Vibration suppression in motion control system is an important problem in industry applications. This paper proposes a novel vibration control of multi-mass resonant system based on the resonant ratio control and phase-lead compensator. The resonance ratio control is one of the effective control methods of two-mass resonant system. In this method, the ratio between the resonant frequency of motor and arm is determined arbitrary according to the feedback of estimated reaction torque. However, conventional resonant ratio control has not considered the higher order of resonant frequencies. This paper clarifies the influence of the parameter variation of a disturbance observer on acceleration control system. The effect of phase-lead on the acceleration reference is attained by setting the nominal inertia value larger than the real inertia. The phase-lead compensator can stabilize all resonant poles of multi-mass resonant system. The proposed phase-lead compensator by the disturbance observer is based on both PD control and the resonance ratio control and the determination method of pole placement is discussed. Since the proposed phase-lead system is based on disturbance observer technique, it can realize both suppression of vibration and robustness in motion systems. The numerical and experimental results show viability of the proposed method.
Reactance calculation based on FEM from changing frequency point of view described here is effective on considering various kinds of transient phenomena. Moreover, electromagnetic force on the end-winding is described here to evaluate its support system, especially for large capacity cylindrical synchronous machines, where end-winding portion is the longest and electro-magnetic forces on it is the greatest of all rotating machinery.
Recently, the discontinuous armature PM-LSM is proposed as the driving source of transportation systems. We have proposed and examined a constant load angle control without position feedback, to suppress the velocity ripple which occurs at the re-acceleration portion with the aim of achieving smooth drive of the discontinuous armature PM-LSM. This paper presents the effectiveness of a constant load angle control without position feedback in the re-acceleration portion. We also examined the re-acceleration using constant load angle control with velocity feedback, and the results were compared.
The influence of flux waveform on magnetostriction of silicon steel strip and noise of transformer core are described. In the analysis the magnetostriction characteristics under a sinusoidal-flux condition are approximated by Fourie series. By the numerical analysis relations between the flux waveform and the magnetostriction waveform are obtained. The analytical results agree roughly with the experimental results, it is shown that harmonic components of magnetostriction varies depending on the flux waveform. The relation between flux waveform and noise of the core are also obtained by the experiments, it is shown that noise of the core differs depending on the flux waveform. These are mainly due to the fact that harmonic components of magnetostriction varies depending on the flux waveform.
In recent years, high-precision and high-resolution encoders are expected for a nanotechnology control system. High-precision angle calibration apparatuses are required and hence, they have been developed according to industry expectations. The accuracy of the disk and angle sensor were calibrated with high precision using the same accuracy measurement system, and a high-precision angle sensor was achieved. Using the high-precision angle calibration system, the encoder was realized with a high level of wide accuracy of 0.2 seconds. In addition, a high-resolution angle sensor with 30-bit could be achieved, and the multi-functional angle sensor which have acceleration data and bus-communications for servo system was developed. The principle by which the angle sensor calibrates the accuracy by it-self has been developed. The base technology of applying an angle sensor to a nanotechnology system was established.
The majority of the conventional system purifying exhaust gas is composed of a three-way catalyst and an electronic fuel injection. However, harmful pollutants are increasingly emitted when the catalyst becomes aged. Therefore, it is necessary to detect the deterioration of the catalyst by means of on board diagnosis. In this paper, we propose a diagnosis method of the aged catalyst using recursive system identification method with variable forgetting factor. We focus on the parameter of identified model which represents a characteristic of the catalyst, and possibility to describe the diagnosis of the aged catalyst.
This paper presents a sensorless vector control system for induction motors by taking into account iron loss, in which a flux-observer-based method is applied. Since the flux observer is constructed in a synchronously rotating reference frame with respect to the rotor flux of a current model and the iron loss resistance of parallel exiting circuit is used, the proposed system is very simple and the compensation of iron loss related to the operating frequency is directly realized while calculating rotor fluxes and slip frequency. The accuracies of estimated torque and speed are improved. The effectiveness of the proposed system has been verified by digital simulation and experimentation.
