Browsing by Subject "gain scheduling"

Now showing 1 - 3 of 3

Access status: Open Access ,
Gain-scheduled state-feedback control for active cancellation of multisine disturbances with time-varying frequencies
(2011) Heins, Wiebke; Ballesteros, Pablo; Bohn, Christian
The paper presents a discrete-time LTV controller for the rejection of harmonic disturbances with time-verying based on a state-augmented observer-based state-feedback controller with a time-verying internal model and a scheduled state-feed back gain. The control design method is based on quadratic stability for LPV systems. The design is carried out in discrete time and the controller can easily be implemented on real-time hardware.
Access status: Open Access ,
MR damper inverse modeling dependent on operating conditions
(2013) Wolnica, Mateusz
For semi-active control of vehicle suspension magnetoreological (MR) dampers are usually used. Construction of such dampers suggests that their properties should be dependent on fluid temperature, current of the coil and the relative velocity of the rod, which all change during operation. Then, an inverse model used to work out the current based on the required damping force may not be adequate, and performance of the overall semi-active control system can be significantly degraded. MR damper reaches its operating temperature in a short period of time, and thus it should be modelled, and the obtained inverse model should reflect such state. However, it has been observed that the hysteric behaviour of the MR damper significantly differs depending on the current. The paper presents results of such analysis and recommends using a set of simple models appropriate for different ranges of this parameter. During control the models should be switched to guarantee the best operating conditions. Experiments for this research have been performed using MTS system.
Access status: Open Access ,
Rejection of harmonic and transient disturbances of a smart structure with piezoelectric actuators
(2013) Duarte Vera, Franklyn Gerardo; Ballesteros, Pablo; Shu, Xinyu; Bohn, Christian
Light flexible structures are easily prone to vibrate due to external forces or due to forces generated in the inner structure. This situation is common in machinery or mechanical structures with rotational devices. The unwanted vi-bration of such structures can be compensated with the addition of piezoelectric actuators for active vibration control (AVC). The rejection of harmonic disturbances is frequently done with controllers based on the internal model principle. The goal of this research is to reduce the effect of harmonic disturbances with known (measured) time-varying fre¬quencies acting on a system as well as to increase the damping of the system for the transient response (first mode of vibration). The experimental setup is made up of a slender aluminium flexible beam, a pair of piezoelectric actuators, an accelerometer and two DC motors, as well as the data acquisition and signal conditioning equipment. The harmonic disturbance is generated by DC motors. The control design utilizes an augmented description of the plant. The plant including the disturbance is modelled as a polytopic linear parameter-varying (pLPV) system. An observer-based gain-scheduling controller is calculated based on quadratic stability and the stability is guaranteed for the specified range ofvariation of the scheduling parameters, also restriction in the performance is introduced in the sense of the H2-norm. Experimental results show very good disturbance cancellation.