Ing. Evžen Thöndel, Ph.D.

The primary purpose of the project is research in the field of virtual reality to be used in general vehicle simulators (including flight simulators or any self-propelled or self-moving equipment). The project is focusing on the development of a complex solution of all scenes VR applications using VR headsets. This fast-growing technology, which can significantly enhance the simulation fidelity, has a high potential for a future wide range of applications, but there are also unsolved problems, which are related to particular applications. One of the unwanted phenomena of virtual reality is simulation-sickness. The modern VR systems require a full range of cues, and one the most important is the motion one. A motion platform with advanced motion cueing algorithm must be used to avoid or at least to minimize the occurrence of VR sickness. This should be done with the use of hi-precision control but also advanced knowledge-based and predictive algorithms. The use of VR headsets also requires low latency and precise tracking of the observer's head in a reference frame of the virtual and real-world assets. Solving the complex of problems the virtual reality deployment recently faces will open a wide range of applications in many fields. In this project, we are focusing on R&D applications, for professional simulators usable in industrial development, education, or medical treatment application. The paper deals with some aspects of deployment of VR in these main areas with a particular focus on general usability and VR-sickness.

Interactive motion platforms are intended for vehicle simulators, where the direct interaction of the human body is used for controlling the simulated vehicle (e.g. bicycle, motorbike or other sports vehicles). The second use of interactive motion platforms is for entertainment purposes or fitness. The development of interactive motion platforms reacts to recent calls in the simulation industry to provide a device, which further enhances the virtual reality experience, especially with connection to the new and very fast growing business in virtual reality glasses. The paper looks at the design and control of an interactive motion platform with two degrees of freedom to be used in virtual reality applications. The paper provides the description of the control methods and new problems related to the virtual reality sickness are discussed here.

The paper deals with the modelling, simulation and optimal control of parallel robotic structures (in particular those with six degrees of freedom) driven by permanent magnet linear electric motors using energy regeneration and during power outages. By virtue of their kinematic and dynamical properties, these robotic structures can be used for a variety of purposes, for instance in industrial automation or simulation technology, where motion platforms (especially hexapods) are used for motion cueing. Electric drive parallel mechanisms provide several significant benefits, in particular with regard to optimum energy distribution and regeneration options. The main research motivation is the prevailing need to develop a solution ensuring that the parallel mechanism can safely return after a power cut to the default or ‘park’ position in a fully controlled way (simulators, for instance, have to be capable of sliding back to the boarding position) using solely the energy accumulated in the system. This research goal requires the development of exact and fast simulation models providing insight into transient system behaviour and, subsequently, determining the optimum control strategy. Therefore, the paper will provide a detailed simulation model which can also be used in optimizing the structures of the mechanism and determining the optimum servo drive design.

Generator vibrations occur as a result of unbalanced revolving masses, loading forces and torques, starting and coasting of driving motors and other effects. Suitable mounting of the generator is possible using damping components such as steel springs, pneumatic springs, rubber pads or other damping components. The article describes a numerical calculation of individual deviations of the generator in dependence on time for the given machine parameters and the selected damping components of its mounting using the Matlab program.

The paper deals with the impacts of unbalance on the start-up behaviour of flexibly mounted rotors with viscous damping. It provides an overview of the dimensionless parameters describing the system in question as well as the properties determining the influence of various degrees of static unbalance on the system start-up behaviour for different driving torque scenarios, such as transient-state and steady-state differences as opposed to balanced rotors, vibration-induced power losses, etc.

The paper deals with the modelling and simulation of a six-degree-of-freedom (6DOF) motion platform with permanent magnet linear actuators. The notion and structure of a 6DOF platform (a.k.a. Stewart platform) is well known. The main aim of this paper is to find and describe a suitable solution for applications requiring high dynamics and position accuracy. For this reason, permanent magnet linear actuators, characterised by their high dynamics and accuracy, have been used – despite their still considerable (albeit gradually decreasing) price tag per unit of power. Furthermore this paper develops a mathematical model to be later employed for the scaling and design of the platform controls.

