Smooth Speed Research Articles

Experimental Verification of Critical-Speed Increase of Single-Phase Induction Machines via Winding Reconfiguration With Solid-State Switches

The concept of online electronic switching of windings will be applied to a single-phase induction motor with two separate windings with different pole numbers p1 = 4 and p2 = 6 and an auxiliary winding required for starting. During switchover from the low-speed winding to the high-speed winding, and vice versa, lasting less than a few milliseconds, small electrical torque and speed transients occur. Relying on closed-loop speed control, a smooth speed response is measured. This concept is, therefore, applicable to variable-speed drives, where a large speed range is desirable. Test data indicate that a speed-control range from 600 to 4000 r/min is obtainable with a single-phase induction motor.

Speed Sensorless Control of Induction Motors Based on a Reduced-Order Adaptive Observer

A novel speed sensorless indirect field-oriented control for the full-order model of the induction motor is presented. It provides local exponential tracking of smooth speed and flux amplitude reference signals together with local exponential field orientation, on the basis of stator current measurements only and under assumption of unknown constant load torque. Speed estimation is performed through a reduced-order adaptive observer based on the torque current dynamics, while no flux estimate is required for both observation and control purposes. The absence of the flux model in the proposed algorithm allows for simple and effective time-scale separation between the speed-flux tracking error dynamics (slow subsystem) and the estimation error dynamics (fast subsystem). This property is exploited to obtain a high performance sensorless controller, with features similar to those of standard field-oriented induction motor drives. Moreover, time-scale separation and physically-based decomposition into speed and flux subsystems allow for a simple and constructive tuning procedure. The theoretical analysis based on the singular perturbation method enlightens that a persistency of excitation condition is necessary for the asymptotic stability. From a practical viewpoint, it is related to the well-known observability and instability issues due to a lack of back-emf signal at zero-frequency excitation. A flux reference selection strategy has been developed to guarantee Persistency of excitation in every operating condition. Extensive simulation and experimental tests confirm the effectiveness of the proposed approach.

Smooth speed control of motor drives with asymptotic disturbance compensation

For electrical drive speed control, this paper presents a scheme of jerk-constrained time-optimal control (JCTOC) that guarantees a minimum-time output response of the nominal drive under a magnitude constraint on machine jerk. By confining the machine jerk to the admissible range, smooth machine operations are achieved. Furthermore, the JCTOC is augmented with a novel disturbance observer (DOB) that ensures asymptotic rejection of an unknown disturbance with multiple frequency components. This is attained by incorporating a lowpass filter and several bandpass filters into the DOB structure, which is tuned based on the knowledge of the disturbance frequencies. The effectiveness of the proposed scheme is demonstrated through experimental studies of a permanent-magnet synchronous motor drive suffering from multiple-frequency disturbances.

Sliding mode control with integral augmented sliding surface: design and experimental application to an electromechanical system

In this study, an integral augmented sliding mode control (SMC + I) has been proposed to improve control performance of systems. Stability of the closed-loop system is guaranteed in the sense of Lyapunov stability theorem. The effectiveness of the control solution is established by the stability analysis of the closed-loop system dynamics. The proposed controller is adopted to control speed of an electromechanical system. The experimental set-up reflects the emphasis on the practicability of the proposed sliding mode controller. The experimental results are presented and compared with the results obtained from conventional sliding mode control and Proportional + Integral + Derivative (PID) control. The experimental results verify that the proposed controller provides favorable tracking performance, faster and smoother speed regulation with regard to parameter variations and disturbances. The present study shows that the proposed controller, with its straightforward solution, is easily applicable to industrial problems and an alternative to conventional PID and sliding mode controllers.

GERICO: A HUMAN CENTRED ECO-DRIVING SYSTEM

This paper presents the evaluation of a new onboard system designed to reduce fuel consumption and CO2 production. The GERICO system enables the driver to adopt the best driving behaviour, smooth speed and good gear management. We carried out 80 tests (with training and GERICO) with 40 drivers in the Toulouse area. The main results show that training contributes to a 11% consumption reduction whereas using the GERICO system contributes to a 16% consumption reduction. Drivers consider that the system is useful and a good aid to fight against bad habits and reduce fuel consumption.

