This paper presents the design procedure of the integral sliding mode controller with enhanced robustness properties for a class of nonlinear uncertain systems. The integral sliding mode control (I-SMC) is synthesized with the generalized disturbance attenuation scheme called robust internal-loop compensator (RIC) through the Lyapunov redesign framework, thus introducing a generalisation of the well-known case for linear systems. The resulted two-layer control structure employs the classical controller with the feedforward term in the outer control loop to track the reference, while the inner control loop compensates the generalized disturbance and provides robust stability. The closed-loop system is proved to be asymptotically stable via Lyapunov stability theory. The developed control algorithm is used for attitude tracking of the small-scale helicopter system in the presence of additional parametric uncertainties and external disturbances. An excellent tracking performance and robustness stability of the proposed control method are revealed through computer simulations and experimental testing over the whole domain of the helicopter outputs.

Control design for a small-scale helicopter is quite challenging due to its nonlinearities, unknown and unmodelled dynamics, strong cross-coupling effects produced by the vehicles actuators, parametric uncertainties and external disturbances. This paper introduces the design of robust and stable disturbance observer (DOB) based sliding mode control (SMC) to meet these issues. It consists of the disturbance observer in the inner control loop which estimates and attenuates plant input generalized disturbance, and the sliding mode controller in the outer control loop which enforces convergence to the reference and stability of the equilibrium. Introduced disturbance observer is a linear low-pass filter capable to compensate unwanted chattering effects of the sliding mode control. The highly nonlinear helicopter model is introduced to illustrate effectiveness of the proposed control method. Designed controllers are implemented in the simulation mode and experimentally tested in a realistic environment. Obtained results showed that developed DOB based SMC controllers improve tracking performances o ver the entire range of the helicopter output variables even in the presence of additional parametric uncertainties, and external disturbances in the form of wind gusts.

This paper addresses the challenges of the disturbance observer (DOB) algorithms faced with highly nonlinear electromechanical systems which are dealing with high resolution and high speed operations. It describes the synthesis of robust and stable controllers and their applications in controlling azimuth and elevation angles of the helicopter model CE 150 supplied by Humosoft. Description of the helicopter, including its mechanical characteristics and mathematical model, is given in the paper. Tracking error, transient performances, power consumption and motor strains are used for the validation of control quality. Implementation of the control system on the experimental setup is also explained. MATLAB and Simulink are used as tools for developing the simulation model of the helicopter system. Obtained simulations are showing that developed controllers provide significantly improved results even in the presence of unknown and unpredictable inputs (disturbance and noise), unpredictable and unknown dynamics, external forces (torques) and change of the system parameters.

This paper examines the capabilities of fuzzy logic based controllers in the process of active suspension of a heavy vehicle seat vibrations. The hydraulic cylinder is used as an active element, while the damper and the air spring are used as passive elements for reducing vibrations. MATLAB and Simulink are used as tools for developing the simulation model of the driver seat. The mathematical model was created according to the physical setup of the vehicle seat at the testing laboratory. Description of the seat, including its mechanical characteristics and mathematical model, is given in the paper. Control system description and implementation on the experimental setup using dSPACE module, is also explained. The SEAT value is used for the validation of control quality. The obtained simulations show that the developed suspension controllers provide superior passenger comfort for different types of road.

One of the main components that determines the status of the country in the world today, is its educational system. A good quality of education system guarantees high-quality new work force and energy of young people who are then trained to work in the area for which they are educated. Like many systems, the education system can be placed within the frame of Electrical Engineering as a science. In this paper the analysis of the educational system (higher education) in terms of adaptive control with reference model is carried out. For a better understanding of the educational system itself, it is considered from the aspect of social cognitive theory of career development.

This paper presents a history of development of digital computers, PCs, and experimental mobile robots. Criteria for forming performance indexes of experimental mobile platforms are defined. A comparison of feature of development of digital computers and experimental mobile robots are given. Effects of applications of PCs in mobile robotics are stressed, and certain future development of mobile robotics have been discussed.

An osteotomy is a surgical operation whereby a bone is cut to shorten, lengthen, or change its alignment. Corrective tibial osteotomies correct non-physiological axis, thus eliminating knee and ankle joint loads. In preoperative planning of the osteotomy a preoperative drawing should be made and it requires knowledge of biomechanics and physiology of the lower limbs.

The aim of this study is to mathematically approximate the shape of the femoral articulating line and compare radiuses of condylar curves within and between males and females. Ten male and ten female participants were included in the study. Radiuses of medial and lateral condylar curves were calculated from the side view knee X-ray by original mathematical equation. Average radiuses of condylar curves were between 4.5 and 1.7 cm medially, and between 3.2 and 1.8 cm laterally, for 0 degrees and 90 degrees flexion contact point respectively. Males had longer curve radiuses of both condyles (p < 0.05). Differences turned out to be statistically insignificant after adjusting to body height. Even small changes in the joint geometry during lifetime could make a joint susceptible to osteoarthritis or injuries. Approximation of the radiuses of femoral condyle curves is a useful method in anthropometric, radiological and virtual calculations of the knee geometry, and other ellipsoidal structures in human body, like wrist, scull segments, dental arches, etc.

