5 research outputs found
Diagonalisation of a class of multivariable system via an actuator linearisation technique
Many multivariable (systems with many inputs/outputs) industrial processes can, to a
good degree of approximation, be modelled by a transfer function matrix, where all of
the interaction occurs in a matrix of constant coefficients. This reflects the fact that the
dynamics of the section in which the interaction occurs are very fast compared with the
other dynamics in the system. Examples of such systems include steel rolling mills and
boiler systems.
Such multivariable systems are relatively easy to design controllers for, since the
system may be diagonalised by an inverse of the constant gain matrix, followed by
suitable single-loop dynamic compensation. However, this approach depends on the
linearity of the dynamical elements in the system. Such a condition is voilated by
the presence of non-linear actuators, which are a feature of many industrial systems. The
presence of such actuators within a multivariable control system as described above can
cause very significant interaction problems, with associated degradation in performance,
particularly during transients.
This paper describes a straightforward technique, which is effective in linearising
typical non-linear industrial actuators, allowing diagonalisation to be effectively
achieved at all frequencies. The technique relies on a simple describing function analysis
and manifests itself as a time-varying linearising precompensator for each non-linear
actuator. A simple example is used to demonstrate the effectiveness of the method and it
is then shown in application with multivariable boiler and steel mill models
Robust shape control in a sendzimir cold-rolling steel mill
The shape control problem for a Sendzimir 20-roll cold rolling steel mill is characterised by operation over a wide range of conditions arising from roll changes, changes in rolling schedules and changes in material gauge, width and hardness. Previous approaches to the problem suggest storing a large number of precompensator matrices to cater for the full range of operating conditions. This paper, on the other hand, attempts to synthesise a controller which is optimally robust to changes in the conditions associated with the rolling cluster, resulting in a reduced storage requirement for the controlling computer. The performance of the robust controller is evaluated via nonlinear simulation
Diagonalisation of a class of multivariable system via an actuator linearisation technique
Many multivariable (systems with many inputs/outputs) industrial processes can, to a
good degree of approximation, be modelled by a transfer function matrix, where all of
the interaction occurs in a matrix of constant coefficients. This reflects the fact that the
dynamics of the section in which the interaction occurs are very fast compared with the
other dynamics in the system. Examples of such systems include steel rolling mills and
boiler systems.
Such multivariable systems are relatively easy to design controllers for, since the
system may be diagonalised by an inverse of the constant gain matrix, followed by
suitable single-loop dynamic compensation. However, this approach depends on the
linearity of the dynamical elements in the system. Such a condition is voilated by
the presence of non-linear actuators, which are a feature of many industrial systems. The
presence of such actuators within a multivariable control system as described above can
cause very significant interaction problems, with associated degradation in performance,
particularly during transients.
This paper describes a straightforward technique, which is effective in linearising
typical non-linear industrial actuators, allowing diagonalisation to be effectively
achieved at all frequencies. The technique relies on a simple describing function analysis
and manifests itself as a time-varying linearising precompensator for each non-linear
actuator. A simple example is used to demonstrate the effectiveness of the method and it
is then shown in application with multivariable boiler and steel mill models
Diagonalisation of a class of multivariable system via an actuator linearisation technique
Many multivariable (systems with many inputs/outputs) industrial processes can, to a
good degree of approximation, be modelled by a transfer function matrix, where all of
the interaction occurs in a matrix of constant coefficients. This reflects the fact that the
dynamics of the section in which the interaction occurs are very fast compared with the
other dynamics in the system. Examples of such systems include steel rolling mills and
boiler systems.
Such multivariable systems are relatively easy to design controllers for, since the
system may be diagonalised by an inverse of the constant gain matrix, followed by
suitable single-loop dynamic compensation. However, this approach depends on the
linearity of the dynamical elements in the system. Such a condition is voilated by
the presence of non-linear actuators, which are a feature of many industrial systems. The
presence of such actuators within a multivariable control system as described above can
cause very significant interaction problems, with associated degradation in performance,
particularly during transients.
This paper describes a straightforward technique, which is effective in linearising
typical non-linear industrial actuators, allowing diagonalisation to be effectively
achieved at all frequencies. The technique relies on a simple describing function analysis
and manifests itself as a time-varying linearising precompensator for each non-linear
actuator. A simple example is used to demonstrate the effectiveness of the method and it
is then shown in application with multivariable boiler and steel mill models
Diagonalisation of a class of multivariable system via an actuator linearisation technique
Many multivariable (systems with many inputs/outputs) industrial processes can, to a
good degree of approximation, be modelled by a transfer function matrix, where all of
the interaction occurs in a matrix of constant coefficients. This reflects the fact that the
dynamics of the section in which the interaction occurs are very fast compared with the
other dynamics in the system. Examples of such systems include steel rolling mills and
boiler systems.
Such multivariable systems are relatively easy to design controllers for, since the
system may be diagonalised by an inverse of the constant gain matrix, followed by
suitable single-loop dynamic compensation. However, this approach depends on the
linearity of the dynamical elements in the system. Such a condition is voilated by
the presence of non-linear actuators, which are a feature of many industrial systems. The
presence of such actuators within a multivariable control system as described above can
cause very significant interaction problems, with associated degradation in performance,
particularly during transients.
This paper describes a straightforward technique, which is effective in linearising
typical non-linear industrial actuators, allowing diagonalisation to be effectively
achieved at all frequencies. The technique relies on a simple describing function analysis
and manifests itself as a time-varying linearising precompensator for each non-linear
actuator. A simple example is used to demonstrate the effectiveness of the method and it
is then shown in application with multivariable boiler and steel mill models