The pole placement with fractional-order PI controllers for time-delay systems is discussed by using the parameter space approach.The damping ratio angular sector region and the relative stability region in complex plane,which form a trapezoid region in the left-half of the complex plane,are mapped into the controller parameters space.Thus,the corresponding controller parameters can place all the closed-loop poles in the specified trapezoid region,and guarantee the performances of the closed-loop systems.Si...