Sudden Speed Changes Research Articles

Type-2 fuzzy logic control based MRAS speed estimator for speed sensorless direct torque and flux control of an induction motor drive

In this research study, a model reference adaptive system (MRAS) speed estimator for speed sensorless direct torque and flux control (DTFC) of an induction motor drive (IMD) using two adaptation mechanism schemes are proposed to replace the conventional proportional integral controller (PIC). The first adaptation mechanism scheme is based on Type-1 fuzzy logic controller (T1FLC), which is used to achieve high performance sensorless drive in both transient as well as steady state conditions. However, the Type-1 fuzzy sets are certain and unable to work effectively when higher degree of uncertainties presents in the system which can be caused by sudden change in speed or different load disturbances, process noise etc. Therefore, a new Type-2 fuzzy logic controller (T2FLC) based adaptation mechanism scheme is proposed to better handle the higher degree of uncertainties and improves the performance and also robust to various load torque and sudden change in speed conditions, respectively. The detailed performances of various adaptation mechanism schemes are carried out in a MATLAB/Simulink environment with a speed sensor and speed sensorless modes of operation when an IMD is operating under different operating conditions, such as, no-load, load and sudden change in speed, respectively. To validate the different control approaches, the system also implemented on real-time system and adequate results are reported for its validation.

The relationship between reorientational molecular motions and phase transitions in [Mg(H2O)6](BF4)2, studied with the use of (1)H and (19)F NMR and FT-MIR.

A (1)H and (19)F nuclear magnetic resonance study of [Mg(H2O)6](BF4)2 has confirmed the existence of two phase transitions at Tc1 ≈ 257 K and Tc2 ≈ 142 K, detected earlier by the DSC method. These transitions were reflected by changes in the temperature dependences of both proton and fluorine of second moments M2 (H) and M2 (F) and of spin-lattice relaxation times T1 (H) and T1 (F). The study revealed anisotropic reorientations of whole [Mg(H2O)6](2+) cations, reorientations by 180° jumps of H2O ligands, and aniso- and isotropic reorientations of BF4 (-) anions. The activation parameters for these motions were obtained. It was found that the phase transition at Tc1 is associated with the reorientation of the cation as a whole unit around the C3 axis and that at Tc2 with isotropic reorientation of the BF4 (-) anions. The temperature dependence of the full width at half maximum value of the infrared band of ρt(H2O) mode (at ∼596 cm(-1)) indicated that in phases I and II, all H2O ligands in [Mg(H2O)6](2+) perform fast reorientational motions (180° jumps) with a mean value of activation energy equal to ca 10 kJ mole(-1), what is fully consistent with NMR results. The phase transition at Tc1 is associated with a sudden change of speed of fast (τR ≈ 10(-12) s) reorientational motions of H2O ligands. Below Tc2 (in phase III), the reorientations of certain part of the H2O ligands significantly slow down, while others continue their fast reorientation with an activation energy of ca 2 kJ mole(-1). This fast reorientation cannot be evidenced in NMR relaxation experiments. Splitting of certain IR bands connected with H2O ligands at the observed phase transitions suggests a reduction of the symmetry of the octahedral [Mg(H2O)6](2+) complex cation.

Wind Shear Target Echo Modeling and Simulation

Wind shear is a dangerous atmospheric phenomenon in aviation. Wind shear is defined as a sudden change of speed or direction of the wind. In order to analyze the influence of wind shear on the efficiency of the airplane, this paper proposes a mathematical model of point target rain echo and weather target signal echo based on Doppler effect. The wind field model is developed in this paper, and the antenna model is also studied by using Bessel function. The spectrum distribution of symmetric and asymmetric wind fields is researched by using the mathematical model proposed in this paper. The simulation results are in accordance with radial velocity component, and the simulation results also confirm the correctness of the established model of antenna.

A novel adaptive, real-time algorithm to detect gait events from wearable sensors.

A real-time, adaptive algorithm based on two inertial and magnetic sensors placed on the shanks was developed for gait-event detection. For each leg, the algorithm detected the Initial Contact (IC), as the minimum of the flexion/extension angle, and the End Contact (EC) and the Mid-Swing (MS), as minimum and maximum of the angular velocity, respectively. The algorithm consisted of calibration, real-time detection, and step-by-step update. Data collected from 22 healthy subjects (21 to 85 years) walking at three self-selected speeds were used to validate the algorithm against the GaitRite system. Comparable levels of accuracy and significantly lower detection delays were achieved with respect to other published methods. The algorithm robustness was tested on ten healthy subjects performing sudden speed changes and on ten stroke subjects (43 to 89 years). For healthy subjects, F1-scores of 1 and mean detection delays lower than 14 ms were obtained. For stroke subjects, F1-scores of 0.998 and 0.944 were obtained for IC and EC, respectively, with mean detection delays always below 31 ms. The algorithm accurately detected gait events in real time from a heterogeneous dataset of gait patterns and paves the way for the design of closed-loop controllers for customized gait trainings and/or assistive devices.

