In this paper, a model predictive control (MPC) approach for controlling an active front steering system in an autonomous vehicle is presented. At each time step, a trajectory is assumed to be known over a finite horizon, and an MPC controller computes the front steering angle in order to follow the trajectory on slippery roads at the highest possible entry speed. We present two approaches with different computational complexities. In the first approach, we formulate the MPC problem by using a nonlinear vehicle model. The second approach is based on successive online linearization of the vehicle model. Discussions on computational complexity and performance of the two schemes are presented. The effectiveness of the proposed MPC formulation is demonstrated by simulation and experimental tests up to 21 m/s on icy roads

Predictive Active Steering Control for Autonomous Vehicle Systems

1. Introduction: An Overview of Classical Sliding Mode Control 2. Differential Inclusions and Sliding Mode Control 3. Higher-Order Sliding Modes 4. Sliding Mode Observers 5. Dynamic Sliding Mode Control and Output Feedback 6. Sliding Modes, Passivity, and Flatness 7. Stability and Stabilization 8. Discretization Issues 9. Adaptive and Sliding Mode Control 10. Steady Modes in Relay Systems with Delay 11. Sliding Mode Control for Systems with Time Delay 12. Sliding Mode Control of Infinite-Dimensional Systems 13. Application of Sliding Mode Control to Robotic Systems 14. Sliding Modes Control of the Induction Motor: A Benchmark Experimental Test

Sliding Mode Control in Engineering

Distributed consensus tracking is addressed in this paper for multi-agent systems with Lipschitz-type node dynamics. The main contribution of this work is solving the consensus tracking problem without the assumption that the topology among followers is strongly connected and fixed. By using tools from M-matrix theory, a class of consensus tracking protocols based only on the relative states among neighboring agents is designed. By appropriately constructing Lyapunov function, it is proved that consensus tracking in the closed-loop multi-agent systems with a fixed topology having a directed spanning tree can be achieved if the feedback gain matrix and the coupling strength are suitably selected. Furthermore, with the assumption that each possible topology contains a directed spanning tree, it is theoretically shown that consensus tracking under switching directed topologies can be achieved if the control parameters are suitably selected and the dwell time is larger than a positive threshold. The results are then extended to the case where the communication topology contains a directed spanning tree only frequently as the system evolves with time. Finally, some numerical simulations are given to verify the theoretical analysis.

Consensus Tracking of Multi-Agent Systems With Lipschitz-Type Node Dynamics and Switching Topologies

This article proposes new methodologies for the design of adaptive sliding mode control. The goal is to obtain a robust sliding mode adaptive-gain control law with respect to uncertainties and perturbations without the knowledge of uncertainties/perturbations bound (only the boundness feature is known). The proposed approaches consist in having a dynamical adaptive control gain that establishes a sliding mode in finite time. Gain dynamics also ensures that there is no overestimation of the gain with respect to the real a priori unknown value of uncertainties. The efficacy of both proposed algorithms is confirmed on a tutorial example and while controlling an electropneumatic actuator.

https://hal.archives-ouvertes.fr/hal-00626498/document

New methodologies for adaptive sliding mode control

The effective application of sliding mode control to mechanical systems is not straightforward because of the sensitivity of these systems to chattering. Higher-order sliding modes can counteract this phenomenon by confining the switching control to the higher derivatives of the mechanical control variable, so that the latter results are continuous. Generally, this approach requires the availability of a number of time derivatives of the sliding variable, and, in the presence of noise, this requirement could be a practical limitation. A class of second-order sliding mode controllers, guaranteeing finite-time convergence for systems with relative degree two between the sliding variable and the switching control, could be helpful both in reducing the number of differentiator stages in the controller and in dealing with unmodelled actuator dynamics. In this paper different second-order sliding mode controllers, previously presented in the literature, are shown to belong to the above cited class, and some cha...

A survey of applications of second-order sliding mode control to mechanical systems

Sliding Mode Control (SMC) is gaining increasing importance as a universal design tool for the robust control of linear and nonlinear systems. The strengths of sliding mode controllers result from the ease and flexibility of the methodology for their design and implementation. They provide inherent order reduction, direct incorporation of robustness against system uncertainties and disturbances, and an implicit stability proof. They also allow for the design of high performance control systems at low costs. SMC is particularly useful for electro-mechanical systems because of its discontinuous structure. In fact, since the hardware of many electro-mechanical systems (such as electric motors) prescribes discontinuous inputs, SMC has become the natural choice for direct implementation. The book is intended primarily for engineers and establishes an interdisciplinary bridge between control science, electrical and mechanical engineering.

