Use Of Feedback Control Research Articles

Optimal uses of feedforward type and feedback type adaptive control algorithms in active noise control

One‐dimensional active noise control problems such as canceling noise propagating down a duct or longitudal vibration within a structural vibration mount are considered, in general, to be well suited for active noise control. However (through the use of feedback control), active noise control can also be successful in applications where there are many sources of noise and low coherence between possible sensor locations. Feedback control requires only an error sensor and an actuator to minimize the noise at the error sensor. There is no question that if all the noise components at a sensor location can be observed before the noise propagates to the actuator and error sensor, then the best choice of controller involves a feedforward algorithm. However, if the noise propagates faster than the actuator can respond (a good example is high‐frequency bending waves), random impacts or spectrally white noise cannot be canceled and complexity can be reduced by using feedback control to obtain the same theoretical performance. Feedback control also allows multiple periodic noise sources to be controlled using a single control loop.

Global Dynamics Achievable by Feedback Controls: Some Preliminary Results

Any control system that uses a feedback control law leads to globally defined control dynamics. To understand control systems, it is therefore important to understand the global dynamics possible through the use of feedback controls. This is a point of view different, in many respects, from that of established aproaches such as that of controllability theory. We are no longer interested in a, single trajectory, or trajectories that originate or terminate in a given point, but in the behaviour of ensembles of trajectories.In this paper, we formulate the basic definitions and prove some theorems that constitute a preliminary treatment of this very difficult problem. After defining our topic and describing the main classes of dynamics, we come to a discussion of 'closeness' and of structural stabilty, adapted to the control problem. Having separated the 'transient' from the 'asymptotic' part of the dynamics, we then turn to a discussion of the elementary kinds of asymptotic behaviour, namely isolated equilibrium points and limit cycles.What makes this treatment possible is the input from dynamical systems theory. It provides a point of view and motivates many of the results.

State-Variable Steady-State Analysis of a Controlled Current Induction Motor Drive

The exact equations defining steady-state operation of a controlled current induction motor drive system are derived by solving the system state equations in the stationary reference frame. These equations, which assume ideal current filtering, eliminate the difficulties involved in taking derivatives of discontinuous currents by defining a pair of pseudocurrent variables. Effects of saturation are included by using the slope ratio method. Electromagnetic torque and current pulsations are computed for various load conditions, and experimental confirmation of the calculated results is made. Similarities and differences to voltage controlled characteristics are presented. It is shown that normal open-loop operation occurs on the unstable side of the torque-slip characteristic necessitating the use of feedback control for stable operation.

Active Machine Tool Controller Requirements for Noise Attenuation

The use of feedback control to regulate the position of the cutting tool relative to the workpiece on a machine tool such as a lathe is examined with respect to the reduction of vibratory noise effects on workpiece surface finish. Both control mode and controller characteristics are examined relative to noise effect attenuation. An examination of system stability (the chatter tendency) is also included as a necessary part of the evaluation of each type of controller that is considered.