Mitsuo Hirata

H/sub /spl infin// control versus disturbance-observer-based control

In the motion control field, a disturbance observer-based disturbance canceling control is often used as a robust control methodology. However, this method is nothing more than an alternative design of an integral controller, and the robust stability issue cannot be directly accounted for. In this paper, an extended H/sub /spl infin// control scheme is proposed as a new robust motion control method which achieves the disturbance cancellation ability and guarantees robust stability automatically.

Autonomous Control for Micro-Flying Robot and Small Wireless Helicopter X.R.B

This paper presents autonomous control for micro-flying robot (muFR) and small helicopter X.R.B. In case of natural disaster like earthquake, a MAV is very effective for surveying the site and environment in dangerous area or narrow space, where human cannot access safely. In addition, it is a help to prevent secondary disaster. This paper is concerned with autonomous hovering control, guidance control of muFR, and automatic takeoff and landing control of X.R.B

Power assist control for slide doors using an ideal door model

A power assist system for automobile slide doors that can provide comfortable operational feelings has been developed. The system incorporates a reference door model having preferable operational feelings. In order to follow virtual motion of the ideal door, both feedforward- and feedback-controllers are employed to drive a power assisting motor. Simulations and experiments have proved that the motion of the actual door corresponds well with that of the ideal door.

Short track seeking of hard disk drives under multirate control-computationally efficient approach based on initial value compensation

This paper proposes a design method for short track-seeking control based on one degree of freedom (ODOF) control and initial value compensation (IVC). IVC uses nonzero initial values of the feedback controller to improve the step reference response of the ODOF tracking control system. This makes feedforward control unnecessary to shape the transient response of short track seeking. As a result, the amount of computation during short track seeking may be minimal. The proposed design method minimizes tracking errors in multirate control framework for a step reference input taking into account the inter-sampling behavior. The effectiveness of the proposed method is shown by simulation and experiment.

Servo Performance Enhancement of Motion System via a Quantization Error Estimation Method—Introduction to Nanoscale Servo Control

When compared to the accuracy of nanoscale control, the resolution of current positioning sensors is relatively low. Because of this, the output from low-precision sensors normally includes quantization errors that could degrade control performance. As a result, in this paper, a method of quantization error estimation based on the least square method is examined. In the proposed method, estimation accuracy is improved by taking into account the effect of input disturbances. Furthermore, a bias adjustment method is proposed that is expected to satisfy the constraints on quantization error. The effectiveness of the proposed method is demonstrated by simulations and experiments.

Autonomous Control of Micro Flying Robot

In the case of a natural disaster such as an earthquake, a micro air vehicle (MAV) would be very effective for surveying the site and environment in dangerous areas or narrow spaces that humans cannot access safely. In addition, it would be helpful for preventing secondary disaster. This paper discusses autonomous hovering control and guidance control of a micro flying robot (μFR). Since a μFR is very small and light, sensors such as a global positioning system (GPS) cannot be carried. So, the three-dimensional position of a μFR is measured by using one charge coupled device (CCD) camera to recognize a marker attached to the μFR. We adopted proportional—integral—derivative (PID) control because its performance can be increased by tuning, even when there is no model. Nevertheless, it is not easy to find the gain of the PID controller for the X and Y directions. Therefore, the first step that we took is modeling based on system identification and then we designed a model-based controller.

Final-state control using a polynomial and time-series data

This paper proposes a final-state control method in which the feedforward input is generated by both of a polynomial and time-series data. Simulation results show that a combination use of a polynomial and time-series data can improve control performance.

Vibration minimized trajectory design for information devices

This paper proposes a design method of the vibration minimized trajectory based on final-state control method. We discuss about the selection of the design parameter of final-state control method to achieve fast and accurate track seeking. The effectiveness of the proposed method is demonstrated by the hard disk benchmark problem developed by a technical committee of IEE of Japan

Exact linearization of PWM-hold discrete-time systems using input transformation

This report is concerned with discrete-time systems that are derived for continuous-time LTI systems by the pulse-width-modulation (PWM) -hold. The input term of the difference equation describing the discrete-time system is a nonlinear map of the control parameter of the PWM signal, i.e., duty ratio. It is shown that for two-dimensional systems, the nonlinearity of the PWM-hold systems can be exactly compensated by varying the center of each rectangular pulse-waves as well as its duty ratio.

Final-State Control Using a Time-Symmetric Polynomial Input

For information devices such as hard disk drives, actuators must be controlled as quickly and precisely as possible. The design of the feedforward input is very important in satisfying these requirements. Therefore, we have proposed design methods based on final-state control so as to reduce its spectrum at the desired frequency points. Furthermore, the final-state control method has been extended to generate the feedforward input using a polynomial. By using a polynomial, the required memory size can be drastically reduced because only the coefficients of the polynomial must be stored. However, when the step number of the input increases, the method may not produce a correct solution because of a numerically ill-posed problem. In this paper, we propose a design method for the final-state control based on a time-symmetric polynomial input. The simulation results show that the proposed method contributes to the improvement of not only the numerically ill-posed problem but also the performance.