Iulian Birou

Fuzzy based obstacle avoidance system for autonomous mobile robot

The goal of this research was to develop a fuzzy obstacle avoidance system for an autonomous mobile robot using IR detection sensors. This paper presents implemented control architecture for behavior-based mobile robot. The mobile robot is able to interact with an unknown environment using a reactive strategy determined by sensory information. Current research in robotics aims to build autonomous and intelligent robots, which can plan its motion in a dynamic environment. Autonomous mobile robots are increasingly used in well structured environment such as warehouses, offices and industries. Fuzzy behavior able to make inferences is well suited for mobile robot navigation because of the uncertainty of the environment. A rule-based fuzzy controller with reactive behavior was implemented and tested on a two wheels mobile robot equipped with infrared sensors to perform collision-free navigation. The experimental results have shown that the proposed architecture provides an efficient and flexible solution for small wheeled mobile robots.

Nomograms for sizing the vertical earth grounding

The design of earth grounding at rated values corresponding to the role to be accomplished is relatively laborious and there are no highlighted optimum criteria giving the justification for the chosen solution. The vertical earth grounding calculus is restructured in this paper, realizing sizing nomograms which include all characteristic sizes, the final goal being the determination of the electrodes number which ensures the rated value achieving for the dispersion resistance. For the designing simplification, the unitary earth grounding is defined versus which the earth grounding may be easily finalized with different values compared to the unitary one. The dispersion resistance determination for the simple earth grounding with only one electrode is considered as the first step in earth grounding sizing, for which a calculation nomogram was conceived. The second step is represented by the electrodes number determination for the multiple earth grounding which leads to the obtaining of the rated value for the earth grounding dispersion resistance.

Real-time robust controlled driving system with permanent-magnet synchronous motor

This paper is concerned with robust vector control of a permanent magnet synchronous motor (PM-SM) using a fix-point DSP based computing architecture. Speed control systems are analyzed for different operation conditions. A hardware architecture was developed based on a TMS320C5x fixed-point processor, a PWM control unit realized in FPGA technology, an interfacing unit to the incremental encoder and A/D converters for the stator-phase current inputs, a high speed TDM-type serial bus and an emulating and debugging driver. The software was written in both, DSP-assembler language for acquisition and communication programs and in C language for the control algorithm computation. The computing system solution based on a minimal hardware configuration offers a flexible solution for different control strategies applied to a large scale of driving systems.

Virtual Models of Special Class of PARTNER Robots

This paper presents basic elements concerning modeling and simulation of parallel robots which are used for machine-tools development. The advantages of this new kind of machine-tools consist on their reconfigurability, on the possibility to improve accuracy of those machines etc. The main point of the paper is that few variants of parallel mechanisms with only one mobile platform and with number of degrees of freedom between 3 and 6 were emphases. It must be also remarked that these variants are developed into modular manner in order to ensure full reconfigurability. The paper presents also numerical results obtained with the virtual models which were developed

Developing embedded control system platform for testing PMSM drives

The paper presents an Embedded Motor Drive Prototyping test bench for developing and study energy efficient of the motor drives. The development platform uses an eZdsp target controller with power stage converter that employs Targeted Code Generation from Matlab-Simulink and the Target Support Package for the TI C2000 microcontrollers. Computer Aided Control System Design (CACSD) tools are used to generate real-time code automatically. The reason is to simplify the programming process by making it more graphical and thus more intuitive. Application performances of the electrical drives require energy efficiency, flexibility, outstanding reliability and robust control. Servo drives with Permanent Magnet Synchronous Motors (PMSM) have wide industrial applications where the speed and torque response with high-performance operations are required. The controller drives are implemented by field-orientation control mode (FOC) since the method laid the motors at maximum theoretical performances. A graphical programming interface with hardware-in-loop design processes is used for testing the algorithms controller. The performances are tested in a rapid prototyping approach using Matlab/Simulink and the Real Time Workshop (RTW) toolbox and represent a solution for educational purposes.

Comparative evaluation of vector control versus direct torque control for PM-SM drives

Based on previous research experience proved by simulated and experimental results a comparative discussion about advantages and disadvantages of using Vector Control or Direct Torque Control for PM-SM drives is presented.

Methodologies regarding the application of optimum criteria to the vertical earth grounding design, with rectangular outline

The earth grounding (EGR) computation model contained in normative acts has multiple nonlinearities and functions with implicit definitions. In addition, through the values indicated for the utilization coefficients, the designers are oriented towards relatively large distances between electrodes and no optimal criteria are defined. In earlier works, the authors have realized nomograms in order to calculate the earth resistances for both simple and multiple EGR with more electrodes and have proposed a number of five overall characteristic sizes for the EGR that may constitute optimal criteria. Continuing the development of the dimensioning methods with the application of optimal criteria, the algorithms for the application of two of the optimal criteria, namely the EGR footprint area and the EGR total volume, are formulated and exemplified in the paper. The minimum of the ground footprint area is obtained for the biggest lengths of the electrodes and the minimum distances between them, that are practicable in the given soil and with the technology available to the potential manufacturer. Similarly, the criterion of minimum total volume of the EGR leads also to the minimum distances between electrodes, but to their smaller lengths, within the range of considered lengths.

DMS steady state function validation by comparative study

The maim aim of this paper is to compare the rezults obtained for the steady-state run by using a new software, as Distribution Management System/Energy Management System (DMS/EMS) type, with the results delivered by traditional software products, as Paladin Design Base, which is extensively used in the design, analysis and maintenance of electrical networks. This comparison is particularly useful to argue to what extent these systems, that operate in real-time with data collected from the process, are able to provide information which gives confidence that the operative decisions to be taken based on them are perfectly reasonable in order to obtain an efficient distribution of the electrical energy.

Efficient distribution through the medium voltage network belonging to Cluj-centre electrical power station

To know the electrical power losses of an electrical network from an established perimeter and to adopt some measures in order to obtain their decrease represent very important problems in the electrical networks exploitation and maintenance. Thus, this paper aims to realize the model of the medium voltage (MV) network belonging to the electrical station Centre from the urban area of Cluj-Napoca in order to determine its own technological consumption. The model of the established zone has been performed by using Paladin DesignBase determining, at the same time, the self technological consumption (STC) on the entire network in several situations. Also, through the different scenarios proposed in the paper, starting from the normal operating scheme, another target of the authors was to determine the optimum specific methods to obtain a higher efficiency for the end-users supplying in the considered area.

Voltage slow variations and harmonics analysis in a LV distribution point

Both suppliers and end-users are more interested in knowing the power quality (PQ) level through their common network. Unfortunately, there are no clear experimental methods and especially interpretable for all PQ aspects. This is also the case of the slow voltage variations about which it is theoretically known that they include variations with periods between (5 min+24 h), so practically the voltage wave will be decomposed in harmonics, being considered those which are in the mentioned range and then the statistical indicators will be determined. The paper aims to analyze the experimental voltage waves, but applying a new principle, that is the decomposition of the voltage wave firstly in step type actions and secondly in harmonics. The step type actions may resulting after the switching power transformers or autotransformers plots, change of electrical networks configurations, commutation of capacitor banks steps or after some jumps recorded by electrical power consumption. Beside the voltage variations analysis it was considered useful the voltage wave harmonic analysis in order to report some possible operating modes located outside of admissible limits. Overall, this paper represents a case study and also an analysis guide for slow voltage variations.