Load variables from Simscape component
[ returns
cell arrays containing the names, values, and units of all variables
from the Simscape™ component called names,values,units]
= symReadSSCVariables(componentName)componentName.
[
returns the names as symbolic functions of variable names,values,units]
= symReadSSCVariables(componentName,'ReturnFunctions',true)t.
Load the names, values, and units of the variables of a Simscape component.
Suppose you have the Simscape component friction.ssc in
your current folder.
type('friction.ssc');component friction < foundation.mechanical.rotational.branch
parameters
brkwy_trq = { 25, 'N*m' }; % Breakaway friction torque
Col_trq = { 20, 'N*m' }; % Coulomb friction torque
visc_coef = { 0.001, 'N*m*s/rad' }; % Viscous friction coefficient
trans_coef = { 10, 's/rad' }; % Transition approximation coefficient
vel_thr = { 1e-4, 'rad/s' }; % Linear region velocity threshold
end
parameters (Access=private)
brkwy_trq_th = { 24.995, 'N*m' }; % Breakaway torque at threshold velocity
end
function setup
% Parameter range checking
if brkwy_trq <= 0
pm_error('simscape:GreaterThanZero','Breakaway friction torque' )
end
if Col_trq <= 0
pm_error('simscape:GreaterThanZero','Coulomb friction torque' )
end
if Col_trq > brkwy_trq
pm_error('simscape:LessThanOrEqual','Coulomb friction torque',...
'Breakaway friction torque')
end
if visc_coef < 0
pm_error('simscape:GreaterThanOrEqualToZero','Viscous friction coefficient')
end
if trans_coef <= 0
pm_error('simscape:GreaterThanZero','Transition approximation coefficient')
end
if vel_thr <= 0
pm_error('simscape:GreaterThanZero','Linear region velocity threshold')
end
% Computing breakaway torque at threshold velocity
brkwy_trq_th = visc_coef * vel_thr + Col_trq + (brkwy_trq - Col_trq) * ...
exp(-trans_coef * vel_thr);
end
equations
if (abs(w) <= vel_thr)
% Linear region
t == brkwy_trq_th * w / vel_thr;
elseif w > 0
t == visc_coef * w + Col_trq + ...
(brkwy_trq - Col_trq) * exp(-trans_coef * w);
else
t == visc_coef * w - Col_trq - ...
(brkwy_trq - Col_trq) * exp(-trans_coef * abs(w));
end
end
endLoad the names, values, and units of the variables of
the component friction.ssc.
[names,values,units] = symReadSSCVariables('friction.ssc');In this example, all elements of the resulting cell arrays are scalars. You can convert the cell arrays to symbolic vectors.
names_sym = cell2sym(names)
names_sym = [ t, w]
values_sym = cell2sym(values)
values_sym = [ 0, 0]
Create individual symbolic variables from the elements of the cell array
names in the MATLAB® workspace. This command creates the symbolic variables
t and w as sym objects in the
workspace.
syms(names)
Load the names of the variables of a Simscape component
while converting them to symbolic functions of the variable t.
Suppose you have the Simscape component source.ssc in
your current folder.
type('source.ssc');component source
% Electrical Source
% Defines an electrical source with positive and negative external nodes.
% Also defines associated through and across variables.
nodes
p = foundation.electrical.electrical; % :top
n = foundation.electrical.electrical; % :bottom
end
variables(Access=protected)
i = { 0, 'A' }; % Current
v = { 0, 'V' }; % Voltage
end
branches
i : p.i -> n.i;
end
equations
v == p.v - n.v;
end
endLoad the names of the variables of the component
source.ssc by setting
'ReturnFunctions' to true.
[names,~,~] = symReadSSCVariables('source.ssc','ReturnFunctions',true);
In this example, all elements of the resulting cell arrays are scalars. You can convert the cell arrays to symbolic vectors.
names_symfun = cell2sym(names)
names_symfun = [ i(t), v(t)]
Create individual symbolic functions from the elements of the cell array
names in the MATLAB workspace. This command creates the symbolic functions
i and v as symfun objects, and their
variable t as a sym object in the
workspace.
syms(names)
componentName — Simscape component nameSimscape component name, specified as a file name enclosed
in single quotes. The file must have the extension .ssc.
If you do not provide the file extension, symReadSSCVariables assumes
it to be .ssc. The component must be on the MATLAB path
or in the current folder.
Example: 'MyComponent.ssc'
names — Names of all variables of Simscape componentNames of all variables of a Simscape component, returned as a cell array.
Data Types: cell
values — Values of all variables of Simscape componentValues of all variables of a Simscape component, returned as a cell array.
Data Types: cell
units — Units of all variables of Simscape componentUnits of all variables of a Simscape component, returned as a cell array.
Data Types: cell