Abstract
〈Vol.6 No.6(2013.11)〉
Titles
[Contributed Papers]
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■ Modified Virtual Reference Feedback Tuning and Its Application to Shape
Memory Alloy Actuators
Yamaguchi Univ.・Yuji WAKASA, Ryo AZAKAMI,
Kanya TANAKA, and Shota NAKASHIMA
This paper first proposes a kind of virtual reference feedback tuning (VRFT)
method with a performance index which is obtained by modifying that of
the standard VRFT. Then analysis results on optimality conditions for the
modified VRFT method are presented. Next a VRFT method under hysteresis
compensation is proposed by combining the modified VRFT method and the
hysteresis compensation technique proposed in the previous work. The proposed
VRFT method with hysteresis compensation is applied to an experimental
shape memory alloy actuator system, and its effectiveness is verified.
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■ A High-Speed CMOS OP Amplifier with a Dynamic Switching Bias Circuit
Tokyo Metropolitan College of Industrial Tech.・Hiroo WAKAUMI
This paper presents a high-speed CMOS operational amplifier (OP Amp) with a dynamic switching bias circuit, capable of processing video signals of over 2 MHz with decreased dissipated power. The OP Amp was designed to operate at a 10 MHz dynamic switching rate and, through simulations, was shown to have a dissipated power of 66 % of conventional continuous operation. This OP Amp was applied to a switched capacitor (SC) non-inverting amplifier with a gain of 2, and its high-speed 10 MHz dynamic switching operation, capable of processing video signals, was demonstrated. By increasing the switching duty ratio to 70 %, its power dissipation decreased to 56 % of normal operation. Some inaccuracy in the SC amplifier performance resulted mainly from the limited open loop gain of the OP Amp. This circuit configuration should be extremely useful in realizing low-power wide-band signal processing ICs.
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■ Steady-State Mean-Square Performance of the Hyper H-∞ Filter
Hikawa Kohbou・Hidenori MATSUZAKI
The Hyper H1 Filter is an adaptive filtering algorithm, where a forgetting
factor is built into the H1 optimization framework as a function of the
robustness parameter f and determined through the process of -iteration.
This paper examines how the choice of f a ects the resultant steady-state
mean-square error of this algorithm. For moderately large f , a theoretical
expression of the excess mean-square error is derived, which turns out
to coincide with that of RLS. Based on this expression and numerical simulations,
it is shown that there is a trade-o between the robustness and the mean-square
performance at steady-state. For balancing this trade-o , preferable values
of f are also considered.
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■ Tuning of Performance Index in Nonlinear Model Predictive Control by
the Inverse Linear Quadratic Regulator Design Method
Osaka Univ.・Fatima TAHIR and Kyoto Univ.・Toshiyuki OHTSUKA
In this paper, we propose the use of the inverse linear quadratic (ILQ)
regulator design method for the efficient tuning of the performance index
in nonlinear model predictive control (NMPC). First, a linear quadratic
regulator is designed for the linearized model using the ILQ regulator
design approach and then the inverse optimality conditions are applied
to the designed regulator to tune the quadratic weights in the performance
index of NMPC. After that, the NMPC algorithm is applied to the nonlinear
model. This approach provides some tuning parameters that give a trade-off
between the speed of the system’s response and the magnitude of the control
input. Moreover, this tuning methodology provides a free parameter that
can be utilized to adjust the transient response as well as to obtain a
balance between the magnitudes of the control inputs.
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■ Estimation of Transition Times of a Hopping Machine Based on Wavelet
Analysis
Niihama National College of Tech.・Tomoaki KASHIWAO,
The Univ. of Tokushima・Kenji IKEDA, and Takao SHIMOMURA
The transition time of a hopping machine (HM) as a piecewise linear (PWL)
system is estimated by using the wavelet analysis method proposed in previous
papers. The HM is a nonlinear system because its equation of motion has
a nonlinear drag coefficient term owing to air resistance. The effectiveness
of the proposed method for real (nonlinear) systems is verified through
instrumental experiments performed on the HM. First, the effect of nonlinearity
on the estimation of the transition time is examined. The HMhas a discrete
transition caused by the nonlinearity in a real system. In addition, two
types of discrete transitions are detected from the output data: one caused
by the change between discrete free-fall and spring-mass states and the
other caused by inversion of the sign of the nonlinear term owing to a
change in the velocity of the mass. These transition times are estimated
using the proposed method. Finally, the proposed method is compared with
a conventional method based on a clustering technique.
