the APDA for the Soyuz. The analysis done in the development showed that the mechanism for the back-up opening of the locks with an additional drive is substantially more complex and contains a large number of moving elements which are sensitive to clearances and tolerances. As a result, the locks maintained the pyrotechnic bolts for back-up firing of the active clamps. Tn addition, eight pyrotechnic bolts were installed for the passive clamps, which made it possible to undock from the passive APDA. This construction of locks with pyrotechnic bolts in the passive clamps was used later in subsequent modifications of the docking device for the Soyuz-Salyut complex. Features of docking control. The control of the APDAs reflects the specifications of construction of the control systems of the Soyuz and Apollo craft. Ry analogy to the earlier docking systems, control of the APDA on Soyuz was constructed so that standard docking began automatically as a direct continuation of the approach. The process of docking with the APDA began with activation of two of the three sensors indicating the displacement of the ring from the equalized position. On the signal from these sensors, the orientation system of the spacecraft was turned off, and the engines of the jet control system were turned on to “forward.” On the signal from the linkage sensor the jet control system was shut off, and the “dock” command was formed. On this command, in standard execution of the process, with a 60-second delay intended for shock absorption of the relative oscillations of the spacecraft and equalization of the ring with the guides, the docking mechanism drive was switched on for coupling. The docking process was monitored by an automatic time program which shut off the system if the time sequence of the execution of individual operations was disrupted. These operations could be done by commands from the ship or from Earth. Monitoring the work and condition of the docking system was done by cosmonauts on their control panel and at the Flight Control Center using the telemetry system. Docking of the Apollo could only be done with the control and monitoring of the crew. Limited Earth monitoring through the telemetry system was provided. The supply of alternating current for the asynchronous engines of the docking mechanism drives and locks of the docking frame was done from static transformers which converted direct current into three-phase alternating current.
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