Presentation of the Department of Electric Drives and Traction in a popular science magazine

The paper deals with the modelling and simulation of a six-degree-of-freedom (6DOF) motion platform with permanent magnet linear actuators. The notion and structure of a 6DOF platform (a.k.a. Stewart platform) is well known. The main aim of this paper is to find and describe a suitable solution for applications requiring high dynamics and position accuracy. For this reason, permanent magnet linear actuators, characterised by their high dynamics and accuracy, have been used – despite their still considerable (albeit gradually decreasing) price tag per unit of power. Furthermore this paper develops a mathematical model to be later employed for the scaling and design of the controls of the platform, which is planned to be used for wind tunnel testing.

The paper looks at the possibilities of applying a model predictive control (MPC) algorithm to control and optimize the motion cueing algorithm (MCA) employed in the state-of-the-art simulators for the purposes of reproducing motion effects.

This book covers a comprehensive summary of the simulation technology and tools especially those used for training of professional truck drivers. The problems of development of simulation systems, their components and measuring devices are described within several chapters as well as problems and methodic of professional drivers training, its evaluation and research activities in this area. The text is accompanied with theory on topic of system reliability applied on driver-vehicle interaction.

This paper describes the design and optimisation of a motion cueing algorithm for a truck simulator. However, the optimisation process described here can be applied for other simulators, in particular ground vehicle simulators. With the washout filter being the most common solution in simulation technology applications, the main idea of the optimisation procedure presented in this paper is the use of numerical tools to determine suitable washout algorithm parameters while respecting all kinematic and dynamical limitations of the motion platform including the perceptual thresholds of the vestibular system. These limitations are covered by a detailed mathematical model of the whole motion cuing system also described here. Washout algorithm consists of many different parameters the impact of which on the quality of motion cueing has not been clearly identified yet or is difficult to deduce. Therefore, the setup is often based on the programmer's experience. This article describes a method of optimising these parameters by means of a genetic algorithm. The optimisation criterion, expressed in the form of a fitness function, is the highest fidelity of motion cueing.

This paper looks at the impact of backlash between the worm and worm gear in an electric- driven machine the vibrations of the propelled section of the machine. Eventual backlash in the worm gear will result in cage vibrations, which cause problems with ride smoothness and imprecision in stopping in desired stations. The lift has been chosen to analyse the matter in hand; in this kind of machine, excessive backlash between the worm and worm gear results in vibration of the lift cab. Equations of motion have been prepared for the lift model and worm drive backlash which can be solved in the Matlab application for different lift parameters. The equations provide cab velocity and acceleration data which can be subsequently compared with the desired values as defined in the applicable technical standards. When designing a machine tool, it is necessary to start from desired machine output parameters. It is advisable to check the dynamic behaviour of the machine tool before making constructional design, which is combined with dimensional and strength calculation of individual machine parts. We assume that dynamic behaviour will be assessed using a suitably built machine tool model, which describes the machine tool itself as closely as possible. The model then can by described by system of motion equations, which we solve numerically using Matlab. Based on the results calculated, we asses the most often generated inappropriate vibrations of individual machine parts. By simulating input parameters, or respectively, by change of structure, we try to minimize such vibrations. The described procedure is demonstrated by an example of lift drive with consideration backlash design. After considering carefully all the parameters the electrical kind of drive is selected, with worm gear unit. . The result is the velocity and acceleration of time behaviour, which are compared with the required courses given by the standards.

This paper looks at the design and optimal control of an electromechanical linear actuator to be used in a six-degrees-of-freedom motion platform application intended for use in simulation technology. The paper reacts to recent calls in the simulation industry to replace hydraulic cylinders with electromechanical actuators while keeping the kinematic and dynamic parameters unaffected. The paper provides a comparison of both system types with a description of the design of optimal control for electromechanical actuators.

This paper looks at the design and optimal control of an electromechanical linear actuator to be used in a six-degrees-of-freedom motion platform application intended for simulation technology. The paper reacts to recent calls in the simulation industry to replace hydraulic cylinders by electromechanical actuators while keeping the kinematic and dynamic parameters unaffected. The paper provides a comparison of both system types with a description of the design of optimal control for electromechanical actuators.

The aim of the paper is to acquaint the reader with the design of the incorporated absorber to the vibration machine with rotating members, which makes the reduction of the vibration of the machine to a minimum possible. Vibration in a machine has two effects. First, the very high peak accelerations can mean that the effective weight of the vibration machine increases several-fold, and this may cause its destruction. Secondly, people near machine feel these accelerations, which can be uncomfortable or even dangerous. A vibration absorber is used to protect the machine from steady-state harmonic disturbance. The present article will discuss a method of vibration control LQR (Linear Quadratic Control) for structure using the vibration absorber without damping. Depending on the driving frequency of the original system, the absorber needs to be carefully tuned, that is, to choose adequate values of absorber mass and stiffness, so that motion of the original mass is a minimum.

