Worker Activity Recognition in Smart Manufacturing Using IMU and sEMG Signals with Convolutional Neural Networks

In a smart manufacturing system involving workers, recognition of the worker\u27s activity can be used for quantification and evaluation of the worker\u27s performance, as well as to provide onsite instructions with augmented reality. In this paper, we propose a method for activity recognition using Inertial Measurement Unit (IMU) and surface electromyography (sEMG) signals obtained from a Myo armband. The raw 10-channel IMU signals are stacked to form a signal image. This image is transformed into an activity image by applying Discrete Fourier Transformation (DFT) and then fed into a Convolutional Neural Network (CNN) for feature extraction, resulting in a high-level feature vector. Another feature vector representing the level of muscle activation is evaluated with the raw 8-channel sEMG signals. Then these two vectors are concatenated and used for work activity classification. A worker activity dataset is established, which at present contains 6 common activities in assembly tasks, i.e., grab tool/part, hammer nail, use power-screwdriver, rest arm, turn screwdriver, and use wrench. The developed CNN model is evaluated on this dataset and achieves 98% and 87% recognition accuracy in the half-half and leave-one-out experiments, respectively

1-(4-Methyl­phenyl­diazo­nium­yl)-2-naphtholate

In the title compound, C17H14N2O, the dihedral angle between the benzene ring and naphthalene ring system is 11.0 (3)°. The azo group adopts an anti configuration and an intra­molecular N—H⋯O hydrogen bond exists. Mol­ecules are packed by π–π inter­actions between adjacent mol­ecule (closest approach between centroids of benzene and naphthalene rings of 3.501 Å)

3-Mesityl-2-oxo-1-oxaspiro­[4.4]non-3-en-4-yl 2-(4-chloro­phen­yl)-3-methyl­butyrate

In the title compound, C28H31ClO4, the five-membered cyclo­pentyl ring displays an envelope conformation with the atom at the flap position 0.519 (3) Å out of the mean plane formed by the other four atoms. The furan ring makes dihedral angles of 72.9 (1) and 82.4 (1)°, respectively, with the trimethyl- and chloro­phenyl rings. The dihedral angle between the two benzene rings is 15.3 (1)°. In the crystal, mol­ecules are linked through inter­molecular C—H⋯Cl hydrogen bonds, forming a chain running along the b axis