Patent ID: 8433486

Claim:
A method to determine a preferred operating point for an internal combustion engine mechanically coupled to an electro-mechanical transmission to transmit power to a driveline in response to an operator torque request, wherein a controller executes the following: determining a current set of candidate operating points for a current search iteration; iteratively determining an operating cost for operating the internal combustion engine at each candidate operating point of the current search iteration, determining one of the candidate operating points for the current search iteration having a lowest of the operating costs, determining a search direction relative to the current set of candidate operating points for the current search iteration based on the candidate operating point of the current search iteration having the lowest operating cost, and determining a subsequent set of candidate operating points for a subsequent search iteration based upon the search direction; wherein the current set of candidate operating points for the current search iteration and the subsequent set of candidate operating points for the subsequent search iteration have a common operating point; selecting the subsequent set of candidate operating points for the subsequent search iteration that define a rectangle having a common side with a rectangle defined by the current set of candidate operating points for the current search iteration when the same candidate operating point is identified as a base point for three consecutive iterations; determining the preferred operating point for operating the internal combustion engine comprising the candidate operating point with the lowest operating cost determined after a predetermined number of iterations; and controlling the powertrain based on the preferred operating point for the internal combustion engine.