Lower leg muscle activity contributes to body control; thus, monitoring lower leg muscle activity is beneficial to understand the body condition and prevent accidents such as falls. Amplitude features such as the mean absolute values of electromyography (EMG) are used widely for monitoring muscle activity. Garment-type EMG measurement systems use electrodes and they enable us to monitor muscle activity in daily life without any specific knowledge and the installation for electrode placement. However, garment-type measurement systems require a high compression area around the electrodes to prevent electrode displacement. This makes it difficult for users to wear such measurement systems. A less restraining wearable system, wherein the electrodes are placed around the ankle, is realized for target muscles widely distributed around the shank. The signals obtained from around the ankle are propagated biosignals from several muscles, and are referred to as distal EMG signals. Our objective is to develop a sock-type wearable sensor for estimating lower leg muscle activity using distal EMG signals. We propose a signal processing method based on multiple bandpass filters from the perspectives of noise separation and feature augmentation. We conducted an experiment for designing the hardware configuration, and three other experiments for evaluating the estimation accuracy and dependability of muscle activity analysis. Compared to the baseline based on a 20-500 Hz bandpass filter, the results indicated that the proposed system estimates muscle activity with higher accuracy. Experimental results suggest that lower leg muscle activity can be estimated using distal EMG signals.
In previous work, we introduced the Shape Memory Alloy actuator based Robot Mask that can be used to enhance the expressiveness of the face. The basic concept of that design was the pulling of the skin through wires attached to the face and we explained the human anatomy based criteria of selecting these pulling points and directions. In this paper, we describe a case study of using the Robot Mask to assist physiotherapy of a hemifacial paralyzed patient.Earlier we reported the general design criteria of the Robot Mask. However, the significant difference in shape and size of human head among different individuals demands further customization of the Robot Mask. In this research a number of adjustment and customization stages were employed, from the design level to the implementation level and this paper briefly describes them. We also explain a depth image sensor data based analyzing method, which can record dynamics of facial expression in a continuous manner. We then evaluate the effectiveness of the Robot Mask by analyzing the range sensor data. We show that, while providing quick responses, the Robot Mask can also reduce the asymmetry of a smiling face.
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