Systematic fuzzy logic control of a gantry crane

This article deals with the design and implementation of a systematic fuzzy logic controller (FLC) to control the position and sway of gantry cranes. The philosophy of this controller is to interpret the uncertainties in the crane system parameters (payload, cable length, and frictions) as sources of fuzziness in the system dynamics. Then an equivalent fuzzy dynamical model of the uncertain dynamical system is provided. The development of the fuzzy model uses knowledge already available in crisp physical modelling of the system to get around the need for an expert. Finally, the concept of sliding mode control is extended to include fuzzy dynamical systems to design robust controllers for uncertain dynamical systems without restrictive assumptions on the system parameter uncertainties and/or without imposing matching conditions. The new controller was implemented in hardware and tested on a scale model crane. The test results display robust stability and performance for different payloads and cable lengths and good disturbance rejection. The FLC controller performance was compared to a PID controller. The experimental results are provided.