Smooth Function Modeling for On-Line Trajectory Reshaping Application (Postprint)
Abstract
This report was developed under a SBIR contract. Online vehicle trajectory reshaping is desired for a class of autonomous air vehicles such as RLVs in order to avoid catastrophic failure when subjected to performance restricting damages and failures. An Adaptive Trajectory Reshaping and Control (ATRC) system is envisioned that responds to altered vehicle conditions by continuously retargeting and reshaping the reference RLV trajectory satisfying the feasibility constraints. On-line trajectory reshaping to determine a feasible reference trajectory is computationally a difficult problem for real time applications. ATRC is exploring the principles of vehicle dynamics inversion for online generation of feasible reference trajectory. Two essential components for generating reference trajectory for air-vehicles using "inverse dynamics" methodology are aerodynamic model of the vehicle that is representative of the current state of the vehicle, and a framework for modeling the vehicle trajectory. Physics based modeling software such as Missile DATCOM allows fast computation of aerodynamic coefficients for given flight points and the results can be stored in tabular form. However, for efficient real-time trajectory reshaping application, it is desirable to represent aerodynamic coefficients in smooth functional forms that are governed by a few parameters. Similarly, trajectories must also be represented by smooth functions. In this paper we present modeling of smooth functions using a set of basis functions that are suitable for aerodynamic modeling and trajectory reshaping of the air vehicles. A desirable feature for function modeling is the easy imposition of boundary as well as mid point constraints in the function using a small number of parameters without limiting the scope of the function. In this paper we present a design method for generating orthonormal polynomial basis functions in one and two dimensions with constraints.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 2006
- Accession Number
- ADA462780
Entities
People
- Ajay Verma
- David B. Doman
- Kalyan Vadakkeveedu
- Michael W. Oppenheimer