CPP1軸1舵船の停止操船における操舵制御について

It is well known that a controllable pitch propeller (CPP) can provide smooth speed control. On the other hand, unstable yaw moment is often exerted during the stopping maneuver of ships with single CPP and single rudder, which introduces a significant reduction in maneuverability, and, under this condition, it is difficult to control CPP ships by steering. A simulation study has been performed in order to investigate the effective ship-handling method in a harbor to control the unstable stopping motion of CPP ships. Based on the results of the simulation study, the authors propose an effective ship-handling method that applies turning moment to the ship by maximum rudder angle steering prior to the reversing operation of the CPP. And it is confirmed that the unstable stopping motion of CPP ships can be controlled sufficiently by the proposed method. The proposed ship-handling method is applicable to the ship-handling for anchoring under windy condition and crash astern maneuver in a harbor area.

Feature-preserving mesh denoising based on contextual discontinuities

Motivated by the conception of Lee et al. (2005)’s mesh saliency and Chen (2005)’s contextual discontinuities, a novel adaptive smoothing approach is proposed for noise removal and feature preservation. Mesh saliency is employed as a multiscale measure to detect contextual discontinuity for feature preserving and control of the smoothing speed. The proposed method is similar to the bilateral filter method. Comparative results demonstrate the simplicity and efficiency of the presented method, which makes it an excellent solution for smoothing 3D noisy meshes.

A speed-sensorless indirect field-oriented control for induction motors based on high gain speed estimation

The authors design a new speed sensorless output feedback control for the full-order model of induction motors with unknown constant load torque, which guarantees local asymptotic tracking of smooth speed and rotor flux modulus reference signals and local asymptotic field orientation, on the basis of stator current measurements only. The proposed nonlinear controller exploits the concept of indirect field orientation (no flux estimation is required) in combination with a new high-gain speed estimator based on the torque current tracking error. The estimates of unknown load torque and time-varying rotor speed converge to the corresponding true values under a persistency of excitation condition with a physically meaningful interpretation, basically equivalent to non-null synchronous frequency. Stability analysis of the overall dynamics has been performed exploiting the singular perturbation method. The proposed control algorithm is a “true” industrial sensorless solution since no simplifying assumptions (flux and load torque measurements) are required. Simulation and experimental tests show that the proposed controller is suitable for medium and high performance applications.

A Differential-Algebraic Approach to Speed Estimation in an Induction Motor

This note considers a differential-algebraic approach to estimating the speed of an induction motor from the measured terminal voltages and currents. In particular, it is shown that the induction motor speed /spl omega/ satisfies both a second- and a third-order polynomial equation whose coefficients depend on the stator voltages, stator currents, and their derivatives. It is shown that as long as the stator electrical frequency is nonzero, the speed is uniquely determined by these polynomials. The speed so determined is then used to stabilize a dynamic (Luenberger type) observer to obtain a smoother speed estimate. With full knowledge of the machine parameters and filtering of the sensor noise, simulations indicate that this estimator has the potential to provide low speed (including zero speed) control of an induction motor under full rated load.

Illumination of the shadow zone in a two-channel oceanic waveguide with a fine structure of sound speed inhomogeneities

The experimental data on the sound field structure, which were obtained by emitting a continuous pseudonoise signal (a midfrequency of 3.2 kHz) in a two-channel oceanic waveguide, are compared with the calculations performed by the wave program with allowance for the fine structure of the sound speed inhomogeneities. A considerable increase in the intensity of the sound field with a definite angular spectrum is observed in the upper channel in the first shadow zone, and, in the experiment, the increase begins nearer to the sound source than predicted by the wave and ray calculations for a smooth sound speed profile. These features of the field structure are explained by the illumination of the shadow zone by the regular scattering of signals from highly anisotropic fine-structure inhomogeneities of the sound speed profile, which are clearly pronounced in the region of the given oceanic experiment.

