Input-output Linearization Method Research Articles

Research on the coordinated control of oxygen excess ratio and air pressure for PEMFC's air supply system

The proton exchange membrane fuel cell (PEMFC) air supply system is a complex nonlinear system with strong coupling of air flow and pressure. To avoid oxygen starvation and unstable output performance during rapid load changes, the oxygen excess ratio (OER) and air pressure need to be controlled effectively. To cope with the nonlinearity, coupling and uncertainty of the PEMFC air system, this paper puts forward a coordinated controller regulating OER and air pressure based on the input-output linearization and sliding mode methods. Firstly, a control-oriented third-order model is proposed to describe the dynamic behavior of the air supply system. Secondly, this paper decouples the flow and pressure of the PEMFC air system by using an input-output linearization method to obtain two independent linear subsystems. Moreover, a sliding mode method, effectively coping with the uncertainty of the system model, is designed to regulate the OER and air pressure of the PEMFC, which enhances the robustness of the control system. The overall simulation outcomes show that the proposed controller regulates OER and cathode pressure with smaller root mean square error (RMSE) and mean absolute percentage error (MAPE) compared with the combined proportional integral (PI) and feedforward controller.

Phase-Unsynchronized Power Decoupling Control of MMC Based on Feedback Linearization

The traditional power decoupling control of modular multilevel converter (MMC) is based on the phase synchronization achieved by the phase-locked loop (PLL), and MMC intricate inner dynamics are ignored, which jeopardizes the system stability and power decoupling. To improve the performance, a nonlinear phase-unsynchronized power decoupling control for MMC is proposed without PLL. At first, the MMC model as a nonlinear multi-input multi-output system is developed. The developed model illustrates that the MMC power coupling is caused by the ac current as well as the MMC capacitor voltages. Then, through the input–output linearization method, the proposed method decouples the MMC output powers without the phase synchronization. Involving integral control, the dynamics of MMC output powers are designed as second-order systems so that the control parameters can be easily determined based on the required transient performance. To verify the accuracy and correctness of the developed model, a comparison of MMC dynamics with the proposed control is conducted between the numerical solution in MATLAB and the EMT simulation in PSCAD/EMTDC. Moreover, seven cases in the EMT simulations and four cases in the experimental results demonstrate the desired phase asynchronization and power decoupling performance of the proposed method compared with the conventional <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> control. At last, the system zero dynamic stability is investigated and the influences of MMC control parameters, ac-side voltage, dc-side voltage and equilibrium points are analyzed to evaluate the stability performance of the proposed method.

Output Tracking of Some Class Non-Minimum Phase Nonlinear Systems via linearization Input-Output

We present an output tracking problem for a non-minimum phase nonlinear system. In this paper, the input control design to solve the output tracking problem is to use the input output linearization method. The use of the input output linearization method cannot be initiated from output causing the system to be non-minimum phase. Therefore the output of the system will be redefined such that the system will become minimum phase with respect to a new output.

Obstacle Avoidance Using CTC and Virtual Structure for Leader-Follower Formation on Mobile Robot

This research examined the development of the combination of virtual structure and leader-follower as an obstacle avoidance method in the formation control of a mobile robot. The formation of the robots are designed with the Separation Bearing Control (SBC) approach between the leader robot (RL) and the virtual robot (RV). The virtual robot is used as a virtual follower and a reference trajectory for the follower robot (RF). When the follower robot detects an obstacle, the follower robot trajectory is adjusted using a trajectory planner for obstacle avoidance. After passing the obstacle, the follower robot will track its position back in formation using virtual robot position and heading as reference. Leader robot and follower are perturbed by disturbances. In order to ensure the achievement of small error tracking, a controller is designed using the integration of kinematic and dynamics controllers with disturbance observer. The kinematic and dynamics controllers are designed using input-output linearisation (IOL) method and computed torque control (CTC). The effectiveness of the proposed method is verified by the simulation result.Keywords: CTC, leader follower, obstacle avoidance, SBC, virtual structure.

UUB 이론을 이용한 해상작업용 크레인의 부하위치제어계 설계

This paper introduces a payload position control system for an offshore crane to cope with uncertainties. On the sea, marine systems are exposed to various disturbances and uncertainties provoked by the vessel motion, hydrodynamic forces, etc. These factors deteriorate the safety and efficiency of work operations. To overcome these problems, we propose a novel control system design method based on UUB (Uniformly Ultimately Bounded) theory combined with the input-output linearization method. To guarantee the given state error bound by uniformly ultimately boundedness, the analysis of stability condition using the energy-based Lyapunov function is conducted. Then, the particle swarm optimization technique is used to obtain the optimal control gains of the control system. Finally, the control performance and effectiveness of the proposed control system are validated through a set of simulation tests.

