In the frame of the Future Launchers Preparatory Program (FLPP), embotech carried out a study in 2017 about “On-board Real-Time Trajectory Guidance” (OBRTTG), with a follow-up project planned in 2018. The goal was to assess the feasibility of our approach on two benchmark scenarios:
1. Minimum fuel, minimum time trajectories for rockets, subject to vehicle and path constraints:
- limited available fuel
- max and min thrust
- max thrust vector angle
- glideslope constraint
The following trajectory has been computed in a few milliseconds on flight-representative hardware (ARM 7). The maneuver is similar to the rendering above, a vertical take-off, vertical landing maneuver:
After reaching a trigger altitude the software generates an optimal trajectory on-the-fly to reach the target position allowing for significant fuel savings while satisfying all the constraints encoded in the optimization problem.
2. Minimum fuel, minimum time trajectories for satellites, subject to vehicle and path constraints:
- min and max angular velocity, acceleration and torque
- conic regions to avoid (forbidden zones) and to be inside (mandatory zones)
In this example, we want to reorient a satellite on orbit while keeping a sensitive instrument outside of a conic region that could expose it to damaging radiations. At the same time, we want to keep its antenna pointing at Earth for uninterrupted communications. While the objectives can be satisfied, the flexibility of our approach allows to quickly generate new trajectories for different mandatory/forbidden zones configuration and instrument/antenna placement on the satellite’s body frame.