Designing fractional-order ramp controller with explicit formulas using non-integer plant parameters

This paper aims to achieve two goals. First, the tracking problem with a ramp-type setpoint and disturbance is addressed, where classical methods provide steady-state error. Second, the available fractional-order controller designs in the literature are based on complex calculations. This paper presents a design scheme that employs a target loop-based controller, allowing users to compute tunable parameters without approximation or assumption. The control structure is capable of handling both the step and ramp signals. The main advantage of the proposed design is that it can be analytically tuned using the maximum sensitivity and phase-margin specifications of choice. Explicit relationships are established for the new fractional-order ramp controller (FoRC) parameters to facilitate tuning. The numerical investigations revealed improved servo and regulatory responses compared to recently published strategies. The design controller ensures stability and zero steady-state error as the ramp input increases. Furthermore, hardware verification demonstrates the scheme’s superior performance on a two-tank level loop, even with the influence of disturbances and modeling variations.