• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.22-25
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• 2005

In the paper, algorithms for disturbance observers are newly presented in the time-domain. Attention is paid to observing a ramp disturbance by introducing an integral term to the output equation of a constant disturbance observer. In order to reduce the sensitivity to the measurement noise, the disturbance observer is combined with the state observer. It will be shown that the estimation dynamics can be arbitrarily chosen by assigning the eigenvalues of a characteristic equation. Also, we provide the analysis of observer behaviors subject to non-ramp-style disturbances. Finally, we propose the generalized disturbance observer that accurately estimates disturbances of higher order in time series expansion.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.2
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• pp.61-67
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• 2018

This paper presents a method to apply disturbance observer to PID controller for robustness enhancement of UAVs. The system uncertainties and disturbances bring adverse effects on performance and stability of UAVs. In this paper, we estimate the acceleration disturbances using nonlinear disturbance observer, then compensate disturbances with composite controller. By employing nonlinear disturbance observer and composite controller, we have better performance and robustness than conventional PID controller. The asymptotical stability of nonlinear disturbance observer is presented through theoretical analysis. The estimation performance of nonlinear disturbance observer is evaluated by numerical simulation. And performance of disturbance observer based PID controller is evaluated by comparing the performance with conventional PID controller.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.4
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• pp.652-658
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• 2016

In practical control systems differences between nominal and real systems arise from internal uncertainties and/or external disturbances. This paper presents a model-based low-order disturbance observer for a sinusoidal disturbance with unknown constant offset. By using the disturbance model of a biased harmonic signal, the proposed method can successfully estimate the biased sinusoidal disturbance with unknown amplitude and phase but known frequency. At the first stage of the observer design, a model-based disturbance observer is designed when all the system states are measurable. Next, a sufficient condition is presented for the proposed observer to estimate the sinusoidal disturbance with a minimal-order additional dynamics using only output measurement. Comparative computer simulations are performed to test the performance of the proposed method. The simulation results show the enhanced performance of the proposed disturbance observer.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.4
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• pp.203-211
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• 1999

A control approach for the robust position control of induction motors based on the binary disturbance observer is described. The conventional binary disturbance observer is used to remove the chattering problem of a sliding mode disturbance observer. However, the steady state error may exist in the conventional binary disturbance observer because it estimates external disturbance with a constant boundary layer. In order to overcome this problem, new binary disturbance observer with an integral augmented switching hyperplane is proposed. The robustness is achieved, and the continuous control is realized by employing the proposed observer without the chattering problem and the steady state error. The effectiveness of the proposed observer is confirmed by the comparative experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.199-202
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• 1997

In this paper, a novel disturbance observer is proposed in order to regulate the disturbance in motor systems. The proposed observer does not require the implementation of ideal derivative of the state since the inverse of the nominal model is not used in the design of the observer. The transfer gain from a disturbance to the output of the disturbance observer is one. So, there is no time-delay in the response due to the dynamics of the observer.

• The Journal of Korea Robotics Society
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• v.18 no.1
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• pp.82-87
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• 2023

This paper proposes a disturbance observer-based control for 6-DOF remotely operated underwater vehicles with model uncertainties. The sum of external disturbance and the forces generated from model parameters except for the inertial matrix of the hydrodynamic model is defined as a lumped disturbance in this paper. Then, the lumped disturbance caused by model uncertainties and the external forces is estimated using the disturbance observer. Fortunately, the disturbance observer is constructed as a linear form because all the elements of the inertial matrix of the hydrodynamic model are constants. To verify the proposed control scheme, we show that the actual lumped disturbance is similar to the estimated lumped disturbance obtained by the disturbance observer. Finally, the position tracking performance in the disturbance environment is confirmed through the comparative study with a traditional inverse dynamics PD controller.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.249-254
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• 1998

A control approach for the robust position control of induction motors based on the improved binary disturbance observer is described. The conventional binary disturbance observer is used to remove the chattering problem of a sliding mode disturbance observer. However, the steady state error may be existed in the conventional binary disturbance observer because it estimates external disturbance with a constant boundary layer. In order to overcome this problem, a new binary disturbance observer with an integral augmented switching hyperplane is improved. The robustness is achieved, and the continuous control is realised by employing the improved observer without the chattering problem and the steady state error. The effectiveness of the improved observer is confirmed by the comparative experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2278-2283
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• 2010

This paper deals with the pendubot control using disturbance observer. Experimental results for the motion of pendubot with balancing control show that the limit cycle can be attributed to the disturbance. Therefore, we propose the disturbance compensation method using by disturbance observer to compensate for the disturbance. Through the experimental results, the effectiveness of the proposed method is verified.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.2
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• pp.16-24
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• 2010

This paper is proposed a novel fuzzy disturbance observer based on backstepping method for nonlinear systems with unknown disturbance. Using fuzzy logic systems, a fuzzy disturbance observer with the disturbance observation input is introduced for unknown disturbance. To guarantee that the proposed disturbance observer estimates the unknown disturbance, the disturbance observation error dynamic system is employed. Under the framework of the backstepping design, the fuzzy disturbance observer is constructed recursively and an adaptive laws and the disturbance observation input are derived. Numerical examples are given to demonstrate the validity of our proposed disturbance observer for nonlinear systems.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.7
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• pp.615-620
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• 2015

DOB (Disturbance Observer) is an useful control method for estimating the disturbance applied to dynamic systems. Disturbance observer can be used to implement a robust control system to generate a control input for rejecting the disturbance, and it can be also used to estimate the disturbance to obtain information. The system that uses disturbance estimation is investigated for high performance control such as automatic door systems, walking robot and electric power steering system in vehicles. In this paper, a novel disturbance observer which is called disturbance and current observer for estimating load torque in the motor system is proposed. The difference between the DOB for disturbance rejection and DCOB is mathematically verified. Current and angular velocity are required for estimating the load torque of the motor in DOB. However, the DCOB can estimate load torque and current without current sensor. DCOB is designed based on modeling of the motor system. Appropriate Q-filter is selected and the applicability of DCOB is verified by simulation. The estimated disturbance and current of the electric motor can be verified without current sensor, as experiments of the actual motor system.