A solution for a synchronized set of laboratory exercises covering both control theory and Matlab programming package is proposed in this paper. Some Matlab features are introduced in order to make a control course easy for understanding. Also, some general Matlab abilities are considered allowing usage of this program not only for control purposes but also for other electrical engineering fields. Sections presented in this paper may be used in a control laboratory as well as a sheet giving insight into some control fundamentals and Matlab abilities for non-control engineers

Abstract In this paper, we propose two level control system for a mobile robot. The first level subsystem deals with the control of the linear and angular volocities using a multivariable PI controller described with a full matrix. The position control of the mobile robot represents the second level control, which is nonlinear. The nonlinear control design is implemented by a modified backstepping algorithm whose parameters are adjusted by a genetic algorithm, which is a robust nonlinear optimization method. The performance of the proposed system is investigated using a dynamic model of a nonholonomic mobile robot with friction. We present a new dynamic model in which the angular velocities of wheels are main variables. Simulation results show the good quality of position tracking capabilities a mobile robot with the various viscous friction torques.

Abstract This paper proposes an extension of neural network identification capabilities for on-line identification of a nonlinear closed-loop control system. The neural network (NN) is trained on-line using the backpropagation optimization algorithm with an adaptive learning rate. The optimization algorithm is performed at each sample time to compute the optimal control input. The results confirm the effectiveness of the proposed neural network based identification scheme and control architecture.

In this paper, Pade's rational functions have been simulated for approximating several characteristic values of time delay regarding the plant time constant. Several representative plants were tested in order to show in which cases Pade’s function approximates time-delay block well. Only if the ratio of time delay versus time constant of the plant is rather great, or the plant contains emphasized numerator dynamics; approximation capabilities get poorer. The convergence rate of n-order Pade’s function has been also analyzed by using Taylor series and phase-frequency characteristics.

Ncural networks and fuzzy systcnis havc bccn applicd very succcssfiilly iii tlic idcntification and control of dynamic systcms. This papcr prcscnts combination of the fuzzy logic controllcr and ncural nctwork identification structurc, intcgra~cd into robotic systcm, to providc cxtcnsivc capabilitics. Wc first discuss tiic fuzzy logic controllcr (FLC), dcscribc its maiii compoticnts such as fuzzificr, fuzzy rule basc, fuzzy infcrcncc cnginc and dcfuzzilicr. Wc then lbcus on thc ncural nctwork (NN) plant modcl, traincd on-linc using tllc backpropagation training optimization algorithni with an adaptivc tcamjiig ntc. Thc optimization algorithm is pcrformcd at cadi satnplc time to computc thc optimat control input. The rcsults confirm thc cffcctivcricss o f the proposcd idcoti lication and control arcliitccturcs. Robotic manipulator systcrns arc notihncar, high couplcd, and timc varying. Robots havc to lac, many unccrtaintics in thcir dynamics, in particular structurcd unccrtaintics, which arc causcd by iniprccisioo in the manipulator link propcrlics. unknown loads, and unstructurcd otic, such as nonlincar friction, disturbanccs, and thc high-frcqucncy part of the dynaniics [ I]. Tlic coiitrol pcrforniancc of thc robotic manipulator is inlliicnccd by lhc mcntioncd unccrtaintics of the plant. A convcntional approach to solvc tlic robotic control problem is to iisc [tic coniputcd torqiic algorithm 121. Tlic computcd torque algorithm amounts to tranafomling tlic highly nonlincar robot dynamics into cquivalcnt Lincar systcm. Thcn lincar control tlicory can bc applicd to synthcsizc thc controllcr to mcct the dcsircd specifications. Thc theory of furzy and ncural control S C C ~ S to bc a suitablc tool for both modclling and control of coinpicx, nonlincar systcnis. Fusion fuzzy systcms and ncural nctwork providcs human-like knowlcdgc processing capabilitics. Thc using of FLC for controlling a robot manipulator is justificd liom Ihc followiiig rcasons: thc dynamics of robot is niodclcd by nonlincnr and couplcd diCfcrcntiaI cquations and FLC givcs high flcxibility, that is it lias many dcgrccs 01' liccdoin (shapc and number of mcnibcrship functions, aggregation mcthods, fuzzilkation and dcrtizzification mcthods, ctc.). Fuzzy systcms arc suitnblc for uncertain and approximatc rcasoning, cspccially for tlrc systcm with a miithcmntical iiiodcl that is diflicult to dcrivc [I], [3]-[ 5 ] .

This work is considering three significant factors that affect blood glucose level: food intake, hereditary predisposition and stress. Goal of this paper is to observe blood sugar level in human organism as a dynamic MISO (Multi Input, Single Output) system, and to describe it with differential equations and control system blocks. The system has three inputs; food (carbohydrates), hereditary factor and stress, and a single output--blood glucose level. Basically, several logical assumptions have been made, as the result of few medical researches. A model that gives outputs, very similar to real ones (measurements of glucose level in human body) is used for more detailed analysis. This model is very suitable for computer simulations and it can easily be tested for different input arrangements. Using this property of the system, several modes of food consumption have been proposed, in order to retain blood sugar level inside recommended limits.