The matrix converter (MxC) is an ac-to-ac conversion device that can generate variable magnitude variable frequency output voltage. Nine bi-directional switches of MxC allow PWM control of output voltages and input currents. PWM switching needs “switch commutations” from one switch to another. During the switch commutations, however, unwanted voltage error occurs similar to the dead time effects in Voltage Source Inverter (VSI). When PWM pulse width is narrower than the time required for the commutation, voltage error increases rapidly. This voltage distortion is critical in the low speed operation as system becomes sensitive to even a small voltage error. In this paper, a new PWM strategy is proposed for improving voltage control performance in the low voltage region. Based on the input and output voltage information, PWM pulse-widths are controlled to avoid incomplete commutations. The feasibility of the proposed method is proved by simulation and experimental results. In addition, common mode voltage characteristics of MxC are discussed. Common-mode voltage and dv/dt cause motor bearing and ground leakage currents through the parasitic capacitances. Leakage current creates noise problems that can interfere with other equipment. Common-mode voltage characteristics of MxC are presented and discussed using two PWM methods. Simulated and experimental results are presented. Common-mode voltage of two-level VSI and MxC are also compared.
This paper proposes a robust PID parameter design scheme using Taguchi's robust design method. This scheme is applied to an embedded PID temperature control system which is affected by outside (room) temperature. The effectiveness of this scheme is verified experimentally with a cooking household appliance.
There are few self-gap-detecting electromagnetic suspension (EMS) systems robust enough against variation of coil resistance. The authors succeeded in providing much robustness against the variation of coil resistance with a self-gap-detecting EMS system. An adaptive control for coil resistance and an exciting voltage compensator for differences between the coil resistances were applied to the self-gap-detecting EMS system. The adaptive control was applied to the feedback controller and the state observer which evaluates gap length and its change rate with respect to time. As a result, it made clear that this self-gap-detecting controller yields more robustness against mass variation to EMS systems than conventional controllers with gap detectors. This paper proposes this new self-gap-detecting technique. The adaptive control and the exciting voltage compensator will be explained. Moreover, the robustness against mass variation will be discussed. The experimental results will show a validity of the proposed technique and a possibility to apply the self-gap-detecting EMS system to practical apparatuses in industrial fields.
This paper presents the design and implementation of a two dimensional drive. The moving part of the system is free of any contact and wires. The lightness of the moving part along with the big forces the 2D drive is capable to provide, makes feasible to obtain great accelerations. It has a compact sensoring system, and protected in a way that any colisions will not damage its important parts. The table has a traverse of 160mm in an axe and 125mm in the other one. A resolution of 0.02μm is obtained in each of the moving axes.
This paper describes a novel trajectory control system for human cooperation robots based on behavior mode switching. Human cooperation robots have the great possibility to serve as useful support systems for elderly people and physically handicapped people and it is expected to realize the smooth and human-friendly support movements. This study defines three behavior modes in human cooperation motion and their respective trajectory control system are designed. In the trajectory design, minimum jerk model is introduced to realize the smooth and human-friendly cooperation movements. In addition, the initial value compensation at the mode switching is also developed. Some experiments on two-axis plane robot and performance evaluation by trial subjects show the effectiveness of the proposed trajectory control system.
In this paper, we study an optimal design for a hybrid power source railway vehicle as an alternative to diesel railway vehicles. The hybrid power source railway vehicle is assumed to be composed of the fuel cell and the electric double layer capacitor. We apply the multiobjective optimization based on the genetic algorithm for the vehicle design, aiming at reduction of both initial cost and energy consumption. The pareto optimal solutions are obtained using the multiobjective optimization. First we develop a simulation model of the hybrid power source railway vehicle and its electric power control methods. Next we derive the pareto optimal solutions as a result of the multiobjective optimization. Finally, we categorize the pareto optimal solutions to some groups, which enables us to elucidate characteristics of the pareto optimal solutions. Consequently, using the multiobjective optimization approach we effectively comprehend the problem characteristics and can obtain the plural valuable solutions.
