  This paper provides a solution to the problem of safe region formation
control with reference velocity tracking for a second-order multi-agent system
without velocity measurements. Safe region formation control is a control
problem where the agents are expected to attain the desired formation while
reaching the target region and simultaneously ensuring collision and obstacle
avoidance. To tackle this control problem, we break it down into two distinct
objectives: safety and region formation control, to provide a completely
distributed algorithm. Region formation control is modeled as a high-level
abstract objective, whereas safety and actuator saturation are modeled as a
low-level objective designed independently, without any knowledge of the
former, and being minimally invasive. Our approach incorporates connectivity
preservation, actuator saturation, safety considerations, and lack of velocity
measurement from other agents with second-order system dynamics which are
important constraints in practical applications. Both internal safety for
collision avoidance among agents and external safety for avoiding unsafe
regions are ensured using exponential control barrier functions. We provide
theoretical results for asymptotic convergence and numerical simulation to show
the approach's effectiveness.
