System Parameter Estimation with Projection Algorithm

[rfrederic]

I am recently trying to identify system parameters with projection algorithm, but faced a problem, and the dynamic model is the following:
$\ddot{y}(t)+a\cdot\dot{y}(t)=b\cdot e(t)$

The true value of $a$ is $2.8$, $b$ is $0.1$.

While inputing volt $e(t)=12sin(2\pi t)+5sin(2t)$, I can get a good result showed in 1c_PA_r0.1_a0.jpg, and both of a and b are convergent to the true value.

But while $e(t)=24$, the result showed in doesn't seem right.

My question is: will $e(t)$ affect the convergence of parameters? And why?
By the way, I had also tried to use the least square to identify parameters while $e(t)=24$, the result also seems good.

 

[anorlunda]

will e(t)e(t)e(t) affect the convergence of parameters? And why?

Why not? Different e(t) are different cases. There is no reason to expect that all cases are equally easy to identify.