udaan.utils.trajectory.flip module

Aggressive trajectories for quadrotor — flip and spiral maneuvers.

FlipTrajectory: vertical loop (360° pitch rotation) via circular acceleration in the xz-plane. Requires differential flatness feedforward.

SpiralTrajectory: helical path with circular motion in yz-plane and linear advance along x.

All derivatives up to snap (4th order) are analytic.

class udaan.utils.trajectory.flip.FlipTrajectory[source]

Bases: Trajectory

Vertical loop trajectory: hold -> climb -> 360° pitch flip -> recover -> hold.

The flip phase uses a constant-thrust circular acceleration profile:

a_x(t’) = T * sin(w * t’) a_z(t’) = T * cos(w * t’) - g

The thrust vector rotates 360° in the xz-plane. During the inverted phase (90°-270°), thrust projection is negative — the quadrotor is in free-fall. This is physically correct; the attitude controller maintains rotation via torque feedforward from flat2state.

Parameters:

  • start – starting hover position [x, y, z].

  • flip_duration – time for the 360° rotation (seconds).

  • thrust_ratio – thrust / (m*g) during the flip.

  • climb_time – duration of the climb phase.

  • recover_time – duration of the recovery phase.

  • hold_time – hover duration before and after the maneuver.

__init__(start=array([0., 0., 2.]), flip_duration=0.5, n_loops=3, thrust_ratio=1.5, climb_time=2.0, recover_time=2.0, hold_time=1.0)[source]
property duration
property end_position
get(t)[source]
get_full(t)[source]
class udaan.utils.trajectory.flip.SpiralTrajectory[source]

Bases: Trajectory

Helical spiral: circle in yz-plane while advancing along x.

The trajectory smoothly accelerates from hover, executes N loops of a helix, then smoothly decelerates back to hover.

Parameters:

  • start – starting hover position [x, y, z].

  • radius – radius of the circular motion in yz-plane (meters).

  • speed – tangential speed of the circular motion (m/s).

  • n_loops – number of full loops.

  • advance – total x-distance traveled over all loops (meters).

  • hold_time – hover duration before and after the maneuver.

__init__(start=array([0., 0., 2.]), radius=0.8, speed=2.0, n_loops=2, advance=3.0, hold_time=1.0)[source]
property duration
property end_position
get(t)[source]

Return (position, velocity, acceleration) at time t.

get_full(t)[source]

Return (position, velocity, acceleration, jerk, snap) at time t.