Safety–critical system is important in a human–robot collaborative environment. Control Barrier Functions (CBFs)-based methods have emerged as a practical tool for the safety–critical control of autonomous systems. The design of CBFs is difficult to tune. Also, once additional constraints are introduced, the quadratic programming may encounter infeasibility. This paper proposes a safety–critical controller based on a control barrier function using a quasi-saturation function. To avoid infeasibility, we propose to separate the tracking controller from the safety controller. To facilitate the design of the control barrier function, we also propose the control barrier function using the quasi-saturation function. Numerical simulations are presented to show the effectiveness of the proposed method.