## Abstract

Modern stables and greenhouses are equipped with different components for providing a

comfortable climate for animals and plant. A component malfunction may result in loss

of production. Therefore, it is desirable to design a control system, which is stable, and

is able to provide an acceptable degraded performance even in the faulty case.

In this thesis, we have designed such controllers for climate control systems for livestock

buildings in three steps:

Deriving a model for the climate control system of a pig-stable.

Designing a active fault diagnosis (AFD) algorithm for different kinds of fault.

Designing a fault tolerant control scheme for the climate control system.

In the first step, a conceptual multi-zone model for climate control of a live-stock

building is derived. The model is a nonlinear hybrid model. Hybrid systems contain

both discrete and continuous components. The parameters of the hybrid model are estimated

by a recursive estimation algorithm, the Extended Kalman Filter (EKF), using

experimental data which was provided by an equipped laboratory.

Two methods for active fault diagnosis are proposed. The AFD methods excite the

system by injecting a so-called excitation input. In both methods, the input is designed

off-line based on a sensitivity analysis in order to improve the precision of estimation of

parameters associated with faults. Two different algorithm, the EKF and a new adaptive

filter, are used to estimate the parameters of the system. The fault is detected and isolated

by comparing the nominal parameters with those estimated. The performance of AFD

methods depend on model accuracy, hence, the nonlinear model for the climate control

of the stable is used.

For the reconfiguration scheme, the nonlinear model is approximated to a piecewise

affine (PWA) model. The advantages of PWA modeling for controlling schemes are:

most complex industrial systems either show nonlinear behavior or contain both discrete

and continuous components which is called hybrid systems. PWA models are a relevant

modeling framework for such systems. Some industrial systems may also contain piecewise

affine (PWA) components such as dead-zones, saturation, etc or contain piecewise

nonlinear models which is the case for the climate control systems of the stables.

Fault tolerant controller (FTC) is based on a switching scheme between a set of predefined

passive fault tolerant controller (PFTC). In the FTC part of the thesis, first a

passive fault tolerant controller (PFTC) based on state feed-back is proposed for discretetime

PWA systems. only actuator faults are considered. By dissipativity theory and H1

analysis, the problem is cast as a set of linear matrix inequalities (LMIs). In the next contribution, the problem of reconfigurability of PWA systems is evaluated. A system

subject to a fault is considered as reconfigurable if it can be stabilized by a state feedback

controller and the optimal cost of the performance of the systems is admissible. In the

previous methods the input constraints are not included, while due to the physical limitation,

the input signal can not have any value. In continuing, a passive fault tolerant

controller (PFTC) based on state feedback is proposed to track a reference signal while

the control inputs are bounded.

comfortable climate for animals and plant. A component malfunction may result in loss

of production. Therefore, it is desirable to design a control system, which is stable, and

is able to provide an acceptable degraded performance even in the faulty case.

In this thesis, we have designed such controllers for climate control systems for livestock

buildings in three steps:

Deriving a model for the climate control system of a pig-stable.

Designing a active fault diagnosis (AFD) algorithm for different kinds of fault.

Designing a fault tolerant control scheme for the climate control system.

In the first step, a conceptual multi-zone model for climate control of a live-stock

building is derived. The model is a nonlinear hybrid model. Hybrid systems contain

both discrete and continuous components. The parameters of the hybrid model are estimated

by a recursive estimation algorithm, the Extended Kalman Filter (EKF), using

experimental data which was provided by an equipped laboratory.

Two methods for active fault diagnosis are proposed. The AFD methods excite the

system by injecting a so-called excitation input. In both methods, the input is designed

off-line based on a sensitivity analysis in order to improve the precision of estimation of

parameters associated with faults. Two different algorithm, the EKF and a new adaptive

filter, are used to estimate the parameters of the system. The fault is detected and isolated

by comparing the nominal parameters with those estimated. The performance of AFD

methods depend on model accuracy, hence, the nonlinear model for the climate control

of the stable is used.

For the reconfiguration scheme, the nonlinear model is approximated to a piecewise

affine (PWA) model. The advantages of PWA modeling for controlling schemes are:

most complex industrial systems either show nonlinear behavior or contain both discrete

and continuous components which is called hybrid systems. PWA models are a relevant

modeling framework for such systems. Some industrial systems may also contain piecewise

affine (PWA) components such as dead-zones, saturation, etc or contain piecewise

nonlinear models which is the case for the climate control systems of the stables.

Fault tolerant controller (FTC) is based on a switching scheme between a set of predefined

passive fault tolerant controller (PFTC). In the FTC part of the thesis, first a

passive fault tolerant controller (PFTC) based on state feed-back is proposed for discretetime

PWA systems. only actuator faults are considered. By dissipativity theory and H1

analysis, the problem is cast as a set of linear matrix inequalities (LMIs). In the next contribution, the problem of reconfigurability of PWA systems is evaluated. A system

subject to a fault is considered as reconfigurable if it can be stabilized by a state feedback

controller and the optimal cost of the performance of the systems is admissible. In the

previous methods the input constraints are not included, while due to the physical limitation,

the input signal can not have any value. In continuing, a passive fault tolerant

controller (PFTC) based on state feedback is proposed to track a reference signal while

the control inputs are bounded.

Original language | English |
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Number of pages | 179 |
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ISBN (Print) | 123-223-445 |

Publication status | Published - 2011 |