how to use stepinfo function with non-zero initial value

i am trying to get various step response data like rise time , overshoot, setttling time, etc.. using stepinfo function for my time series data. i am getting appropriate values when step data is starting from 0 to postive value. But unable to use stepinfo function for data with some non-zero initial value or step is negative. any suggestions would be highly appreciated.

Answer 1

[Shresth Sharma]

Hi,

It is my understanding that you are not using a transfer function in ‘stepinfo’, rather trying to use a variable containing array of negative values. I tried in MATLAB 2019b, with a small set of negative valued data for a time period and was able to get the result using ‘stepinfo’. These are the examples I tried:

 stepinfo([-2 -3 -4 -5 -6],1:1:5) 
 stepinfo([-2 -3 -4 -5 0],1:1:5) 
 stepinfo([-2 -4 -4 -5 0],1:1:5) 

You mentioned you are using timeseries data, it would be of much help to resolve if you can give more info about the type of data you are using.

You can refer to the documentation link of ‘stepinfo’ in MATLAB for more insight.

https://www.mathworks.com/help/ident/ref/stepinfo.html#mw_e60d4d41-8dff-4785-aa55-1c2423febe07

[Leelakrishna Jonnadula]

Thank you for your time and answering my question Shresth! I have attached Data.mat file for your reference. This has time series data of verious signals. Column-1 is time and Column-2 through 7 are time series step response data in various iterations. I am trying to find the step response data ( rise time, overshoot, settling time, etc.. ) of these outputs. let me know if you have any questions. It would be highly appreciated if you could reply in a day.

[Leelakrishna Jonnadula]

I will be glad if anybody has answers for my question

[Shresth Sharma]

Hi,

It is my understanding that the first column of the data is time and the rest columns from 2 through 7 is the data and you are trying to calculate the reponse time for each column. You can use the following function to calculate the reponse for each column for the time series

stepinfo(data(:,6),data(:,1))

Here you just have to change the value for the response data of the column you need to calculate. Hope this solves your problem

[Leelakrishna Jonnadula]

Thank you for your reply. my question was how to use stepinfo function for non-zero initial value or final value is less than initial value. stepinfo function returns improper values in any of the these cases. could you please run stepinfo function for the data I attached and see whether results make sense to you or not. Thanks again for helping me on this.