SUMMARY This study addresses a discretization method with Lebesgue sampling for a type of nonlinear system, and proposes a control method based on the discrete system model. A cart-pendulum system is used as an example. Applying this control method to some real system, a crucial problem is how to implement the controller. To overcome the problem, an impulsive Luenberger observer is introduced with numerical forward mapping from the current system state to the one-step-ahead state by the well-known Runge–Kutta method. As a result, a cart-pendulum system with a rotary encoder, whose quantization interval is relatively large, can be controlled effectively. Numerical simulations are performed to verify the effectiveness of the proposed method.