symReadSSCParameters

Load parameters from Simscape component

Syntax

[names,values,units] = symReadSSCParameters(componentName)

Description

[names,values,units] = symReadSSCParameters(componentName) returns cell arrays containing the names, values, and units of all parameters from the Simscape™ component called componentName.

Examples

Parameters of Simscape Component

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

end

Load 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)

Input Arguments

componentName — Simscape component name

file name enclosed in single quotes

Simscape 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'

Output Arguments

names — Names of all parameters of Simscape component

cell array

Names of all parameters of a Simscape component, returned as a cell array.

Data Types: cell

values — Values of all parameters of Simscape component

cell array

Values of all parameters of a Simscape component, returned as a cell array.

Data Types: cell

units — Units of all parameters of Simscape component

cell array

Units of all parameters of a Simscape component, returned as a cell array.

Data Types: cell