Idle Speed Control Design and Verification for an Automotive Engine

The goal of an idle control for automotive engines is to maintain the engine speed within a given range, robustly with respect to load torque disturbances acting on the crankshaft. Mean value models have been used in the past to design idle control algorithms. However, the behavior of the torque generation process and the dynamics of the power{train are not captured with enough accuracy to guarantee that the idle control speci cations as given by car makers are met. We use a cycle-accurate hybrid model to overcome these obstacles. The complexity of the model makes the problem of synthesizing a feedback control law for the system prohibitive. Heuristics have been widely used in the past. In this paper, we present a divide and conquer approach to cope with this problem. The system is decomposed in three parts. For each part in isolation, a control law is derived on a simpli ed model assuming that the other parts can be controlled to yield appropriate inputs. The overall control strategy is then applied to the system and formal veri cation is used to ensure that the behavior of the controlled system meets the speci cations.