Browsing by Author "Liu, Chun-Wei"

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Applications of the Network Controlled System to the Omni-directional Mobile Robot
(2008)
Lin, Yee-Chang
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Liu, Chun-Wei
;
Li, Jian-Lung
;
Hsu, Pau-Lo
;
電控工程研究所
The network control system (NCS) becomes popular in recent industrial applications. Typical advantages of NCS like low cost, reduction of the assembly wires and installation, and maintenance. The command between DSP and each motor can be controlled by either the centralized structure with a voltage signal or the proposed network distributed structure. hi this paper, the serial interface RS-232 is adopted because of its wide applications and support in both hardware and software. The DSP F2812 controls four servo motors through the RS-232 interface. The kinematics model of the omni-directional mobile robot (ODMR) is also considered and the relation between robot and each axis is decoupled by applying its inverse kinematics. The mobile robot was tested with both at a low speed (30 cm/s) and a high speed (100 cm/s). The sampling time for the centralized control structure is usually faster compared with the NCS structure, A suitable sampling time for the NCS with the applications of the ODMR indicates the balance between the sampling time and system performance in real applications.
Precision Control and Compensation of Servomotors and Machine Tools via the Disturbance Observer
(2010-01-01)
Huang, Wei-Sheng
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Liu, Chun-Wei
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Hsu, Pau-Lo
;
Yeh, Syh-Shiuh
;
電控工程研究所
The computerized numerical control machine tool is a highly integrated mechatronic system in manufacturing processes. However, uncertainties degrade its motion accuracy. These include modeling errors, parameter variation, friction, and measurement errors that are present in either linear or nonlinear nature. In this paper, a state-space disturbance observer was successfully applied to servomotors to estimate and compensate for the uncertainties of parameter variation and current measurement problems, in the velocity and current loops, respectively. Furthermore, an autotuning procedure was developed accordingly to identify the varied parameters of the motor. Furthermore, by implementing the present servomotor systems in high-precision machine tools, the nonlinear friction compensation was adopted to reduce the slip-stick effect in contouring motion. Experimental results indicate that the roundness error has been significantly reduced from 13.3 to 2.0 mu m by applying the proposed approaches.