The application provides an improved closed-loop guidance method suitable for a reusable
rocket, and relates to the technical field of
rocket recovery guidance. The method comprises the following steps: determining the velocity and position in the launch inertial
system at the engine shutdown time of the power deceleration stage according to the initial value of the remaining
flight time of the
active stage, the real-time gravity acceleration and the initial value of the program angle of the power deceleration stage; determining the absolute
longitude difference between the position in the launch inertial
system at the engine shutdown time of the power deceleration stage and the target point; determining the remaining
flight time of the passive stage; and determining the required velocity and program angle calculation value of the closed-loop guidance. According to the application, the calculation method of predicting the state of the shutdown point can be used to calculate the required velocity, the program angle change rate of the power deceleration stage is reduced, the
control effect is optimized, and the stability is improved. Moreover, the calculated required velocity can reach the position constraint and velocity direction constraint of the passive stage end point after the
rocket is
shut down, the structure is simple, the operation efficiency is high, and the method is convenient to run on different hardware.