Sergey Drakunov

Sliding mode control in dynamic systems

The concept of sliding modes in abstract dynamic systems described by a semigroup of state space transformations is introduced. The sliding mode design procedure is used for designing finite observers, sliding mode control for systems with delays and differential-difference systems, which is illustrated by sliding mode control of longitudinal oscillations

Sliding mode observers. Tutorial

Discusses the problem of designing observers for state estimation using sliding modes. The theory and design principles are presented for linear and nonlinear systems. For linear systems the observers are developed using a block-observable form which is similar to a lower triangular matrix form. Compared with known approaches such observers have better robustness properties. In the case of nonlinear systems an equivalent control concept makes it possible to develop finite-time observers for a wide class of systems.

Stabilization and tracking in the nonholonomic integrator via sliding modes

In this paper we use an approach based on sliding mode control to design a feedback which stabilizes the origin for the so-called nonholonomic integrator or Heisenberg system, a particular case of a canonical class of nonlinear driftless control systems of the form x=B(x)u which fail Brocketts necessary condition for the existence of a smooth stabilizing feedback.

On Discrete-Time Sliding Modes

In the paper the problems of sliding modes simulation and sliding mode digital control design are considered. The simulation problem of the dynamic systems with discontinuous right-hand side is a nontraditional one. The principle difficulty is in the fact that in such systems there is a special kind of motions - sliding modes. For the purposes of sliding mode simulations a definition of a discrete sliding mode is introduced, which enables the design of discrete-time control algorithms with properties similar to those in continuous time systems with sliding-mode control algorithms.

Delay identification in time-delay systems using variable structure observers

In this paper we discuss delay estimation in time-delay systems. In the introduction section a short overview is given of some existing estimation techniques as well as identifiability studies. In the following sections we propose several algorithms for the delay identification based on variable structure observers.

Stabilization of a nonholonomic system via sliding modes

Uses an approach based on sliding mode control to design a feedback which stabilizes the origin for a class of nonlinear driftless systems of the form x/spl dot/=B(x)u. introduced by Brockett (1993). Brockett showed that these systems fail his necessary condition for the existence of smooth feedback.<<ETX>>

Nonlinear control of a rodless pneumatic servoactuator, or sliding modes versus Coulomb friction

Abstract Coulomb friction remains one of the major difficulties arising in control design for mechanical systems. Control of a translational pneumatic servoactuator is a typical example of such a problem. The aim of this paper is to demonstrate that sliding-mode control can be successfully used to compensate the friction of the piston in the cylinder, which is both viscous and Coulomb. A fourth-order nonlinear state-space model of a rodless pneumatic servoactuator will be developed with both numerical simulation and experimental validation. The comparison of sliding-mode control with classic PID control will be presented.

Yaw control algorithm via sliding mode control

Electronic controls have been developed to improve vehicle dynamics in automotive applications. Several luxury vehicle manufacturers have positioned themselves to offer increased vehicle stability by expanding the current anti-lock brake system (ABS) and traction control system (TCS) technology into the arena of yaw control. A yaw control algorithm is developed to give an additional measure of vehicle stability control during adverse driving maneuvers over a variety of road conditions. By measurements of vehicle states, the control algorithm determines the level of vehicle stability and intervenes as necessary through individual wheel braking to provide added stability and handling predictability. The control law is based on optimum search for minimum yaw rate via sliding mode control.

Tracking in nonholonomic dynamic systems via sliding modes

We use an approach based on sliding mode control to design a feedback which forces the state vector of a nonholonomic integrator to track the desired time function. A discontinuous feedback control is found which allows the /spl epsi/-tracking in spite of the fact that the number of controls is less than the dimensionality of the tracking function. The developed approach is applied to a nonholonomic system which describes the motion of the rotating knife moving on the surface. A numerical example is considered.

Robot path obstacle avoidance control via sliding mode approach

The approach described consists in constructing potential fields in configuration space like an electrostatic one with changes distributed in such a way that the generalized force curves are attracted to the goal point and avoid obstacles. The system follows such force curves by using sliding mode. The strategy of robot path obstacle avoidance control with sliding mode is presented and discussed in the two-dimensional space.<<ETX>>