Near Optimal Explicit Guidance Law with Impact Angle Constraints for a Hypersonic Re-entry Vehicle

• Main Authors: Kalirajan KARTHIKEYAN, Joshi ASHOK
• Format: Article
• Language: English
• Published: National Institute for Aerospace Research “Elie Carafoli” - INCAS 2018-06-01
• Series: INCAS Bulletin
• Subjects: Diveline guidance; Explicit Guidance; Impact angle constrained Guidance; Reentry guidance
• Online Access: http://bulletin.incas.ro/files/karthikeyan__ashok__vol_10_iss_2.pdf
• ISSN: 2066-8201; 2247-4528

Two guidance laws are discussed in this paper. The first one is the Vector guidance law. This guidance law when equipped with the appropriate gains has the capability to hit a target at the desired impact angle. A parametric method to find the optimal gains of this guidance law which will maximize the impact velocity and keep the miss distance and impact angle errors within bounds is developed in this research. Further, it is seen that the separation in the upper and lower bounds increases with increase in one of the gain values. Also, it is found that, only one of the gain values is independent and that the other dependent gain value is related through a simple straight-line expression. Next guidance law to be discussed is the Diveline guidance law. This law uses multiple divelines to hit a target at the desired impact angle. In the present research, the capability of this Diveline guidance law using a single diveline is analyzed. A method to derive the Diveline guidance law from the Vector guidance law is given in this study. The miss distance and impact angle errors evolving because of reducing the maximum acceleration limit is studied using simulations. Finally, three methods to increase the capture region (i.e. bounds on the set of initial states to achieve zero errors) of a guidance law is discussed.