A method comprising receiving user biometric data 310 and vehicle operating data 320, determining a user workload value 340 based on the received data and a workload determination classifier 330 that is based on workload values collected from a plurality of tests of test users driving along one or more routes, and causing an action 360 in the vehicle according to the determined workload. Preferably, the biometric data could include heart or respiration rate, galvanic skin response, acceleration magnitude, or voltage waveform of a heartbeat. Environmental or traffic data may also be incorporated. Statistical features (230, Fig.2) may be calculated from the received data, with the determined workload classifier being based on these statistical features. A feature dimension reduction technique (240) or sliding time intervals may be used to calculate the statistical features. The method could also determine a performance value for the identified classifier, and determine whether the performance value exceeds a minimum performance threshold 350.
Vehicle driver workload management