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# Deriving tranfer function of ramp response out of a plot

## Deriving tranfer function of ramp response out of a plot

(OP)
Hi everyone,

The problem:
The first order ramp unit response is shown in the graph below. Determine:
1. The transfer function.
2. Plot the error function e(t) then determine its maximum magnitude and the time

My solution:
G(s)=(1/T)/(S+1/T) ......... G(s): Standard first order T.F, , T (or tau) is the time constant.
T is the time to reach 63,2% of the final output value.

I know how to solve this if the input was the step unit as shown in the graph:

But that is not my case in ramp unit. How can I get the time constant while the curve is going upward forever?
The only thing I knew that if I plot the error function, then its steady state value will be T (tau or time constatnt). Any help?
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