ressistors with small random offset in SIMULINK

Question

fima v 2020-5-27

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https://ww2.mathworks.cn/matlabcentral/answers/535894-ressistors-with-small-random-offset-in-simulink

评论： Walter Roberson 2020-6-8

采纳的回答： Walter Roberson

Hello , I want to have 10 resistors with a littles offset in resistance by random number arounk 1kohm

i have itried to use matlab simuling VAriable ressistor.

But i dont see how i enter there some random offset in the value.

Thanks.

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Walter Roberson 2020-5-28

I am having difficulty finding resistors in pure simulink. I find resistors in

RF Blockset
Simscape Electrical
Specialized Power Systems

fima v 2020-5-28

Hello Wolter , i am not sure regarding what exact simulink i am using, ithink i have here RF blockset.

could you please say on this platform how to define random argument in the resistor value?

Thanks.

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Answer 1

Walter Roberson 2020-5-29

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/535894-ressistors-with-small-random-offset-in-simulink#answer_442483

编辑：Walter Roberson 2020-5-29

在 MATLAB Online 中打开

SERIES_PARALLEL_RESISTORS.slx

The attached model is adapted (solver parameters updated) from the File Exchange Contribution

SERIES AND PARALLEL CIRCUITS, version 1.0.0, by Chaitanya Jambotkar

It happens to have 11 resistors from Specialized Power Systems (part of Simscape Electrical)

The resistances can be randomized using

for K = 1 : 11
    pn = sprintf('SERIES_PARALLEL_RESISTORS/R_%d', K);
    set_param(pn, 'Resistance', sprintf('%.5g', 1000 + randn(1)));
end

Here, SERIES_PARALLEL_RESISTORS is the model name, and each of the resistors happened to be named R_ followed by a number. Resistance is the name of the parameter used in SPS for resistance (some of the other forms of resistor in Simulink use 'R' as the name for the resistance.)

It was saved with R2020a (you did not indicate which version you are using.)

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Walter Roberson 2020-5-30

在 MATLAB Online 中打开

Easiest way: instead of using Simulink to Run the model, instead, In a MATLAB script (or function)

modname = 'SERIES_PARALLEL_RESISTORS19a'
open_system(modname);
for K = 1 : 11
    pn = sprintf('%s/R_%d', modname, K);
    set_param(pn, 'Resistance', sprintf('%.5g', 1000 + randn(1)));
end
sim(modname);

But it is also possible to set something up that will run in Simulink. I was not able to figure out how to set up the proper callbacks using the GUI, so once you have created the model, once do the following at the command line:

modname = 'SERIES_PARALLEL_RESISTORS19a'
open_system(modname);
for K = 1 : 11; set_param(sprintf('%s/R_%d', modname, K), 'InitFcn', 'set(gcbh, ''Resistance'', string(1000+randn()))'); end

Now you can save the model at the Simulink level.

Once the above is done, each time you Run the model in Simulink, each of the resistors will run initialization code that sets its resistance randomly.

You can of course change the formula 1000+randn() to whatever is appropriate for your purposes.

The same technique can be used with resistors from other domains such as RF Blocksets, but you may need to change the name of the parameter from Resistance to R

Walter Roberson 2020-6-2

在 MATLAB Online 中打开

I posted the exact code that I used for the randomization.

I started from Chaitanya Jambotkar's existing model just to have something with resistors in it to work with.

Here is some example code that creates and positions DC Voltage Sources and Resistors automatically, and configures them to initialize their parameters randomly at run time. It also shows automatically connecting the output of a DC Voltage to the input of a Resistor.

I did not attempt to build the flash ADC for you; I am just giving you the tools to proceed with.

