Texture Classification Based on Sound and Vibro-Tactile Data

Abstract

This paper focuses on the development and validation of an automatic learning system for the classification of tactile data in form of vibro-tactile (accelerometer) and audio (microphone) data for texture recognition. A novel combination of features including the standard deviation, the mean, the absolute median of the deviation, the energy that characterizes the power of the signal, a measure that reflects the perceptual properties of the human system associated with each sensory modality, and the Fourier characteristics extracted from signals, along with principal component analysis, is shown to obtain the best results. Several machine learning models are compared in an attempt to identify the best compromise between the number of features, the classification performance and the computation time. Longer sampling periods (2 s. vs. 1 s) provide more information for classification, leading to higher performance (average of 3.59%) but also augment the evaluation time by an average of 29.48% over all features and models. For the selected dataset, the XGBRF model was identified to represent overall the best compromise between performance and computation time for the proposed novel combination of features over all material types with an F-score of 0.91 and a computation time of 4.69 ms, while kNN represents the next best option (1% improvement in performance at the cost of 2.13 ms increase in time with respect to XGBRF).

Keywords

• texture classification
• accelerometer
• microphone
• machine learning
• feature selection