Browsing by Author "Chiu, Chun-Wei"

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Design and development of a new wireless fall detection module for homecare
(2015-12-01)
Tran, Trong-Hieu
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Chao, Paul C. -P.
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Hsu, Li-Chi
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Chiu, Chun-Wei
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Kao, Yung-Hua
This study aims to develop a decision procedure and associated small-sized, wearable wireless hardware module for successful fall detections of subjects for homecare. The detection procedure is developed based on a newly-proposed two-level criteria framework. The first-level criterion is forged based on two real-time signal vector magnitudes (SVMs) to determine whether falls can occur. The baseline SVM is further modified to accommodate varied gestures of the subjects prior to fall. It is designed that the modified SVM, named SVMB, with level exceeding 2.5 G indicates that the subject has fallen. The criterion at the second level is developed to prevent false detections, which considers especially the cases that some particular body movements other than falling would induce large SVMB values, such as running. Results based on a number of experimental trials validate the effectiveness of the proposed two-level criterion to detect falls while prevent false detections. A total of 100 experimental falls were tested, an average accuracy rate of 97 % in fall detection is achieved.
Design and experimental validation of a sliding-mode stabilizer for a ship-carried satellite antenna
(2012-09-01)
Chao, Paul C. -P.
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Chiu, Chun-Wei
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電機工程學系
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Department of Electrical and Computer Engineering
This study designs a sliding-mode controller to stabilize the angular orientation of a ship-carried satellite antenna. The design process starts with calculating the pointing angle of the considered satellite antenna arm as opposed to given ship vibrations due to certain sea waves. This calculation is carried out by the method of Denavit-Hartenberg (D-H) transformation, which is followed by establishing a dynamic model of the satellite antenna system and platform using conventional kinematics modeling techniques. The resulted kinematics relationships are next used as the basis for designing a sliding-mode controller to maintain the antenna in a specified orientation as the ship pitches and rolls under the combined effects of wind and the sea's waves. The effectiveness of the designed controller is investigated both numerically and experimentally. Both sets of results confirm the feasibility of the proposed control scheme. It is shown that the antenna converges to the required azimuth and elevation angles within 2 s and maintains the specified orientation as the ship continues to pitch and roll.
DYNAMIC MODELLING OF A TRAVELING-WAVE TYPE ULTRASONIC MOTOR WITH BEAM TEETH VIA FINITE ELEMENTS
(2012)
Chao, Paul. C. -P.
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Lu, Po-Hung
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Chiu, Chun-Wei
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電機工程學系
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Department of Electrical and Computer Engineering
The study is dedicated to establish the dynamic model of a traveling-wave type ultrasonic motor (USM) with beam teeth via finite elements. The modeling is accomplished mainly by finite elements, the task of which consists of three parts for stator, rotor and contact. It is first assumed that the complex dynamics of the stator emulates a single one-dimensional Euler-beam vibrating harmonically in the transverse direction. On the top surfaces of the stator are vertical beam teeth that is in contact with rotor, which is simply a thin disk fixed to spindle. The friction between the teeth tips and stator rotates the spindle moves the stator and finally rotates the disk to the desired speed. A contact model between beam tips and rotor disk with proper friction assumed is next built in conjunction with the established finite element model of the rotor disk. With a complete model in hands, the dynamics of the USM is predicted along with associated exerted torques. Experiments are finally conducted for collecting sets of data of rotation speeds versus torques that validate the effectiveness of the built models for the motor, stator and contact force.