced computational complexity and increase convergence rate this approach allows us to use non-stationary audio signals as the excitation input to avoid injection of annoying white noise. For this purpose two non-stationary music and speech signals are used for identification. The performances of the algorithms are measured in terms of minimum mean square error and convergence speed. The results are also compared to a fullband algorithm for the same scenario. The proposed delayless algorithms have a closed loop structure with DFT filterbanks as the analysis filter. To eliminate the delay in the signal path two different weights transformation schemes are compared

An Adaptive Scheme to Estimate Unknown Parameters of an Unmanned Aerial Vehicle

This paper deals with tracking control problem for six degrees of freedom (6-DOF) nonlinear quadrotor unmanned aerial vehicle (UAV). A virtual control design using PD controller is proposed for tracking control position. The rotational dynamics of UAV is considered to have several unknown parameters such as propeller inertia, rotational drag coefficient and an external disturbance parameter. To handle this issue, an adaptive scheme using the certainty equivalence principle is developed. The basic idea behind this scheme is to cancel the nonlinear term by applying a similar nonlinear structure in the feedback control design. The unknown parameters are replaced by estimated parameters generated by adaptation law. The rigorous theoretical design and simulation results are presented to demonstrate the effectiveness of the controller

Model development and energy management control for hybrid electric race vehicles

A Hybrid Electric Vehicle longitudinal dynamics model for the control of energy management is developed. The model is implemented using Simulink and consists of a transitional vehicle speed input parameterized by, for example, the New European Driving Cycle. It is a backward looking model in that engine and motor on/off states are determined by the controller, dependent on wheel torque requirements and output targets. The objective of the simulation is to calculate tractive effort and resistance forces to determine longitudinal net vehicle force at the road. This article addresses model development and initial investigations of its dynamic behaviour in order to establish appropriate energy management strategies for the Hybrid Electric system. In particular, All Wheel Drive, Front Wheel Drive and Rear Wheel Drive drivetrain architectures are evaluated to determine minimum fuel usage and battery state of charge. The use of a logic controller allows a reduction of simulation time and ensures accurate results for charge depletion and harvesting. Simulated fuel consumption is within 1% of actual usage

Validation of a hybrid electric vehicle dynamics model for energy management and vehicle stability control

A Simulink Hybrid Electric Vehicle dynamics model for the control of energy management and vehicle stability is developed. The model encompasses a transitional vehicle speed input parameterized by the New European Driving Cycle. Internal combustion engine torque, motor torque and varying corner radii are set to the same time constraints as the drive cycle. Lateral acceleration, yaw rate and tyre data are validated against measured car data, resulting in a simulation model that can be utilised (with modifications) as a tool to determine stability control and power deployment for front-wheel, rear-wheel or all-wheel drive hybrid vehicles. The model yields similar outputs to a driven vehicle’s normal measured responses

Distributed Robust Synchronization Control of Multiple Heterogeneous Quadcopters with An Active Virtual Leader*

This paper studies leader-following synchronization control of a group of multiple quadrotor unmanned aerial systems (UASs). A robust distributed scheme is developed to maintain the attitude motions of UASs with an active virtual leader. Complicated settings are considered in the design, where the topology is in a directed graph, and only one or some agents are connected to the leader. UASs can have different dynamic parameters. Also, some time-varying disturbances are added to the closed-loop system. A control protocol containing a robust term is proposed to each UAS to achieve asymptotic consensus. A rigorous mathematical proof and numerical example are presented to demonstrate the effectiveness of our scheme

Adaptive Integral Terminal Sliding Mode Control for the Nonlinear Active Vehicle Suspension System under External Disturbances and Uncertainties

Suspension system is one of the most effective vehicle components that play an essential role in the stability and comfort of the vehicle. The passive suspension can not fully meet a car's stability and comfort requirements. Instead, an active suspension system has been proposed to improve these challenges. Active suspension minimizes the vibrations entering the body using a closed-loop control system. To this end, in this research, an integral terminal sliding mode control (integral TSMC) for an active nonlinear car suspension system under external disturbances and uncertainties is designed. First, the integral TSMC is designed to deal with the uncertainties and the external disturbances in the system when the upper bound is known. Next, an adaptation law is recommended to estimate the upper bound of uncertainties and external disturbances. The results show that the proposed integral TSMC improves the convergence rate and tracking error of the closed-loop system. The stability of the nonlinear control system is investigated and proven using Lyapunov's stability theory. The numerical results indicate a good robust performance and stability for the proposed controller for the nonlinear suspension system with different road profiles in the presence of uncertainties and external disturbances. From the results, it can also be understood that important measures such as ride comfort, road holding, and mechanical structural limitations are met using the proposed approach

