Two-step filtering method for reducing dynamical system errors during Mars dynamical descent

Abstract

The invention discloses a two-step filtration method for reducing dynamic system errors at a mars power lowering section. The two-step filtration method comprises the following steps of: 1, constructing an engineering practical equation, 2, setting initial values, 3, filtering a state value, 4, filtering the deviation of a dynamic system, 5, updating relevant coefficients, estimating a correction state and estimating a dynamic deviation, and 6, setting k=k+1, returning to the step 3 and repeating the step 3 until k is equal to the moment T corresponding to the end of the mars power lowering section time, namely until a mars landing machine lands, so that the two-step filtration method for reducing the dynamic system errors at the mars power lowering section is finished. According to the method, in a mars power lowering process, the estimation for the position and the speed of an aircraft by a nonlinear and non-Gaussian random system under the condition of the dynamic system errors is uniformly considered. According to the method, the estimation and the compensation for the dynamic system errors are introduced into a calculation process, so that the navigation errors caused by the dynamic system errors on filtration are reduced, and the estimation for the position and the speed of the aircraft at the mars power lowering section is effectively guaranteed.

Description

technical field [0001] The invention relates to a two-step filtering method for reducing dynamic system errors in the Mars power descent section. It belongs to the technical field of aerospace navigation. Background technique [0002] The Kalman method is a very common method for determining the position and velocity of a spacecraft. It requires precise knowledge of the dynamical system and the measurement system. In actual engineering, the dynamic system is difficult to obtain accurately, and there are certain uncertainties and errors in the dynamic system. In the Mars power descent segment, the vehicle dynamics system uses the inertial navigation of the accelerometer and gyroscope (IMU) to perform track recursion. What the accelerometer measures is non-inertial force, that is, the acceleration due to gravity of Mars cannot be measured. Usually, only the gravity estimated in advance can be used in the calculation, which will cause a large error. For example, in 2012, t...

AI Technical Summary

Problems solved by technology

Even if the gravitational acceleration of the landing site is estimated in advance, there is still a certain error

Especially in the vicinity of some landing sites with complex terrain and landforms that have scientific exploration, the acceleration of gravity on Mars will be difficult to estimate and correct in advance

So it's not very suitable for Mars powered descent

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