Load parameters from Simscape component
[ returns
cell arrays containing the names, values, and units of all parameters
from the Simscape™ component called names,values,units]
= symReadSSCParameters(componentName)componentName.
Load the names, values, and units of the parameters 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 parameters of
the component friction.ssc.
[names,values,units] = symReadSSCParameters('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 = [ Col_trq, brkwy_trq, brkwy_trq_th, trans_coef, vel_thr, visc_coef]
values_sym = cell2sym(values)
values_sym = [ 20, 25, 4999/200, 10, 1/10000, 1/1000]
Create individual symbolic variables from the elements of the cell array
names in the MATLAB® workspace. This command creates the symbolic variables
Col_trq, brkwy_trq,
brkwy_trq_th, trans_coef,
vel_thr, and visc_coef as
sym objects 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, symReadSSCParameters 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 parameters of Simscape componentNames of all parameters of a Simscape component, returned as a cell array.
Data Types: cell
values — Values of all parameters of Simscape componentValues of all parameters of a Simscape component, returned as a cell array.
Data Types: cell
units — Units of all parameters of Simscape componentUnits of all parameters of a Simscape component, returned as a cell array.
Data Types: cell