The article is devoted to the development of a digital control system for the unstable vertical plasma position in the KTM tokamak. A controller with fixed parameters was synthesized using an array of plant models. The synthesized controller ensures the desired control performance and robust stability margins simultaneously for two plant models with varying parameters. A robust stability analysis was carried out. The performance of the system was verified through hardware-in-the-loop (HIL) simulation using a complete nonlinear model of the voltage inverter, taking into account its maximum current and voltage limitations.