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■ Modeling Moving-Block Railway Systems: A Generalized Batches Petri Net
Approach
Istanbul Technical Univ.・Mustafa Seckin DURMUS
and Osaka Univ.・Shigemasa TAKAI
Instead of conventional signaling systems (fixed-block signaling systems),
moving-block signaling systems are in use to increase transport capacity
by reducing headways on railway lines. A moving-block is considered as
the sum of the length of the train and the safe following distance between
trains. Communication Based Train Control (CBTC) systems and European Rail
Traffic Management System (ERTMS) application level 3 are examples of moving-block
signaling systems. In this study, speed control of two consecutive trains
as moving-block is realized in two levels: the modeling level and the control
level. To cope with both discrete and continuous behavior of the moving-block
signaling system, a Generalized Batches Petri Nets (GBPNs) approach is
used for modeling the system whereas a fuzzy logic control method is proposed
at the control level. Simulation results are shown in order to demonstrate
the accuracy of the proposed approach.
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■ Design of a MIMO PID Controller by Integral-Type Optimal Servomechanism
and Fractional Balanced Reduction
National Defense Academy・Yoshimasa OCHI and Hiroyuki KONDO
The present paper proposes an efficient design method for a multiple-input
multiple-output (MIMO) integral preceded by proportional and derivative
(I-PD) controller, which is a type of PID controller. In the proposed method,
a given plant model is first reduced to a lower-order model using fractional
balanced reduction, and an integral-type or robust optimal servomechanism
is then designed for the reduced plant, which is expressed in a peculiar
state-space form, where the state vector is composed of outputs, their
derivatives, and control inputs. The resultant optimal feedback control
law is immediately transformed into a MIMO I-PD control law. The optimal
servomechanism, which is based on the linear quadratic regulator, provides
the controller with desirable control performance, adequate stability margins,
and easy trade-off between the control performance and stability margins
attained through weight selection of the quadratic cost function. Although
these features are not perfectly guaranteed in the resulting control system
due to the model reduction, if the properties are adequately preserved,
they make the controller design very simple and efficient. Through a design
example the effectiveness of the proposed design method as well as its
limitations are illustrated.
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■ Maneuverability Improvement of Front-Drive-Type Electric Wheelchair STAVi
Kumamoto Univ.・Aydin Tarik ZENGIN, Yutaro MARUNO, Hiroshi OKAJIMA,
Nobutomo MATSUNAGA ,and Sanwa Hi-Tech Co. Ltd.・Norihito NAKAMURA
Electric-powered wheelchairs have been used as a convenient transport device
for the elderly and disabled. The riding capability of a wheelchair is
one of the most important functionality for wheelchair users. Therefore,
we developed a new front-drive-type electric wheelchair “STAVi” to achieve
a comfortable ride for wheelchair users. It is easy for a disabled person
to climb into this wheelchair from a bed because they can do so by piggybacking
from a bed or chair. Moreover, the base plane of STAVi is very low compared
with traditional rear-drive-type wheelchairs because the motors and all
electric devices are placed in the front. Such functions are very useful
not only for the disabled but also for care personnel, because the riding
task is very difficult with rear-drive-type wheelchairs. However, front-drive-type
wheelchairs are hard to run straight and difficult to operate because their
sensitivity to disturbances is higher than that of rear-drive-type wheelchairs.
In particular, the dynamics on a slope are complex to allow for easy driving
because the gravitational force acts as a disturbance. In this paper, we
analyze the dynamics of front-drive-type wheelchairs and propose a wheelchair
control method that compensates for the difference between the dynamics
of the actual wheelchair and that of a desired wheelchair model by using
yaw rate and velocity feedback. It is expected that the user can easily
operate STAVi on a slope easily via appropriate compensation. The effectiveness
of the proposed method is confirmed by driving simulations and experiments.
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