In this paper, we consider the design of sheep herd driven algorithm by two sheepdogs. The sheep herd follow simple interaction rules among sheep, namely, separation and cohesion, which are treated as prior knowledge to the sheepdogs. The objective for the sheepdogs is to drive the sheep herd to follow a desired trajectory in a cooperative way. Inspired by the behaviors of real sheepdogs, for each sheepdog, we have developed a semi-circle reciprocation algorithm featuring dynamic turn-around point selection taken into consideration the ingredients of the positions of the sheep, the desired trajectory and the position of the other sheepdog. Numerical simulations are conducted to examine the performance of the proposed algorithm.