The path-following problem for four-wheel independently actuated autonomous ground vehicles is investigated in this paper. A novel output constraint controller is proposed to deal with the lateral offset control in path following and maintain the vehicle lateral stability in the presence of tire sliding effects. The innovations of this work lie in the following two aspects: 1) A novel output constraint control strategy, namely, the hyperbolic projection method, is proposed to strictly bound the lateral offset to prevent the vehicle from transgressing the safety bound in path following; 2) an adaptive and robust linear quadratic regulator controller is adopted to obtain the optimal active front-wheel steering and direct yaw-moment control inputs with vehicle lateral stability consideration and to eliminate the effect of parameter uncertainties. CarSim–Simulink joint simulation results indicate that the proposed controller can compactly bound the lateral offset to avoid transgressing the safe boundary during path following, particularly in extreme driving conditions, in the presence of tire sliding effects and system uncertainties.

Output Constraint Control on Path Following of Four-Wheel Independently Actuated Autonomous Ground Vehicles

This article investigates a novel fast terminal sliding mode control approach combined with global sliding surface structure for the robust tracking control of nonlinear second-order systems with time-varying uncertainties. The suggested control technique is formulated based on the Lyapunov stability theory and guarantees the existence of the sliding mode around the sliding surface in a finite time. Using the new form of switching surface, the reaching phase elimination and the robustness improvement of the whole system are satisfied. Simulation results demonstrate the efficiency of the proposed technique. © 2014 Wiley Periodicals, Inc. Complexity 21: 239-244, 2015

Fast terminal sliding mode controller design for nonlinear second-order systems with time-varying uncertainties

This paper presents a new digital maximum power point tracking control scheme for a standalone photovoltaic (PV) system. It is built up on a single input fuzzy-logic (SIFLC), and based on the constant voltage algorithm. The SIFLC generates a duty cycle (D) signal which is the control one for the DC–DC Boost converter. The proposed SIFLC performances will be compared to these of the well-known P&O algorithm. A stability study for the Mamdani SIFLC controllers is performed and proposed. The Lyapunov method is considered for the stability analysis of the proposed control systems. This MPPT algorithm is then experimentally implemented all around a DSP1104 for a real-time driving. The obtained results show that the proposed SIFLC-MPPT clearly succeeds to track the maximum power point and shows a higher performance than regular MPPTs such as the P&O algorithm. Results of the experimental tests also prove the validity and robustness of the proposed overall PV system control scheme.

Efficiency optimization of a DSP-based standalone PV system using a stable single input fuzzy logic controller

This paper considers the terminal guidance problem of missiles intercepting maneuvering targets with impact angle constraints. Based on an advanced nonsingular fast terminal sliding mode control scheme and adaptive control, an adaptive nonsingular fast terminal sliding mode guidance law is proposed in the presence of the target acceleration as an unknown bounded external disturbance. In the design procedure, an adaptive law is presented to estimate the unknown upper bound of the external disturbance. Theoretical analysis shows that the proposed guidance law can guarantee the finite-time convergence in both the reaching phase and the sliding phase by applying a Lyapunov-based approach. Numerical simulations are presented to demonstrate the effectiveness of the proposed guidance law. Although the proposed guidance law is developed for the constant speed missiles, by the extensive numerical simulations with a realistic missile model, the performance is shown to be equally good for the varying speed missiles.

Adaptive nonsingular fast terminal sliding mode guidance law with impact angle constraints

This paper addresses a novel adaptive global nonlinear sliding surface for a class of disturbed nonlinear dynamical systems. A nonlinear gain function is used in the sliding surface to change the damping ratio and improve the transient performance of the controlled system. Initially, to get a quick response, a low value of damping ratio is obtained using a constant gain matrix. As the response of the system approaches to the origin, the damping ratio of the controlled system is improved and the overshoot and settling time of the closed-loop system are reduced. A novel control law without chattering is designed to satisfy the elimination of the reaching phase and achieve the presence of the sliding around the surface right from the beginning. Moreover, the adaptive tuning control law eliminates the necessity of the knowledge about the bounds of the external disturbances. Illustrative simulations on Genesio chaotic system with different values of the initial conditions and external disturbances are presented to show the robustness and success of the suggested design.

