Page 889 - Mechatronics with Experiments

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MATLAB , SIMULINK , STATEFLOW, AND AUTO-CODE GENERATION 875
hd
mode
h
Scope 1
Supervisory controller Scope 2
1
Ka Kv + 1/A
+ s
Mode 1: Relay with Amplifier Valve gain: Valve – Area Integrator
– hysteresis DAC: Quantizer DAC: ZOH
Desired liquid Multiport 10-bit Flow rate/current Add
level Add 1 switch logic
K2
1/R
Mode 2: Gain
Model info: This model simulates a liquid level control problem. Resistance gain
Simulink models a three different controllers,
A supervisory controllers modeled in stateflow selects
K3 which mode (one of three) the controller should operate.
Mode 3: Gain 1
1
ADC: Quantizer Sensor: Liquid level
10-bit
FIGURE A.45: Liquid level control example using a Stateflow chart for supervisory control
logic.
if (err < err_th1) % Supervisory control logic: select
controller mode.
control_mode = 1;
elseif (err >= err_th1 and err < err_th2 )
control_mode = 2;
elseif (err >= err_th2)
control_mode = 3;
end

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Figures A.45 and A.46 show the new Simulink block diagram of the liquid level
control system as well as the Stateflow chart for this very simple supervisory controller.
A simulation result is shown in Figure A.47. The simulation was run for the following

FIGURE A.46: Liquid level control example using a Stateflow chart for supervisory control
logic: Stateflow chart details. This Stateflow chart implements the supervisory logic shown in
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the MATLAB text programming language above.