Rodrigo Zelir Azzolin

Sensorless Sliding-Mode Rotor Speed Observer of Induction Machines Based on Magnetizing Current Estimation

This paper presents a rotor speed observer for induction-machine drives based on a sliding-mode approach and magnetizing current estimation. The back electromotive force (EMF) is calculated from the stator current and the stator voltage signals. The magnetizing currents are obtained from the back EMF. A theorem which gives the rotor speed estimate in the continuous-time domain is formulated using the magnetizing current estimation. The stability analysis is achieved based on the Lyapunov approach. Moreover, the discrete-time approach of the method is discussed, and a theorem for the discrete-time implementation is proposed. The limits that ensure the system stability for the switching gains and for the observer gain are discussed. This paper shows that the limits for the gains of the discrete-time algorithm are different from the limits for the gains of the continuous-time algorithm. Simulation results are presented to validate the theoretical analysis. In addition, experimental results based on a fixed-point digital signal processor (DSP) platform (DSP TMS320F2812) demonstrate the performance of the proposed scheme.

Discrete-time sliding mode approach for speed estimation of symmetrical and asymmetrical induction machines

This paper presents and analysis a rotor speed estimator for symmetrical and asymmetrical induction machines. The proposed scheme is based on discrete-time formulation of the sliding mode observer. The method is suitable to close-loop sensorless control of induction machines. The stability and parameter convergence of the proposed method are analyzed by using discrete-time likelihood Lyapunov. Experimental results based on DSP platform (TMS320F2812) are presented and they demonstrate the good performance of the proposed sensorless control scheme for symmetrical and asymmetrical induction motor drives.

A pole placement control by states feedback based on State Variable Filter

This article presents a performance comparison between two state observers in a pole placement control (PPC). The first is a classical full order states observer and the second observer is proposed in this work, which is based on a State Variable Filter (SVF). A inverted pendulum on movable base was the system chosen to accomplish performance comparison of the state observers. Simulation results are presented and results are detailed.

Decoupling and sensorless vector control scheme for single-phase induction motor drives

Vector control has improved the performance and energy efficiency in SPIM drives. However, high current and torque pulsations are produced by winding asymmetry of SPIM. This paper proposes a decoupling scheme to reduce the current and torque pulsations and improve the performance of vector control. A stator current observer is used to estimate the coupling signals, which are compensated by control law. This method is an alternative to improve the performance of single-phase induction motor used in hermetic refrigeration systems. The thermal efficiency of refrigeration system can be improved by the variable speed operation and the advantages of robustness and low-cost of single-phase induction motor can be maintained.

Discrete-time sliding mode speed observer for induction machine drives

This paper addresses the rotor speed estimation problem of induction machine drives. A scheme based on discrete-time formulation of the Sliding Mode Observer is proposed and analyzed. The method is suitable to close-loop sensorless control of induction machines. The stability analysis and parameter convergence of the proposed method is presented. Simulation and experimental results based on DSP platform (TMS320F2812) demonstrate the good performance of the proposed sensorless control scheme.

Performance comparison of control strategies applied on welding robot plant

This work shows three control techniques applied individually on velocity control of a welding robot. The system transfer function is found by bench tests and pole allocation method. The control strategies proposed are: Proportional Integral Controller, Pole Place Control and Model Reference Control. The techniques were designed and simulated to compare its performances acting under same situations.

Control of linear welding robot plant by pole placement control based on discrete Kalman Filter

The Pole Placement Control is a control strategy to reallocate poles of a system forcing a desired behaviour to it. The technique is established on states feedback backed by a gain matrix. States are estimated when they are not directly available. Then, in this work a pole placement control based on Discrete Kalman Filter, in discrete time, for feedback states was applied over a linear welding robot. The modelling of this robot and simulations of controlled system are presented and results are argued.

Feedback control based on estimators applied on welding robot motor

A way to impose a desired behaviour in a system is to reallocate their poles, a well-known technique for this is the Pole Placement Control. In this work, it is made a performance comparison between two state observers for state feedback of this controller: an classic state observer and a proposed alternative which is based on State Variable Filter. This alternative filter improves robustness to the control law due to its independence of system plant. Moreover, the filter has a simple structure. To accomplish performance comparison, the plant of a linear welding robot motor was utilised with their identified parameters. The modelling of this plant is also presented, as well as simulation results.

Automated seam tracking system based on passive monocular vision for automated linear robotic welding process

Welding is an important process in the industrial scenario, especially in the shipbuilding industry. This process is recognized by the laborious work and the hazardous work environment. The use of robots to automate the welding process can reduce the human interference and improve the productivity. This paper proposes a system for automated seam tracking based on passive monocular vision. The vision provides a data feedback to the automated robotic welding system allowing quality and productivity gains. A trajectory controller is developed to correct the robots movement over the seam reference. The controller and a visual algorithm to find the seam reference in a real Gas Metal Arc Welding (GMAW) process are presented. The proposed system allows the automated seam tracking, the trajectory control of the welding torch, and a higher automation level in linear robotic welding. The capabilities of the method is evaluated using a commercial linear welding robot showing its viability.

A comprehensive model for miscellaneous mass transfer mode in gas metal arc welding

Welding is an operation that aims to join two or more pieces, holding that on combination of these parts there will has no discontinuity of physical, chemical and metallurgical properties for its use and performance. This work deals with the modeling of this system. For this, two models are presented: one represents the dynamic of drop formation on electrode tip and the second model represents mass transfer dynamic when a short circuit occurs.