modname = 'test_model';
N_voltage_sources = 15;
N_resistor = 15;
SL_powergui_block = 'powerlib/powergui';
SL_DCV_block = 'powerlib/Electrical Sources/DC Voltage Source';
SL_resistor_block = 'powerlib/Elements/Series RLC Branch';
DCV_xbase = 50;
DCV_ybase = -150;    %yes, negative!
DCV_width = 20;
DCV_height = 35;
DCV_yspacing = 75;
R_xbase = 125;
R_ybase = DCV_ybase;
R_width = 80;
R_height = 35;
R_yspacing = DCV_yspacing;
modfile = sprintf('%s.slx', modname);
if exist(modfile, 'file'); delete(modfile); end
try
    h = new_system(modname);
catch
    Simulink.BlockDiagram.deleteContents(modname);
end
add_block(SL_powergui_block, sprintf('%s/powergui', modname));   %required solver component
DCV_blocknames = cell(N_voltage_sources, 1);
DCV_ports = cell(N_voltage_sources, 1);
R_blocknames = cell(N_resistor, 1);
R_ports = cell(N_resistor, 1);
xbase = DCV_xbase;
xend = xbase + DCV_width - 1;
for K = 1 : N_voltage_sources
    ybase = DCV_ybase + (K-1)*DCV_yspacing;
    yend = ybase + DCV_height;
    blockname = sprintf('%s/DCV_%d', modname, K);
    DCV_blocknames{K} = blockname;
    add_block(SL_DCV_block, blockname, ...
        'Position', [xbase, ybase, xend, yend], ...
        'InitFcn', 'set(gcbh, ''Amplitude'', string(0.5+0.1*randn()))' );
    DCV_ports{K} = get_param(blockname, 'PortHandles');
end
xbase = R_xbase;
xend = xbase + R_width - 1;
for K = 1 : N_resistor
    ybase = R_ybase + (K-1)*R_yspacing;
    yend = ybase + R_height;
    blockname = sprintf('%s/R_%d', modname, K);
    R_blocknames{K} = blockname;
    add_block(SL_resistor_block, blockname, 'BranchType', 'R', ...
        'Position', [xbase, ybase, xend, yend], ...
        'InitFcn', 'set(gcbh, ''Resistance'', string(1000+randn()))');
    R_ports{K} = get_param(blockname, 'PortHandles');
end
for K = 1 : N_voltage_sources
    add_line(modname, DCV_ports{K}.RConn, R_ports{K}.LConn);
end
save_system(modname);
open_system(modname);

Walter Roberson 2020-6-5

在 MATLAB Online 中打开

I extended the code to show adding Voltage Measurements, Current Measurements, and Scopes.

The positioning of the Voltage Measurements and Current Measurements, and Scope,could use some improvement -- I positioned them too closely together, so the connecting lines do not show up well.

I have not worked out Op Amps yet. Do you actually want Op Amps, or do you want comparitors? What should the output be for the case where the comparison succeeds?

