Laplace from symbolic to tf tooling.

Hello, I want to use the function stepinfo().

I understood from different posts that "Control System Toolbox objects and Symbolic Math Toolbox objects are inherently incompatible" (@Star Strider). But in all the responses I saw in the forum, the transfer function was already available.

How do I get the the transfer function from a non laplacian function?

The faulty code:

syms t
k = 3
T2 = 10
c = 2

time_vector = [1:1:50];
y =@(t) k*(1.-exp(-t/T2))*c
laplace(y)
results = y(time_vector);
laplace(y)

Error: Check for missing argument or incorrect argument data type in call to function 'laplace'.

Answer 1

[Walter Roberson]

syms s t 
k = 3

k = 3

T2 = 10

T2 = 10

c = 2

c = 2

time_vector = [1:1:50];
y = @(t) k*(1.-exp(-t/T2))*c

y = function_handle with value:
    @(t)k*(1. -exp(-t/T2))*c

Y = laplace(y(t), t, s)

Y = 

[n, d] = numden(Y)

n = 

6

d = 

yTF = tf(sym2poly(n), sym2poly(d))

yTF =
 
      6
  ----------
  10 s^2 + s
 
Continuous-time transfer function.

step(yTF, time_vector)

[am]

I get the below error unfortunately:

'tf' requires one of the following:

Control System Toolbox

DSP System Toolbox

Model Predictive Control Toolbox

RF Toolbox

Signal Processing Toolbox

[Walter Roberson]

The symbolic transfer function is in Y . What do you want to do with it now that you have it?

It seems odd to ask about the compatibility of Control Systems Toolbox and Symbolic toolbox if you do not have the Control System Toolbox ??

[am]

Thank you, I missed you just needed to install it.

I want to see the stepinfo(), the raise time, settling time etc.

Now I do not have errors, I do have a plot but no step responses. How can I visualise the stepinfo()?

syms s t
k = 3
T2 = 10
c = 2
time_vector = [1:1:50];

y = @(t) k*(1.-exp(-t/T2))*c
results = y(time_vector);

plot(time_vector,results)
hold on
grid on
xlabel('Time')
ylabel('Temperature')


Y = laplace(y(t),t, s)
[n,d] = numden(Y)

yTF = tf(sym2poly(n), sym2poly(d))
stepinfo(yTF)

[am]

Sorry to recomment, but I am unsure you get a pling if one simply edits :).

How can I visualise the stepinfo() please?