Question: Non Linear System and PID Controller

Hi guys ;) I have a question. Is it possible to apply a PID controller with the following parameters(P=6,I=4,D=0.02)to a Non Linear System described with the differentiate equation like this mk*diff(x(t),t,t)+kfv*diff(x(t),t)-(ki^2*u(t)^2*kc)/(mk*(x(t)-x10)^2)-mk*g=0 or in the second form, as two differentiate equations like dx1 := (x1,x2) ->x2; dx2 := (x1,x2) ->((u*ki)^2*kc)/(mk*(x1-x10)^2)-g*mk/mk-kfv*x2/mk; without linearisation in operating point, where u - is input variable, x - position, dx/dt - velocity, d^2x/dt - acceleration ? Thanks for your help. Have a good one ;)
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