Discrete-Time Analysis and Synthesis of Disturbance Observer-Based Robust Force Control Systems

This paper analyses Disturbance Observer- (DOb-) based robust force control systems in the discrete-time domain. The robust force controller is implemented using velocity and acceleration measurements. A DOb is employed in an inner-loop to achieve robustness, and another DOb, viz. Reaction Force Obs...

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Autores principales:	Emre Sariyildiz, Satoshi Hangai, Tarik Uzunovic, Takahiro Nozaki
Formato:	article
Lenguaje:	EN
Publicado:	IEEE 2021
Materias:	Discrete-time control disturbance observer force control robustness reaction force observer robust stability and performance Electrical engineering. Electronics. Nuclear engineering TK1-9971
Acceso en línea:	https://doaj.org/article/c68305895b0547978c792277b1bd3f07
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spelling	oai:doaj.org-article:c68305895b0547978c792277b1bd3f072021-11-18T00:10:52ZDiscrete-Time Analysis and Synthesis of Disturbance Observer-Based Robust Force Control Systems2169-353610.1109/ACCESS.2021.3123365https://doaj.org/article/c68305895b0547978c792277b1bd3f072021-01-01T00:00:00Zhttps://ieeexplore.ieee.org/document/9590570/https://doaj.org/toc/2169-3536This paper analyses Disturbance Observer- (DOb-) based robust force control systems in the discrete-time domain. The robust force controller is implemented using velocity and acceleration measurements. A DOb is employed in an inner-loop to achieve robustness, and another DOb, viz. Reaction Force Observer (RFOb), is employed in an outer-loop to estimate interaction forces and improve the performance of force control. First, the inner-loop is analysed. It is shown that the DOb works as a phase-lead/lag compensator tuned by the nominal design parameters in the inner-loop. The phase margin of the inner-loop controller and the bandwidth of the velocity-based (i.e., conventional) DOb are constrained not only by noise-sensitivity but also by the waterbed effect. This explains why we observe unstable responses as the bandwidth of the conventional DOb increases in practice. To eliminate the design constraint due to the waterbed effect, this paper proposes an acceleration-based DOb. Then, the robust force controller is analysed. It is shown that the design parameters of the RFOb have a notable effect on the stability of the robust force control system. For example, the robust force controller has a non-minimum phase zero (zeros) when the RFOb is not properly tuned. This may cause severe stability and performance problems when conducting force control applications. By using the stability and robustness analyses, this paper proposes new design tools which enable one to synthesize a high-performance robust force control system. Simulations and experiments are presented to validate the proposed analysis and synthesis methods.Emre SariyildizSatoshi HangaiTarik UzunovicTakahiro NozakiIEEEarticleDiscrete-time controldisturbance observerforce controlrobustnessreaction force observerrobust stability and performanceElectrical engineering. Electronics. Nuclear engineeringTK1-9971ENIEEE Access, Vol 9, Pp 148911-148924 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Discrete-time control disturbance observer force control robustness reaction force observer robust stability and performance Electrical engineering. Electronics. Nuclear engineering TK1-9971
spellingShingle	Discrete-time control disturbance observer force control robustness reaction force observer robust stability and performance Electrical engineering. Electronics. Nuclear engineering TK1-9971 Emre Sariyildiz Satoshi Hangai Tarik Uzunovic Takahiro Nozaki Discrete-Time Analysis and Synthesis of Disturbance Observer-Based Robust Force Control Systems
description	This paper analyses Disturbance Observer- (DOb-) based robust force control systems in the discrete-time domain. The robust force controller is implemented using velocity and acceleration measurements. A DOb is employed in an inner-loop to achieve robustness, and another DOb, viz. Reaction Force Observer (RFOb), is employed in an outer-loop to estimate interaction forces and improve the performance of force control. First, the inner-loop is analysed. It is shown that the DOb works as a phase-lead/lag compensator tuned by the nominal design parameters in the inner-loop. The phase margin of the inner-loop controller and the bandwidth of the velocity-based (i.e., conventional) DOb are constrained not only by noise-sensitivity but also by the waterbed effect. This explains why we observe unstable responses as the bandwidth of the conventional DOb increases in practice. To eliminate the design constraint due to the waterbed effect, this paper proposes an acceleration-based DOb. Then, the robust force controller is analysed. It is shown that the design parameters of the RFOb have a notable effect on the stability of the robust force control system. For example, the robust force controller has a non-minimum phase zero (zeros) when the RFOb is not properly tuned. This may cause severe stability and performance problems when conducting force control applications. By using the stability and robustness analyses, this paper proposes new design tools which enable one to synthesize a high-performance robust force control system. Simulations and experiments are presented to validate the proposed analysis and synthesis methods.
format	article
author	Emre Sariyildiz Satoshi Hangai Tarik Uzunovic Takahiro Nozaki
author_facet	Emre Sariyildiz Satoshi Hangai Tarik Uzunovic Takahiro Nozaki
author_sort	Emre Sariyildiz
title	Discrete-Time Analysis and Synthesis of Disturbance Observer-Based Robust Force Control Systems
title_short	Discrete-Time Analysis and Synthesis of Disturbance Observer-Based Robust Force Control Systems
title_full	Discrete-Time Analysis and Synthesis of Disturbance Observer-Based Robust Force Control Systems
title_fullStr	Discrete-Time Analysis and Synthesis of Disturbance Observer-Based Robust Force Control Systems
title_full_unstemmed	Discrete-Time Analysis and Synthesis of Disturbance Observer-Based Robust Force Control Systems
title_sort	discrete-time analysis and synthesis of disturbance observer-based robust force control systems
publisher	IEEE
publishDate	2021
url	https://doaj.org/article/c68305895b0547978c792277b1bd3f07
work_keys_str_mv	AT emresariyildiz discretetimeanalysisandsynthesisofdisturbanceobserverbasedrobustforcecontrolsystems AT satoshihangai discretetimeanalysisandsynthesisofdisturbanceobserverbasedrobustforcecontrolsystems AT tarikuzunovic discretetimeanalysisandsynthesisofdisturbanceobserverbasedrobustforcecontrolsystems AT takahironozaki discretetimeanalysisandsynthesisofdisturbanceobserverbasedrobustforcecontrolsystems
_version_	1718425190649561088

Discrete-Time Analysis and Synthesis of Disturbance Observer-Based Robust Force Control Systems

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