Abstract
In this paper, a new multi centralized control system method proposed for unstable systems using gain and phase-margin specifications. Effective relative gain array based loop interactions are considered to design of off-diagonal controllers. Unstable first order plus time delay models are changed to second order plus time delay model without losing model identity to design a two degree of freedom PID diagonal controllers. Equivalent transfer function method Xiong et al. (J Process Control 17(8):665–673, 2007) is extended to unstable system. Simulation results show that; designed robust control system gives good response and control action. Performance evaluation is done by integral absolute error criteria.
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Abbreviations
- EETRA:
-
Effective energy transmission ratio array
- ERGA:
-
Effective relative gain array
- EOTF:
-
Effective open-loop transfer function
- ETF:
-
Effective transfer function
- GPM:
-
Gain and phase margin
- IAE:
-
Integral absolute error
- ISE:
-
Integral square error
- ISE:
-
Multi-centralized control system
- MIMO:
-
Multi-input multi-output
- PI:
-
Proportional integral
- PID:
-
Proportional integral derivative
- PTM:
-
Process transfer function matrix
- RFA:
-
Relative frequency array
- RGA:
-
Relative gain array
- SISO:
-
Single-input single-output
- SOPTD:
-
Second order plus time delay
- TITO:
-
Two-input two-output
- UFOPTD:
-
Unstable first order plus time delay
- \(\Omega \) :
-
Critical frequency matrix
- E :
-
Effective energy transmission ratio array
- \(\otimes \) :
-
Hadamard multiplication
- \(\Omega \) :
-
Critical frequency array
- \(\Phi \) :
-
Effective relative gain array
- \(\Gamma \) :
-
Relative frequency array
- \(\Lambda \) :
-
Relative gain array
- \(u_{i}\) :
-
Controller out-put signals
- \(y_{i}\) :
-
Process response
- \(g_{p,ij}(s)\) :
-
Transfer function
- \(g_{ij}(0)\) :
-
Steady state gain
- \(\theta _{ij}\) :
-
Time delay
- \(a_{1,ij}\) :
-
Process time constant
- \(a_{2,ij}\) :
-
Process 2nd order polynomial time constant
- \(e_{i}\) :
-
Error signals
- \(r_{i}\) :
-
Reference signals
- \(e_{ij}\) :
-
Energy transmission ratio
- \(\omega _{c,ij}\) :
-
Critical frequency
- \(\omega _{u,ij}\) :
-
Ultimate frequency
- \(g_{ij}^0 (j\omega )\) :
-
Steady state gain of the ETF
- \(\lambda _{ij}\) :
-
Relative gain array element
- \(\gamma _{ij}\) :
-
Relative frequency array element
- \(\odot \) :
-
Hadamard division
- \(\hat{g}_{pij}(s)\) :
-
Equivalent transfer function element
- \(\hat{g}_{pij}(0)\) :
-
ETF steady state gain
- \(\hat{\theta }_{ij}\) :
-
ETF time delay
- \(\phi _m\) :
-
Phase margin
- \(\omega _m\) :
-
Gain margin frequency
- \(\omega _p\) :
-
Phase margin
- \(s_{w}\) :
-
Set-point weight
- \(G_{p}(s)\) :
-
Process transfer function
- \(G_{c}(s)\) :
-
Controller transfer function
- \(\hat{G}_{p}(0)\) :
-
ETF gain matrix
- \(\dot{K}_{p,ij}\) :
-
2DoF PID gain
- \(A_m\) :
-
Gain margin matrix
- \(K_{p,ij}\) :
-
PID proportional gain
- \(K_{1,ij}\) :
-
Inner-loop P controller
- \(K_{i,ij}\) :
-
Integral gain
- \(K_{d,ij}\) :
-
Derivative gain
- 2DoF:
-
Two degree of freedom
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Besta, C.S. Multi-centralized control system design based on equivalent transfer functions using gain and phase-margin specifications for unstable TITO process. Int. J. Dynam. Control 6, 817–826 (2018). https://doi.org/10.1007/s40435-017-0345-3
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DOI: https://doi.org/10.1007/s40435-017-0345-3