Thermodynamics application to pipeline engineering problems

Traditional hydrodynamics, based on the theory of the Navier-Stokes equations, is known to deal with great difficulties in describing turbulence. As a result, in practice, empirical formulas have to be used. Moreover, deviations from this theory were found in a number of experiments even in laminar flow in microcapillaries. Recently, on the basis of nonequilibrium thermodynamics, an anisotropic liquid model was proposed. According to this model, besides a conventional Newtonian momentum transfer, the liquid has another one, called heat momentum transfer. Due to that, it became possible to give a new definition of turbulence and explain its origin. Development of this model is continued in this paper by more detailed examination of the flow in the area just near the surface of the body. The flow examination gave an opportunity to make the preceding calculations more precise and demonstrate that there is a sudden change of speed at some distance from the surface, which explains the existence of tangential stress working. This result corresponds to the previously identified characteristics of dissipative heating of the liquid flowing in the pipeline. The Prandtle number effect on hydrodynamic resistance of low-density and heavy oils is shown. Theoretical derivation of smooth pipe hydraulic resistance equation in developed turbulent flow is given. Compared with the known Prandtle equation, it can also be used for muds. It is not necessary to compute the generalized Reynolds number. The influencing parameter is the Peclet number. Theoretical estimate of the drag-reduction limiting value in the presence of high-molecular additives in the flow is given. It is also shown that the mechanism of resistance decrease is not present in the suppression of turbulence in the stream, but in its onset delay.

High-performance direct torque and flux control of an induction motor drive using sliding-mode and fuzzy logic speed controllers

In this research study, direct torque and flux control of an Induction Motor Drive (IMD) using Sliding-Mode Speed Controllers (SMSC) and Fuzzy-Logic Speed Controller (FLSC) are presented to achieve high performance of stator current, electromagnetic torque and motor speed in both transient as well as in steady-state conditions. The PI Speed Controller (PISC) gives good steady-state performance, but poor dynamic response. Therefore, the SMSC is considered to achieve continuous control of motor speed and also electromagnetic torque. Furthermore, FLSC is considered to get high performance, dynamic tracking and speed accuracy at various load torque conditions. The performances of each speed controller techniques are tested under various load toque and speed condition for its robustness. A detailed comparison of different control approaches are carried out in a MATALB/Simulink environment at different operating conditions, such as forward and reversal motoring with no-load, load, sudden change in speed and sudden zero speed.

Type-1 and Type-2 Fuzzy Logic and Sliding-Mode Based Speed Control of Direct Torque and Flux Control Induction Motor Drives – A Comparative Study

Abstract In this research study, the performance of direct torque and flux control induction motor drive (IMD) is presented using five different speed control techniques. The performance of IMD mainly depends on the design of speed controller. The PI speed controller requires precise mathematical model, continuous and appropriate gain values. Therefore, adaptive control based speed controller is desirable to achieve high-performance drive. The sliding-mode speed controller (SMSC) is developed to achieve continuous control of motor speed and torque. Furthermore, the type-1 fuzzy logic speed controller (T1FLSC), type-1 fuzzy SMSC and a new type-2 fuzzy logic speed controller are designed to obtain high performance, dynamic tracking behaviour, speed accuracy and also robustness to parameter variations. The performance of each control technique has been tested for its robustness to parameter uncertainties and load disturbances. The detailed comparison of different control schemes are carried out in a MATALB/Simulink environment at different speed operating conditions, such as, forward and reversal motoring under no-load, load and sudden change in speed.

