  This paper investigates a distributed formation control problem for networked
robots, with the global objective of achieving predefined time-varying
formations in an environment with obstacles. A novel fixed-time behavioral
approach is proposed to tackle the problem, where a global formation task is
divided into two local prioritized subtasks, and each of them leads to a
desired velocity that can achieve the individual task in a fixed time. Then,
two desired velocities are combined via the framework of the null-space-based
behavioral projection, leading to a desired merged velocity that guarantees the
fixed-time convergence of task errors. Finally, the effectiveness of the
proposed control method is demonstrated by simulation results.
