The estimation of the joint angles of upper limb during walking using fuzzy logic system and relation maps

The objects of the study including determining the relationships between movements of upper extremities identifying joint angles using a fuzzy logic system (FS). The authors analyzed ranges of joint angles and simple rhythmical movement: swinging segments of walking subjects' arms moving in-phase (synchronously) or anti-phase (reciprocally), and designed fuzzy expert system which has never been described before. The set of data to create and study fuzzy logic for identifying upper extremity angles was measured in ten volunteers. An Xbus Kit system was used to measure upper limb movements. The joint angles in the sagittal plane and angle in the frontal plane were determined and relation maps of the in-phase and anti-phase movements in the contralateral and ipsilateral joints were designed. The if-then rules were derived from experimental findings and knowledge about ranges of angles and relations between angles of upper limbs during walking. The estimated values of joint angles were compared with the observed values of joint angles. Spearman's correlation coefficients were calculated for this purpose, and strong correlations for the walking speed of 3 km/h and 5 km/h were observed. The FS based on relation maps of the in-phase and anti-phase movements in the contralateral and ipsilateral joints have shown to be suitable for the estimation of joint angles of upper limb during walking. The concept of the FS offers a wide range of application in rehabilitation and prostheses design.