the force of friction (see section 5.6). As in docking with a “rod and cone” docking device, at small angles the forces of interaction also decrease; the alignment of rings is more favorable, but the length of the guide protrusions increases. In practice, and this is frequently done, compromises are made in the APDAs. The range of shifting of the ring with guides during and after linkage is defined by the initial conditions, the mass and geometry parameters of the spacecraft, and the characteristics of the control systems and the shock absorbers. The range of displacements of the ring defines the required course of the rod. For ail possible displacements and rotations, the ring and rod should not contact other elements of the docking device and the spacecraft. This is verified in kinematic analysis and confirmed in dynamic models and tests. The course of the ring with guides from the initial to the retracted position (see Figure 2.5) in a combined shock absorption-drive scheme with differential connections is defined primarily by the maximum values of the angles of inclination of the ring relative to the transverse axes and the course of the longitudinal shock absorber where is the minimal acceptable gap between the ring and the docking frame; a is the thickness of the ring; dk is its diameter. where is the additional rotation of the spacecraft before linkage; 6^ is the rotation of the ring during shock absorption after linkage. For the same range of angular displacements of the ring with guides when it is mounted externally, the course of the rod, as follows from (2.2), increases as the diameter of the docking frame increases. Consequently, the longitudinal size of the peripheral docking devices increases. As a result the values of the parameters of initial conditions of docking and the base size have a great effect on the
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