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180 forces and moments update #182

Merged
merged 10 commits into from
Aug 15, 2024
Merged

180 forces and moments update #182

merged 10 commits into from
Aug 15, 2024

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iandareid
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Updated the multi-rotor forces and moments to agree with chapter 14. In addition, the bugs with going ~Mach 1.8 at full throttle have been fixed.

The model now includes:

  • Dynamic coefficient of thrust and torque based on airspeed through the propellers.
  • Induced drag model (present in the previous version). This is drag in the plane of the propellers.
  • Rudimentary model for drag on the body of the multi rotor, assumes constant cross-sectional area and $C_D$.
  • Ground effect (present in the previous version).
  • Revamped the motor position calculations to reflect chapter 14.
  • Updated motor model to match chapter 4, this means that motor response is more realistic.

In pilot testing it looks like the yaw response is a little sluggish, but still reasonable. It is hard to determine the cause, and it may not even be in the forces and moments, though if it is, it would be in the propeller torque calculations.

For default parameters, the top speed is now 58 mph, the prop speed spans the entire working range of the APC propeller chart and the aircraft responds appropriately to free fall situations.

This publishes and calculates forces, but they are all zero for the
moment.
The multirotor flips and crashes to nans very quickly.
The aircraft flies for a good chunk of time, but it randomly will
acclerate to the ground way to fast. Also the issue was that the forces
were being transformed to the inertial frame. But the forces should be
given in NED body frame.
The vehicle flies pretty well, however, the vehicle yeets off into
infinity at about 300 m/s randomly. It may be connected to when you
change commands randomly. The aircraft can also sustain ~420 m/s and
never slow down.
Working model that reflects reality relativley well. The params are
hardcoded in this commit.
Also pilot tested the sim. The yaw rate control seems slow.
@iandareid iandareid self-assigned this Aug 5, 2024
@iandareid iandareid linked an issue Aug 5, 2024 that may be closed by this pull request
@iandareid iandareid merged commit 4588fb9 into main Aug 15, 2024
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@iandareid iandareid deleted the 180-forces-and-moments-update branch August 15, 2024 22:14
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Forces and Moments for Multi-rotor sim.
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