Citation: Zheng, J.; Jiang, X.; Ren, G.;
Xie, X.; Fan, D. High-Precision
Anti-Interference Control of Direct
Drive Components. Actuators 2022,
11, 95. https://doi.org/10.3390/
act11030095
Academic Editor: Dario Richiedei
Received: 24 January 2022
Accepted: 16 March 2022
Published: 19 March 2022
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Article
High-Precision Anti-Interference Control of Direct Drive Components
Jieji Zheng , Xianliang Jiang, Guangan Ren, Xin Xie * and Dapeng Fan
College of Intelligence Science and Technology, National University of Defense Technology, Changsha 410073, China;
zhengjieji@nudt.edu.cn (J.Z.); jiangxianliang@nudt.edu.cn (X.J.); 369220424@163.com (G.R.); fdp@nudt.edu.cn (D.F.)
* Correspondence: xiexin12@nudt.edu.cn; Tel.: +86-13787043604
Abstract:
This study presents a compound control algorithm that enhances the servo accuracy and
disturbance suppression capability of direct drive components (DDCs). The servo performance of
DDCs is easily affected by external disturbance and the deterioration of assembly characteristics
due to a lack of deceleration device. The purpose of this study is to compensate for the impact of
external and internal disturbances on the system. First, a linear state space model of the system
is established. Second, we analyzed the main factors restricting the performance of DDCs which
includes sensor noise, friction and external disturbance. Then, a fractional-order proportional
integral (FOPI) controller was used to eliminate the steady-state error caused by the time-invariable
disturbance which can also improve the system’s anti-interference capability. A state-augmented
Kalman filter (SAKF) was proposed to suppress the quantization noise and compensate for the
time-varying disturbances simultaneously. The effectiveness of the proposed compound algorithm
was demonstrated by comparative experiments, demonstrating a maximum 89.34% improvement.
The experimental results show that, compared with the traditional PI controller, the FOPISAKF
controller can not only improve the tracking accuracy of the system, but also enhance the disturbance
suppression ability.
Keywords:
direct drive components; disturbance suppression; fractional-order control; state-
augmented Kalman filter
1. Introduction
Direct drive components (DDCs) are widely used in light load and high precision
equipment such as photoelectric pods, seekers, small robots, etc., because of its better
speed versus torque characteristics, high efficiency, high dynamic response, higher speed
operating range and low maintenance cost [
1
,
2
]. Nevertheless, DDCs are susceptible to
external disturbance, internal friction, and sensor noise, making it difficult to meet the
equipment’s stable accuracy index which reaches the micro-radian level under interference.
For the compensation of friction and external disturbance, many scholars have con-
ducted a lot of research. The traditional PI control is the most widely used in the industrial
field due to its simple structure and good robustness. However, as the system accuracy
increases many nonlinear factors and strong interference during practical application occur,
and traditional PI controllers have been unable to meet the requirements. On this basis,
many scholars have studied the integration of various advanced intelligent control algo-
rithms into PI control, e.g., genetic algorithm, expert system algorithm, neural network
algorithm, fuzzy logic control algorithm. Although intelligent algorithms have advantages
such as strong optimization capabilities, they present problems such as a high amount of
calculation, long convergence time, and difficulty in implementation.
During the past decades, researchers have paid attention to fractional-order con-
trollers [
3
–
5
]. Compared with the traditional PI controllers, the fractional-order propor-
tional integral (FOPI) controller adds one additional design parameter, thereby providing
additional degrees of freedom for the control structure. The order of integration in an
FOPI controller is an adjustable parameter, which accounts for the shortcomings of PI
Actuators 2022, 11, 95. https://doi.org/10.3390/act11030095 https://www.mdpi.com/journal/actuators
