Integral of outputs of StateResponse[ ]?

Questions
1

Hi,
I have a small question. I am simulating a nonlinear system

NS.PNG
NS.PNG555×122 14.7 KB

I am interested in plotting the following

NS2.PNG

I dont know how to integrate the state x2 according to figure 2. My code is below

Clear[x];
nsys = NonlinearStateSpaceModel[{{  Subscript[x, 2],
         -Subscript[x, 1]*(Pi/2+ArcTan[5*Subscript[x,1]]) -(5Subscript[x,         
           1]^2/(2+50*Subscript[x,1]^2))-5Subscript[x,2]}, {Subscript[x, 1]}}, {Subscript[x, 1], 
               Subscript[x, 2]},]
J= StateResponse[{nsys, {3,-2}},, {t, 0, 200}];
Plot[J, {t, 0, 20},PlotRange->Full]