Abstract
Numerical simulations play an essential role in the development and testing of navigation and guidance algorithms, especially when developer must keep the development costs as low as possible. Low budget development focuses mainly on utilization of numerical flight mechanics simulators including optimization and hardware in loop tests. Reliable, high fidelity results can be easily obtained by numerical simulations of flight dynamics utilizing computing power provided by a normal off‐the‐shelf home PC. However, it still requires a simple, but good and valid model of the aircraft and environment. This paper describes an approach to a numerical simulation of aircraft motion that respects the requirement for a full environment high fidelity model and keeps a good interface for further development of attitude control. The goal is achieved by directly specifying the aerodynamic angles of the vehicle in the simulation environment by the guidance system, which can later be used as input for attitude control algorithms. It is proved how an appropriate selection of reference frames and formulation of laws of motion gives very quick and reliable results by employing large integration time steps that would be difficult to achieve in 6–degree‐of‐freedom simulations. This paper also investigates the range of applicability, advantages, and drawbacks of this method. An example of an aerodynamic angle‐based guidance law for a UAV is explained and demonstrated by figures. Santrauka Straipsnyje pateiktas lektuvo slenkamojo judesio dinamikos modeliavimo efektyvus ir patikimas metodas. Ivedus konkrečias koordinačiu sistemas, šiuo metodu galima nustatyti aerodinaminius duomenis ir greičio atskaitos sistema. Tai ypač naudinga modeliuojant skrydžio valdymo ir navigacijos algoritmus, nes čia nebūtini visi aerodinaminiai duomenys. Šis metodas ir jo pritaikymas iliustruojamas BSA valdymo pavyzdžiu.
Highlights
Often navigation, guidance and control systems are developed separately and may even be accommodated on separate hardware units
Compared to full 6–degreeof-freedom motion models, point mass models allow state integration with a much larger time step, requiring lower computing power, but providing high accuracy results. Another important aspect in favour of point mass model utilization is usually the limited availability of aerodynamic data and control actuator specifications required for the 6DOF model
This chapter illustrates that just just controlling flight path angle and heading in NED reference frame may achieve the goals of the guidance system
Summary
Guidance and control systems are developed separately and may even be accommodated on separate hardware units. Compared to full 6–degreeof-freedom motion models, point mass models allow state integration with a much larger time step, requiring lower computing power, but providing high accuracy results. If the vehicle’s attitude response information is approximately known (natural frequency, rate damping), it is possible to implement the effect of those characteristics in form of a state filter between commanded attitude and attitude output port from the guidance system. In this way, a point mass model becomes a perfect testbed for navigation and control system development and testing
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