Boost PFC Constant Voltage Control with Constant Power Load

The power factor correction (PFC) can be realized by the input-output linearization method for boost converter, The advantage is that the duty cycle of MOS transistor can be calculated directly without control parameter setting, but when the converter is connected to constant power load (CPL), because the duty cycle formula includes the ratio of output voltage to current, the load of Buck CPL has no current flow during the toff period, so the normal calculation results cannot be given. In order to solve the problem that the output duty cycle cannot be calculated, this paper starts from the relationship of equal input and output power, and merges resistance into the output terminal. At the same time, in order to reduce the power loss, the capacitor is connected to the original circuit to provide continuous current to correct the current discontinuity, and then the output voltage is precisely adjusted to realize the fast constant voltage control of Boost PFC converter under CPL.

Improved DC-Link Voltage Regulation Strategy for Grid-Connected Converters

In this article, an improved dc-link voltage regulation strategy is proposed for grid-connected converters applied in dc microgrids. For the inner loop of the grid-connected converter, a voltage modulated direct power control is employed to obtain two second-order linear time-invariant systems, which guarantees that the closed-loop system is globally exponentially stable. For the outer loop, a sliding mode control strategy with a load current sensor is employed to maintain a constant dc-link voltage even in the presence of constant power loads at the dc-side, which adversely affect the system stability. Furthermore, an observer for the dc-link current is designed to remove the dc current sensor at the same time improving the reliability and decreasing the cost. From both simulation and experimental results obtained from a 15-kVA prototype setup, the proposed method is demonstrated to improve the transient performance of the system and has robustness properties to handle parameter mismatches compared with the input-output linearization method.

Control Design for Preventing Dengue Infections using Input-Output Linearization Method

This study deals with a theoretical study of control design to prevent transmission of dengue fever viruses. The input-output linearization method is a feedback control method that can be applied to design the control functions so that the transmission of dengue viruses can be disrupted. Fogging is considered as an eradication effort and vaccination is considered as a prevention effort. Both treatments are considered as the input controls of the method while infected human variable is considered as the output control. By treating eradication effort and prevention effort as the control inputs we design controls that can stabilize the system and lead the infected population going to zero. Some numerical schemes are presented to confirm the theoretical results and the analytical results.

Design of a central feedforward control of torque vectoring and rear-wheel steering to beneficially use tyre information

ABSTRACT This paper presents the design of a central feedforward control for the two chassis control systems rear-wheel steering (RWS) and torque vectoring (TV) which have related areas of intervention in lateral dynamics. A control strategy is presented in order to follow desired target values consisting of yaw acceleration and sideslip angle velocity. Central attention is given to the use of additional tyre information with the aim of enhancing vehicle handling and stability. With the knowledge of the mounted tyre type, an adaption law for the desired target values is derived. Although the focus is based on the usage of new tyre information, this modelling approach basically has the potential to reduce the need for coordination among the two systems RWS and TV, exploiting the synergies between both of them. Starting from an extended single-track model an exact Input–output linearisation method is used to design the feedforward control. This is followed by a proof of stability for the external and the internal dynamics of the controller. For the subsequent investigation, in a preliminary step, real-world in vehicle tests are carried out under varying tyre types with a wide spreading of characteristics. This serves as a basis to identify the most important tyre parameters for the controller and to derive the target goals. Finally, the controller is implemented in a 14-DOF non-linear entire vehicle model in Matlab/Simulink, that serves for simulations with a virtual vehicle plant. The performance of the presented feedforward control is assessed by specified objective criteria for steady-state and transient open-loop manoeuvres in lateral dynamics. These criteria are used to investigate the effectiveness of the control design with the aim to achieve the defined target motion. In addition to that, the manoeuvre results also serve to evaluate the control effort, involved in the coordinated cooperation of both systems.

Improved adaptive backstepping sliding mode control for a three‐phase PWM AC–DC converter

The stability problem of a three-phase voltage source PWM AC-DC converter is addressed through an improved adaptive backstepping method, which combines the following contents: input-output linearisation, adaptive backstepping method, error compensation and sliding mode control. The state equation of the three phase system is obtained by the power balance relationship between the input current and the output voltage, and then the coordinate conversion is carried out in order to design the controller. When the input-output linearisation method transfers the system model to a strict-feedback form, an improved adaptive backstepping control approach is given to stabilise the converter. Finally, the simulation results show that the improved method has three benefits: retain a faster stability of rectifier, reduce overshoot of DC voltage and bring about a real-time parameter estimation.

