Treatment and restoration of motor abilities to individuals with spinal cord injury (SCI) is possible with neuro-rehabilitative systems for unsupported upright stance, also known as quiet stance. The aim of this research project is to develop a controller that will regulate active ankle torque during electrical stimulation for quiet stance. This study uses a novel technique of applying an optimal robust servomechanism controller to bring the human's centre of mass (COM) to a specified reference position independent of external disturbances. The robust controller obtained was able to track quiet stance within 1 second, and highly attenuate both constant and Gaussian noise disturbances intensity. The robust controller presented can be considered as a step forward in neuro-rehabilitative systems for quiet stance, as previous controllers have not considered dealing with the servomechanism control problem in the regulation of ankle torque.