E-stop and docking

The falcon application supports an emergency stop (E-stop) feature that can be configured to immediately brake the motor in case of an emergency. The e-stop can be extended with prop docking and/or position hold.

info

All e-stop related parameters are located in the /estop/ folder.

Rampdown stage

The rampdown stage is useful for controlled deceleration (preventing an abrupt stop).

ramp

defines how quickly the motor will be brought to a stop when the e-stop is triggered.

max_cmd

sets the maximum command value that can be sent to the motor during the active brake rampdown after e-stop trigger.

voltage_thr

defines minimum voltage threshold the motor must reach in order to enter the hold stage.

Hold stage

The hold stage offers three options:

• short circuit brake,
• active position hold,
• active position hold with absolute reference (prop docking).

hold_max_cmd

sets the maximum active voltage drive level for position hold. If this parameter is set to zero, position hold is disabled and the hold stage falls back into simple short circuit brake.

hold_gain

defines the dynamics of the position hold. The higher the value, the faster the response, but the higher the chance of stability issues.

Hold stage with prop docking

For the absolute position hold, you need to provide absolute reference sensor. This is usually an additional hall sensor mounted on the motor, which triggers once per mechanical revolution. FALCON expects this sensor to be connected:

controller class	MSENS signal pin for reference
SC, SL	ENCA/CLK

FALCON supports two methods of sensor readout. This choice depends on kind of attached homing sensor as well as commutation mode (sensored/sensorless):

• 'level' mode - the hall signal is expected to stay at level when the prop is at desired homing position. In this mode, you can not select angle offset, but there is no risk of slippage due to parasitic torque, even in sensorless mode. To choose level mode, set dock_level_polarity to either -1 or +1 to define the polarity of the reference hall sensor signal which is considered as DOCKED.

• 'edge' mode - the hall signal is expected to deliver an edge when rotor goes through a reference point. To choose edge mode, set dock_edge_angle to your desired angle offset in revolutions.

homing_speed

sets the speed for finding the reference signal from hall sensor.