Electro-mechanical system control based on observers

International audienceThe prediction of the gear behavior is becoming major concerns in many industries. For this reason, in this article, an electro-mechanical modeling is developed in order to simulate a gear element driven by an asynchronous motor. The electrical part, which is the induction motor, is simulated by using the Kron's model while the mechanical part, which is the single stage gear element, is accounted for by a torsional model. The mechanical model that simulates the pinion-gear pair is obtained by reducing the degree of freedom of the global spur or helical gear system. The electrical and mechanical state variables are combined in order to obtain a unique differential system that describes the dynamics of the elecro-mechanical system. The global coupled electro-mechanical model can be characterized by a unique set of non-linear state equations. The contribution of this work is to apply the control based on observers in order to supervise the electrical and mechanical behavior of the electro-mechanical system from only its inputs and its measurements outputs (sensors outputs). Some simulations on pinon/motor angular speed, electromagnetic torque, currents, are presented, which illustrate the system evolution (i.e., the electrical and mechanical quantities) and the good performances of the proposed observers

Application of homogeneous observers with variable exponent to a mechatronic system

International audiencePreventive maintenance becomes nowadays more and more essential in many industrial applications. In fact, researchers are always looking for new techniques and analysis tools to monitor the dynamic behavior of their machines. In this context, firstly, we deal with the modeling of an electromechanical system which is accounted for by a hybrid model obtained by assembling the mechanical model of a gear element and the electrical model of an asynchronous motor. Secondly, we use Sliding Mode Observers to supervise the gear dynamic behavior. The observers parameters are suitably chosen to ensure rapid and accurate convergence between the real and the estimated system quantities. Finally, a comparative study between three simulations is presented in order to illustrate the observers performances and the influence of the mechanical dynamics on the electrical ones

A second order sliding mode differentiator with a variable exponent

International audienceIn this article, a new second order sliding mode differentiator with a variable exponent is proposed. Inspired by the classical super twisting differentiator, the dedicated differentiator allows to give a solution for reducing the effect of variable noise of sensor output measurement. To achieve this objective, the parameter α that is fixed in a super twisting differentiator is made variable in the proposed differentiator. First of all, the proposed differentiator is presented in free noise case, after that the extension to the case with output noise is given in details. In both cases the practical convergences of the observation error are guaranteed. In the first the radius of the practical stability is depending on the considered unknown input while in the second case this radius depends also on the noise. Finally some simulation results are given in order to show the performances and the effectiveness of the proposed differentiator compared to existing one

Discrete-time differentiators: design and comparative analysis

This work deals with the problem of online differentiation of noisy signals. In this context, several types of differentiators including linear, sliding-mode based, adaptive, Kalman, and ALIEN differentiators are studied through mathematical analysis and numerical experiments. To resolve the drawbacks of the exact differentiators, new implicit and semi-implicit discretization schemes are proposed in this work to suppress the digital chattering caused by the wrong time-discretization of set-valued functions as well as providing some useful properties, e.g., finite-time convergence, invariant sliding-surface, exactness. A complete comparative analysis is presented in the manuscript to investigate the behavior of the discrete-time differentiators in the presence of several types of noises, including white noise, sinusoidal noise, and bell-shaped noise. Many details such as quantization effect and realistic sampling times are taken into account to provide useful information based on practical conditions. Many comments are provided to help the engineers to tune the parameters of the differentiators