The paper proposed a calculation method of control moments based on the studying the regularities of controlled motion of a three-link manipulator. The model of system has an elastic-viscous medium that simulates human muscles, proposing a mathematical model of the system, which includes a description of the kinematics and dynamics of the device. The results of numerical simulation made it possible to synthesize the relationship of the change of control moments in time. An automatic control system has been developed for the biomechanical device, in which the reactions in the hinges are determined. These patterns can be applied in the design of exoskeletons to understand at what point in time it experiences the maximum load, which will be considered when developing and designing the device.