Huy Hung Nguyen

A Model Reference Adaptive Controller for Belt Conveyors of Induction Conveyor Line in Cross-Belt Sorting System with Input Saturation

Model reference adaptive controller for belt conveyors of induction conveyor line in cross-belt sorting system with input saturation subjected to parametric uncertainties and input saturation is proposed in this paper. There exist 3 inputs and 3 outputs in the proposed controller for belt conveyors of induction conveyor line in cross-belt sorting system named the MIMO linear system. In this controller, an auxiliary system is introduced for compensating the error dynamics of the MIMO linear system when the saturation input occurs. Therefore, the steady state error is guaranteed to be bounded when a saturated input error does not equal to zero. Finally, the experimental results are shown to verify the effectiveness and the performance of the proposed controller for the MIMO linear system with input saturation and a MRAC controller for that without input saturation.

Implementation of an Active Wire Tensioner Using a Cascade Fuzzy Logical Controller for a Brush-Less Direct Current Coil Winding Machine

This paper is to implement an active wire tensioner which uses a cascade fuzzy logical controller to handle wire tension on a brush-less direct current (BLDC) coil winding machine during the winding process. A manifold winding process of the BLDC machine found by an analysis among various winding processes shows that the wire tension in winding process of the BLDC winding machine is more fluctuated than that in other winding processes. Based on the result of the analysis, a mechanism called as a wire accumulator using a pneumatic servo system is designed to decay the vibration of wire tension encountered with the harsh condition of winding process. In order to ensure the wire accumulator working properly, a magnetic powder clutch is adopted to prevent the wire passing through the wire accumulator freely. The active wire tensioner is defined as a multi-input single-output system with two control inputs for driving the magnetic powder clutch/the pneumatic cylinder and single output as the wire tension force. For such sophisticated behavior of the system’s response, a novel cascade fuzzy logical controller (CC-FLC) with the fuzzy rule constructed based on a split-range method is appropriate for controlling the active wire tensioner. Additionally, the CC-FLC is convenient to be built into DSP alone-chip since its processing calculation consumes a low time. The effectiveness of the proposed active wire tensioner using CC-FLC is compared to that of a passive wire tensioner existing on the BLDC winding machine when both wire tensioners are used for coil producing process of the BLDC winding machine. Experimental results show that the BLDC winding machine equipped with the proposed active wire tensioner can operate at high winding speed without breaking the wire and reducing the coil size in the view of dimension.

Backstepping-based model reference adaptive controller for a multi-axial system in the presence of external disturbance and saturated input

This paper presents a backstepping-based model reference adaptive controller for a multi-axial system in the presence of external disturbance and saturated input. The proposed controller synthesizes the backstepping technique and the model reference adaptive control method to construct control inputs for recursive structure and uncertain modelling of the multi-axial system. To cope with the limit of saturated input, an auxiliary system is adopted. A dead-zone modification is introduced to avoid the drift phenomenon of adjusted adaptive parameters. The stability of the proposed controller is proven by Lyapunov’s theory while considering the effect of the auxiliary system and the dead-zone modification in the design stage. The effectiveness and performance of the proposed controller are evaluated by experiment on a transformer winding system.

Cross-coupling synchronous velocity control using model reference adaptive control scheme in an unsymmetrical biaxial winding system

Motion control with high accuracy for each axial system is the fundamental requirement to reduce a synchronous motion error of a multi-axis system. Especially, designing a model-based controller for an uncertainty system with unknown parameters is not easy without using system identification. To overcome the mentioned issue, this article proposes a cross-coupling synchronous velocity controller using a backstepping-based model reference adaptive control scheme in an unsymmetrical biaxial winding system called a transformer winding system. The proposed controller deals not only with the uncertainty but also with the recursive structure of the system. The backstepping technique for the recursive structural system and the model reference adaptive control method for the uncertainty of the system are designed to stabilize two axial systems with unknown parameters. An auxiliary system is added to build the proposed controller for coping with input constraints of physical actuators. To improve the proposed controller’s ability to cope with external disturbances, a dead-zone modification is utilized to modify the adaptation laws to avoid the drift phenomenon. Moreover, a cross-coupling mechanism is integrated into the proposed controller to reduce the synchronous velocity error between the velocities of the biaxial winding system. The proposed controller is also transformed into discrete time to be run on a digital signal processor alone chip. The experimental results are shown to verify the high performance and efficiency of the proposed controller for practical applications.

A simple path planning for Automatic Guided Vehicle in Unknown Environment

A Simple Path Planning algorithms for Automatic Guided Vehicle in Unknown Environment based on D∗ lite algorithm is proposed in this paper. The proposed algorithm changes method determining traversal cost of edge between two adjacent nodes to prevent AGV from traversing across obstacles sharp corners, avoid complicated obstacles and prevent AGV from traversing in between two obstacles. The simulation and experimental results are shown to verify the effectiveness of the proposed algorithm.