Robust fuzzy neural network sliding mode control scheme for IPMSM drives

This article proposes a robust fuzzy neural network sliding mode control (FNNSMC) law for interior permanent magnet synchronous motor (IPMSM) drives. The proposed control strategy not only guarantees accurate and fast command speed tracking but also it ensures the robustness to system uncertainties and sudden speed and load changes. The proposed speed controller encompasses three control terms: a decoupling control term which compensates for nonlinear coupling factors using nominal parameters, a fuzzy neural network (FNN) control term which approximates the ideal control components and a sliding mode control (SMC) term which is proposed to compensate for the errors of that approximation. Next, an online FNN training methodology, which is developed using the Lyapunov stability theorem and the gradient descent method, is proposed to enhance the learning capability of the FNN. Moreover, the maximum torque per ampere (MTPA) control is incorporated to maximise the torque generation in the constant torque region and increase the efficiency of the IPMSM drives. To verify the effectiveness of the proposed robust FNNSMC, simulations and experiments are performed by using MATLAB/Simulink platform and a TI TMS320F28335 DSP on a prototype IPMSM drive setup, respectively. Finally, the simulated and experimental results indicate that the proposed design scheme can achieve much better control performances (e.g. more rapid transient response and smaller steady-state error) when compared to the conventional SMC method, especially in the case that there exist system uncertainties.

Linking cortisol responsiveness and aggressive behaviour in gilthead seabream Sparus aurata: Indication of divergent coping styles

Farmed animals, including fish, often exhibit a pronounced individual variation in stress coping styles with proactive and reactive individuals differing in a variety of neuroendocrine and behavioural responses. In this study we disclosed that individual differences in cortisol responsiveness after a restraining test were predictive of aggressive behaviour in gilthead seabream Sparus aurata, one of the most important Mediterranean farmed fish. Seabream juveniles (n=24, initial weight: 49.3±7.3g) were exposed to a restraining test that consisted of keeping each fish in an emerged net for three minutes. Afterwards fish returned to their home tank and 30min after were rapidly caught and anaesthetised for blood sampling. Blood was collected from the caudal vein and analysed for cortisol (radioimmunoassay). After 3 months the same individuals were exposed to an aggression test: fish were allowed to interact with a naïve fish of similar size (max 10% weight difference) for 20min. Aggressive behaviour was determined as follows: latency to start chasing (time taken until the first chase; chase was defined as a sudden change in swimming direction and speed as a response to an approach by the opponent); number of chases; latency to fighting (time taken until the first fight; fight was defined when fish engaged in a circle movement around each other) and number of fights. Results showed that individuals exhibiting lower cortisol responsiveness after a restraining test were more aggressive (cortisol vs number of chases: rs=−0.479, p=0.021) In conclusion, seabream juveniles exhibited pronounced individual differences in cortisol responsiveness and aggression that are interrelated and likely to be distinctive traits of coping styles.

Speed Control of Switched Reluctance Motor Using New Hybrid Particle Swarm Optimization

Problem statement: The main objective of this research is to obtain the speed control of switched reluctance motor with minimum settling time and without overshoot. Approach: A new algorithm has been developed with the combination of differential evolution and particle swarm optimization and applied for speed control of switched reluctance motor under sudden change in speed. Also speed control of switched reluctance motor was obtained by other artificial intelligence methods such as fuzzy logic controller, fuzzy PI controller and particle swarm optimization based tuning of fuzzy PI controller. Matlab/Simulink environment was used for the simulation. Results: Results are discussed and tabulated based on the performance of the controllers. Conclusion: From the comparison of all above methods, the algorithm has given better results in speed response than other controllers.

Threshold received sound pressure levels of single 1–2 kHz and 6–7 kHz up-sweeps and down-sweeps causing startle responses in a harbor porpoise (Phocoena phocoena)

Mid-frequency and low-frequency sonar systems produce frequency-modulated sweeps which may affect harbor porpoises. To study the effect of sweeps on behavioral responses (specifically "startle" responses, which we define as sudden changes in swimming speed and/or direction), a harbor porpoise in a large pool was exposed to three pairs of sweeps: a 1-2 kHz up-sweep was compared with a 2-1 kHz down-sweep, both with and without harmonics, and a 6-7 kHz up-sweep was compared with a 7-6 kHz down-sweep without harmonics. Sweeps were presented at five spatially averaged received levels (mRLs; 6 dB steps; identical for the up-sweep and down-sweep of each pair). During sweep presentation, startle responses were recorded. There was no difference in the mRLs causing startle responses for up-sweeps and down-sweeps within frequency pairs. For 1-2 kHz sweeps without harmonics, a 50% startle response rate occurred at mRLs of 133 dB re 1 μPa; for 1-2 kHz sweeps with strong harmonics at 99 dB re 1 μPa; for 6-7 kHz sweeps without harmonics at 101 dB re 1 μPa. Low-frequency (1-2 kHz) active naval sonar systems without harmonics can therefore operate at higher source levels than mid-frequency (6-7 kHz) active sonar systems without harmonics, with similar startle effects on porpoises.

