Vibration control of a single-link flexible arm subjected to disturbances

In this work, a new control methodology to achieve accurate position control of an AC servo motor subjected to external disturbance is proposed. Unlike conventional sliding mode controller which requires a prior knowledge of the upper bound of external disturbance, the proposed technique, called sliding mode controller with disturbance estimator (SMCDE), can offer robust control performances without a prior knowledge of the disturbance bound. The SMCDE is featured by an integrated average value of the imposed disturbance over a certain sampling period. By doing this, undesirable chattering phenomenon in the estimation process can be effectively alleviated. The benefits of the proposed control methodology are empirically demonstrated on AC servo motor and control responses are evaluated through a comparative work between the proposed and conventional control schemes.

Position Control of an AC Servo Motor Using Sliding Mode Controller with Disturbance Estimator

This article presents a new sliding mode controller (SMC) for the position control of a robotic manipulator subjected to perturbations, such as parameter uncertainties and extraneous disturbances. The SMC is designed so that the sliding mode condition is satisfied and integrated with the perturbation estimator. The estimator is formulated by adopting a concept of the integrated average value of the imposed perturbation over a certain sampling period and realized using the Taylor series. In the formulation of the estimator, the relationship between control performance and sensor performance is established by adjusting the sampling ratio. Subsequently, in order to improve control performance, the actuating condition for the estimator is introduced: on-off switching condition (OSC). This condition is decided on the basis of the estimation error between actual and predicted values. By imposing the OSC, control accuracy can be enhanced when high frequency perturbations exist in the system. The benefits...

New Sliding Mode Controller for Robotic Manipulator Subjected to Disturbance and Uncertainty

In this work, a new perturbation estimator associated with a sliding mode controller is proposed to enhance control performance of linear or non-linear systems under perturbations such as parameter uncertainties and extraneous disturbances. The estimator is designed by adopting an integrated average value of the imposed perturbation over a certain sampling period. Subsequently, in order to improve control performance, a so-called perturbation filtering condition (PFC) is introduced for the estimator. By applying the PFC in which useful components of the imposed perturbations are kept, control performance can be substantially improved without additional control input. Some benefits of the proposed methodology are demonstrated on a two-link planar robotic manipulator. The position tracking control performances of the manipulator are evaluated in the time domain and a comparative work between the proposed methodology and conventional scheme for the perturbation estimation is undertaken.

A new perturbation estimator in a sliding mode control system with application to robot control

This paper presents a perturbation estimator in sliding mode control system and applies it to vibration control of a flexible arm subjected to torque disturbance. The proposed estimator is featured by an integrated average value of the imposed perturbation over a certain sampling period. By implementing this type of estimator, undesirable chattering phenomenon can be effectively alleviated in the estimation process. In addition, the proposed method offers a flexibility for tuning the ratio of the estimation sampling time to the control input sampling time. In order to demonstrate the effectiveness of the proposed methodology, a single-link flexible arm is constructed. After formulating the governing equation of motion, a sliding mode controller which is integrated with the proposed estimator is designed. Vibration control performances of the flexible arm subjected to sinusoidal torque disturbances are evaluated through both computer simulation and experimental realization.

Robust vibration control of a flexible arm subjected to torque disturbance

The levitation system of high speed electromagnetic system (EMS) MAGLEV-vehicles has been successfully controlled by sliding mode control (SMC). This nonlinear control method is robust with respect to parameter variations and force disturbances but fails to compensate guideway disturbances just like linear controllers. To maintain the desired robustness and minimize the effect of guideway disturbances SMC is combined with a linear disturbance observer whose weighted output is added to the set point. Various simulations using an extensive nonlinear model show the excellent performance of the new approach. >

Kozek

Papers

A MISO sliding mode control for a high speed EMS MAGLEV-vehicle using disturbance estimation