pendulum=StateSpaceModel[{(M+m)x''[t]-m l Sin[θ[t]] ((θ'[t])^2)+m l Cos[θ[t]] θ''[t]==F[t]+d[t] Cos[θ[t]], m x''[t] Cos[θ[t]]+m l θ''[t]==m g Sin[θ[t]]+d[t]},{θ[t],θ'[t],x[t],x'[t]},{F[t],d[t]},{θ[t],x[t]},t]/.{M->5.6,m->0.53,l->0.85,g->9.8};
poles={-1+2I,-1-2I,-5,-7};

k=Join[StateFeedbackGains[SystemsModelExtract[pendulum,1],poles],{ConstantArray[0,4]}]

Plot[OutputResponse[{SystemsModelStateFeedbackConnect[pendulum,k],{0,0.01,0,0}},{0},{t,4}]//Evaluate,{t,0,4},PlotRange->All,PlotStyle->{Blue,Red},Epilog->Inset[Column[{Style["x(t)",10,Blue],Style["θ(t)",10,Red]}],{3,0.004}],AxesLabel->{"t"}]

Plot[OutputResponse[SystemsModelStateFeedbackConnect[pendulum,k],{0,UnitStep[t]-UnitStep[t-1]},{t,4}]//Evaluate,{t,0,4},PlotRange->All,PlotStyle->{Blue,Red},Epilog->Inset[Column[{Style["x(t)",10,Blue],Style["θ(t)",10,Red]}],{3,0.5}],AxesLabel->{"t"}]