Longitudinal Control of Heavy Trucks in Mixed Traffic: Environmental and Fuel Economy Considerations

In this paper, longitudinal vehicle-following controllers for heavy trucks with different spacing policies are designed, analyzed, simulated, and experimentally tested, and their performance in mixed traffic with passenger vehicles is evaluated. A new vehicle-following controller for trucks, which has better properties than existing ones with respect to performance and impact on fuel economy and pollution during traffic disturbances, is developed. The response of trucks to disturbances caused by lead passenger vehicles is smooth due to the limited acceleration capabilities of trucks whether they are manual or equipped with adaptive cruise control (ACC) systems. Vehicles following the truck are therefore presented with a smoother speed trajectory to track. This filtering effect of trucks is shown to have beneficial effects on fuel economy and pollution. However, it creates large intervehicle gaps that invite cut-ins from neighboring lanes, creating additional disturbances. These cut-ins, under certain realistic scenarios, may reduce any benefits obtained by the smooth response of trucks as well as increase travel time. The results of this paper indicate possible benefits trucks may have in mixed traffic and also reinforces what is already known-that trucks could be detrimental to traffic flow

Adaptive smoothing via contextual and local discontinuities

A novel adaptive smoothing approach is proposed for noise removal and feature preservation where two distinct measures are simultaneously adopted to detect discontinuities in an image. Inhomogeneity underlying an image is employed as a multiscale measure to detect contextual discontinuities for feature preservation and control of the smoothing speed, while local spatial gradient is used for detection of variable local discontinuities during smoothing. Unlike previous adaptive smoothing approaches, two discontinuity measures are combined in our algorithm for synergy in preserving nontrivial features, which leads to a constrained anisotropic diffusion process that inhomogeneity offers intrinsic constraints for selective smoothing. Thanks to the use of intrinsic constraints, our smoothing scheme is insensitive to termination times and the resultant images in a wide range of iterations are applicable to achieve nearly identical results for various early vision tasks. Our algorithm is formally analyzed and related to anisotropic diffusion. Comparative results indicate that our algorithm yields favorable smoothing results, and its application in extraction of hydrographic objects demonstrates its usefulness as a tool for early vision.

Design of hybrid machines for nonuniform motion production

Linkage mechanisms driven at constant angular velocity (CV) using a motor and flywheel have traditionally been used to produce fixed nonuniform motions. This type of system offers advantages of smooth motor torques, energy conservation and fast operational speeds. By incorporating a servo motor drive with a conventional CV drive in a two degree of freedom (DOF) linkage, the resulting hybrid machine can provide programmability. In this paper, two different hybrid mechanisms are optimally designed to provide a range of output motions with minimized torque and power requirements from the servo motor. The results are compared with those for a direct servo motor drive system.

CASCADED NONLINEAR RECEDING-HORIZON CONTROL OF INDUCTION MOTORS

In this paper the optimal nonlinear receding-horizon control structure is presented with application to induction motors in cascade structure, which provides global asymptotic tracking of smooth speed and flux trajectories. The controller is based on a finite horizon continuous time minimization of nonlinear tracking errors. Both the rotor flux and load torque are estimated by Kalman filter. The robustness properties with respect to electrical parameter variations and load disturbance are presented. Finally computer simulations show the flux-speed tracking performances and the disturbance rejection capabilities of the proposed controller in the nominal and mismatched parameters case.

Development of Toyota's transaxle for mini-van hybrid vehicles

In June 2001, Toyota Motor Corporation developed the Toyota Hybrid System-CVT (THS-C) for mini-vans. A new transaxle developed for the front drive unit of the THS-C system is compact, lightweight, and highly efficient. The unit achieves excellent driving comfort with smooth speed change by CVT control and provides high-level driving power control by wet multiple disc clutches.

