第二章英文

2. The characteristics of the tasks of several typical carrier rocket and spacecrafts

This lecture mainly talks about several typical space missions to introduce their characteristics of control.

2.1 carrier rocket

Measurement and control of launch vehicle mainly happens during its powered phase and the availabilities of Measurement and control system are evaluated only when the rocket is in its emission period. The powered phase is generally defined as the period of time from the start of the rocket launching to the separation of the rocket and the satellite. Measurement and control for carrier rocket of its powered phase includes the following contents.

(1)Tracking: the measurement of the instantaneous position and velocity of a carrier rocket which is also called exterior trajectory measurement

(2)Telemetry: the remote measuring of the internal parameters, environmental parameters and independent navigation positioning data of a flying rocket by radio

(3)Telecontrol: safety control. The flying rocket will be exploded through the instructions from radio remote control apparatus when it is abnormal and may endanger the safety of the ground.

Safety control happens only in real time. Telemetry and tracking functions can not only provide correct measurement results in real time for safety system decision but also make integrated information processing after the flight to provide a basis for evaluating the performance of the rocket and improving its design.

The flight during the powered phase with its short distant is not long, and therefore the measurement and control of the powered phase has the following characteristics.

(1) Measuring time with its short measuring distance is not long.

(2)The key of the measurement and control is trajectory measurement with high measurement precision by complex trajectory measurement system.

(3) Telemetry task is relatively simple. The amount of remote transmission information is not large, but there are many kinds of the information.

(4) The tasks of control are simple. The safety control for the carrier rocket and the astronauts (Manned space mission) is the only task.

(5) Strong real- timeliness. The measurement and control system must provide the flight trajectory and the important engineering parameters timely and correctly as the basis for security decision of the launching site. The time from the measurement and control system capturing the goal and outputting the measurement information to the computer processing for a variety of information according to its qualification is generally within hundreds of milliseconds.

(6) The time relations between the various control information are very strict, and the timing and frequency calibration precision provided by the unified time system should be