Ltiview and negative step response of a linear system

• MATLAB
• dRic2
In summary, The speaker's professor provided them with code to evaluate the response of a linear system to a step increase in input variables, but they are having trouble getting the response for a negative step. They are advised to check the MathWorks site for help, and if that doesn't work, to ask their professor for assistance. It is noted that in a linear system, the response to a negative step is the negation of the response to a positive step of the same size.
dRic2
Gold Member
Hi, my professor gave me I code where he used to evaluate the answer of a linear system to a step increase in the input variables like this:

Code:
MySystem = ss(A, B, C, D);
ltiveiw('step', MySystem, 'r-', 300);

My problem is that with this code I get the response only for a positive step. I'd like to see what happens for a negative step as well, but I can't figure out how to do it.

Thanks
Ric

Check the MathWorks site on these functions you might spot something to help you there.

I did find this reference creating a state space that is input to the lti view function

https://www.mathworks.com/help/control/ref/ss.html
This may be where you can define your params.

If not check with your prof if possible.

Thanks, I'll keep searching.

Last edited:
If the system is linear, the response to a negative step is the negation of the response to a positive step of the same size.

dRic2

1. What is Ltiview and how is it used to analyze linear systems?

Ltiview is a tool used in control systems engineering to visualize and analyze the response of a linear system to different inputs. It allows for the examination of the system's time-domain and frequency-domain characteristics, such as step response, impulse response, and frequency response.

2. How is the negative step response of a linear system different from the positive step response?

A positive step response refers to the output of a linear system when the input is a unit step function, starting at time t=0. The output increases from 0 to a steady-state value. In contrast, a negative step response refers to the output when the input is a negative unit step function, starting at t=0. In this case, the output decreases from 0 to a steady-state value.

3. What information can be derived from the negative step response of a linear system?

The negative step response of a linear system provides information about the system's stability and its ability to reject disturbances. It can also indicate the presence of any overshoot or undershoot in the system's response and the time it takes for the output to reach its steady-state value.

4. How do we interpret the Ltiview plot of a negative step response?

The Ltiview plot of a negative step response shows the output of the system over time. The initial value of the output is 0, and as time progresses, the output decreases towards its steady-state value. The slope of the plot indicates the speed at which the output is changing, and the steady-state value can be used to determine the overall behavior of the system.

5. Can the negative step response of a linear system be improved or modified?

Yes, the negative step response of a linear system can be improved or modified by adjusting the system's parameters, such as gain, time constants, and poles and zeros. These modifications can help to improve the system's stability, response time, and rejection of disturbances.

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