answer from lecturer:answer from lecturer: Root locus attempts to trace the closed loop poles as we vary K. This starts from the open loop poles and ends either at infinity or the zeros. All the construction is based on the vector equation: 1 + KGH = 0.. The open loop poles and zeros refer to GH. 也就是说不是看整个T.F,只看GH来决定zeros 难道是 国大和南大不一样？