Path Planning for Automatic Guided Vehicle with Multiple Target Points in Known Environment

Today, Automatic Guided Vehicles (AGVs) with a path planning algorithm are being used in many industrial fields. There are A*, D*, and D* lite algorithms in the path planning algorithm. In this paper, propose a modified D* lite algorithm using the most efficient D* lite among these algorithms. The modified D* lite path planning algorithm is proposed to improve these D* lite path planning algorithm’s weaknesses such as traversing across obstacles sharp corners, or traversing between two obstacles. The modified D* lite path planning algorithm has function to set target points differently from the existing D* lite path planning algorithm. To do this task, the followings are done. First, a work space is divided into square cells. Second, cost of each edge connecting current node to neighbor nodes is calculated. Third, the shortest paths from the initial point to all multiple target points are computed and the shortest paths from any target point to remaining target points including the goal point are computed by using Hamilton path. Fourth, a cost-minimal path is re-calculated as soon as the laser sensor detects an obstacle and make an updated list of target points. Finally, the validity of the proposed modified D* lite path planning algorithm is verified through simulation and experimental results in known environment.

Tracking Controller Design for Omni-Directional Automated Guided Vehicles Using Backstepping and Model Reference Adaptive Control

This paper proposes a tracking controller for omni-directional automated guided vehicle using backstepping and model reference adaptive control. To design the proposed controller, the followings are done. Firstly, a system modeling is obtained by analyzing a dynamic modeling of an OAGV. Secondly, a backstepping technique is utilized to design the proposed controller since a system modeling has a recursive structure. Moreover, there exist uncertain parameters in the system modeling, a known reference model is utilized so that the output of the reference model tracks a virtual control input. Thirdly, uncertain parameters are estimated by update laws in order that the velocity vector of the OAGV tracks the output vector of the reference model control input. Finally, the stability of the proposed controller is analyzed by Lyapunov theory and the effectiveness of the proposed controller are verified by simulation results.

Backstepping-Based Adaptive Velocity Tracking Controller Design for a Winding Spindle System

This paper presents a backstepping-based modified model reference adaptive velocity tracking controller design method to track a trapezoidal reference type of rotational velocity for a winding spindle system (WSS). To design the proposed controller, the following are done. Firstly, the system modeling of the WSS is obtained as a combined form of direct current motor and mechanical parts. Secondly, a modified model reference system with known parameters is chosen according to the dimension of the given system such that its rotational velocity output tracks the trapezoidal reference input of the winding spindle system. Then, the rotational velocity output of the winding spindle system is controlled to track the rotational velocity output of the modified model reference system by designing update laws for updating the adaptive controller parameters. Thirdly, since the system modeling of the winding spindle system is constructed as a recursive structure system, the modified model reference adaptive controller is developed based on backstepping approach. Finally, the effectiveness and performance of the proposed controller are evaluated with comparison to those of a conventional PID controller by experimental results.

A New Approach of 2D Measurement of Injury Rate on Fish by a Modified K-means Clustering Algorithm Based on L*A*B* Color Space

Based on basic properties of L*A*B* color space, this paper proposes a new approach of 2D image processing which is used for measurement of injury rate on fish by a modified K-means clustering algorithm and Otsu’s threshold algorithm. Then, experimental results of the proposed method are compared to the results of a manual threshold method on L*A*B* color space. To do this issue, the following tasks are done. Firstly, an original color image is transferred into L*A*B color space. Secondly, channel “a” is separated from L*A*B* color space image. Thirdly, the value of channel “a” is adjusted by changing the contrast algorithm. Fourthly, the modified K-means clustering algorithm on a new channel “a” image is applied to define and divide data elements into different groups. Fifthly, Gaussian Filter is used to filter the random “noises” in shape of injury and fish images. Sixthly, Otsu’s threshold algorithm is used to transfers the filtered images into binary images. Seventhly, final images are obtained after filtering the rest of “noises” by morphological processing. Finally, the areas of injury and fish shapes are obtained by counting pixels on both of the final binary images. The experiment results show that the proposed new approach is closer to the real injury and injury rate on fish than the results of the manual threshold method on L*A*B color image.

A Combination of Direct and Indirect Types in Modified Model Reference Adaptive Controller for a SISO Uncertain System

This paper proposes a modified model reference adaptive controller based on a combination of direct and indirect types for a single input-single output (SISO) uncertain system. The estimation of plant parameters is based on feedbacks of the state and the control input while the estimation of controller parameters is based on feedbacks of the state and the reference input. The reference model system and the prediction model are modified by feedbacks of a modeling error and a prediction error. The stability analysis of the closed-loop control system is shown by using Lyapunov’s theory. The experimental results on a servomechanism system show that the performance of the proposed controller has a good tracking the reference input in transient and asymptotic.