Active Vehicle Suspension with Anti-Roll System Based on Advanced Sliding Mode Controller

In the paper authors consider the active suspension of the wheeled vehicle. The proposed controller consists of a sliding mode controller used to roll reduction and linear regulators with quadratic performance index (LQRs) for struts control was shown. The energy consumption optimization was taken into account at the stage of strut controllers synthesis. The studied system is half of the active vehicle suspension using hydraulic actuators to increase the ride comfort and keeping safety. Instead of installing additional actuators in the form of active anti-roll bars, it has been decided to expand the active suspension control algorithm by adding extra functionality that accounts for the roll. The suggested algorithm synthesis method is based on the object decomposition into two subsystems whose controllers can be synthesized separately. Individual suspension struts are controlled by actuators that use the controllers whose parameters have been calculated with the LQR method. The mathematical model of the actuator applied in the work takes into account its nonlinear nature and the dynamics of the servovalve. The simulation tests of the built active suspension control system have been performed. In the proposed solution, the vertical displacements caused by uneven road surface are reduced by controllers related directly to suspension strut actuators.

Optimization of the Inverted Pendulum Controller with Friction Compensation by Means of the New Method of Lyapunov Exponents Estimation

This text covers optimization of an inverted pendulum control system with friction compensator. The control system is tuned with respect to a performance index based on the novel method of the Largest Lyapunov Exponent estimation. The detailed description of the method is provided. Model of the control object is presented. A simple controller is proposed. Two control systems are compared: the one with compensator and the one without. Parameters of both controllers are optimized with respect to the novel criterion by means of the Differential Evolution method. Results of numerical simulations are presented. It is shown that the new criterion can be successfully applied to both: typical linear regulators and controllers with compensators.

Design of Linear Parameter-Varying Based Sliding Mode Regulator for Limit Protection of Aero-Engines

In aircraft engine control, replacing linear regulators by sliding mode control (SMC) regulators is considered as an effective approach to reducing the conservatism in the traditional treatment for limit protection. However, most of the relevant studies are based on linear descriptions, which cannot represent the nonlinear systems directly due to their limited valid range. Even if gain scheduling techniques are employed, the stability of the nonlinear systems cannot be theoretically guaranteed. In this paper, a sliding mode strategy for a class of uncertain linear parameter varying (LPV) systems is studied. LPV descriptions are applied to extend the valid range of the linear models covering the entire operation envelope with guaranteed performance and stability. The mismatch between LPV and the real systems is considered as uncertainties. With a sliding surface defined by the tracking errors, system properties on the surface are proved to be satisfactory. After that, a reaching law is designed to ensure global invariance of SMC. Based on a reliable model turbofan, simulation results show that the SMC method can fully exploit the limit margin and, compared to the traditional proportional-integral-derivative (PID) control, has a faster response. In addition, stability and effectiveness of the proposed method are verified in a temperature protection case.

POLYNOMIAL METHOD FOR THE SYNTHESIS OF MULTICHANNEL SYSTEMS BY TRANSITION TO MATRIX POLYNOMIAL REPRESENTATION

Polynomial methods for synthesizing linear regulators for automatic control systems with linear objects, proposed by a number of authors, including Chen, Kailath, Gaiduk, and others, along with methods of synthesis in the state space, are becoming increasingly widespread. The synthesis of multichannel regulators caused by the need to use the matrix polynomial calculus is of a special difficulty, which is aggravated by a significant increase in the dimension of the matrices during the transition from polynomial matrices to numeric ones, in which Sylvester matrices are used. Herewith, it is necessary to take into account the requirements of controllability and observability, leading to the need to check for the presence of identical roots in polynomial matrices corresponding to the numerator and denominator of the object. This leads to the requirement of a relatively prime matrix polynomial fraction, which can be significantly weakened if it is possible to include in the desired characteristic matrix of the system some zeros and poles of the object located far to the left of the imaginary axis. In calculations using numerical matrices and, consequently, using Sylvester matrices, the latter degenerate due to the lowering of the rank, which complicates the calculations. The research continues to study polynomial synthesis of multichannel regulators based on the results obtained by Chen and other researchers and presents an algorithm for the synthesis of regulators, the feature of which is the possibility of introducing additional so-called free parameters that allow additional requirements for the automatic control system. The free parameters allow to obtain strictly proper regulators, along with the proper regulators.