  In this paper, two cooperative guidance laws based on two-point boundary
value are designed to deal with the problem of cooperative encirclement and
simultaneous attack under condition of both known target acceleration and
unknown target acceleration. The only requirement for the multi-attacker
communication network is that it contains a directed spanning tree. The
guidance laws can function properly as long as at least one attacker can
observed the target. The acceleration components along the attacker-target line
of sight in the novel guidance laws can reduce the relative remaining distance
between each of the attackers and the target at the same speed, thus completing
simultaneous attack and avoiding the calculation of the remaining time. The
components of the guidance laws perpendicular to the attacker-target line of
sight can make the normal overload of relative motion zero, so that the
trajectory will be smooth and the collision problem within the attacker can be
avoided. Simulation results verified the practicability of the novel guidance
laws.
