Papers by Author: Chin Sheng Chen

Abstract: This paper proposes an optimal method for NCC-based template matching on modern CPUs for time-critical applications. In order to achieve the superior computation efficiency, the brand-and-bound (BB) scheme and the streaming SIMD extensions 2 (SSE2) instructions are employed to quickly find out the target object with rotation, translation and scaling in monochrome or color image. And we show how to reject unpromising image location very quickly using BB scheme in search process. Furthermore, an efficient implementation for similarity coefficient calculation is also pointed out by using the integration SSE2 instructions. Finally, the results show that the proposed method is very powerful when dealing with the NCC-based template matching in monochrome and color images.

Abstract: In this paper, we develop the auto-focus measurement system which includes the hardware and software systems. The hardware system is composed of both modules of the motion stage and the auto-focus optic-mechanism. And the software system consists of two phases: (1) training the response surface model (RSM) for auto-focus technology in offline phase and (2) automatically capturing mesh images by RSM and robustly measuring holes by the area-based diameter (ABD) and average diameter (AD) in online phase. The experiments presented that the proposed auto-focus technology using RSM can effectively obtain the correct focusing position. The accuracy of the diameter on a hole can reach up at most 0.891 μm using the above two algorithms. The successful measure rate is almost 98 %; the measure time is averagely 4.8 seconds per mesh. The above results revealed that the proposed system is not only robust for the auto-focus technology but also efficient and effective for the mesh membrane measurement.

Abstract: High precise positioning and high-speed performance are demanded for servo mechanical systems in recent industry. However, the nonlinear friction is a main factor to make the positioning mechanism imprecision. To improve the positioning the positioning precision of stages driven by ball-screws, there are two types of compensations including model and non-model based methods. In this study, the LuGre friction Model is applied to model the nonlinear friction behavior for a ball-screw driven stage. A Modified Charge Search System (MCSS) was proposed to identify the system’s parameter. After the system’s parameters are obtained, a feed-forward control integrated with a disturbance observer is proposed to eliminate the external disturbance and improve its tracking performance.

Abstract: The laser manufacture has been widely used in micro-machining as a burgeoning technology. Galvanometric scanning systems is an important component in laser machines, but the galvanometric scanning system is usually combines the image field distortion that is from the mechanism and optical devices. The paper has presented a novel correction algorithm based on ride regression method for compensates the image field distortion. And the Euclidean distance error and the maximum error are 0.0422 and 0.09, respectively. This novel correction technique can effectively increase the accuracy of laser spot position and can further improve the performance of the galvanometric scanning system.

Abstract: In this paper, we present the design and control of continuous passive motion (CPM) machine based on Constraint-Induced Movement Therapy (CIMT) for a patient who needs knee rehabilitation. First, the dynamic model of the CPM machine is derived by the principal of virtual work in dynamics. Then, an intelligent sliding-mode control (ISMC) system which involved recurrent Chebyshev neural network (RCNN) estimator to estimate the unknown external disturbance and uncertainty online is proposed to track the angular position and velocity of the CPM machine. Furthermore, we prove that the proposed ISMC system is asymptotically stable via Lyapunov theory. Finally, the experimental results are illustrated to demonstrate that the ISMC system can effectively reduce chattering phenomenon and precisely track reference trajectory of the CPM machine.

Abstract: In this paper, a fuzzy neural network (FNN) compensator is proposed for the synchronous motion control of a gantry position stage. Firstly, the cascade control strategy is applied to reduce the single axis position tracking error. However, the synchronous error between dual servo systems is inevitable due to their inequality in characteristics and the environmental uncertainties. The FNN compensator and an online learning algorithm perform a fuzzy reasoning with two inputs of synchronous position and velocity errors between dual drive servo systems and generate the compensated force; the compensated force is fed back to the controller of each axis. The online learning algorithm adjusts the connected weighting of the neural network by using a supervised gradient descent methods, such that the define error function can be minimized. Finally, two kinds of position commands with high and low frequency are designed for the experiments, and the experimental results show that the proposed FNN compensator is feasible to improve the synchronous error of gantry stage.

Abstract: Cathodic-anodization process was performed to treat titanium sheets to improve biocompatible performance. Grazing incident X-ray diffraction, transmission electron microscopy, scanning electron microscopy and electrochemical measurement were used to evaluate the influence of hydrogen on the formation of nanoporous TiO2. Multimeshworked and nanoporous TiO2 was observed after treatment with cathodic-anodization process. The nanoporous oxide layer is hard to form without nano-TiH2. The nano-TiH2 plays an important role in forming multimeshworked and nanostructured TiO2 layer. Hydrogen charging by cathodization is believed to enhance the formation of nanoporous oxide film and thus promote biocompatibility.

Abstract: This paper presented a digital servo driver that realizes an auto-tuning feedback and feedforward controller design using on-line parameters identification. Firstly, the variant inertia constant, damping constant and the disturbed load torque of the servo motor are estimated by the recursive least square (RLS) estimator, which is composed of an RLS estimator and a disturbance torque compensator. Furthermore, the auto-tuning algorithm of feedback and feedforward controller is realized according to the estimated parameters to match the tracking specification. The proposed auto-tuning digital servo controllers are evaluated and compared experimentally with a traditional controller on a microcomputer-controlled servo motor positioning system. The experimental results show that this auto-tuning digital servo system remarkably reduces the tracking error.