The Jerk-limited trajectory type should be used when smooth motion is required in response to user stick input or mission changes (e.g.: for filming, mapping, cargo). It generates symmetric smooth S-curves where the jerk and acceleration limits are always guaranteed.
The jerk-limited type is used by default on all airframes, in both auto and position modes. Setpoint Tuning (Trajectory Generator) also supports MC Slew-rate Trajectory Tuning for a faster (albeit "jerky") response.
The graph below shows a typical jerk-limited profile with the following constraints:
jMax: maximum jerk
a0: initial acceleration
aMax: maximum acceleration
a3: final acceleration (always 0)
v0: initial velocity
vRef: desired velocity
aMax are configurable by the user via parameters and can be different in manual position control and auto mode.
The resulting velocity profile is often called "S-Curve".
In manual position mode, the sticks are mapped to velocity where a full stick deflection corresponds to MPC_VEL_MANUAL.
In auto mode, the desired velocity is MPC_XY_CRUISE but this value is automatically adjusted depending on the distance to the next waypoint, the maximum possible velocity in the waypoint and the maximum desired acceleration and jerk.
Distance to velocity gains when close to a waypoint: