A.V. Alpatov1, M.S. Ashapkina2

1,2 Ryazan State Radio Engineering University n. a. akad. V.F. Utkin (Ryazan, Russia)

1,2 IIP BIOTEPRODACTS LLC (Ryazan, Russia)

Quarantine restrictions caused by the pandemic in 2020 have increased a significance of online technologies in the area of fitness, home training, including clinically justified medical services. Within a long period of time, rehabilitation physicians have emphasized an importance of home rehabilitation during the post-recovery period. Patients were strictly recommended to execute regular exercises for recovery of the joint mobility after injuries and diseases. Complete execution of exercises in the online mode is impossible without special technical means – training equipment dosing the load and controlling motion trajectories of the joint within the exercise execution. Authors’ papers have implemented a set of smartphone applications «Nefitness» containing complexes of exercises and using smartphone motion sensors to control execution and correctness of exercises and transmitting all the information to the rehabilitation physician’s online-office. First approbations of the system «Nefitness» within the framework of the mutual project with the State-Financed Institution “Clinical and Research Institute of Emergency Pediatric Surgery and Trauma” have shown that requirements for a patient to have a smartphone and necessity of its fixation on the extremity sharply decrease the range and age of potential users [1]. Usage of classic activity trackers in the form of a bracelet does not also solve the issue because they are only sensors and the full control is performed in the mobile application.

Purpose of the present paper – development of the concept and implementation of a portable device being able to check a correctness of the exercise execution itself without active participation of the smartphone during the exercise execution and using the vibrotactile feedback to correct in real time. Such implementation of a portable device allows providing correct adherence to protocols for rehabilitation exercise execution preliminary prescribed by a doctor in order to increase objectivity and reliability of the remote control.

«Method of rehabilitation and recovery of motion activity under audio-visual self-control» has been developed and patented as a part of authors’ work carried out to implement the supporting system for online rehabilitation. Application of the suggested method provides a possibility to ensure a personal calibration and recording of individual physiological peculiarities of a patient and also a possibility to self-control the recovery exercise execution correctness without a trainer. Such result has been achieved due to the coordinated operation of a portable device for motion activity registration which is fixed on the patient’s body where correspondence between the animated image of the pattern and animated movement of the patient's body is provided in real time.
Authors’ system «Nefitness» have integrated an additional feedback unit to the algorithm for calculation of the correction metrics to control vibromotors. Three control channels are interconnected there: control of the exercise execution order and rhythm, determination of the motion direction according to the data obtained from inertial sensors, control of the vibromotor within the fixed orientation. According to the suggested operational algorithm, the micro-controller continuously calculates the current position in relation to the initial one according to the acceleration and angulator rate sensors. Then the present values are wirelessly transmitted to the control module which calculates the motion trajectory from the registering device and records it. Then the device compares it with the pattern of the correct exercise trajectory taking into account the individual threshold coefficient using the previously developed algorithm based on the DTW method and also informs through the voice control or vibrotactile interface information on the motion trajectory correctness. Rotation patterns calculate compliance metrics and forms the numerical score of the exercise correctness with a threshold coefficient. The bracelet informs data on the motion trajectory correctness through the voice control of vibrotactile interface. So, the patient receives the stable perception of the motion direction.

Alpatov A.V., Ashapkina M.S. Portable device equipped with the vibrotactile feedback to support the home physical rehabilitation. Biomedicine Radioengineering. 2021. V. 24. № 4. P. 107–112. DOI: 10.18127/j15604136-202104-14 (in Russian)

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