Stability analysis and controller design for the performance improvement of disturbed nonlinear systems using adaptive global sliding mode control approach

A global sliding mode controller (GSMC) is proposed for the missile electromechanical actuator (EA) servo system, where exists high uncertainties, such as parameter variations and external disturba...

A global sliding mode controller for missile electromechanical actuator servo system

Linear quadratic regulator (LQR) is an optimal controller being used for linear systems, and it can minimize the comprehensive quadratic performance index (QPI) with respect to convergence error and control consumption. However, LQR lacks the robust property to cope with parameter perturbations and external disturbances. Aiming at the above deficiency of LQR, a robust LQR (RLQR) is proposed for linear systems under the guideline of planes cluster approaching mode (PCAM). In the proposed RLQR, one nonlinear item is introduced into control law, and it cooperates with the other linear item to guarantee the global asymptotic stability in the presence of equivalent disturbances. The conditions of global asymptotic stability are deduced by the method of Lyapunov function. Simulation results present that, the chosen LTI plant using RLQR possesses smaller QPI in the existence of timevarying disturbances, compared with the conventional LQR and sliding mode controller (SMC).

A control method to make LQR robust: A planes cluster approaching mode

Considering sliding mode control (SMC) method using the estimation of upper bound on disturbances in motor servo system, if the upper bound is underestimated, the position tracking precision is poor. Contrarily, the control input is overlarge and even chatters violently. To solve the above problems, an adaptive sliding mode controller (ASMC) is proposed. It utilizes a fuzzy decision maker (FDM), which exports the estimation of upper bound on disturbances according to the information of position tracking error and control input. The computer simulations on a dc motor present that the proposed method guarantees satisfactory position tracking accuracy and the chattering at control input is evidently suppressed. Moreover, the output of FDM is sensitive to the changes of disturbances realtimely and precisely. Subsequently, the proposed scheme possesses strong robust performance against disturbances in motor servo system.

The research of adaptive sliding mode controller for motor servo system using fuzzy upper bound on disturbances

For the attitude control of unmanned aerial vehicle(UAV), this paper proposes a kind of adaptive sliding mode controller based on backstepping. Backstepping control has the characteristics of simpleness in designing and convenience in application. Adding the backstepping method in the sliding mode controller can avoid the appearance of the signal function, simplify the controller and maximize the advantages of the two control methods. Interference estimator based on adaptive control realizes the estimation of interference compensation without establishing interference model and foreseeing the unknown upper bound of interference. The simulations' result shows that the novel approach has considerable steady and dynamic performances, as well as good robustness, which confirms the effectiveness of the proposed control method.

Sliding mode controller design for UAV based on backstepping control

Infrared Guidance Hardware-in-loop Simulation technology has great significance In the aerospace. Further research of the simulation system had been made by many institutions and scientists both at home and abroad. In this text, based on the infrared theory and the optical configuration of infrared hardware-in-loop simulation system, the equivalent model of target and background infrared radiation is established, describing a infrared background modeling method. Then the brightness and radiation difference between the target and backgroud under test was calculated to measure parameter of infrared radiation characteristic of close and remote target. Simulation results show that ranging error caused by the environment can be avoided effectively and the ranging accuracy will be improved sequentially through ruducing the background temperature of infrared simulation system.

Yunjie Wu

Papers

A global sliding mode controller for missile electromechanical actuator servo system

A control method to make LQR robust: A planes cluster approaching mode

The research of adaptive sliding mode controller for motor servo system using fuzzy upper bound on disturbances

Sliding mode controller design for UAV based on backstepping control

Background modeling in infrared guidance hardware-in-loop simulation system