🦸 Trajectory Optimizer

Previously, the majority of flight optimizers mentioned in the literature remained closed-source, which posed a significant drawback in terms of reproducible research.

The trajectory optimizer (TOP) addresses this lack of open-source flight trajectory optimizer by providing everyone with open access to trajectory optimization based on a non-linear optimal control direct collocation approach.

The TOP library can consider 3D or 4D wind fields. It can be utilized in various flight phases, either individually or in combination. It provides traditional fuel and cost index objectives alongside climate metrics-based objectives that incorporate global warming or temperature potential.

Furthermore, There is a mechanism to include a 3D or 4D cost grid in trajectory optimization. This implementation allows easy generation of, for example, contrail-optimal trajectories, or generate trajectories that avoid areas with convective weathers.

Supported aircraft types

The TOP library supports a wide range of aircraft types, however, the most accurate performance models are available for the following aircraft:

Narrow-body aircraft:

  • A20N, A21N, A319, A320, A321
  • B38M, B39M, B737, B738, B739
  • E190, E195

Wide-body aircraft:

  • A332, A333
Caution

The optimizer also supports other aircraft types in the OpenAP library, but the performance models for these aircraft may not be as accurate.

Use cases

The following chapters demonstrate various optimization scenarios and practical applications:

  • Simple optimal flights: explains how you can easily generate fuel and other simple cost-optimal trajectories.
  • Wind optimal flights: provides two approaches to obtaining wind fields and using them in your optimization.
  • Using cost grids: dives deeper into optimization with more complex 3D or 4D grids.
  • Contrails: provides a concrete example of flight optimization considering contrails.
  • Command-line interface: running the optimizer and precomputing grid caches from the shell.

Install

The opentop library builds on top of openap. You can install the most recent release through pip:

pip install --upgrade opentop

Alternatively, if you want to install the most recent development version (usually it is also recommended to update openap to the latest dev version):

pip install --upgrade git+https://github.com/junzis/openap
pip install --upgrade git+https://github.com/junzis/openap-top
Note

Prior to v2.0, opentop shipped as openap.top, a namespace extension of openap. v2.0 drops that and installs as a top-level opentop package instead.

Paper

The optimization framework was first published in the following paper: Sun (2022)

To cite the paper:

@article{sun2022top,
  title = {OpenAP.top: Open Flight Trajectory Optimization for Air Transport and Sustainability Research},
  author = {Sun, Junzi},
  journal = {Aerospace},
  volume = {9},
  number = {7},
  pages = {383},
  year = {2022},
  month = jul,
  publisher = {Multidisciplinary Digital Publishing Institute},
  link = {https://doi.org/10.3390/aerospace9070383},
  doi = {10.3390/aerospace9070383},
}
Caution

While the fundamental principle of trajectory optimization (based on non-linear optimal control) remains unchanged, the software has evolved significantly since the paper’s publication.

Key improvements include:

  • Enhanced performance models
  • More robust trajectory generation logic, and better convergence
  • Optimized computational performance, much faster πŸš€