Feed-forward pressure control of balancing cylinder for hybrid electric-pneumatic ultra-precision vertical positioning device

Current research in offshore wind turbines is proposing a novel concept of using seawater-based hydraulics for large-scale power transmission and centralized electrical generation. The objective of this paper is to investigate the control of such an open-loop circuit, where a fixed line pressure is desirable for the sake of efficiency and stability. Pressure control of the open-loop hydraulic circuit presents an interesting control challenge due to the highly fluctuating flow rate along with the nonlinear behavior of the variable-area orifice used by the pressure controller. The present analysis is limited to a single turbine and an open-loop hydraulic line with a variable-area orifice at the end. A controller is proposed which uses a combination of feed-forward compensation for the nonlinear part along with a feedback loop for correcting any errors resulting from inaccuracies in the compensator model. A numerical model of the system under investigation is developed in order to observe the behavior of the controller and the advantages of including the feedback loop. An in-depth analysis is undertaken, including a sensitivity study of the compensator accuracy and a parametric analysis of the actuator response time. Finally, a Monte Carlo analysis was carried out in order to rank the proposed controller in comparison to a simple feed-forward controller and a theoretical optimally tuned controller. Results indicate an advantageous performance of the proposed method of feedback with feed-forward compensation, particularly its ability to maintain a stable line pressure in the face of high parameter uncertainty over a wide range of operating conditions, even with a relatively slow actuation system.

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Feed-forward model development of a hybrid electric truck for power management studies

2011 2nd International Conference on Intelligent Control and Information Processing ◽

10.1109/icicip.2011.6008305 ◽

2011 ◽

Cited By ~ 1

Author(s):

Shi-Jie Hou ◽

Yuan Zou ◽

Rui Chen

Keyword(s):

Power Management ◽

Model Development ◽

Forward Model ◽

Feed Forward ◽

Hybrid Electric ◽

Feed Forward Model

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Sub-Nanometer Positioning Combining New Linear Motor with Linear Motion Ball Guide Ways

International Journal of Automation Technology ◽

10.20965/ijat.2009.p0241 ◽

2009 ◽

Vol 3 (3) ◽

pp. 241-248

Author(s):

Jiro Otsuka ◽

◽

Toshiharu Tanaka ◽

Ikuro Masuda ◽

◽

...

Keyword(s):

Permanent Magnets ◽

Linear Motor ◽

General Motors ◽

Step Response ◽

Precision Positioning ◽

Positioning Device ◽

Ultra Precision ◽

New Type ◽

Force Ripple ◽

Flux Leakage

A new type of linear motor described in this paper has some advantages compared with the usual types of motors. The attractive magnetic force between the stator (permanent magnets) and mover (armature) is diminished almost to zero. The efficiency is better because the magnetic flux leakage is very small, the size of motor is smaller and detent (force ripple) is smaller than the general motors. Therefore, we think that this motor is greatly suitable for ultra-precision positioning as an actuator. An ultra-precision positioning device using this motor and liner motion ball guide ways is newly developed. Moreover, the positioning performance is evaluated by a positioning resolution, deviational and dispersion errors. As the results of repeated step response tests, the positioning resolution is 0.3 nm, the deviational error is -0.001nm and the dispersion error (3σ) is 0.29 nm. Consequently, the positioning device achieves sub-nanometer positioning. In addition, very large rigidity can be achieved.

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