Multirate forward-model disturbance observer for feedback regulation beyond Nyquist frequency

2016 ◽  
Vol 94 ◽  
pp. 181-188 ◽  
Author(s):  
Xu Chen ◽  
Hui Xiao
Keyword(s):  
Disturbance Observer ◽  
Feedback Regulation ◽  
Forward Model ◽  
Nyquist Frequency

scholarly journals Exoskeleton transparency: feed-forward compensation vs. disturbance observer

2018 ◽  
Vol 66 (12) ◽  
pp. 1014-1026 ◽  
Author(s):  
Fabian Just ◽  
Özhan Özen ◽  
Philipp Bösch ◽  
Hanna Bobrovsky ◽  
Verena Klamroth-Marganska ◽  
...  
Keyword(s):  
Disturbance Observer ◽  
Human Robot Interaction ◽  
Forward Model ◽  
Training Effectiveness ◽  
Robot Interaction ◽  
Systematic Analysis ◽  
Feed Forward ◽  
Model Based ◽  
Rehabilitation Robots ◽  
Feed Forward Model

Abstract Undesired forces during human-robot interaction limit training effectiveness with rehabilitation robots. Thus, avoiding such undesired forces by improved mechanics, sensorics, kinematics, and controllers are the way to increase exoskeleton transparency. In this paper, the arm therapy exoskeleton ARMin IV+ was used to compare the differences in transparency offered by using the previous feed-forward model-based controller, with a disturbance observer in a study. Systematic analysis of velocity-dependent effects of controller transparency in single- and multi-joint scenarios performed in this study highlight the advantage of using disturbance observers for obtaining consistent transparency behavior at different velocities in single-joint and multi-joint movements. As the main result, the concept of the disturbance observer sets a new benchmark for ARMin transparency.

Composite disturbance rejection control for hydraulic classification

2017 ◽  
Vol 40 (6) ◽  
pp. 1863-1872
Author(s):  
Dan Niu ◽  
Xisong Chen ◽  
Xiaojun Wang ◽  
Xingpeng Zhou
Keyword(s):  
Disturbance Rejection ◽  
Disturbance Observer ◽  
Control Strategies ◽  
Water Pressure ◽  
Feedback Regulation ◽  
Disturbance Attenuation ◽  
Proportional Integral Derivative ◽  
Large Coupling ◽  
Proportional Integral ◽  
Hydraulic Classification

In the hydraulic classification, precise control for the flow rate of overflow water is vital to guarantee the uniformity and stability of the powder product size. Usually the multiple overflow tanks are supplied by a shared overflow pipeline, which gives rise to large coupling effects in the controls for the flow rates of multiple overflow tanks simultaneously. To solve this issue, it is necessary to keep the water pressure in the shared overflow pipeline accurately constant, which is not easy due to strong disturbances. Several control strategies have been proposed to control the constant water pressure. However, most of them (such as proportional-integral-derivative and model predictive control) reject disturbances just through feedback regulation and do not reject disturbances directly. This may cause poor control performances in the presence of strong disturbances. For improving the disturbance rejection performance, a control scheme based on proportional-integral-derivatives and disturbance observer is put forward in this paper. The scheme employs disturbance observer as feedforward compensation and a proportional-integral-derivative controller as feedback regulation. The disturbance rejection properties under both model mismatches and external disturbances are discussed. The test results illustrate that the proposed method can remarkably improve the disturbance attenuation property compared with the conventional proportional-integral-derivative method in the hydraulic classification process.

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