Transient EHL of Two Surfaces under Elliptical Contact with Non-Newtonian Lubricant

This paper presents the effects of a sudden load change and sudden speed change on the performance characteristics of two surfaces under elliptical contact with elastohydrodynamic lubrication. The non-Newtonian lubricant for the research work are modeled based on Carreau viscosity model. The time dependent modified Reynolds equation and elastic equation were formulated for compressible fluid. Perturbation method, Newton Raphson method and full adaptive multigrid method were implemented and solved to obtain the film pressure, film thickness profiles and friction coefficient in the contact regime at various applied loads and speeds. Simulation results show the friction coefficient increase significantly under sudden loads. The minimum film thickness and friction coefficient both decrease significantly as speed is decreased.

Transient EHL of Two Surfaces under Elliptical Contact with Non-Newtonian Lubricant

This paper presents the effects of a sudden load change and sudden speed change on the performance characteristics of two surfaces under elliptical contact with elastohydrodynamic lubrication. The non-Newtonian lubricant for the research work are modeled based on Carreau viscosity model. The time dependent modified Reynolds equation and elastic equation were formulated for compressible fluid. Perturbation method, Newton Raphson method and full adaptive multigrid method were implemented and solved to obtain the film pressure, film thickness profiles and friction coefficient in the contact regime at various applied loads and speeds. Simulation results show the friction coefficient increase significantly under sudden loads. The minimum film thickness and friction coefficient both decrease significantly as speed is decreased.

A PLC-based modified-fuzzy controller for PWM-driven induction motor drive with constant V/Hz ratio control

In this paper, a method to develop and design a fuzzy-hybrid control on an industrial controller to control speed of an induction motor and implementing a constant V/Hz ratio control is presented. Detailed discussions on the controller for a PWM-driven induction motor drive system, the system identification for the model transfer function, and the analysis on output responses and the associated manipulated variables are presented. The control objective is to provide an effective control action to sudden changes in reference speed and/or load torque. A switching type controller consisting of two control modes are devised: a PID-type fuzzy controller consisting of a PI-type and a PD-type fuzzy controller, and a conventional PID. At the early phase of the control action, the control task is handled by the PID-type fuzzy controller. At a later phase when the absolute of error is less than a threshold value, the input of integrator at the output side is no longer given by fuzzy action but fed by the incremental PID action. In term of control action, this is an enhanced proportional and derivative action when the actual value is closed to reference. Detailed evaluations of the controller's performance based on pre-defined performance indices under several conditions are presented. The findings demonstrate the ability of the control approach to provide a viable control solution in response to the different operating conditions and requirements.

Development and Experimental Validation of Resolution-Level Controlled Wavelet-Modulated Inverters for Three-Phase Induction Motor Drives

This paper presents the development, implementation, and performances of a resolution-level vector controller (RLVC) for three-phase induction motor (IM) drive systems. The RLVC is structured to adjust the output voltages of a three-phase voltage-source wavelet-modulated inverter which is used to supply a three-phase IM. The objectives of the RLVC are established by controlling the quadrature axis component of the stator currents while maintaining a constant direct axis component of the stator currents. The complete IM drive system incorporating the RLVC is successfully implemented in real time for performance testing using a three-phase squirrel-cage IM. The performances of the proposed IM drive system are tested for sudden changes in load torque and command speed. Simulated and experimental performances demonstrate reliable, stable, fast, and accurate responses of the proposed controller under various operating conditions.

Analysis and evaluation of the thermal shock phenomena in the in-cylinder surfaces of a DI diesel engine during its transient operation

