Method to define desired trajectories of the exoskeleton in the Cartesian coordinate system for movement in sagittal plane in pre-determined in advance motion mode of user with support-motor apparatus functional impairment using exoskeleton including pelvic section, left and right foot rests each of which consists of femoral (5; 6) and shank (7; 8) sections and foot steps (9; 10), wherein the adjacent sections are connected using corresponding pivotal joints (11 - 16) providing the possibility of their rotation in sagittal plane and equipped with corresponding sensors (17, 18, 20, 21) of relative angle rotation integrated in the current angles and angular velocities measurement unit, wherein hip (11; 14) and knee (12; 15) joints are configured motorized and equipped with corresponding drives, for example, electric drives, as well as on-board controller connected with sensors (17, 18, 20, 21) of relative angle rotation of adjacent sections and control inputs of the motorized joints drives, wherein according to the present method using motion capture system including serially connected measuring devices unit to collect and transfer the captured motion parameters data, captured motion parameters data processing unit and captured motion parameters storage unit, the output of which is connected to the output of motion capture system, ensure measuring of Cartesian coordinates of pre-selected human body points in the process of its motion, characterized in that the motion capture system is used as a part of the desired Cartesian trajectories parameters determination system, and a person without support-motor apparatus functional impairment is used to measure the Cartesian coordinates of the pre-selected body points, and the points of intersection between the hip joint axis and ankle joints axes, lying in the frontal plane, with sagittal plane are used as the pre-selected body points, the Cartesian coordinates of which are measured, depending on time in the form of trajectories along the axes of the Cartesian coordinates system of the above sagittal plane during motion of the above person for each of the pre-determined in advance motion mode, and saved in the captured motion parameters storage unit in the form of data arrays for each measured trajectory, wherein axis of ordinates of the above coordinates system of the sagittal plane is directed vertically, while axis of abscissas - along the course of exoskeleton motion, and further in the integrated into the desired Cartesian trajectories parameters determination system captured motion parameters processing unit, the input of which is connected to the output of the motion capture system, processing is conducted of parameters and/or interpolation coefficients of the captured motion calculating, based on the above table set arrays of the time functions of the Cartesian coordinates, the parameters and/or interpolation coefficients for each of the chosen in advance smooth, interpolating the above trajectories, analytic function, differentiated at least twice, for example, splines, including cubic splines, wherein the calculated parameters and/or interpolation coefficients are saved in the desired exoskeleton Cartesian trajectories parameters and/or interpolation coefficients storage unit, connected to the output of the captured motion parameters processing unit and integrated into the desired Cartesian trajectories parameters determination system, wherein the above measurements, processing of data obtained as the result of these measurements and storage of these data processing results are conducted for groups of people with various ratios of shank length to the femur length, wherein preserving the data on the above ratios and shank length for each person in this group.