modname = 'test_model';
N_voltage_sources = 15;
N_resistor = 15;
N_scopes = 1;
N_VM = 1;
N_CM = 1;
SL_powergui_block = 'powerlib/powergui';
SL_DCV_block = 'powerlib/Electrical Sources/DC Voltage Source';
SL_resistor_block = 'powerlib/Elements/Series RLC Branch';
SL_VM_block = 'powerlib/Measurements/Voltage Measurement';
SL_CM_block = 'powerlib/Measurements/Current Measurement';
SL_Scope_block = 'simulink/Sinks/Scope';
DCV_xbase = 50;
DCV_ybase = -150;    %yes, negative!
DCV_width = 20;
DCV_height = 35;
DCV_yspacing = 75;
R_xbase = 125;
R_ybase = DCV_ybase;
R_width = 80;
R_height = 35;
R_yspacing = DCV_yspacing;
modfile = sprintf('%s.slx', modname);
if exist(modfile, 'file'); delete(modfile); end
try
    h = new_system(modname);
catch
    Simulink.BlockDiagram.deleteContents(modname);
end
add_block(SL_powergui_block, sprintf('%s/powergui', modname));   %required solver component
DCV_blocknames = cell(N_voltage_sources, 1);
DCV_ports = cell(N_voltage_sources, 1);
R_blocknames = cell(N_resistor, 1);
R_ports = cell(N_resistor, 1);
VM_blocknames = cell(N_VM, 1);
VM_ports = cell(N_VM, 1);
CM_blocknames = cell(N_CM, 1);
CM_ports = cell(N_CM, 1);
Scope_blocknames = cell(N_scopes, 1);
Scope_ports = cell(N_scopes, 1);
xbase = DCV_xbase;
xend = xbase + DCV_width - 1;
for K = 1 : N_voltage_sources
    ybase = DCV_ybase + (K-1)*DCV_yspacing;
    yend = ybase + DCV_height;
    blockname = sprintf('%s/DCV_%d', modname, K);
    DCV_blocknames{K} = blockname;
    add_block(SL_DCV_block, blockname, ...
        'Position', [xbase, ybase, xend, yend], ...
        'InitFcn', 'set(gcbh, ''Amplitude'', string(0.5+0.1*randn()))' );
    DCV_ports{K} = get_param(blockname, 'PortHandles');  %- (L) || + (R)
end
xbase = DCV_xbase + 50;
xend = xbase + R_width - 1;
for K = 1 : N_resistor
    ybase = R_ybase + (K-1)*R_yspacing;
    yend = ybase + R_height;
    blockname = sprintf('%s/R_%d', modname, K);
    R_blocknames{K} = blockname;
    add_block(SL_resistor_block, blockname, 'BranchType', 'R', ...
        'Position', [xbase, ybase, xend, yend], ...
        'InitFcn', 'set(gcbh, ''Resistance'', string(1000+randn()))');
    R_ports{K} = get_param(blockname, 'PortHandles');  %L || R
end
xbase = R_xbase + 50;
for K = 1 : N_VM
    ybase = R_ybase + (K-1)*R_yspacing;
    yend = ybase + R_height;
    blockname = sprintf('%s/VM_%d', modname, K);
    VM_blocknames{K} = blockname;
    add_block(SL_VM_block, blockname, ...
        'Position', [xbase, ybase, xbase + 35, yend]);
    VM_ports{K} = get_param(blockname, 'PortHandles');  % + - || outport
end
xbase = R_xbase + 100;
for K = 1 : N_CM
    ybase = DCV_ybase + (K-1)*R_yspacing;
    yend = ybase + R_height;
    blockname = sprintf('%s/CM_%d', modname, K);
    CM_blocknames{K} = blockname;
    add_block(SL_CM_block, blockname, ...
        'Position', [xbase, ybase, xbase+35, yend]); % + || outport -
    CM_ports{K} = get_param(blockname, 'PortHandles');
end
xbase = R_xbase + 150;
for K = 1 : N_scopes
    ybase = DCV_ybase + (K-1)*R_yspacing;
    yend = ybase + R_height;
    blockname = sprintf('%s/Scope_%d', modname, K);
    Scope_blocknames{K} = blockname;
    add_block(SL_Scope_block, blockname, ...
        'Position', [xbase, ybase, xbase + 35, yend], ...
        'NumInputPorts', '2');
    Scope_ports{K} = get_param(blockname, 'PortHandles');
end
for K = 1 : N_voltage_sources
    add_line(modname, DCV_ports{K}.RConn, R_ports{K}.LConn);
end
add_line(modname, R_ports{1}.RConn, VM_ports{1}.LConn(1));
add_line(modname, VM_ports{1}.LConn(2), CM_ports{1}.LConn);
add_line(modname, CM_ports{1}.RConn, DCV_ports{1}.LConn);
add_line(modname, VM_ports{1}.Outport, Scope_ports{1}.Inport(1));
add_line(modname, CM_ports{1}.Outport, Scope_ports{1}.Inport(2));
save_system(modname);

fima v 2020-6-5

编辑：fima v 2020-6-5

Hello Walter, My comperator needs to have input noise 10nV/sqrt(Hz), bandwidth(100MHZ) ,amplitude(200) , the theshhold of the comperator is 0.6v.

VDD=1V VCC=0V .

so if for example (V_plus-V_minus)*Amplitude>0.6 the output is 1V else 0V.

I have tried to used the simscape bandlimited component to achieve those properties.

but then i couldnt connect with the other components as shown above.

If you could make N such comparators , it would be great.

Thanks you very much.

Walter Roberson 2020-6-8

There does not appear to be any one block to implement what you describe. See however https://www.mathworks.com/help/physmod/sps/examples/op-amp-with-noise.html

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Answer 2

Fangjun Jiang 2020-5-27

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/535894-ressistors-with-small-random-offset-in-simulink#answer_440724

编辑：Fangjun Jiang 2020-5-28

This "Variable Resistor" is not the right one to use. This "Variable Resistor" represents a physical variable resistor in the lab where you can move a handle or turn a knob to adjust the value of the resistor. The "PS" port of this block can be connect to a motor (for example) to move the handle or turn the knob thus change the resistor.

To implement what you want, you just need to set "R=10e3-10+20*rand(10,1)" in workspace and drop 10 regular resistor blocks in your model, set the parameter for the first resistor to be R(1), ... and the last one to be R(10).