Study on nonlinear friction compensation control in the electro-hydraulic servo loading system of triaxial apparatus

Nonlinear friction and uncertain disturbance are two of the most important factors affecting the tracking performance and the robustness in the electro-hydraulic servo loading system of triaxial apparatus. In this paper, an iterative learning control (ILC) based sliding mode control (SMC) has been proposed to solve such a problem. A P-type learning function is used to compensate the model of nonlinear friction. The state-space model of the triaxial apparatus is established and the corresponding controller is designed. The controller employs an ILC based SMC of input-output feedback linearisation (IOFL) method to determine the control rule and accomplish the compensation for the nonlinear friction. A Lyapunov method is applied to analyse the condition of convergence in the finite time and the impact acting on the system caused by the control parameters. The simulation results indicate that the tracking performance and the robustness of the system have been remarkably improved.

Heave Compensation System Design for Offshore Crane based on Input-Output Linearization

A heave motion of the offshore crane system with load is affected by unpredictable external factors. Therefore the offshore crane must satisfy rigorous requirements in terms of safety and efficiency. This paper intends to reduce the heave displacement of load position which is produced by rope extension and sea wave disturbance in vertical motion. In this system, the load position is compensated by the winch actuator control. The rope is modeled as a mass-damper-spring system, and a controller is designed by the input-output linearization method. The model system and the proposed control method are evaluated on the simulation results.

An optimal model-based trajectory following architecture synthesising the lateral adaptive preview strategy and longitudinal velocity planning for highly automated vehicle

ABSTRACTAutomated driving has received a broad of attentions from the academia and industry, since it is effective to greatly reduce the severity of potential traffic accidents and achieve the ultimate automobile safety and comfort. This paper presents an optimal model-based trajectory following architecture for highly automated vehicle in its driving tasks such as automated guidance or lane keeping, which includes a velocity-planning module, a steering controller and a velocity-tracking controller. The velocity-planning module considering the optimal time-consuming and passenger comforts simultaneously could generate a smooth velocity profile. The robust sliding mode control (SMC) steering controller with adaptive preview time strategy could not only track the target path well, but also avoid a big lateral acceleration occurred in its path-tracking progress due to a fuzzy-adaptive preview time mechanism introduced. In addition, an SMC controller with input–output linearisation method for velocity tracking is built and validated. Simulation results show this trajectory following architecture are effective and feasible for high automated driving vehicle, comparing with the Driver-in-the-Loop simulations performed by an experienced driver and novice driver, respectively. The simulation results demonstrate that the present trajectory following architecture could plan a satisfying longitudinal speed profile, track the target path well and safely when dealing with different road geometry structure, it ensures a good time efficiency and driving comfort simultaneously.

Pressure model based coordinated control of VGT and dual-loop EGR in a diesel engine air-path system

This paper describes a pressure-model-based coordinated control method of a variable geometry turbine (VGT) and dual-loop exhaust gas recirculation (EGR) in a diesel engine air-path system. Conventionally, air fraction or burnt gas fraction states are controlled for the control of dual-loop EGR systems, but fraction control is not practical since sensors for fractions are not available on production engines. In fact, there is still great controversy over how best to select control outputs for dual-loop EGR systems. In this paper, pressure and mass flow states are chosen as control outputs without fraction states considering the availability and reliability of sensors. A coordinated controller based on the simple control-oriented model is designed with practical aspects, which is applicable for simultaneous operations of high pressure (HP) EGR, low pressure (LP) EGR, and VGT. In addition, the controller adopts the method of input-output linearization using back-stepping to solve the chronic problems of conventional pressure-based controllers such as coupling effects between operations of HP EGR, and VGT. The control performance is verified by simulation based on the proven GT-POWER model of a heavy-duty 6000cc diesel engine air-path.

Tracking control of modified Lorenz nonlinear system using ZG neural dynamics with additive input or mixed inputs

The tracking-control problem of a special nonlinear system (i.e., the extension of a modified Lorenz chaotic system) with additive input or the mixture of additive and multiplicative inputs is considered in this paper. It is worth pointing out that, with the parameters fixed at some particular values, the modified Lorenz nonlinear system degrades to the modified Lorenz chaotic system. Note that, due to the existence of singularities at which the nonlinear system fails to have a well-defined relative degree, the input–output linearization method and the backstepping design technique cannot solve the tracking-control problem. By combining Zhang neural dynamics and gradient neural dynamics, a new effective controller-design method, termed Zhang-gradient (ZG) neural dynamics, is proposed for the tracking control of the modified Lorenz nonlinear system. With singularities conquered, this ZG neural dynamics is able to solve the tracking-control problem of the modified Lorenz nonlinear system via additive input or mixed inputs (i.e., the mixture of additive and multiplicative inputs). Both theoretical analyses and simulative verifications substantiate that the tracking controllers based on the ZG neural dynamics with additive input or mixed inputs not only achieve satisfactory tracking accuracy but also successfully conquer the singularities encountered during the tracking-control process. Moreover, the applications to the synchronization, stabilization and tracking control of other nonlinear systems further illustrate the effectiveness and advantages of the ZG neural dynamics.

