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An uncertain ocean environment demands robust control to manoeuvre autonomous underwater vehicle (AUV) to achieve the control objectives. The desired depth of the vehicle can be achieved by implementing an efficient pitch angle control law to satisfy the longitudinal motion of AUV. In this paper, a linearized pitch channel model of MAYA AUV is used. A norm-based robust controller is designed to achieve the design requirements in the presence of parametric uncertainty and disturbance. The efficacy and feasibility of control laws demonstrated through a computational tool MATLAB.

This study presents the design of interconnection and damping assignment passivity-based control for active suspension systems. It is well known that interconnection and damping assignment passivity-based control’s design methodology is based on the physical properties of the system where the kinetic and potential energy profiles are shaped, and asymptotic stability is achieved by damping injection. Based on the choice of control variables, special cases of the control law are derived, and tuning of the control law with the physical meaning of the variables is demonstrated along with their simulation results. The proposed control law is experimentally validated on a scaled model of a quarter-car active suspension system with different road profiles, varying load conditions, and noise and delay in the sensor measurements and actuator respectively. The results are compared with that of an uncontrolled system with linear quadratic regulator and sliding mode control.

The capability to localize or identify position in the field of deployment is a primary requirement of future autonomous system in domains such as warehouse transportation, ambient-assisted living/ health care systems, search and rescue, motion monitoring, etc. Although reliable indoor localization in the order of few centimeters can be achieved with the existing localization systems in Line-of-Sight (LOS) conditions, the localization under Non-line-of-Sight (NLOS) conditions is an open area of research. In range-based localization systems, distance estimation is a pre-requisite for location estimation. Time of Arrival (ToA) is considered to be the most accurate technique for distance estimation when compared to Time Difference of Arrival (TDoA) or Received Signal Strength Indication (RSSI). Most of the work available as literature on indoor localization under NLOS conditions is based on the profiling of the indoor deployment area under various NLOS conditions and mitigating NLOS affected timestamps from the ToA measurements. However, it is not practically possible to obtain a comprehensive data set containing all possible conditions of NLOS in indoor environments. In this paper, an Artificial Neural Network based Location Estimation Unit (ANN-LEU) based scheme is proposed to estimate the two-dimensional (2-D) location of an object under LOS and NLOS conditions. One of the unique features of the novel location estimation scheme is that the training of the system is required to be performed only under LOS conditions, thus facilitating the quick deployment in new environments. The proposed ANN-LEU is robust as it identifies the presence of NLOS if any, in the ToA measurements and thus removing false position estimations if any. The Mean Average Error (MAE) error in position estimated during the performance analysis of the proposed system was restricted to lesser than 20 cm, if the object is in range of three beacons in LOS, and also for the scenarios in which one of the three beacon nodes are in NLOS. The proposed scheme eliminates false position identification. The proposed scheme requires lesser number of beacons for localization when compared to the available indoor localization systems, thus also improving the cost and energy efficiency.

A linearized decoupled depth plane model is used to formulate the control problem of an autonomous underwater vehicle (AUV). This paper describes the design and simulation of a depth plane control for a diving autopilot system for MAYA AUV. An effective control strategy on pitch angle is inevitable to achieve the specified depth of the vehicle. The resonant controller is designed by introducing a pole assignment technique to control the pitch angle with disturbance. The proportional controller is used to command and regulate the depth of the vehicle. The robustness analysis is done using the proposed control scheme with achieved performance. The efficacy of the proposed control scheme to track the sinusoidal reference input and reject the sinusoidal disturbance is reported with and without uncertainties in depth plane model using the computational simulation tool.

A diving system control problem for an autonomous underwater vehicle (AUV) is considered. Linearized decoupled model is used to represent the kinetics/dynamics of the system for diving control. A single sensor is used to estimate the unmeasured state through diving system control structure. Two controller design schemes are defined and used for steady-state tracking and noise reduction. A proportional derivative (PD) controller and pole placement with estimator approach are adopted to synthesize the control law. The selection of the desired closed-loop pole and initial condition are discussed. Performance of the controller based on the desired specification and steady-state tracking is examined using simulation and its results are discussed.

