LindiCopter is an autopilot for multicopters. It is based on the control method incremental nonlinear dynamic inversion (INDI). There is one inner control loop for the attitude and one outer control loop for the position. In both control cascades INDI is used. Currently, five flight modes are available. The flight path following flight mode uses splines based on defined waypoints.
- You need LADAC
The autopilot Simulink block is called LindiCopter Autopilot and is located in lindiCopter_lib. The autopilot parameters can be computed automatically using the function lindiCopterAutoCreate based on a quadcopter parameters struct (see copter_params_default):
copter = copterLoadParams(copter_params_default');
lindiCopter_params = lindiCopterAutoCreate(copter);
For tuning have a look at the optional input arguments of the lindiCopterAutoCreate function.
Inputs:
| Input | Explanation |
|---|---|
| flightmode_number | 0: Loiter, 1: Guided, 2: Stabilized, 3: Altitude Hold, 4: AutoTune |
| cmd_roll_-1_1 | Roll stick command (-1 ... 1) |
| cmd_pitch_-1_1 | Pitch stick command (-1 ... 1) |
| cmd_yaw_-1_1 | Yaw stick command (-1 ... 1) |
| cmd_throttle_-1_1 | Throttle stick command (-1 ... 1) |
| is_cmd_in_NED | Define whether the commanded velocities are in FRD or NED frame (currently not supported) |
| waypoints | Waypoints (4xN array), first three rows is position in NED frame (in meters), fourth row is velocity in m/s, N is number of waypoints |
| num_waypoints | Number of waypoint (should match with input waypoints) |
| trigger_wp_update | This input triggers an internal update of the waypoints, the splines will be recomputed |
| M_bg | Rotation matrix (3x3) from geodetic frame g (NED) to body-fixed frame b (FRD) |
| omega_Kb | Angular velocity (3x1) of body w.r.t. earth represented in body-fixed frame b, in rad/s |
| s_Kg | Position (3x1) in geodetic frame g, in m |
| s_Kg_dt | Time-derivative of position s_Kg (3x1), m/s |
| s_Kg_dt2 | Second time-derivative of position s_Kg (31), in m/s/s |
| external_reset | Reset controller states (currently not supported) |
Outputs:
The output is a Simulink bus.
Have a look inside the block if the signal names are not clear.
EKF and Flight Test:
LindiCopter does not contain an extended Kalman filter (EKF) for state estimation and can not be used direction for flight tests.
However, you can use the ArduPilot custom controller interface.
Using the ArduPilot custom controller interface means, that the ArduPilot EKF is used.
With the ArduPilot custom controller interface you can perform software in the loop simulations as well as flight tests.
As a starting point there is an example in LADAC-Examples.
You can prepare the C++ Code Generation by running init_Arducopter_MinnieLindiCopter.
Flight Mode Info
- Loiter: Note that the Loiter flight mode currently runs in NED frame.
- Guided: Note that the Guided flight mode has currently a limit of 6 waypoints. Moreover, the autopilot currently may not enter the Guided flight mode in flight test (but it will work in Simulink and ArduCopter SITL). We are working on a bug fix.
- AutoTune: This mode is based on the work:
Smeur, E. J., Chu, Q., & De Croon, G. C. (2016). Adaptive incremental nonlinear dynamic inversion for attitude control of micro air vehicles. Journal of Guidance, Control, and Dynamics, 39(3), 450-461.
The control effectiveness will be adjusted online by random excitations of the copter. This mode should be run for approximately 30 seconds. There may be issues for the yaw control effectiveness. Note that all adjustments are gone after reboot. Therefore, the Simulink signalsautotune.factors_G1andautotune.factors_G2can be logged to adjust the copter parameters before the next flight test.
Flight Test Info
You should not use LindiCopter for take off and landing.
Use any ArduCopter flight mode for take off and landing.
You can switch into LindiCopter when the copter is in the air.