Virtual Cascade PID controller with strong robustness

In view of control performance is not ideal while traditional Proportional-Integral-Derivative (PID) controller being used to high order and large inertia system, a novel control method called Virtual Cascade PID (VC-PID) controller is proposed in this paper, which is based on a Virtual Model (VM) and a Virtual Controller (VC). On the basic theory of traditional PID controller, cascade PID control, Smith predictor control and Internal Model Control (IMC), virtual model and virtual controller becomes inner-loop, a filter is introduced in outer-loop in order to improve the closed-loop performance, negative effect due to large time constant plant is overcome effectively. From this ideal, a novel cascade correction method is deduced, i.e. virtual model and virtual controller together equals to cascade correction unit, and so correction unit has physical meaning. Simulation results of several kinds of models mismatch and signal disturbance show that the new method is much better than traditional PID controller in control performance and robustness.