Patched Corridor: A Novel Lateral Logic for Skip Entry Guidance

Skip entry guidance using numerical predictor–corrector and patched corridor

“…5). Regarding the characteristics of the Kepler phase, the second term in the right-hand side of (11) can be approximated by a timedependent linear function, i.e.,z c (τ ) ≈z c1 + (z c2 −z c1 ) τ/T , wherez c1 = 2Ωv 1 sin φ 1 , z c2 = 2Ωv 2 sin φ 2 , T is the duration of the Kepler phase, and τ ∈ [0, T ] (Luo et al, 2014). Thus, Eq.…”

“…A large z 2 orż 2 may tend to produce a crossrange that surpasses the lateral capability of the final phase (Brunner and Lu, 2008;Luo et al, 2014). Thus, a quasi-crossrange parameter Γ, combined with the crossrange z and the crossrange rateż, is used as the lateral feedback parameter (Zhao, 1997).…”

“…The bank angle reversals are determined by the so-called "patched corridor", which is proposed in our previous work (Luo et al, 2014). For the sake of completeness and for ease of presentation, the derivation of the patched corridor is introduced in the following.…”

“…The purpose of the guidance algorithm is to continuously produce the guidance command, i.e., the magnitude and sign of the bank angle. The former is obtained by a numerical predictor-corrector method and the latter is determined by the patched corridor developed in Luo et al (2014).…”

“…As a result, the Earth's rotational effect plays a significant role in the crossrange excursion when observing from a fixed Earth frame (Brunner and Lu, 2008;Luo et al, 2014). A heading angle corridor that is defined in the inertial frame was used to manage the crossrange in the Apollo, PredGuid, and Numeric Skip-Entry Guidance (NSEG) algorithms, wherein the latter two algorithms were developed for the Orion program and almost inherited the Apollo lateral control logic (Bairstow, 2006;Tigges et al, 2007).…”