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Design of Q-filters for disturbance observers via BMI approach |
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Jung-Su Kim(Seoul National University of Science and Technology, Republic of Korea), Juhoon Back(Kwangwoon University, Republic of Korea), Gyunghoon Park(Seoul National University, Republic of Korea) |
| The type-k disturbance observer, also known as high order
disturbance observer, is a robust output feedback controller which can reject polynomial-in-time disturbances exactly and at the same time unmodeled disturbances approximately. To ensure the robust stability of the closed-loop system, the key component of the controller called Q-filter should be designed appropriately. In this paper, we formulate the design problem in terms of a set of bilinear matrix inequalities so that the coefficients of Q-filters are chosen simultaneously. |
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Reinterpretation of Disturbance Observer as an Add-on Controller |
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Hyungtae Seo, Kyung-Soo Kim, Soohyun Kim(KAIST, Republic of Korea) |
| In the paper, the reinterpretation of a disturbance observer formulated in the transfer function domain has been considered. By manipulating the general configuration for a disturbance observer in [9], it was shown that the disturbance observer can be an add-on controller only to suppress the disturbances. Also, it has been represented that the robust stability margin reduction phenomenon is inevitable since the disturbance observer gives an additonal feedback. |
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High Order Extended Observer Based Output Feedback Control for Unknown Nonlinear Systems |
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Wonhee Kim(Dong-A University, Republic of Korea), Chung Choo Chung(Hanyang University, Republic of Korea) |
| We propose a robust output feedback control to guarantee the semi-global uniform ultimate boundedness of the output tracking error using only output feedback for unknown nonlinear systems with external disturbance. The high order extended observer (HOEOB) is developed to estimate the lumped extended state variables and full state. The backstepping controller is designed to guarantee the semi-global uniform ultimate boundedness of the output tracking error occurred by the disturbance estimation error. |
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Reduced Order Type-k Disturbance Observer based on Generalized Q-filter Design Scheme |
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Youngjun Joo, Gyunghoon Park(Seoul National University, Republic of Korea) |
| As a robust control scheme, a disturbance observer (DOB) has been widely employed in industrial applications to reject the effect of disturbances and plant uncertainties. The disturbance rejection performance of DOB is mainly determined by the design of two Q-filters, which are the core components of DOB structure. Despite the different roles of each Q-filter, they have been typically designed to have the same structure. In this paper, we generalize Q-filters’ structures based on the observation about each Q-filter’s objective and derive a robust stability condition for the proposed DOB ... |
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Frequency-Shaped Impedance Control for Safe Human-Robot Interaction in Reference Tracking Application |
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Kyoungchul Kong, Sehoon Oh, Hanseung Woo(Sogang University, Republic of Korea) |
| In the control of industrial robots, both safety and reference tracking performance are required. For safe human-robot interaction, robots should exhibit low mechanical (or controlled) impedance so that they react to the interaction forces in a compliant manner. On the other hand, the reference tracking requires for the robots to reject exogenous disturbances, which results in an increased impedance. In order to achieve these two conflicting objectives, a frequency-shaped impedance control (FSIC) method is proposed in this paper. The proposed method utilizes the two different functionalities o |
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Application of a Disturbance Observer for Wireless Network Control Systems |
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Yeongtae Jung, Joonbum Bae(UNIST, Republic of Korea) |
| In this paper, a control algorithm based on a disturbance observer (DOB) is proposed for wireless network control systems. In order to deal with possible packet losses over the wireless network, a modified linear quadratic Gaussian (MLQG) controller, which includes modeling of the packet loss as a Bernouilli variable, is applied. Since the packet loss of the control command can be considered as an external disturbance, the disturbance observer is added to deal with such virtual disturbance by the packet loss. Performance of the proposed control algorithm is verified by simulations. |
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