A Spintronic Memristor Based PID Controller
Zhekang Dong
1
, Shukai Duan
1
, Xiaofang Hu
2
, Lidan Wang
1
, Fanyi Meng
1
1
School of Electronics and Information Engineering, Southwest University, Chongqing, 400715, China
2
Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong
Abstract—The spintronic memristor was proposed based
upon the magnetic theory shortly after the discovery of the
Hewlett-Packard (HP) TiO2 memristor. Different from
that of the TiO2 memristor, the resistance of a spintronic
memristor not only depends on the historic profile of
voltage and current through the device, but also is closely
related to the current density. In this work, we review the
mathematical model of the spintronic memristive device
based on magnetic theory and analyze its memristive
effects in detail. Then we provide a corresponding
Simulink model. Furthermore, by incorporating the
spintronic memristor into a conventional PID control
circuit, the paper investigates an implementation
approach for a novel compact memristive PID controller.
The findings of the study may contribute to further
development of the modern control technology, especially
in hardware realization of micro-control system. Finally,
reported simulations demonstrate the effectiveness of the
proposed scheme.
Keywords- spintronic memristor; PID control circuit;
micro-control system.
I. INTRODUCTION
In 1971, Professor Chua defined the relationship
between flux linkage and charge through a device based
on the symmetry arguments of circuit theory and thus
predicted the existence of the fourth fundamental circuit
element, called memristor [1]. In 2008, the first
realization of the memristor was illustrated in HP
Laboratory, which garnered increasingly extensive
interests from numerous researchers [2]. Soon later,
three possible structures of spintronic memristors were
proposed by Chen et al. [3, 4] in which the memristive
effect was obtained by the spin-torque-induced
magnetization switching or the magnetic-domain-wall
motion. Unlike the solid-state TiO
2
thin film device
presented in [2], the performance of the spintronic
memristor is more flexibly. Meanwhile, the magnetic
device can be integrated into CMOS devices with
exquisite technology and low cost [4]. As a promising
nano-electronic, the spintronic device captures a
number of unique properties that have found attractive
potentials in various fields, such as nonvolatile memory,
nonlinear circuit and system, neuromorphic system,
signal processing, control, and learning system etc
[5-7].
In the past several decades, the well-known
proportional-integral-derivative (short for PID)
controllers have been playing a significant role in the
modern industry control area [8]. There is a growing
popularity of PID controllers mainly on account of their
simplicity and superior dynamic performance.
Generally, the PID controllers, almost the linear fixed
gain PID controllers, are adequate for controlling a
physical process. The demands for high-performance
control with environmental parameters or operating
conditions varying are far beyond the capabilities of
common PID controllers [9, 10]. In this regards, many
effective and feasible approaches have been proposed,
which contain the self-tuning method, fuzzy logic,
general predictive control and neural networks strategy,
and so forth [11, 12]. In this paper, we introduce the
physical model of spintronic memristor, describe its
mathematical model and Simulink model accordingly,
and analyze the memristive characteristics according to
numerical simulation. Moreover, a spintronic memristor
takes the place of the linear resistor in the PID
controller circuit, in so doing, the memristance could be
adjusted flexibly with the transient current density
varying, as a result, the spintronic memristive device
realizes the tunable gain.
The rest of the paper is organized as below. In
Section II, the mathematical model and Simulink model
of the spintronic memristor based on
magnetic-domain-wall motion mechanism are presented.
The nonlinear adaptive PID controller based on
spintronic memristor (abbreviated to SM-PID controller)
is proposed in Section III. Next, the Section IV exhibits
the simulation results and corresponding analysis of
SM-PID controller. At last, the conclusions are given in
Section V.
II. T
HE SPINTRONIC MEMRISTOR MODEL
A. The mathematical model of spintronic memristor
Among various existing spintronic memristor
devices proposed in [4], the spintronic memristive
device based upon magnetic-domain-wall motion is a
promising option for its simple structure. Fig. 1 shows
the physical structure of the spintronic memristor and
its corresponding simplified equivalent circuit.
(a) (b)
Figure 1. A spintronic memristor based on magnetic-domain-wall
motion. (a) 3 dimension structure. (b) equivalent simplified circuit.
As shown in Fig. 1(b), the total resistance of the
spintronic memristor,
)(xM
, is expressed as two
resistors connected in series:
)()( xDrxrxM
LH
−⋅+⋅
(1)
2015 AASRI International Conference on Industrial Electronics and Applications (IEA 2015)
© 2015. The authors - Published by Atlantis Press