14 research outputs found
AMC'24 "Analysis and Synthesis of the Disturbance Observer-based Robust Force Control Systems in State Space"
This paper extends the result of my previous papers on the analysis and
synthesis of disturbance observer based robust control systems in state space
A Stability Analysis for the Acceleration-based Robust Position Control of Robot Manipulators via Disturbance Observer
This paper proposes a new nonlinear stability analysis for the
acceleration-based robust position control of robot manipulators by using
Disturbance Observer (DOb). It is shown that if the nominal inertia matrix is
properly tuned in the design of DOb, then the position error asymptotically
goes to zero in regulation control and is uniformly ultimately bounded in
trajectory tracking control. As the bandwidth of DOb and the nominal inertia
matrix are increased, the bound of error shrinks, i.e., the robust stability
and performance of the position control system are improved. However, neither
the bandwidth of DOb nor the nominal inertia matrix can be freely increased due
to practical design constraints, e.g., the robust position controller becomes
more noise sensitive when they are increased. The proposed stability analysis
provides insights regarding the dynamic behavior of DOb-based robust motion
control systems. It is theoretically and experimentally proved that
non-diagonal elements of the nominal inertia matrix are useful to improve the
stability and adjust the trade-off between the robustness and noise
sensitivity. The validity of the proposal is verified by simulation and
experimental results.Comment: 9 pages, 9 figures, Journa
Disturbance Observer-based Robust Control and Its Applications: 35th Anniversary Overview
Disturbance Observer has been one of the most widely used robust control
tools since it was proposed in 1983. This paper introduces the origins of
Disturbance Observer and presents a survey of the major results on Disturbance
Observer-based robust control in the last thirty-five years. Furthermore, it
explains the analysis and synthesis techniques of Disturbance Observer-based
robust control for linear and nonlinear systems by using a unified framework.
In the last section, this paper presents concluding remarks on Disturbance
Observer-based robust control and its engineering applications.Comment: 12 pages, 4 figure
An Adaptive Periodic-Disturbance Observer for Periodic-Disturbance Suppression
Repetitive operations are widely conducted by automatic machines in industry.
Periodic disturbances induced by the repetitive operations must be compensated
to achieve precise functioning. In this paper, a periodic-disturbance observer
(PDOB) based on the disturbance observer (DOB) structure is proposed. The PDOB
compensates a periodic disturbance including the fundamental wave and harmonics
by using a time delay element. Furthermore, an adaptive PDOB is proposed for
the compensation of frequency-varying periodic disturbances. An adaptive notch
filter (ANF) is used in the adaptive PDOB to estimate the fundamental frequency
of the periodic disturbance. Simulations compare the proposed methods with a
repetitive controller (RC) and the DOB. Practical performances are validated in
experiments using a multi-axis manipulator. The proposal provides a new
framework based on the DOB structure to design controllers using a time delay
element.Comment: 11 pages, 22 figures, journa
Disturbance/uncertainty estimation and attenuation techniques in PMSM drives–a survey
This paper gives a comprehensive overview on
disturbance/uncertainty estimation and attenuation (DUEA) techniques in permanent magnet synchronous motor (PMSM) drives.
Various disturbances and uncertainties in PMSM and also other alternating current (AC) motor drives are first reviewed which shows they have different behaviors and appear in different control loops of the system. The existing DUEA and other relevant control methods in handling disturbances and uncertainties widely used in PMSM drives, and their latest developments are then discussed and summarized. It also provides in-depth analysis of the relationship between these advanced control methods in the context of PMSM systems. When dealing with uncertainties,it is shown that DUEA has a different but complementary mechanism to widely used robust control and adaptive control. The similarities and differences in disturbance attenuation of DUEA and other promising methods such as internal model
control and output regulation theory have been analyzed in detail. The wide applications of these methods in different AC
motor drives (in particular in PMSM drives) are categorized and summarized. Finally the paper ends with the discussion on future
directions in this area
Robust hovering and trajectory tracking control of a quadrotor helicopter using acceleration feedback and a novel disturbance observer
Hovering and trajectory tracking control of rotary-wing aircrafts in the presence of uncertainties and external disturbances is a very challenging task. This thesis focuses on the development of the robust hovering and trajectory tracking control algorithms for a quadrotor helicopter subject to both periodic and aperiodic disturbances along with noise and parametric uncertainties. A hierarchical control structure is employed where high-level position controllers produce reference attitude angles for the low-level attitude controllers. Reference attitude angles are usually determined analytically from the position command signals that control the positional dynamics. However, such analytical formulas may produce large and non-smooth reference angles which must be saturated and low-pass filtered. In this thesis, desired attitude angles are determined numerically using constrained nonlinear optimization where certain magnitude and rate constraints are imposed. Furthermore, an acceleration based disturbance observer (AbDOB) is designed to estimate and suppress disturbances acting on the positional dynamics of the quadrotor. For the attitude control, a nested position, velocity, and inner acceleration feedback control structure consisting of PID and PI type controllers are developed to provide high sti ness against external disturbances. Reliable angular acceleration is estimated through an extended Kalman filter (EKF) cascaded with a classical Kalman lter (KF). This thesis also proposes a novel disturbance observer which consists of a bank of band-pass filters connected parallel to the low-pass filter of a classical disturbance observer. Band-pass filters are centered at integer multiples of the fundamental frequency of the periodic disturbance. Number and bandwidth of the band-pass filters are two crucial parameters to be tuned in the implementation of the new structure. Proposed disturbance observer is integrated with a sliding mode controller to tackle the robust hovering and trajectory tracking control problem. The sensitivity of the proposed disturbance observer based control system to the number and bandwidth of the band-pass filters are thoroughly investigated via several simulations. Simulations are carried out on a high delity model where sensor biases and measurement noise are also considered. Results show that the proposed controllers are very effective in providing robust hovering and trajectory tracking performance when the quadrotor helicopter is subject to the wind gusts generated by the Dryden wind model along with plant uncertainties and measurement noise. A comparison with the classical disturbance observer-based control is also provided where better tracking performance with improved robustness is achieved in the presence of noise and external disturbance