Kwang-Bae Kim

Sensorless vector control of induction motor using a novel reduced-order extended Luenberger observer

A synthesis method of the reduced-order extended Luenberger observer (ROELO) and its design procedure for a nonlinear dynamic system are presented. This paper proposes a method to reduce the order of the observer and to select the observer gain matrix. The main features of the proposed observer are discussed and compared with the characteristics of the other observers. The proposed algorithm is applied for high-performance induction motor drives without a speed sensor. The simulation results show that the proposed ROELO provides both the rotor flux and rotor speed estimation with good transient and steady state performance.

A human-like real-time grasp synthesis method for humanoid robot hands

Abstract This paper addresses a real-time grasp synthesis of multi-fingered robot hands to find grasp configurations which satisfy the force closure condition of arbitrary shaped objects. We propose a fast and efficient grasp synthesis algorithm for planar polygonal objects, which yields the contact locations on a given polygonal object to obtain a force closure grasp by a multi-fingered robot hand. For an optimum grasp and real-time computation, we develop the preference and the hibernation process and assign the physical constraints of a humanoid hand to the motion of each finger. The preferences consist of each sublayer reflecting the primitive preference similar to the conditional behaviors of humans for given objectives and their arrangements are adjusted by the heuristics of human grasping. The proposed method reduces the computational time significantly at the sacrifice of global optimality, and enables grasp posture to be changeable within 2-finger and 3-finger grasp. The performance of the presented algorithm is evaluated via simulation studies to obtain the force-closure grasps of polygonal objects with fingertip grasps. The architecture suggested is verified through experimental implementation to our developed robot hand system by solving 2- or 3-finger grasp synthesis.

Vibration control of 2-mass system using a neural network torsional torque estimator

A new control scheme using a torsional torque estimator based on a neural network is proposed and investigated for improving control characteristics of the high-performance motion control system. This control method presents better performance in the corresponding speed vibration response, compared with the disturbance observer-based control method. This result comes from the fact that the proposed neural network estimator keeps the self-learning capability, whereas the disturbance observer based torque estimator with the low pass filter should adjust the time constant of the adopted filter according to the natural resonance frequency determined by considering the system parameters varied. The simulation results show the validity of the proposed control scheme.

Prediction of crest factor of electronic ballast for fluorescent lamp using pulse frequency modulation control

When electronic ballasts are used for fluorescent lamps, lifetime of the lamp is greatly affected by starting scenario and crest factor. A new method to reduce the crest factor of the lamp is proposed, and the proposed electronic ballast is controlled in the mode of pulse frequency modulation (PFM). Electronic ballasts with 50% valley-fill PFC are dealt with in this paper. The characteristics of electronic ballast with the proposed PFM control scheme are comprehensively investigated through several simulations and experiments.

Minimal balanced realization of SISO systems using closed-form Gramians

This paper develops a simple approach to minimal balanced realizations, which enable balanced realizations for arbitrary linear discrete SISO systems. First, the controllability, observability, and cross Gramians are obtained from the Lyapunov matrix equations in a closed-form. Based on these Gramians, an algorithm is proposed to obtain a minimal balanced realization directly from the coefficients of the transfer function using the Jury array. This algorithm is simpler and numerically more efficient in computing the Gramians than presently existing algorithms. Thus it can be very useful for adaptive control or model reduction of time-varying discrete-time systems.

Electrical instability of induction motor driven by CSI with output capacitors

A load commutated current source inverter (LCCSI)-fed induction motor system, where large output capacitors are provided to perform the load commutation, is faced with an electrical instability problem. An electrical instability analysis of the LCCSI-fed induction motor drive system is done by evaluating the eigenvalues of the resulting system matrix. It is also shown that a proposed compensation method can permit the LCCSI-fed induction motor drive system to avoid the electrical instability problem under the nominal operating frequency region.<<ETX>>

Real-time simulation for continuous processing of an electrolytic tinning line

In this paper, a real-time simulation is performed to insure the continuous processing of an electrolytic tinning line (ETL). An ETL is modelled mathematically and a simple type of tension and speed controllers are designed to control the tension and speed of the strip to be within the tolerance error bound. The designed controller is implemented and tested by using a real-time simulation system which consists of 32 bit VME-based single board computers and a real-time operating system (VRTX).<<ETX>>

A Novel MRAC Scheme for Electrical Servo Drives — Signal Synthesis Method

Abstract A novel model reference adaptive control (MRAC) scheme for electrical servo drives is proposed, in which the control input is synthesized without any parameter identification mechanism and a PI controller is inserted ahead of the plant to reduce the steady state chattering. The proposed scheme is shown to be asymptotically stable in case that load torque disturbance sati sfies a certain condition. An application to a permanent magnet synchronous motor drive shows that the output error between the plant and the reference model tends to zero and the chattering is greatly reduced.

Two Adaptive Nonlinear Control Schemes for an Induction Motor

Abstract Two adaptive nonlinear control schemes are presented for an induction motor: tuning function and modular design approaches. The objective here is to control the speed and flux in an independent manner despite rotor resistance uncertainty. In most existing adaptive schemes with this objective, load torque is regarded as a constant but unknown parameter to be estimated rather than a disturbance. On the other hand, this paper uses an integrator to deal with the low-frequency load torque instead of trying to estimate it. Simulations show that the proposed adaptive schemes lead to uniform closed-loop performance despite the uncertainty of the rotor resistance.

Function Block Diagram Approach for Manufacturing Process Control Programming

Abstract A process control language using function block diagram approach is designed for real-time control of continuous manufacturing process automation system, in which five groups of primitIVe functIon blocks and macro-type function blocks are defined to make an operator easy to implement target programs. To effectively utilize the proposed function block diagram language, a graphic editor, compiler and executer are also designed. The validity of the concept in its design and implementation is assured by on-line simulation in the multi-function controller designed for continuous process automation.