Help with 'Matrix Interpolation' Block in Simulink

I’m trying to use the Matrix Interpolation block (https://www.mathworks.com/help/simulink/ref_extras/matrixinterpolation.html) in Simulink, and I’d appreciate any guidance on how to set it up for my use case.

I have three 4×4 matrices—A1, A2, and A3—which correspond to speeds of 0 m/s, 8 m/s, and 15 m/s, respectively. I would like to perform linear interpolation for all 16 elements of the matrix element-wise between these matrices based on a varying speed input, using breakpoints at 0, 8, and 15 m/s.

Could someone please advise how to configure the Matrix Interpolation block to achieve this interpolation?

Answer 1

[Abhas]

Hi @Shashank Verma,

To interpolate your three 4×4 matrices A₁, A₂, A₃ over speeds 0, 8, 15 m/s using Simulink’s Matrix Interpolation block, follow these steps:

• Concatenate matrices into "TableData(:,:,1:3)".
• Use breakpoints [0 8 15], "InterpolateDimension = 1", Linear + Clip.
• Use "Prelookup" to compute "k1/f1" from speed.
• Connect "Prelookup" outputs to "Matrix Interpolation block" for element‑wise interpolation.

The sample code to reflect the above steps is:

%% Define breakpoints and dummy matrices
speeds = [0, 8, 15];
A1 = [0 1 2 3; 1 2 3 4; 2 3 4 5; 3 4 5 6];
A2 = [6 5 4 3; 5 4 3 2; 4 3 2 1; 3 2 1 0];
A3 = [1 1 1 1; 2 2 2 2; 3 3 3 3; 4 4 4 4];
TableData = cat(3, A1, A2, A3);  % => size 4×4×3

%% Create Simulink model
model = 'interpMatrixDemo';
new_system(model);
open_system(model);

% Add blocks
add_block('simulink/Sources/In1',          [model '/Speed']);
add_block('simulink/Lookup Tables/Prelookup', [model '/Prelookup']);
add_block('simulink/Lookup Tables/Interpolation Using Prelookup', [model '/MatrixInterp']);
add_block('simulink/Sinks/Out1',           [model '/Out']);

% Wire up
add_line(model,'Speed/1','Prelookup/1');
add_line(model,'Prelookup/1','MatrixInterp/1'); % k1 (index)
add_line(model,'Prelookup/2','MatrixInterp/2'); % f1 (frac)
add_line(model,'MatrixInterp/1','Out/1');

% Configure Prelookup
set_param([model '/Prelookup'], ...
    'BreakpointsSpecification','Explicit values', ...
    'BreakpointsValues','[0 8 15]', ...
    'OutputSelection','Index and fraction', ...
    'ExtrapMethod','Clip');

% Configure Matrix Interpolation
set_param([model '/MatrixInterp'], ...
    'NumberOfTableDimensions','1', ...
    'TableSpecification','Explicit values', ...
    'TableSource','Dialog', ...
    'TableValue',mat2str(TableData), ...
    'InterpMethod','Linear', ...
    'ExtrapMethod','Clip');

% Save model
save_system(model);
open_system(model);

You may refer to the below documentation links to know more about the same:

• https://www.mathworks.com/help/simulink/ref_extras/matrixinterpolation.html
• https://www.mathworks.com/matlabcentral/answers/2104521-any-good-resources-on-how-to-use-matrix-interpolation-block-in-simulink

I hope this helps!

[Shashank]

Thanks a lot. This works for me.