How to change the axis limits?

Hi, I have been trying to reverse engineer a vehicle model and to check if I get back a similar response by creating my own model. Now, my model has got the response as expected but with a different y-axis limits. So I'm trying to change the limits as in the model's response that was reverse engineered to make the outputs seem exactly the same.

But I was not able to do that since when I changed the y-axis limits using the command- axis([xmin xmax ymin ymax]) ,I get a different response.

For instance, the y-axis limits in the response of my model is [-2 to 14]*10^-4 and the y-axis limits in the response of the model being reverse engineered is [-14 to 4]*10^-4, which is the limit I want to use for my model. Could you please help me with this.

[Jan]

The question is not clear.

Answer 1

[Amit]

From the plots you posted, I can see that your output and your expected outputs are different. The original plot's steady output is ~0 after time 5 secs. However, your created plots steady value is ~10e-4. Possibly, your reverse engineered model is not the same what was used to plot the original one.

[Priya]

Thanks very much for your reply. Since I have just started off with matlab, I have a problem in identifying the mistakes and finding difficult to rectify it. Could you please suggest any methods of doing this especially while reverse engineering a model.

[Amit]

Reverse Engineering a model is tricky. There are (to my thought) 2 ways one can try: #1 You know something about the model and all you're missing is the parameters. Then you can fit your model with the data (in your case, the original plot) with the model and find the parameters.

#2 You go blind and start fitting the data with all and many functions you know. This would be challenging. This is similar to brute forcing a password.

[Amit]

I'd say recheck the equation you retrieved from Simulink and check if it is anyhow different than what you have used. If your equation and the one you obtained from simulink are same, they would result in same output.

Moreover, 'small' is a very relative term.

[Priya]

Thank you.

Answer 2

[Azzi Abdelmalek]

ylim([-14  4]*1e-4)

[Priya]

Thanks for your reply. But I have tried this already and still I could not make it.

[Andreas Goser]

Then please create and post an example.