Sliding mode controllers for the benchmark bioreactor system

Static, dynamic, and two chatter-free sliding mode control (SMC) schemes are proposed for the bioreactor benchmark problem. A key step in the design is the introduction of a nonlinear transformation that maps the state equations of the bioreactor dynamics into the generalized controller canonical form. The four proposed sliding mode controllers are shown to drive the system trajectories to their desired values, hence ensuring the asymptotic stability of the closed-loop system of the transformed system as well as the original system. The performances of the controlled bioreactor system are simulated using the nominal parameters of the system. In addition, the performances of the system are simulated when the system parameters are perturbed. The simulation results indicate that the proposed controllers asymptotically stabilize the bioreactor system, and that the closed-loop system possesses great insensitivity to parameter variations.