In chemical plants, anticorrosion magnetic drive pump is commonly used to deliver corrosive chemical liquid because of its high anti-corrosion performance. However, when bubbles enter in the chemical pump and accumulate between the shaft and the bearing, the shaft is often broken by thermal shock. The magnetic bearing which holds the rotor in non-contact has a good advantage to avoid thermal shock and to keep the rotor in a stable state by restoring force induced from eddy current in the conductor. The model of magnetic bearing was analyzed using three dimensional finite element method. In this model, the restoring force of 68.6N and the braking torque of 8.7N·m were obtained. The locus of rotation axis was also estimated from a radial load and a drag coefficient. The rotor may locate inside the movable range.
This paper discusses the effect of manufacturing deterioration and permanent magnet conditions on cogging torque and iron loss in 12-pole small motors using 9-slot cores (20mm outer dia.). Manufacturing stress and strain increase 12n-th order cogging torques and iron loss, and smaller-clearance punching and larger-clearance clinching reduces iron loss althouogh they hardly affect cogging torque. The 9n-th order cogging torques are influenced a little by stress-relief annealing. The magnetization conditions of permanent magnet influences not only iron loss, but also cogging torque, which may be proportional to the square of magnet magnetization. However, cogging torques are hard to be induced at lower magnet magnetization.
This paper examines the cogging torque of permanent magnet motors resulting from the magnetic anisotropy of non-oriented steel sheets used for magnetic core. The cogging torque due to the magnetic anisotropy is calculated by FEM using two modeling methods; one is the newly developed method which takes account of the two-dimensional magnetic properties in arbitrary directions, and the other is the conventional method which uses only two magnetization curves both in rolling and transverse directions. In the proposed method, the measured magnetic properties are treated in two different ways; in the first way the data are used directly, and in the second way the data are interpolated using Bèzier surface. As a result, all of three models show the cogging torque component resulting from the magnetic anisotropy, that has less pulsation numbers per rotation than that of isotropic model. The difference of the cogging torque amplitude between the three models is small in the region of low magnetic flux density, however, it gradually becomes large along with the increase in magnetic flux density. The measured results of cogging torque is proximate to the results calculated by two-dimensional magnetic property method using the magnetic property data directly. The error is approximately 4% at the point where the cogging torque component resulting from the magnetic anisotropy is maximum.
In order to speculate motor performance with high precision, it is important to understand correctly motor parameters, such as reactance, in an actual operation state. This paper presents a study of three reactance evaluation methods: Dalton-Cameron method, the method applying direct magnetic field and the method considering cross-magnetizing reactance. Dalton-Cameron method and the method applying direct magnetic field are superior in simplicity of measurement. But the reactance under saturated magnetic field could not be calculated correctly by two former methods, because magnetic saturation in the actual operation state is not taken into consideration. In this paper, it is indicated that the results calculated by the two former methods have errors to the measured results, and that the reactance should be calculated by the method considering cross-magnetizing reactance, when we treat the machine that has a complicated magnetic circuit.
The performance of a stand-alone permanent-magnet induction generator (PMIG) with single-phase output is analyzed using the method of symmetrical components and is compared to that of the same-sized conventional induction generator (IG). Experimental results conducted on a 2.2-kW testing machine are also provided to justify the theoretical analysis. Calculation and experimental results show that containing a permanent-magnet (PM) rotor generates electric power without fail and contributes to the improvement of efficiency and frequency variation.
Jitter is a technical issues of network bilateral control system. Hence, this paper proposed the jitter buffer method, which makes transmission delay constant. The validity of proposed system is confirmed by the experiments.