A vertical plane control problem for an autonomous underwater vehicle (AUV) is considered. Linearized decoupled model is used to represent the dynamics of the system for vertical plane control. Three different feedback control schemes are used to synthesize the control law. The proposed control scheme design gives full control to place the dominant closed-loop poles at desired speed and damping. The selection of dominant closed-loop poles is based on the control effort should be minimal. Performance of the controller is examined using simulation. Simulation results are discussed.

Multiple mini-UAVs can be used in various disaster monitoring applications. These UAVs can be controlled from ground based control stations, or they can form flying ad-hoc networks (FANET) with fully distributed nature of operations. To achieve distributed operations, a set of network protocols need to be developed as a part of protocol stack. Various networking protocols for FANET have been developed in this paper namely clustering, time division based MAC protocol and routing protocol for a particular networking topology. This FANET network can be used for exploring a larger and disjoint terrain with the help of multiple cluster formations. To maintain isolation between clusters and to optimise energy of the network, UAVs make use of adaptive power communication techniques. Extensive simulation experiments have been performed using a platform developed by linking NS-3, ROS and Gazebo tools. Results of network performance are shown with respect to scalability and mobility of UAVs.

Minimization of car vibrations has been a topic of research over the years and many control strategies have been developed. Therefore, there needs to be a method for active vibration control in cars. This paper presents two methods for designing the controller for a quarter car model which would help in minimizing car vibrations and increasing passenger comfort subjected to road disturbances. The methodologies used are H-infinity and H-2 optimal control. The main aim of this article is to design a controller to control the response of a quarter car model to various road inputs. This is a non-linear model with 2 degrees of freedom. It is linearized and modelled as a disturbance rejection (regulatory) problem wherein the effect of disturbances are minimised. Different weighing functions have been considered to take the impact of road disturbances into account. The results are compared with the Proportional Integral Derivative (PID) controller designed using the same system parameters and performance specifications. The behaviour of the open loop and closed loop system is observed by examining the impulse and frequency responses in MATLAB. A detailed discussion is done with the choice of weighing functions. It is found that the disturbance rejection techniques suggested in this paper help in improving the system response

SUMMARY The immersion and invariance (II 48(4):590–606) is a recently proposed control methodology for stabilizing nonlinear systems. Here we apply this philosophy to stabilize a single machine infinite bus (SMIB) system using a controllable series capacitor (CSC). The synchronous generator is modeled using the second-order swing equation and a first-order model is used for the CSC. The control objective here is to immerse a desired second-order dynamic model into the higher order system manifold and design an asymptotically stabilizing control law. Copyright © 2011 John Wiley & Sons, Ltd.

The modeling and control of a single machine infinite bus (SMIB) system using a controllable series capacitor (CSC) is presented here. The SMIB is modeled using two different models- the well-known second order swing equation and the third order flux-decay model. The actuator dynamics is incorporated as a first order system and the interconnection and damping assignment passivity-based control (IDA-PBC) approach is used for controller synthesis. The control objectives are to asymptotically stabilize a desired operating point and modify the transient response of the system. The two objectives are achieved by assigning a suitable energy function and modifying the interconnection structure between the electrical and mechanical subsystems, thereby improving the coupling between the two subsystems. Estimates of the domain of attraction of the operating point are also given.

A controllable series device (CSD) is used to damp the transient oscillations in a power system. The power system studied here is the single machine infinite bus (SMIB) and the CSD used is a controllable series capacitor (CSC). Interconnection and damping assignment passivity-based control (IDA PBC) is used for controller synthesis. The SMIB system is described with two different types of models - the second order swing equation model and the classical third order flux decay model. For the second order model the control objective of damping assignment as well as energy shaping is achieved. In case of the third order model the control objective is just damping injection.

In this chapter, we give a brief introduction to modeling of electrical power systems. An electrical power system consists of many nodes or buses with synchronous generators or loads or both connected to them, and these nodes connected with each other through long transmission lines and devices such as transformers.

A stability result based on the Immersion and Invariance control strategy is derived for a class of systems described by differential equations with algebraic constraints. The result is then applied to synthesize a stabilizing control law for a two machine electrical power system with a controllable series capacitor (CSC). The dynamics of the two-machine system. is given by differential equations and the active power balance at the load buses is given by algebraic equations. The CSC dynamics is described by a first order differential equation.

