A Predictive Initialization of Hidden State Parameters in a Hidden Markov Model for Hand Gesture Recognition

Abstract

A hidden Markov model (HMM) has been widely used as a cost-effective solution for time series based applications such as hand gesture recognition. A large number of parameters in an HMM often result in a degradation of classification accuracy due to overfitting. Furthermore, the accuracy is often affected by the initialization values of the parameters. Left-right banded (LRB) HMM is one of the representative models which improve the classification accuracy by reducing the number of parameters. However, LRB HMM still suffers from false negative misclassification when it is applied for hand gesture recognition. Misclassification in hand gesture recognition arise from similar trajectories of multiple gestures that are represented by hidden states. This paper proposes a new initialization process that reduces not only state transition parameters but also hidden state observation parameters. To this end, the gesture trajectory is predicted and then the parameters are masked out when their probabilities are negligibly small in the predicted trajectory. Experiment results show that the confusion rate is nearly 14% lower than the LRB HMM while maintaining the classification accuracy.