Simulation of movement of an active exoskeleton with five electric controlled links

The article simulates the movements of an anthropoid model of a mechatronic mechanism such as an exoskeleton containing five rods interconnected by cylindrical hinges. The exoskeleton is a system of links that undergo relative rotations around the coordinate axes under the influence of the corresponding links of the user's musculoskeletal system, on which the exoskeleton is put on, gravity, support reactions and internal control forces implemented by electric drives. To describe the movement of each link, the angles between the links are used and local coordinate systems are introduced, which allow determining their position in space. The control of the change in the angles between the links is carried out using electric drives. Modeling is carried out for a gait close to human race walking, in which there is an instantaneous alternation of single-support phases. Biomechanical modeling of an exoskeleton with five movable controlled links allows us to identify the tasks that need to be solved: the synthesis of the motion trajectory, the determination of control moments, the selection of electric drives, and the development of a system for impulse motion control. To set the anthropomorphic movement of the exoskeleton, periodic functions are introduced that specify changes in the angles between the links. Compiled a system of differential equations. The Cauchy problem is solved numerically. The results of the numerical solution are compared with the initial motion, a conclusion is made that the system is unstable, and possible ways of stabilizing the unstable motion are discussed. The impact of the presence of electric drives on the dynamics of the entire exoskeleton has been estimated.