Mathematical modeling of the force interaction between an exoskeleton and a human in the rehabilitation of patients with lower limb injuries

Purpose of reseach. Ensuring the specified accuracy of sequential and parallel movements in the ankle, knee, hip of an active rehabilitation exoskeleton of the lower extremities with simultaneous partial unloading of the ankle and knee joints from axial loads by installing one of the rotary motion actuators on the hip joint. Tasks. The development and implementation of an active - passive movement strategy (ADF), in which the phases of passive movement of the lower extremities (while the exoskeleton provides movement of the limbs) are combined with the phases of active movement, when the patient himself performs the desired movement, and the exoskeleton assists him. Comparative analysis of experimental results and assessment of the adequacy and applicability of the mathematical model.

Methods. The study was performed in accordance with generally accepted methods of conducting and planning experimental studies. When modeling the movement of the lower extremities, the parameters characterizing the force interaction of the exoskeleton and the human are taken into account, which makes it possible to determine reactions in the hip joint and synthesize the parameters of the control system taking into account external disturbing influences.

Results. A mathematical model of the movement of the lower extremities of a rehabilitation training complex has been developed, which differs from the known ones in that, along with taking into account the kinematic and dynamic features of the movement of the links of the rehabilitation device, parameters characterizing the force interaction of the exoskeleton and a person are taken into account, which makes it possible to determine reactions in the hip joint and synthesize the parameters of the control system taking into account external disturbing influences.

Conclusion. The mathematical model and structure of the rehabilitation device proposed in the paper in the form of a flat exoskeleton manipulator equipped with two actuators, one of which is aligned with the axis of the human hip joint, makes it possible to compensate for the influence of active and reactive forces acting on the human hip joint during medical manipulations.

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