Stanislav Aranovskiy

Identification of Frequency of Biased Harmonic Signal

We consider a problem of identification of unknown frequency of a biased sinusoidal signal y(t) = σ0 + σ sin(ωt + φ) + δ(t) with bounded disturbance or harmonic noise δ(t). A new proposed approach to estimation of frequency of biased sinusoidal signal is robust with regard to unaccounted disturbances, which are present in measurement of effective signal. Unlike known analogs, this approach allows to regulate time of estimation of unknown frequency ω. The proposed approach also allows online amplitude and bias estimation. The proposed identification algorithm has smaller dimension than other known analogs.

Adaptive compensation of disturbances formed as sums of sinusoidal signals with application to an active vibration control benchmark

An intuitive solution for the problem of adaptive attenuation of a disturbance formed as a finite sum of unknown sinusoidal signals is proposed for an internally stable discrete-time plant. The compensator is formed as a weighted sum of stable filters. An identification-based procedure for adaptive tuning of the coefficients is proposed for the case of unknown disturbance. We also propose a time-invariant compensator that provides perfect attenuation of a disturbance for the case when a model identification error is sufficiently small and disturbance frequencies are known. The technique is applied to a case study on a challenging benchmark example in the field of active vibration control. Attenuation of a disturbance formed as a sum of up to three sinusoidal signals with unknown/time-varying frequencies is demonstrated via simulation and experimental studies.

Identification of frequency of biased harmonic signal

Abstract The paper is dedicated to problem of identification of unknown frequency of a biased sinusoidal signal y(t) = σ 0 + σ sin(ω t +). A new proposed approach to estimation of frequency of biased sinusoidal signal is robust with regard to unaccounted disturbances, presenting in measurement of effective signal. Unlike known analogs, this approach allows to regulate time of estimation of unknown frequency ω. The proposed approach also allows online amplitude and bias estimation. Dimension of the proposed identification algorithm is less than known analogs have.

Performance Enhancement of Parameter Estimators via Dynamic Regressor Extension and Mixing

A new procedure to design parameter estimators with enhanced performance is proposed in the technical note. For classical linear regression forms, it yields a new parameter estimator whose convergence is established without the usual requirement of regressor persistency of excitation. The technique is also applied to nonlinear regressions with “partially” monotonic parameter dependence—giving rise again to estimators with enhanced performance. Simulation results illustrate the advantages of the proposed procedure in both scenarios.

Output controller for quadcopters with wind disturbance cancellation

In the paper an output control approach for a class of nonlinear MIMO systems is presented. A multicopter with four symmetrical rotors, i.e. a quadcopter, is chosen to illustrate proposed adaptive control approach based on the high-gain principle, so-called, “consecutive compensator”. Output controller is designed by decomposition of the mathematical model on two parts. The first one is a static MIMO transformation (more precisely, in the considering case a system of linear equations which relates control signals for actuators and virtual control inputs). The second one is a few SISO channels. Such trick allows to design a control law in two steps. At the first step we design virtual controls for each SISO channel. Here we apply the mentioned systematic approach “consecutive compensator”, which also allows to cancel unknown wind disturbances changing their values and directions negligibly slowly. Then after the inverse MIMO transformation we get control signals for actuators.

Modeling and identification of spool dynamics in an industrial electro-hydraulic valve

Approximate models of spool dynamics are proposed to deal with dynamic delays observed for an industrial electro-hydraulic valve. The suggested model consists of a linear block and two static nonlinearities. A method for identification of parameters is suggested that allows to deal with a case when only pressure in a hydraulic cylinder is measured but not the displacement of the spool. The approach is verified experimentally.

Time-Varying Gain Differentiator: A Mobile Hydraulic System Case Study

In mobile hydraulic systems, velocities are typically not measured. However, using their reliable estimates for feedback is known to allow designing better control laws. We are going to present a specialized technique to compute such estimates using measurements of positions and pressures in the chambers of hydraulic cylinders. With a rough estimate for an upper bound of the second derivative, computed online from pressures, the goal is to find the first derivative of the position signal in the presence of noise. We propose a differentiator with a continuous time-varying gain, constructed from pressure measurements, achieving chattering attenuation without compromising the performance of estimation. The gain is constructively tuned using analysis based on a time-varying Lyapunov function. In addition, the obtained ultimate bounds on differentiation errors provide a criterion for the enhancement of the precision of the proposed algorithm with a constructive design of its parameters. The experimental results over a forestry-standard mobile hydraulic crane confirm the advantages of the methodology.

A parameter estimation approach to state observation of nonlinear systems

A novel approach to the partial state estimation problem is proposed. Instrumental to this approach is the reformulation of the state estimation problem as a problem of estimation of a constant parameter related to the systems initial conditions. The admissible class of the systems is defined via two assumptions related to solvability of a partial differential equation and our ability to estimate the unknown parameters. The proposed approach is shown to be applicable to position estimation of a class of electromechanical systems.

Sliding mode control of a forestry-standard mobile hydraulic system

In this paper, a sliding mode control design for a forestry-standard mobile hydraulic system, including bounded model uncertainties and external disturbances, is proposed. The approach includes inverse of a dead-zone-like nonlinearity and a feedforward compensation. Besides, two strategies for chattering attenuation are implemented, improving the overall performance. Experimental results performed over an industrial setup confirm efficacy of the proposed methodology. Additionally, a comparison with a PID controller is presented.

Time-Varying Gain Second Order Sliding Mode Differentiator

The problem of first order differentiation, when an estimation of an upper bound of the second derivative is available on-line, is studied in this paper. The proposed method include two approaches: ...