Quoc Chi Nguyen

Transverse Vibration Control of Axially Moving Membranes by Regulation of Axial Velocity

In this brief, a novel control algorithm that suppresses the transverse vibrations of an axially moving membrane system is presented. The proposed control method is to regulate the axial transport velocity of the membrane so as to track a desired profile according to which the vibration energy of the membrane at the end of transport decays most quickly. An optimal control problem that generates the desired profile of the axial transport velocity is solved by the conjugate gradient method. The Galerkin method is applied in order to reduce the partial differential equations describing the dynamics of the axially moving membrane into two sets of ordinary differential equations (ODEs) representing longitudinal/lateral and transverse displacements. For control design purposes, these ODEs are rewritten into state-space equations. The vibration energy of the axially moving membrane is represented by a quadratic form of the state variables. In the optimal control problem, the cost function modified from the vibration energy function is subject to the constraints on the state variables, and the axial transport velocity is considered as a control input. The effectiveness of the proposed control method is illustrated via numerical simulations.

Design and implementation of high performance motion controller for 2-D delta robot

Conventionally, software-based motion controllers are used to execute many automation systems in the industry. Most of these controller reveal several drawbacks such as large accumulated error, does not guarantee real-time characteristics when generating motion profile based on software. In this paper, the implementation of embeded motion controller for many applications is presented. ARM Cortex M4 is designed in this controller to handle the communication between host PC and controller. To enhance the high performance of generating trajectory path, hardware-based motion chipset is integrated into the controller. Experimental platform of 2-D delta robot is driven by proposed controller to show the pick and place operations. Several results are carried out to validate the effectiveness and feasibility.

Nonlinear adaptive control of a 3D overhead crane

In this paper, a nonlinear adaptive control of a 3D overhead crane is investigated. A dynamic model of the overhead crane is developed, where the crane system is assumed as a lumped mass model. Under the mutual effects of the sway motions of the payload and the hoisting motion, the nonlinear behavior of the crane system is considered. A nonlinear control model-based scheme is designed to achieve the three objectives: (i) drive the crane system to the desired positions, (ii) suppresses the vibrations of the payload, and (iii) velocity tracking of hoisting motion. The nonlinear control scheme employs adaptation laws that estimate unknown system parameters, friction forces and the mass of the payload. The estimated values are used to compute control forces applied to the trolley of the crane. The asymptotic stability of the crane system is investigated by using the Lyapunov method. The effectiveness of the proposed control scheme is verified by numerical simulation results.

Longitudinal and transverse vibration control of an axially moving string

An active control scheme of an axially moving string system for suppressing longitudinal and transverse vibrations simultaneously is investigated. The control scheme incorporates three inputs: one control force to the right boundary (roller) and two control torques applied to the left and right rollers. Two nonlinear partial differential equations derived using Hamiltons principle govern the longitudinal and transverse motions, where the spatially varying tension due to the transverse and longitudinal vibrations is considered. The asymptotic stability of the closed-loop system is proved using the Lyapunov method. Numerical simulations demonstrate the effectiveness of the proposed control scheme.

Improving Control Performance of a Container Crane Using Adaptive Friction Compensation

This paper investigates an adaptive control scheme for container cranes that transport containers between a container ship and trucks. Three unknown parameters (the mechanical friction between the trolley and the guide rails, the mass per unit length of the rope, and the payload mass) are estimated. Since the rope of the crane is flexible, an axially moving string equation is introduced to model the rope dynamics. The Lyapunov method is used to assure the uniform stability of the closed loop system. The experimental results demonstrate the effectiveness of the proposed control scheme.

Transverse Vibration Control of Axially Moving Beams by Regulation of Axial Velocity

Abstract In this paper, a novel control algorithm for suppression of the transverse vibration of an axially moving system is presented. The principle of the proposed control algorithm is the regulation of the axial transport velocity of an axially moving system so as to track a profile according to which the vibration energy decays most quickly. The optimal control problem that generates the proposed profile of the axial transport velocity is solved by the conjugate gradient method. The Galerkin method is applied in order to reduce the partial differential equation describing the dynamics of the axially moving beam into a set of ordinary differential equations (ODEs). For control design purposes, these ODEs are rewritten into state-space equations. The vibration energy of the axially moving beam is represented by the quadratic form of the state variables. In the optimal control problem, the cost function modified from the vibration energy function is subject to the constraints on the state variables, and the axial transport velocity is considered as a control input. Numerical simulations are performed to confirm the effectiveness of the proposed control algorithm.

Transverse vibration control of axially moving web systems by regulation of axial tension

In this paper, an active control scheme that suppresses transverse vibrations and regulates axial speed so as to track a desired profile for an axially moving web system is investigated. The spatially varying tension and the time-varying axial speed of the axially moving web are considered. The system dynamics includes the equations of motion of the moving web and the velocity dynamics of the drive rollers at boundaries of the web span. The two roller motors provide control torque inputs for the control system. The principle of the vibration control strategy is the regulation of the axial tension by a designed profile according to which the vibration energy of the moving web decays. The designed profile for the axial tension is generated by using vibration analysis based on the total mechanical energy of the axially moving web system. Lyapunov method is employed to derive the model-based torque control laws ensuring that the transverse vibration and the speed tracking error converge to zero exponentially. The effectiveness of the proposed control scheme is demonstrated via numerical simulations.

Secured-OFS: A Novel OpenFlow Switch Architecture with Integrated Security Functions

Although OpenFlow network protocol is a promising network approach with many advantages compared to traditional network approaches, it still suffers from network attacks. In this paper, we propose a novel architecture for an OpenFlow-based switch with associated multiple network security techniques, so-called Secured-OFS. The proposed Secured-OFS can not only function as a switch following the OpenFlow protocol but also help protect a network against many attack types. We implement the first FPGA-based prototype version of our proposed Secured-OFS using a Xilinx Virtex 5 xc5vtx240t device. In this first prototype version, we integrate two different DDoS defense techniques, Hop-Count Filtering and Port Ingress/Egress Filtering. The experimental results show that the switch not only fulfills the OpenFlow protocol but also be able to defense against DDoS attacks. The system achieves a maximum throughput at 19.729 Gbps while a 100 % DDoS attack detection rate is obtained.