The IDA-PBC methodology relies on the concept of exact model matching of the closed-loop system with a certain desired behaviour. Immersion and Invariance [1], on the other hand, is based on (a) immersing a lower order desired target dynamics onto a manifold in the original space, and (b) matching the closed-loop system with the immersed system asymptotically. The control objective is to make the immersed manifold attractive and invariant. This methodology, as it is based on the concept of asymptotic model matching, offers more flexibility over IDA-PBC.

Electrical power systems are naturally described by nonlinear differential-algebraic equations (DAEs). The dynamics of the dynamical components in the system such as the synchronous generators are given by the set of differential equations, while various network constraints such as power balance equations at different nodes are expressed by a set of algebraic equations. In this chapter we extend the I&I methodology to a class of differential algebraic systems, without the need for solving for the nonlinear algebraic equations explicitly.

We now summarize the work done in this monograph. We have presented two nonlinear control techniques for power system stabilization at an equilibrium using a CSC. Both the control laws were based on passivity ideas: one involves the notion of interconnection and damping assignment, the other is based on choosing target dynamics on a lower dimensional manifold. The synchronous generator was described using two well known nonlinear models—the second order swing equation and the third order flux-decay model. The actuator, that is the CSC, was modeled using an injection model and a first order model.

The method of Interconnection and Damping Assignment is a passivity-based control synthesis technique. It is based on matching a closed-loop system with a desired behaviour, specified using a desired interconnection and damping structure and a desired energy function. Applications of this technique for synthesizing stabilizing control laws for excitation control of electrical power systems have been reported in the literature. In this chapter the IDA-PBC methodology is used to derive stabilizing control laws for electrical power systems using controllable series capacitors. The swing equation model is used to represent the generators. The CSC is modeled using the injection model. The control objective is to asymptotically stabilize a desired operating point and modify the transient response of the system. It is achieved by assigning a suitable energy function to the closed-loop system and modifying the interconnection and damping structures. Estimate of the domain of attraction of the operating point are also given.

A nonlinear control law is proposed to asymptotically stabilize a single machine infinite bus (SMIB) system based on immersion and invariance (I&I) control strategy. The actuator used is a controllable series capacitor (CSC). The SMIB system is described using the nonlinear second order swing equation model, and the CSC is modeled using a first order system. The control objective here is to approximate the complete third order system with a second order dynamics, for which we have an asymptotically stabilizing control law.

A prevalent approach to control in the gantry crane industry is to track a trajectory using an open-loop strategy based on notions of differential flatness. Point-to-point control is achieved by selecting a suitable trajectory to be followed. To cope with disturbances and uncertainties, a nominal feedback controller is added to the loop. We have approached the objective of point-to-point transfer with swing suppression along the trajectory by combining notions of flatness and the IDA-PBC technique. The applications like handling liquid filled container demand such kind of quasistatic trajectories. Initially, a flatness based control law is used to follow a desired trajectory that transfers the system to a neighbourhood of the final state. Then the IDA-PBC control law is switched on for robust stabilization of the system.

Passivity based controllers are known to provide robust stability for inherently passive dynamic systems. Recently, with the development of "passification" techniques, these controllers are also shown to be effective in robust stabilization of non-passive systems. However, the robustness of stability in this case depends on the robustness of passification. The frequency domain sufficient conditions also exist in the literature for checking robustness of passification. This paper presents a new condition for robust passification using different norm-bounded uncertainty models. In particular, the coprime factor uncertainty models are considered and corresponding robust passification conditions are presented.

A stability result, based on the Immersion and Invariance (I&I) control strategy, for a class of systems with constraints is derived. The result is used to synthesize a stabilizing nonlinear control law for a single machine infinite bus (SMIB) system. The SMIB system is described by the structure preserving model (SPM) where the rotor dynamics is given by the nonlinear second order swing equation model, and the power balance equation at the generator terminal bus is given by an algebraic constraint. The actuator used is a controllable series capacitor (CSC). The CSC is modeled using a first order system. The control objective here is to stabilize the generator dynamics at a given equilibrium.