Input–output linearization minimum sliding mode error feedback control for synchronization of chaotic system

Under the existence of system uncertainties and external disturbances, complete synchronization of chaotic systems is achieved by introducing a novel input–output linearization minimum sliding mode error feedback control with high control precision, which is based on the input–output linearization method and sliding mode control. In the literature, the magnitudes of bounded nonlinear dynamics of synchronous error system were required in the designed sliding mode controller. In this study, this article proposed a new approach to estimate the various uncertainties and disturbances on the basis of chaotic system. To facilitate the analysis, the concept of equivalent control error is introduced, which is the key to the utilization of input–output linearization minimum sliding mode error feedback control. A cost function is formulated on the basis of the principle of minimum sliding mode covariance constraint; then, the equivalent control error is estimated and fed back to the conventional sliding mode. It is shown that the sliding mode after the input–output linearization minimum sliding mode error feedback control will approximate to the ideal sliding mode, resulting in improved control performance and quality. Finally, the chaotic gyro system and chaotic FitzHugh–Nagumo neurons system have been employed to verify the proposed controller. Sufficient conditions to guarantee stable synchronization are given and the numerical simulations of complete synchronization of the two chaotic systems are performed to verify the effectiveness of the presented schemes.

Identification, control and robustness analysis of a robotic system using fractional control

This paper presents the identification, control and robustness analysis for a robotic system of 1 degree of freedom using fractional and integer PID controllers. Initially, an ADAMS-MATLAB co-simulation model is built to simulate the dynamic model of robotic system. The identification of the dynamic model parameters of the system employs the recursive least-squares method. The controller design uses a linearized model of the robotic system obtained by the method of input-output linearization, and then, the fractional PID and integer PID controllers are designed based on it. The robustness of the PID controllers is analyzed in the frequency and the time domain. The robustness analysis in the frequency domain uses The Gang of Four (sensibility, complementary sensibility, sensibility of the plant and sensibility of the controller effort). The time domain analysis uses the ADAMS-MATLAB co-simulation model, considering external disturbances, noise in the feedback loop, parametric uncertainty and set-point variation, using as performance criteria ISE, average value and standard deviation of the control action. The tests are performed for positioning and tracking tasks. The obtained results show that the fractional PID controller has a better behavior in presence of external disturbances and lower energy consumption.

Singularity‐conquering tracking control of a class of chaotic systems using Zhang‐gradient dynamics

This study investigates the tracking-control problems of the Lorenz, Chen and Lu chaotic systems. Note that the input–output linearisation method cannot solve these tracking-control problems because of the existence of singularities, at which such chaotic systems fail to have a well-defined relative degree. By combining Zhang dynamics and gradient dynamics, an effective controller-design method, termed Zhang-gradient (ZG) method, is proposed for tracking control of the three chaotic systems. This ZG method, with singularities conquered, is capable of solving the tracking-control problems of the chaotic systems. Both theoretical analyses and simulative verifications substantiate that the tracking controllers based on the ZG method can achieve satisfactory tracking accuracy and successfully conquer singularities encountered during the tracking-control process.

Dynamic surface control based on neural network for an air-breathing hypersonic vehicle

Summary In this paper, an adaptive dynamic surface control approach is presented for the longitudinal motion of an air-breathing hypersonic vehicle. Fully tuned radial basis function neural network that regulates weights, width, and center of Gaussian function simultaneously is developed to estimate aerodynamic uncertainties and atmospheric disturbances. The nonlinear control law is subsequently designed by dynamic surface control approach for the vehicle model converted into strict block feedback form by input–output linearization method. Simulation results show that the velocity can be successfully tracked over a large range from Mach 11 to Mach 12 and an altitude range from 26 to 30 km. The presented approach has perfect ability of restraining unknown and time-varying nonlinear dynamics during flight. Copyright © 2014 John Wiley & Sons, Ltd.

Optimal Control of Exhaust Recovery Generator System with Scroll Expander

A scroll expander exhaust recovery system with the battery is proposed to improve exhaust recovery efficiency. Based on the exhaust flow, storage pressure and the battery current, expander supply pressure was optimized with the loss model based on the expansion and generator loss. And then the supply pressure controller was designed to track the optimized supply pressure reference using the input-output linearization method. DC bus voltage was efficiently regulated by the PI voltage controller, the duty feedforward compensation and the operation mode of battery storage system. Experimental results proved the control strategy validity, realizing the efficiency maximum of the recovery system and exhaust discharging system.