A feedforward neural network controlling the movement of a 3-DOF finger

This paper describes the dynamic control of a 3 degree of freedom (DOF) ringer emulating a human finger for reaching a desired fingertip position in space. The control consists of a neural network (NN) which provides the necessary three torques to the phalanges granting a smooth speed profile of the fingertip motion. To obtain the results, we face these problems: 1) the elimination of the redundancy due to the third joint; 2) the mathematical description of a natural movement; 3) the calculation of the torques for executing movement; and 4) the optimization of the NN's structure. Assuming a cognitive approach well-established in the literature, the first and the second points are solved by adopting an extension of the minimum jerk theory. The classic Lagrange equations are applied to compute the three-motor torque. Finally, a multilayer perceptron (MLP) NN is trained to move the device in a natural manner. The generalization capabilities of the NN are checked on new never-seen movements, and different MLP architectures are compared on the basis of indexes representing the motor performance. The results suggest we should pursue this approach for multifinger hand in order to achieve a natural NN prosthetic/robotic dynamic control system.

END POINT CONSTRAINTS NONLINEAR CONTINUOUS PREDICTIVE CONTROL FOR INDUCTION MOTORS

In this paper the optimal nonlinear predictive cascaded control structure is presented with application to induction motors, which provides global asymptotic tracking of smooth speed and flux trajectories. The controller is based on a finite horizon continuous time minimization of nonlinear predicted tracking errors. With full state measurement assumption, the robustness properties with respect to electrical parameter variations and load disturbance is presented. Finally computer simulations show the flux-speed tracking performances and the disturbance rejection capabilities of the proposed controller in the nominal and mismatched parameters case.

Learning to write letters: transfer in automated movements indicates modularity of motor programs in human subjects.

Many automatic movements are open-loop, feed-forward motor programs (MP) that are kinematically well characterized by smooth speed and acceleration curves. However, it is unclear whether their internal representation consists of monolithic blocks or subroutines. This question was investigated using a learning paradigm of a writing task. Fifty-nine normal subjects were presented with two similar, but different new letters. Every subject practiced each letter in a series of 60 trials, with the order of letter series randomized. Every session was continuously recorded by a digitizing tablet. Using kinematic analysis, we measured the number of vertical acceleration peaks as an indication of the number of corrective movements (COM). Since COM declined as automatization was approached, we could quantitatively infer progress in motor learning under natural learning conditions. In the case of modular storage of MP, transfer in-between letters was expected due to the re-use of pre-learned motor subroutines. Statistical analysis showed that the exponential model described the data much better than the linear model (residual error: P<0.88 and P<0.00001, respectively), as expected for a learning paradigm. There was no difference between letters per se (P<0.77). Motor improvement differed significantly (P<0.02) between the first and the second series; there was a much greater reduction of COM in the second series (50.1 vs. 41.1%). This difference can be logically ascribed to transfer, indicating that automated movements are stored in motor subroutines.

High-performance indirect field-oriented output-feedback control of induction motors

A new indirect field-oriented output feedback control for induction motors is presented which provides global asymptotic tracking of smooth speed and flux reference trajectories in the presence of unknown constant load torque. A tuning procedure for controller parameters is also developed. Transient performance and robustness properties with respect to structural unmodeled dynamics of the current control loops can easily be specified. Simulation and experimental tests demonstrate better dynamic performance compared to that of standard indirect field-oriented control. The proposed control algorithm can be viewed as an improvement of standard field-oriented controllers.

Global adaptive output feedback control of induction motors with uncertain rotor resistance

The authors design a global adaptive output feedback control for a fifth-order model of induction motors, which guarantees asymptotic tracking of smooth speed references on the basis of speed and stator current measurements, for any initial condition and for any unknown constant value of torque load and rotor resistance. The proposed seventh-order nonlinear compensator generates estimates both for the unknown parameters (torque load and rotor resistance) and for the unmeasured state variables (rotor flux); they converge to the corresponding true values under persistency of excitation which actually holds in typical operating conditions. The control algorithm generates references for the magnetizing flux component and for the torque component of stator current which lead to significant simplification for current-fed motors. Simulations show that the proposed controller is suitable for high dynamic performance applications.