Ales Richter

Feedback control method based on servomechanism speed estimating and processing to reduce residual vibration

The paper presents a functional method for suppression of the two-mass system residual vibrations. The vibrations are excited due to the common effect of torsion plasticity and large moment of inertia of kinematical chain components. The described strategy is based on a mathematical model of servomechanism which is predicting the actual speed of the kinematical chain end-point. The estimated speed of the endpoint is consequently subtracted from the internally measured speed at the motor shaft and by means of weighting and phase shifting there is computed the correction signal which is ready to be used in conventional control structure and in this way to effectively damp the residual vibrations of the kinematical chain end-point. The method functionality was tested first in the numerical simulation of the servomechanism mathematical model and after that it was integrated into the existing cascade structure of the standard servo control unit Siemens Sinamics S120 and verified experimentally on the real system. The result both of the simulations and experiments on the real device, shown in the final part of the article, demonstrate the ability of this method to effectively damp the residual vibrations of the mechanism end-point.

Efficiency of mechanical energy recovery from a tram by different input conditions

At present, more and more traction vehicles use energy recovery while braking. During this recuperation, electric traction motor becomes a generator and kinetic energy with potential energy is converted into electrical energy. Thereby the direction of current turns and electrical energy is returned to the contact line. Efficiency of the energy recovery depends on a number of factors and conditions (braking intensity, quality and a profile of a track, switching losses in transistors, rolling resistance between the wheels and rails, and other). The article deals with the evaluation of some of the factors influencing the success of regenerative process based on real measured data in the tramway service.

3D EM modelling of DC traction motors for pairing of motors in tram undercarriages

The article deals with modelling of tram DC series motors. The finite element method in 3D and 2D ANSYS / Maxwell program is used. The main objective is to focus on the effects of the electromagnetic imbalances or imperfections that they arise in the maintenance and repair of DC series motors.

Pulse driving of piezoceramic actuators and their present technical limitations

Abstract The article describes new operating principles of ultrasonic actuators. The technical limitations of driving the piezoelectric actuators using the pulse-width modulation (PWM) will be discussed. The limitations caused by parameters of high-speed switching transistors (namely ultra-fast MOSFETs), by speed of the field-programmable gate arrays (FPGA) and by parameters of piezoceramic actuators will be examinated. Further, usage possibilities of resonant converters for the driving of piezoceramic actuators with travelling acoustic wave will be analysed. The aim is to find such courses of driving signals as to minimize requirements for switching transistors and computing performance of FPGA. In conclusion a methodology for measurement of the dynamic properties of piezoceramic actuators will be introduced. The measuring system developed at the Technical University of Liberec will be presented.

Physical Analysis of Pulse Low-Dynamic Magnetic Field Applied in Physiotherapy

This article makes an effort to explain some physical and energy aspects of practice using magneto therapy in the treatment of the musculoskeletal system (orthopaedic surgery, physiotherapy and the rehabilitation). We are presenting the principles of electromagnetic induction in muscle tissue as typical example of the parts of human body. The main accent of presenting theory is put on macroscopic physical behaviour of low-frequency electromagnetic field in living body parts. The problems are indicated with modelling. This approach use simplified model of tissue conductivity. One of the goals is to warn about different distribution of magnetic field in parts of body caused by different position, spatial orientation and metal implants too. The each metal part implanted into human body has strongly influence on distribution physical effects into. Another analyse introduces physical and energy differences among individual types of power sources of magnetic field and their dynamic behaviour.

Electromagnetic Compatibility of Cardiostimulation Technology in Relation to Human Body—The Introductory Study

The session deals with interdisciplinary topic of the electromagnetic compatibility of cardiostimulation devices that are used in patients with cardiac pathology. This study is thematically interested in physical and energy impacts of artificial electromagnetic fields, particularly in the influence of strong energy time-variable fields, on cardiostimulation system implanted into human organism. We consider implanted electronic device, pacemaker or cardioverter-defibrillator with fixed electrodes, and human heart, especially cardiac conduction system, as a whole. In this article we present the functional principles of implantable cardiac pacemakers and describe its interaction with the source of external interference by using modelling and simulation methods by electric circuit substitution. Subsequently, we discuss the physical mechanisms of disturbance signals and methods to minimize its consequences. The aim of the study is the theoretical analysis and the introduction to this issue and also the definition of the terms. This session does not occupy with medical clinical problems but the emphasis is put on physical and energy aspects of external electromagnetic fields on heart implanted device and to refer and analyze the possible risks of interaction.

Physical and energy analysis of therapy applying low-dynamic magnetic fields

This article makes an effort to explain physical and energy aspects of practice using magneto therapy in physiotherapy and rehabilitation. We are presenting the principles of electromagnetic induction in muscle tissue as a typical example of parts of human body. The main goal of these analyses is to warn about physical and energy differences among individual types of power sources of magnetic field and their dynamic behaviour. In theory the problems are indicated with modelling of low dynamic magnetic field in the living tissue.

Remote measurement in electrical engineering laboratories power measurement in electrical drive system, synchronization of stepper motors

The remote access and diagnostics are very common in modern industrial system. Some of them use own proper system, some others use public standards, web based visualization or virtual network computing VNC. On Technical university of Liberec we would like to enhance education in combined, distant study form. The most of the students are experienced people which would like to increase their knowledge in their field of interest or enhance the knowledge in wider range. The main idea for education of those people is usage of programmable logical controller to handle the laboratory task and allow them to do the measurement remotely by their own. In the paper there are several examples how to create or modify laboratory tasks in this way.

Dynamic Properties Modelling of Piezoelectric Motor with Travelling Elastic Wave

There is a basic mathematical model of a piezoelectric motor with travelling elastic wave introduced in this article. The model is based on considerations resulting from physical relations of the piezoelectric motor behaviour. The model enables to find out the basic dynamic properties of the motor, e.g. its behaviour in dependence on pressure or exciting signal amplitude. Classical methodology well-known in electromagnetic drives is used, only the size of motors and tools are smaller in this modelling.