Machine vibration occurs as a result of unbalanced revolving masses, loading forces and moments, starting and coasting of driving motors and other effects. We try to eliminate these undesirable vibrations by suitable mounting of the mechanical system. Another possibility of suppression of the vibration machine is to use an absorber. A model of a vibration mechanical system with a vibration absorber is presented in the paper. The results from the numerical solution are then possible to compare with the measured values of the experimental model.

In this paper, the coupled non-linear differential equations of the model of machine as non-linear dynamical two-degree-of-freedom vibrating system including cubic non-linearity are solved. The system consists of the main system and the absorber. Consider the non-linearity dynamical vibrating system as a model machine, which is compiled of a driven motor, gearbox and mechanisms with elastic and damping parts and driven parts. The absorber is used to control the main system vibrations when subjected to external excitation force. This system represents many applications in machine tools, ultrasonic cutting process, etc. Optimum working conditions for the absorber are by the same frequencies = 2 [1] of the action force F=F0 sin t and main mass m1. The effects of different parameters of the system are studied numerically with Matlab.

Machinery vibrations occur as a result of unbalanced revolving masses, loading forces and moments, starting and coasting of driving motors and other effects. We try to eliminate these undesirable vibrations by suitable mounting of the machinery and its parts as much as possible. Suitable mounting of the machinery is possible using torsion springs, pneumatic springs, rubber pads or other components. The article describes numerical calculation of the optimal displacements of the machinery for the given parameters and the selected components of its mounting using the Simulink program. For the optimization it is possible to use various numerical methods, looking for extremes of functions. In this application a numerical method was used that on genetic algorithm.

The article provides an insight into the development and implementation of a flight simulator intended for the training of pilots of light and ultra-light sports aircraft.

This paper provides an insight into the development and implementation of a flight simulator intended for the training of pilots of light and ultra-light sports aircraft.

Numerical solution use MATLAB and Simulink to create a comprehensive, dynamic model of the mechanical system with two degree of freedom to suppression of vibration. A concept for active vibration suppression with an absorber is presented. Use the model to produce optimized linear transfer functions based on the step response of the system. The major concepts of multiple degrees of can be understood by looking at just a 2 degree of freedom model is shown.

The simulation model of dynamical mechanical system with absorber is in the paper present. The model represents vibration plate-on the left part are bearings and right part springs. On the plate operates harmonic excitation force. The plate is connected through a spring-mass absorber, suppressed vibrations of the plate to a minimum. The model is intended to allow the simulation of amplitude and frequency of excitation force and the mass plates and absorber and stiffness of the springs. The solution is performed numerically, using Matlab and supplemented by a laboratory model design.

This paper provides description of the simulative model of the motion effects simulation algorithm (wash-out algorithm), which is being developed within the project, whose main aim is to develop and to verify general system of motion effects simulation intended for R&D in the field of human-machine interface (e.g. simulators design). The system is composed of the hardware part, which consists of a hydraulic or electric motion platform with six degrees of freedom, and the software part, which consist of control algorithm, simulation algorithm and user interface. The system is designed to be easily used with common simulation programs.

The present article will discuss the method online optimization of the vibration and damping control for systems by using a vibration tuneable mass with damping. The numerical solution for car body absorption, in cooperation with the Matlab-Simulink program, is shown on model of the car.

In paper ishow numerical modelling of machines vibration part With Matlab.

The simulation of motion effects adds another dimension to the simulation process, thus significantly enhancing its authenticity. This paper describes the simulation of motion effects via a hydraulic base with six degrees of freedom. It provides a kinematic description of the hydraulic base and explains the motion effect controlling concept. We shall also present an actual implementation of the concept discussed herein which is used as an IFV simulator by the armed forces of the Czech Republic.

This article describes the design and implementation of the mathematical model of a steam engine used as pressure regulator in a pressure reduction station. The present model is a part of a comprehensive mathematical model of a cogeneration unit and also a part of the author's doctoral thesis. The model assumes detailed mathematical description of physical processes in a steam engine and implementation in an MATLAB-SIMULINK software environment.