Design and Development of a Novel Controller for Robust Attitude Control of an Unmanned Air Vehicle for Nuclear Environments

This study presents two new robust nonlinear control algorithms based on the theory of time-varying sliding mode control (TVSMC) strategy to stabilize the attitude of an unmanned aerial vehicle (UAV) for nuclear decommissioning applications. Constant radiation affects the UAV performance. For instance, its parameters are time-varying and subject to uncertainty all the time. This is especially important in designing sliding mode control as the motion of the control system in the reaching phase is highly sensitive against environmental disturbances and parameter uncertainties. In this study, two types of time-varying sliding manifolds are proposed to eliminate the reaching phase and to enhance the robust performance in the aforementioned phase. Therefore, two novel types of time-varying sliding surfaces are introduced based on the initial condition as intercept-varying sliding mode control (IVSMC) approaches. In the first proposed method, the reaching time from initial manifold to the desired one is similar to that of the conventional SMC method. While in the second proposed IVSMC scheme, one can accelerate or decelerate the motion of the time-varying sliding manifolds at any selected time. Furthermore, chattering phenomenon can be avoided using two techniques known as boundary layer and continuous SMC. Finally, to highlight the robust performance of the proposed methods, a quadrotor UAV subject to external disturbances is simulated

Modeling and analysis of secondary sources coupling for active sound field reduction in confined spaces

This article addresses the coupling of acoustic secondary sources in a confined space in a sound field reduction framework. By considering the coupling of sources in a rectangular enclosure, the set of coupled equations governing its acoustical behavior are solved. The model obtained in this way is used to analyze the behavior of multi-input multi-output (MIMO) active sound field control (ASC) systems, where the coupling of sources cannot be neglected. In particular, the article develops the analytical results to analyze the effect of coupling of an array of secondary sources on the sound pressure levels inside an enclosure, when an array of microphones is used to capture the acoustic characteristics of the enclosure. The results are supported by extensive numerical simulations showing how coupling of loudspeakers through acoustic modes of the enclosure will change the strength and hence the driving voltage signal applied to the secondary loudspeakers. The practical significance of this model is to provide a better insight on the performance of the sound reproduction/reduction systems in confined spaces when an array of loudspeakers and microphones are placed in a fraction of wavelength of the excitation signal to reduce/reproduce the sound field. This is of particular importance because the interaction of different sources affects their radiation impedance depending on the electromechanical properties of the loudspeakers

Development of dynamic model of a 7DOF hydraulically actuated tele-operated robot for decommissioning applications

In this paper the problem of system integration and dynamic modeling of a hydraulically actuated manipulator with seven degrees of freedom, i.e. HydroLek HLK-7W is investigated. The arm is fitted on Multi-Arm mobile Robot System for Nuclear Decommissioning (MARS-ND) applications purposes. This is a step forward with respect to the previous works where only kinematics of the robot was taking into account. As the decommissioning robot has to perform precise and complex tasks autonomously using effective model-based nonlinear control algorithms having an accurate dynamic model of the arm which is reliable enough to predict the behavior of the manipulator under different operating conditions would be crucial. To this end the symbolic, and numerical model of the dynamic of robot is developed and a first attempt for model validation and tuning the parameters of the model is taken forward

A Nonlinear Discrete-Time Sliding Mode Controller for Autonomous Navigation of an Aerial Vehicle Using Hector SLAM

In this paper, a discrete-time sliding mode controller (DTSMC) is designed for full position and attitude control of a quadrotor UAV. The aim of this study is to design a controller suitable for practical implementation on an autonomous quadrotor for remote sensing in hostile nuclear environments. A nested DTSMC is developed and compared against two continuous-time sliding mode control methods; classical SMC, as well as a chattering-free SMC (CFSMC), studied in the previous works. The performance of the controllers is evaluated in combination with the Hector SLAM algorithm for localisation in GPS-denied environments. For this purpose, MATLAB in combination with the Robotic Operating System (ROS) is used to develop the controllers. Control signals are sent from MATLAB to the Gazebo simulation environment in ROS, which simulates the quadrotor and runs the Hector SLAM algorithm