511 research outputs found

    Sliding modes in power electronics and motion control

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    In the paper the general approach to motion control systems in the sliding mode framework is discussed in details. It has been shown that, due to the fact that a motion control system with n d.o.f may be mathematically formulated in a unique way as a system composed on n 2 d.o.f systems, design of such a system may be formulated in a unique way as a requirement that the generalized coordinates must satisfy certain algebraic constrain. Such a formulation leads naturally to sliding mode methods to be applied where sliding mode manifolds are selected to coincide with desired constraints on the generalized coordinates. In addition to the above problem the design of full observer for IM based drive is discussed

    Sliding-mode neuro-controller for uncertain systems

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    In this paper, a method that allows for the merger of the good features of sliding-mode control and neural network (NN) design is presented. Design is performed by applying an NN to minimize the cost function that is selected to depend on the distance from the sliding-mode manifold, thus providing that the NN controller enforces sliding-mode motion in a closed-loop system. It has been proven that the selected cost function has no local minima in controller parameter space, so under certain conditions, selection of the NN weights guarantees that the global minimum is reached, and then the sliding-mode conditions are satisfied; thus, closed-loop motion is robust against parameter changes and disturbances. For controller design, the system states and the nominal value of the control input matrix are used. The design for both multiple-input-multiple-output and single-input-single-output systems is discussed. Due to the structure of the (M)ADALINE network used in control calculation, the proposed algorithm can also be interpreted as a sliding-mode-based control parameter adaptation scheme. The controller performance is verified by experimental results

    External Control Interface, Dynamic Modeling and Parameter Estimation of a Research Treadmill

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    Treadmills providing linear continuous movement are used for robotic testing of prostheses in order to study their operating characteristics. However, traditional exercise treadmills are not able to simulate various conditions such as avoiding an obstacle, climbing, descending, reversing direction, or stopping instantly. The focus of this thesis is to examine control algorithms (position, speed and force) for the drive mechanism of a research treadmill to fulll the gap in the situations described above. The system consists of a power supply, a computer with Matlab, and the treadmill that includes a DC motor, a pulley and belt. Also, an external encoder is installed on the motor to measure the position of the belt. The bond graph method is used to model the system to nd the symbolic transfer function. Simultaneously, system identication techniques are used to estimate a numeric transfer function. Some parameters of the model are experimentally measured, and the rest are extracted by matching two transfer functions. Control algorithms such as proportional-integralderivative and sliding mode are implemented in the system for simulation and realtime operation. The results demonstrate that this system is suitable for producing motion paths that traditional treadmills cannot, and it can handle dicult-to-model situations such as the synchronized movement of the treadmill with a prosthesistesting robo

    External Control Interface, Dynamic Modeling and Parameter Estimation of a Research Treadmill

    Get PDF
    Treadmills providing linear continuous movement are used for robotic testing of prostheses in order to study their operating characteristics. However, traditional exercise treadmills are not able to simulate various conditions such as avoiding an obstacle, climbing, descending, reversing direction, or stopping instantly. The focus of this thesis is to examine control algorithms (position, speed and force) for the drive mechanism of a research treadmill to fulll the gap in the situations described above. The system consists of a power supply, a computer with Matlab, and the treadmill that includes a DC motor, a pulley and belt. Also, an external encoder is installed on the motor to measure the position of the belt. The bond graph method is used to model the system to nd the symbolic transfer function. Simultaneously, system identication techniques are used to estimate a numeric transfer function. Some parameters of the model are experimentally measured, and the rest are extracted by matching two transfer functions. Control algorithms such as proportional-integralderivative and sliding mode are implemented in the system for simulation and realtime operation. The results demonstrate that this system is suitable for producing motion paths that traditional treadmills cannot, and it can handle dicult-to-model situations such as the synchronized movement of the treadmill with a prosthesistesting robo

    Motion Control of an Open Container with Slosh Constraints

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    General motion control of conveyor belts does not present difficulties. When the conveyor belt carries open containers filled with liquid, significant analysis needs to be carried out to design controllers. The objective of this thesis was to design a control system which will allow an open container filled with liquid to be transferred between two stations as fast as possible and without excessive slosh causing the liquid to spill out of the container. This control problem has applications to industrial processing facilities, where open containers are carried by a conveyor belt. The speed at which the open container can be transferred between stations has a direct impact on productivity. The thesis involves determination of the plant (conveyor belt dynamics and the container filled with liquid) model using system identification techniques and examination of candidate control techniques. Simulation results have been shown to validate the approac

    Force feedback control based on VGSTA for single track riding simulator

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    International audienceA direct application of the variable-gain super-twisting algorithm (VGSTA) is implemented for torque feedback on a handlebar of a riding simulator. This control strategy aims to compensate perturbations changing with the system states. Thanks to the good tracking performance and robustness/insensitiveness of such a control method, a precise estimation of the rider's torque applied on the riding simulator handlebar is possible. A first-order sliding-mode observer with stabilization is designed for the estimation of the unknown input rider action. Experimental implementation and analysis are provided to point-out the effectiveness of the proposed approach

    A Compound Fuzzy Disturbance Observer Based on Sliding Modes and Its Application on Flight Simulator

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    A compound fuzzy disturbance observer based on sliding modes is developed, and its application on flight simulator is presented. Fuzzy disturbance observer (FDO) is an effective method in nonlinear control. However, traditional FDO is confined to monitor dynamic disturbance, and the frequency bandwidth of the system is restricted. Sliding mode control (SMC) compensates the high-frequency component of disturbance while it is limited by the chattering phenomenon. The proposed method uses the sliding mode technique to deal with the uncompensated dynamic equivalent disturbance. The switching gain of sliding mode control designed according to the error of disturbance estimation is a small value. Therefore, the proposal also helps to decrease the chattering. The validity of the proposal method is confirmed by experiments on flight simulator

    Sliding-Mode control for high-precision motion control systems

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    In many of today's mechanical systems, high precision motion has become a necessity. As performance requirements become more stringent, classical industrial controllers such as PID can no longer provide satisfactory results. Although many control approaches have been proposed in the literature, control problems related to plant parameter uncertainties, disturbances and high-order dynamics remain as big challenges for control engineers. Theory of Sliding Mode Control provides a systematic approach to controller design while allowing stability in the presence of parametric uncertainties and external disturbances. In this thesis a brief study of the concepts behind Sliding Mode Control will be shown. Description of Sliding Mode Control in discrete-time systems and the continuous Sliding Mode Control will be shown. The description will be supported with the design and robustness analysis of Sliding Mode Control for discrete-time systems. In this thesis a simplified methodology based on discrete-time Sliding Mode Control will be presented. The main issues that this thesis aims to solve are friction and internal nonlinearities. The thesis can be outlined as follows: -Implementation of discrete-time Sliding Mode Control to systems with nonlinearities and friction. Systems include; piezoelectric actuators that are known to suffer from nonlinear hysteresis behavior and ball-screw drives that suffer from high friction. Finally, the controller will be implemented on a 6-dof Stewart platform which is a system of higher complexity. -It will also be shown that performance can be enhanced with the aid of disturbance compensation based on a nominal plant disturbance observer
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