[ Eq(x3, Piecewise((1/100*sin(1571/1000000*(-500 + t)), And(Gt(t, 500), Lt(t, 250254614894971/100000000000))), (0, True))),
  Eq(2*k2*x1 + 2*k2*x2 + 4*k2*x4 + 4*k1*x5 + 2*k1*x6 + 2*k1*x7, k1*k19 + k2*k18) ]