In this paper, we propose a method to avoid "no-solution" situations of the
control barrier function (CBF) for distributed collision avoidance in a
multiagent autonomous robotic system (MARS). MARS, which is composed of
distributed autonomous mobile robots, is expected to effectively perform
cooperative tasks such as searching in a certain area. Therefore, collision
avoidance must be considered when implementing MARS in the real world. The CBF
is effective for solving collision-avoidance problems. However, in extreme
conditions where many robots congregate at one location, the CBF constraints
that ensure a safe distance between robots may be violated. We theoretically
demonstrate that this problem can occur in certain situations, and introduce an
asymmetric design for the inequality constraints of CBF. We asymmetrically
decentralized inequality constraints with weight functions using the absolute
speed of the robot so that other robots can take over the constraints of the
robot in severe condition. We demonstrate the effectiveness of the proposed
method in a two-dimensional situation wherein multiple robots congregate at one
location. We implement the proposed method on real robots and the confirmed the
effectiveness of this theory