This paper presents the results from the analysis of an experimental investigation with the aim of providing an insight into the cyclic thermal shock phenomena occurring in the internal cylinder wall surfaces of a direct injection (DI), air-cooled diesel engine during the initial stage of a transient operation. The mechanism of cyclic heat transfer is investigated during engine transient events, viz. after a sudden change in engine speed and/or load. The experimental installation allowed both long- and short-term signal types to be recorded on a common time reference base during the transient event. Processing of experimental data was accomplished using a modified version of one-dimensional heat conduction theory with Fourier analysis, capable of catering for the special characteristics of transient engine operation. Based on this model, the evolution of local surface heat flux during a transient event was calculated. Two engine transient events are examined, which present a key difference in the way the load and speed changes are imposed on each one. During the analysis of experimental results the most important parameters characterizing thermal shock, such as the heat wave velocity and length of penetration, are quantified for each event, providing a comprehensive insight into the causes and consequences of this dangerous phenomenon. The results, in addition, confirm the theoretical predictions for the development of the thermal field during an engine transient event, as presented by the authors in previous work. Each thermal transient event is characterized by two distinct phases, that is the ‘thermodynamic’ and the ‘structural’ one, which are appropriately configured and analysed. From the results it is revealed that in the case of a severe variation, in the first 20 cycles after the beginning of the transient event, the wall surface temperature and heat flux amplitude on the cylinder head was almost three times higher than that observed in the ‘normal’ temperature oscillations occurring during steady-state operation.

Dealing with individual variability: When telling what is real depends on telling who is acting

You are queuing at the bus stop, and notice that someone suddenly turns her walk into a run: typically, you assume that she wants to catch the bus and may want to tell the driver to wait. Faced with a sudden speed change, rather than considering it bizarre or unnatural, observers attach a meaning to it, and act consequently. In a social context, speed of a movement often bears as much significance as its form, and can be adapted to vehicle precise meanings. This pragmatic rule facilitates decoding of non-verbal messages from other individuals, but may not necessarily apply when observing one's own movements, for which intentions should be informative enough. Hence, the range of motion speeds labeled as ‘natural’ could be broader for other people's actions compared to one's own. We explored this possibility through a task in which human observers decided whether speed of a gesture had been artificially modified. A virtual hand was presented, which – unbeknownst to participants – moved according to the kinematics of either the observer, or another individual. Although a self/other distinction was never required, participants applied different criteria when dealing with self compared to other people's gestures, suggesting that the brain implicitly extracts identity information before any overt judgment is produced. Interestingly, observers were reluctant to labeling movements of another individual as artificial, in keeping with the hypothesis that large variations in movements’ speed can vehicle social messages, and therefore are not regarded a priori as unnatural.

Performance Analysis of Field Oriented Induction Motor using Fuzzy PI and Fuzzy Logic based Model Reference Adaptive Control

This paper presents the dynamic performances of an indirect vector controlled induction motor (IVCIM) using a fuzzy logic (FL) based model reference adaptive control (MRAC) slip gain tuner for speed regulation in the drive. In high performance AC drives the motor speed should closely match with the specified reference speed irrespective of the variations in the load, motor parameters and model uncertainties. Two fuzzy controllers combined with MRAC reactive power and stator direct axis (d-axis) voltage estimator have been used to tune the slip gain of the IVCIM drive against parameter variations and model uncertainties. An integrated mathematical model of the control scheme has been developed and simulated in MATLAB for Indirect vector control of an Induction motor. The simulated performances of the FL-MRAC slip gain tuner based IVCIM drive is compared to fuzzy PI controller. The simulated results in different dynamic operating conditions such as sudden change in command speed, step change in load, etc are demonstrated through necessary waveforms. The comparison of simulated results show that the fuzzy logic MRAC slip gain tuner based IVCIM drive is more robust and effective in minimizing the detuning effect in the drive due to parameter variations and model uncertainties.

LabVIEW FPGA Implementation Of a PID Controller For D.C. Motor Speed Control

This Paper presents a novel hardware design methodology of digital control systems. For this, instead of synthesizing the control system using Very high speed integration circuit Hardware Description Language (VHDL), LabVIEW FPGA module from National Instrument (NI) is used to design the whole system that include analog capture circuit to take out the analog signals (set point and process variable) from the real world, PID controller module, and PWM signal generator module to drive the motor. The physical implementation of the digital system is based on Spartan-3E FPGA from Xilinx. Simulation studies of speed control of a D.C. motor are conducted and the effect of a sudden change in reference speed and load are also included.

LabVIEW FPGA Implementation Of a PID Controller For D.C. Motor Speed Control

This Paper presents a novel hardware design methodology of digital control systems. For this, instead of synthesizing the control system using Very high speed integration circuit Hardware Description Language (VHDL), LabVIEW FPGA module from National Instrument (NI) is used to design the whole system that include analog capture circuit to take out the analog signals (set point and process variable) from the real world, PID controller module, and PWM signal generator module to drive the motor. The physical implementation of the digital system is based on Spartan-3E FPGA from Xilinx. Simulation studies of speed control of a D.C. motor are conducted and the effect of a sudden change in reference speed and load are also included.