Sliding mode control in electromechanical systems

Introduction Examples of Dynamic Systems with Sliding Modes Sliding Modes in Relay and Variable Structure Systems Multidimensional Sliding Modes Outline of Sliding Mode Control Methodology Mathematical Background Problem Statement Regularization Equivalent Control Method Physical Meaning of Equivalent Control Existence Conditions Design Concepts Introductory Example Decoupling Regular Form Invariance Unit Control Second-Order Sliding Mode Control Sliding Mode Control of Pendulum Systems Design Methodology Cart Pendulum Rotational Inverted Pendulum (Model) Rotational Inverted Pendulum (Control) Simulation and Experiment Results for Rotational Inverted Pendulum Control of Linear Systems Eigenvalue Placement Invariant Systems Sliding Mode Dynamic Compensators Ackermanns Formula Output Feedback Sliding Mode Control Control of Time-Varying Systems Sliding Mode Observers Linear Asymptotic Observers Observers for Linear Time-Invariant Systems Observers for Linear Time-Varying Systems Observer for Linear Systems with Binary Output Integral Sliding Mode Motivation Problem Statement Design Principles Perturbation and Uncertainty Estimation Examples Summary The Chattering Problem Problem Analysis Boundary Layer Solution Observer-Based Solution Regular Form Solution Disturbance Rejection Solution State-Dependent Gain Method Equivalent Control-Dependent Gain Method Multiphase Chattering Suppression Comparing the Different Solutions Discrete-Time and Delay Systems Introduction to Discrete-Time Systems Discrete-Time Sliding Mode Concept Linear Discrete-Time Systems with Known Parameters Linear Discrete-Time Systems with Unknown Parameters Introduction to Systems with Delays and Distributed Systems Linear Systems with Delays Distributed Systems Summary Electric Drives DC Motors Permanent-Magnet Synchronous Motors Induction Motors Summary Power Converters DC/DC Converters Boost-Type AC/DC Converters DC/AC Converter Summary Advanced Robotics Dynamic Modeling Trajectory Tracking Control Gradient Tracking Control Application Examples Automotive Applications Air/Fuel Ratio Control Camless Combustion Engine Observer for Automotive Alternator

Sliding Mode Control in Electro-mechanical Systems

For an automatic steering problem of a city bus the reference maneuvers and specifications are introduced. The robustness problem arises from large variations in velocity, mass, and road-tire contact. Two controller structures, both with feedback of the lateral displacement and the yaw rate, are introduced: a linear controller and a nonlinear controller. The controller parameters are first hand-tuned and then refined by performance vector optimization. Both controllers meet all specifications. Their relative merits are analyzed in simulations for four typical driving maneuvers. >

Linear and nonlinear controller design for robust automatic steering

SUMMARY In this paper, steering control for passenger cars on automated highways is analyzed, concentrating on look-down reference systems. Extension of earlier experimental results for low speed to highway speed is shown to be non-trivial. The limitations of pure output-feedback of lateral vehicle displacement from the road reference are examined under practical constraints and performance requirements like robustness, maximum lateral error and comfort. The in-depth system analysis directly leads to a new alternative design direction which allows to preserve look-ahead reference systems for highway speed automatic driving.

Analysis of automatic steering control for highway vehicles with look-down lateral reference systems

This paper describes a robust control design for automatic steering of passenger cars. Previous studies showed that reliable automatic driving at highway speed may not be achieved under practical conditions with look-down reference systems which use only one sensor at the front bumper to measure the lateral displacement of the vehicle from the lane reference. An additional lateral displacement sensor is added here at the tail bumper to solve the automatic steering control problem. The control design is performed stepwise: an initial controller is determined using the parameter space approach in an invariance plane; and this controller is then refined to accommodate practical constraints and finally optimized using the multiobjective optimization program. The performance and robustness of the final controller was verified experimentally at California PATH in a series of test runs.

Jürgen Guldner

Papers

Sliding mode control in electromechanical systems

Sliding Mode Control in Electro-mechanical Systems

Linear and nonlinear controller design for robust automatic steering

Analysis of automatic steering control for highway vehicles with look-down lateral reference systems

Robust automatic steering control for look-down reference systems with front and rear sensors