Fumio Harashima

MOSFET Converter-Fed Position Servo System with Sliding Mode Control

Sliding mode control is an effective means to keep a system insensitive to parametric variations and disturbances. In the conventional sliding mode control applied to position servo systems, the sliding mode regime is restricted near the origin, and, therefore, insensitivity cannot be ensured throughout an entire response. This paper presents a new method in which a sliding curve is used instead of a straight line. The sliding curve is defined in such a way that in general the system responds following a max acceleration curve, then a max speed curve, and finally a max deceleration curve. Experimental results confirm that the new method can keep the system robust completely throughout a transient response, which demonstrates the advantage of the proposed sliding curve over the conventional sliding mode strategy.

A new approach for minimum-torque-ripple maximum-efficiency control of BLDC motor

Torque-ripple control of the brushless DC motor has been the main issue of the servo drive systems in which the speed fluctuation, vibration, and acoustic noise should be minimized. Most methods for suppressing the torque ripples require Fourier series analysis and either iterative or least-mean-square minimization. In this paper, a novel approach to achieve ripple-free torque control with maximum efficiency based on the d-q-0 reference frame is presented. The proposed method optimizes the reference phase current waveforms which include the case of three-phase unbalanced conditions. As a result, the proposed approach provides a simple way to obtain optimal motor excitation currents. The validity and practical applications of the proposed control scheme are verified through the simulations and experimental results.

A Microprocessor-Based Robot Manipulator Control with Sliding Mode

The application of a sliding-mode control based on a Variable Structure System (VSS) for a multijoint manipulator is presented. The high-gain effect of a sliding-mode control suppresses the complicated interactions between each joint of a robot arm. The resulting system is completely robust whereas the obtained control law is simple and easy to apply to on-line computer control. In this-paper, the practical sliding-mode controller, which has a simple nonlinear compensator and proper continuous function, is implemented for a two-linkage manipulator. The validity of this technique is confirmed in experiments where the system shows robust performance in spite of the existing nonlinear interactions and unknown parametric changes. In addition, this sliding-mode control is improved to track the desired path.

Brushless servo motor control using variable structure approach

The variable structure system (VSS) is expected to be a powerful tool for constructing a control strategy for AC machines since it is based on discontinuous control inputs, i.e. variable structures. The application of VSS to the position control of a brushless servo motor is discussed. The resulting system is robust with respect to parametric variations and disturbances. On-off patterns for switching devices are generated directly by VSS, and the robustness is obtained in a total system including the inverter. This approach is useful for a nonlinear plant such as a direct-drive robot arm. >

Visual control of robotic manipulator based on neural networks

A control scheme for a robotic manipulator system that uses visual information to position and orient the end-effector is described. The control system directly integrates visual data into the servoing process without subdividing the process into determination of the position and orientation of the workplace and inverse kinematic calculation. The feature of the control scheme is the use of neural networks for the determination of the change in joint angles required in order to achieve the desired position and orientation. The proposed system is able to control the robot so that it can approach the desired position and orientation from arbitrary initial ones. Simulations for a robotic manipulator with six degrees of freedom are described. The validity and the effectiveness of the proposed control scheme are verified by computer simulations. >

Integration of mobile vehicles for automated material handling using Profibus and IEEE 802.11 networks

This paper focuses on a method to integrate mobile devices such as a mobile robot, automated guided vehicle, and unmanned container transporter to form an automated material handling system. In this paper, the stationary devices are connected via a Profibus network while the mobile devices are communicating via an IEEE 802.11 wireless LAN. In order to integrate these two networks, a protocol converter is developed on a PC platform that runs two interacting processes with shared internal buffers. The protocol converter performs a role of translator between two different protocols by converting the format of a data frame. In addition to this basic conversion function, the protocol converter has a virtual polling algorithm to reduce the uncertainty involved in accessing the wireless network. Finally, the integrated network. of Profibus and IEEE 802.11 is experimentally evaluated for its data latency and throughput, which shows the feasibility of the Profibus-IEEE 802.11 network for industrial applications involving mobile devices.

Microprocessor-Controlled SIT Inverter for Solar Energy System

A microprocessor-controlled static induction transistor (SIT) inverter is proposed to link a solar battery with a utility ac power line. The main control objectives are to optimize the power flow from the solar battery to the utility power line and to compensate the reactive power, including harmonic distortion. The performance is well realized by the experimental setup.

VSS observer for linear time varying system

The problem of designing an observer for state estimation using variable structure system (VSS) theory is discussed. The theory and design principles for linear time-varying systems are presented. The observer is constructed by introducing a block-observable from which is similar to a lower triangular matrix. The convergence of the observer is guaranteed by a sliding mode with first-order filter. Simulation results show that the proposed observer is able to provide correct estimated values of the states.<<ETX>>

Multimicroprocessor-Based Control System for Quick Response Induction Motor Drive

Two types of vector control induction motor are discussed. One is the conventional vector control with high gain current feedback loop, the other is the decoupling control based on the voltage model of an induction motor with no current feedback. Several comparison tests show the superiorities of the decoupling control. The multimicroprocessor-based hardware configuration is presented.

Internet-Based Teleoperation of an Intelligent Robot With Optimal Two-Layer Fuzzy Controller

Research on Internet-based teleoperation has received increased attention in the past few years. In this paper, an Internet-based teleoperation system was implemented. In order to robustly transmit the surroundings and control information of the robot, packet-type data were used. The central problem in Internet-based teleoperation is data transmission latency or data loss. For this specific problem, an autonomous mobile robot with optimal two-layer fuzzy controller (2LFC) was introduced. When data transmission is failed, the robot automatically moves and protects itself. In addition, a color detection system was implemented so that the robot can perceive an object and move to another object. The fuzzy controller was optimized by using the schema coevolutionary algorithm (SCEA), which finds an optimal solution. Using these technologies, the efficacies of the 2LFC, the SCEA, and the teleoperation system were verified