The RTD-A controller is a rapidly developing alternative to the traditional PID controller. RTD-A can manage systems with unpredictable behavior since it contains a separate robustness tuning parameter. With a straightforward interface unit, the RTD-A control method has been applied to regulate the liquid level in the spherical tank system. The main goal of this research paper is to develop a system for regulating the liquid level in a spherical tank using RTD-A controller. RTD-A algorithm is used to regulate the liquid level in a spherical tank. To regulate the nonlinear process, gain scheduling for the RTD-A controller was also performed. PID and RTD-A controllers are compared with simulation outputs. Based on the outcome observation, it can be concluded that the performance of the closed loop process using RTD-A algorithm is superior to than that of PID controller.