1. A non-transitory computer-readable medium or media comprising one or more sequences of instructions which, when executed by one or more processors, causes steps for recognizing a sequence of actions, comprising: segmenting input sensor data into time frames; for a time frame from a set of time frames, generating a feature using at least some of the input sensor data associated with the time frame; and for a time frame from the set of time frames, assigning an estimated action label for the time frame based upon an output of a state space model that comprises a substructure transition model and a discriminative boundary model, the state space model using the feature of the time frame as an input.