Model-Based Friction and Limp Home Compensation In Electronic Throttle Control

In this paper, we present an estimation of the coulomb friction and return spring effects in an automotive electronic throttle control (ETC) system using a nonlinear model-based estimator. The non-linear model-based estimator smoothly estimates this static non-linear behavior based on a priori knowledge of the feedback signals of the position error and the angular velocity of the throttle plate. Extensive simulations showed that the estimator sufficiently predicts the actual static non-linear behavior. The performance of the estimator was compared to an approximation based on the experimental nonlinear characteristics of the throttle. The non-linear model-based estimator can be used for compensation and can cancel the effect of the static nonlinearity in the throttle actuator to improve throttle position control. To validate how the adaptation of the static nonlinearities can improve the tracking performance, we integrated the estimator as a TargetLink block within the controller into the ETC software using a rapid prototyping real-time system, and tested the position control on an actual electronic throttle body. The control structure with the estimator was simple to implement and was robust in operation. The experimental closed-loop results revealed acceptable position tracking and satisfied requirements for control performance, controller cost, and processor load.