Stabilization of the motions of mechanical systems with non-holonomic constraints

Mechanical systems possibly containing non-holonomic constraints are considered. The problem of stabilizing the motion of the system along a given manifold of its phase space is solved. A control law which does not involve the dynamcal parameters of the system is constructed. The law is universal, that is, it stabilizes motion along any given manifold. It is only necessary that the manifold be feasible, that is, conform to the dynamics of the system.     

Stabilization of the motions of non-autonomous mechanical systems

The problem of stabilizing the motions of mechanical systems that can be described by non-autonomous systems of ordinary differential equations is considered. The sufficient conditions for stabilizing of the motions of mechanical systems with assigned forces due to forces of another structure are obtained by constructing a vector Lyapunov function and a reference system. Examples of the solution of the problems of stabilizing the rotational motion of an axisymmetric satellite in an elliptic orbit, a non-tumbling gyro horizon, etc. are considered ©2009     

Stabilization of the stationary motions of non-holonomic mechanical systems

The possible stabilization of the unstable stationary motions of a non-holonomic system is studied from the standpoint of general control theory /1, 2/. As distinct from the case previously considered /3/, when forces of a certain structure are applied with respect to both positional and cyclical coordinates, the stabilization is obtained here by applying control forces only with respect to the cyclical coordinates /4/; the control forces may be applied with respect to some or all of the cyclical coordinates, and depend on the positional coordinates, the velocities, and the corresponding cyclical momenta. It is shown that, just as in the case of holonomic systems /5, 6/, depending on the control properties of the corresponding linear subsystem, the stationary motions, whether stable or unstable, can be stabilized, up to asymptotic stability with respect to all the phase variables, or asymptotic stability with respect to some of the phase variables and stability with respect to the remaining variables. The type of stabilization with respect to the given phase variables depends on the Lyapunov transformations which are needed in order to reduce the critical cases obtained to singular cases /7, 8/.     

Stabilization of the motions of mechanical systems in prescribed phase-space manifolds

A method for constructing a mathematical model of the dynamics of a mechanical system is proposed. An algorithm is constructed for determining the expressions for the control forces and the components of the constraint reactions. A modification is made to the dynamic equations which enables one to solve the problem of stabilizing the constraints and which ensures the required accuracy in the numerical solution of the corresponding system of differential-algebraic equations describing the constraints imposed on the system, its kinematics and dynamics. By virtue of well-known dynamic analogies, the proposed method can be used to investigate the dynamics of different physical systems. The problem of modelling the dynamics of an adaptive optical system with two degrees of freedom is considered.     

Reverse motions of mechanical systems

The possibility of the occurrence of sections of reverse motions in natural mechanical systems, when, in the second half of a time interval, the motion in the first half of the interval is repeated in the reverse order and the opposite velocity with a specified accuracy, is investigated. It is shown that such motions are characteristic of natural mechanical systems in the neighbourhood of a non-degenerate equilibrium position if the natural frequencies are independent. Systems with gyroscopic and dissipative forces are also considered. It is shown that, in these systems, sections of reverse motion can be observed in a special system of coordinates. Examples are presented.     

Controllability and observability of one-dimensional oscillations of mechanical systems with nested masses

Controllability and observability conditions are derived for a three-mass oscillatory system with nested masses. Modal controllers and observers are constructed that take the system to a prescribed spectral region. Cases are considered when the state vector function or a linear combination of its components is observed.Kiev University. Tadzhik University. Translated from Vychislitel'naya i Prikladnaya Matematika, No. 75, pp. 103–107, 1991.     

The stabilization of program motions of controlled nonlinear mechanical systems

We consider a controlled nonlinear mechanical system described by the Lagrange equations. We determine the control forcesQ ₁ and the restrictions for the perturbationsQ ₂ acting on the mechanical system which allow to guarantee the asymptotic stability of the program motion of the system. We solve the problem of stabilization by the direct Lyapunov's method and the method of limiting functions and systems. In this case we can use the Lyapunov's functions having nonpositive derivatives. The following examples are considered: stabilization of program motions of mathematical pendulum with moving point of suspension and stabilization of program motions of rigid body with fixed point.     

Invariant sets and symmetric periodic motions of reversible mechanical systems

A method of constructing and classifying all symmetric periodic motions of a reversible mechanical system is proposed. The principal solution of the above problem is given for the Hill problem, the restricted three-body problem (including the photogravitational problem), the problem of a heavy rigid body with a fixed point, and that of a heavy rigid body on a rough plane. In particular, problems requiring a systematic numerical study are therby formulated.     

Stabilization of switched linear systems by a controller of variable structure

We study the state stabilization problem for switched linear systems operating under parametric uncertainty and bounded coordinate disturbances. To solve the problem, we suggest an algorithmfor constructing a controller of variable structure on the basis of methods of simultaneous stabilization theory.     

Controllability and observability in the problem of stabilizing steady motions of non-holonomic mechanical systems with cyclic coordinatest

The approach to the solution of stabilization problems for steady motions of holonomic mechanical systems [1, 2] based on linear control theory, combined with the theory of critical cases of stability theory, is used to solve the analogous problems for non-holonomic systems. It is assumed that the control forces may affect both cyclic and positional coordinates, where the number r of independent control inputs may be considerably less than the number n of degrees of freedom of the system, unlike in many other studies (see, e.g., [3–5]), in which as a rule r = n. Several effective new criteria of controllability and observability are formulated, based on reducing the problem to a problem of less dimension. Stability analysis is carried out for the trivial solution of the complete non-linear system, closed by a selected control. This analysis is a necessary step in solving the stabilization problem for steady motion of a non-holonomic system (unlike holonomic systems), since in most cases such a system is not completely controllable.     

Controllability and stabilization of programmed motions of reversible mechanical and electromechanical systems

Problems of controllability and methods of stabilizing programmed motions of a large class of mechanical and electromechanical systems which are reversible with respect to the control are considered. Criteria of the controllability and stabilizability of reversible systems are obtained. Programmed motions and algorithms of programmed control are designed in analytical form and algorithms of programmed motions for non-linear reversible systems are synthesized.     

The determination of the periodic motions of systems with delay

Continuing the development of results previously obtained for systems with delay described by first-order differential equations with delay [1], a system without delay is constructed which enables the periodic motions of systems with delay to be found.     

Near-resonant motions in systems with random perturbations

The effect of random perturbations on near-resonant motions in non-linear oscillatory systems is investigated. It is assumed that the equations of motion of the system can be reduced to standard form with a small parameter ϵ, and that an isolated primary resonance exists in the unperturbed system [1]. The behaviour of the perturbed system in the ϵ-neighbourhood of the resonance surface is considered and an effect analogous to deterministic “capture in resonance” [1] in an asymptotically long time interval is investigated.     

Stability of the periodic motions of autonomous systems with lag

In the article we give a generalization of the theorem of A. A. Andronov and A. A. Vitt on the stability of the periodic motions of autonomous systems described by ordinary differential equations to autonomous time-lag systems. The investigation is based on the procedures developed by N. N. Krasovskii which consider the differential equations with lag in a functional space of continuous functions. There is a bibliography of eight items.Translated from Matematicheskie Zametki, Vol. 2, No. 5, pp.561–568, November, 1967.