Simulink Example File Issue - Anti-Lock Braking Using Extremum Seeking Control

I was running the code for the "Anti-Lock Braking Using Extremum Seeking Control" example (Anti-Lock Braking Using Extremum Seeking Control) and noticed that the results do not match what is shown in the documentation plots.

I simply copy and pasted the code as written in the documentation into the command window and made no modifications otherwise.The documentation plot screenshots seem correct and what should be observed but is not seen in the simulation.

For example, the objective function mu should converge to the optimum shown in the linked documentation page, instead it demonstrates an oscillatory behaviour. I have attached scope outputs for the default 6 seconds and then with increased simulation time to 50 seconds for reference. The velocity plots similarly do not match the expected performance shown in the example documentation page.

I can't see any obvious issues in the documentation or in the code, and neither did I see any notable differences in the associated Matlab Video (ABS ESC Example Video) that also produced the same results as in the documentation.

Appreciate any insight and recommendations!

Answer 1

[Nirupama]

Hi @Adam,

I tried running the same example in MATLAB R2022b as mentioned in the following documentation: https://www.mathworks.com/help/releases/R2022b/slcontrol/ug/anti-lock-braking-using-extremum-seeking-control.html

The results obtained via simulation match with the ones present in the documentation.

I checked the model/block parameters and the MATLAB live script of the example in MATLAB R2023a and R2023b. The results differ from what is mentioned in the documentation.

I tried to compare the models across the 3 releases (R2022b, R2023a and R2023b) and found no obvious difference. Likewise the documentation for all the 3 releases seem to be exactly the same.

For now, I would recommend you to use MATLAB R2022b to explore around this example.

You can also try comparing the model and parameters of the example across the 3 releases of MATLAB to see if you can spot the root cause of the issue.

Hope this helps!

[Adam]

Thanks! I tried running in R2022b and saw the correct performance matching the documentation like you did. I'll continue working through it and see if I can find what was changed across versions. In the meantime this will work.

Thanks again!