Abstract: Some space load has a high demand for the accuracy of orbit and flight attitude, and the accuracy of the perturbation guidance method applied in the launch vehicle cannot meet its requirements. The traditional iterative guidance method (IGM) cannot restrain the terminal attitude. Therefore, one quadratic curve IGM which satisfies the multi-terminal constraint was proposed. The method was used to plan the flight guidance program angle of the whole vacuum section through the quadratic curve, which satisfies the position constraint, velocity constraint and terminal attitude constraintinrealtime, making the attitude angle of rocket achieve high precision orbital parameters. Results show that the quadratic curve IGM can guarantee the high accuracy parameters of the orbit and the attitude of the orbit, and can adapt to the deviation states, the varieties of the constraint attitude angle and the number of the orbital parameters are slightly changed, and it has high engineering application value.

Key words: multi-terminal constraints, iterative guidance, quadratic curve, guidance algorithm