PX4 Instructions

ARK FlowPX4 Autopilot

Most up to date PX4 Documentation

Mounting

Mount the ARK Flow as shown in Mounting. This corresponds to the default value (0) of the parameter SENS_FLOW_ROT. Change the parameter appropriately if using a different orientation.

The sensor can be mounted anywhere on the frame, but you will need to specify the focal point position, relative to vehicle centre of gravity, during PX4 configuration.

Flight Controller Setup

The ARK Flow will not boot if there is no SD card in the flight controller when powered on.

Connect the ARK Flow CAN to the flight controller's CAN port, as described in Wiring. Once parameters are set the module will be detected on boot. See DroneCAN > Enabling DroneCAN for more detail.

Flight Controller Parameters

Set the following in QGroundControl and reboot the flight controller.

Required

Parameter	Value	Description
UAVCAN_ENABLE	2	Enable DroneCAN with dynamic node allocation (use 3 if also driving DroneCAN ESCs)
EKF2_OF_CTRL	1	Enable optical flow fusion in the EKF
UAVCAN_SUB_FLOW	1	Subscribe to DroneCAN optical flow messages
UAVCAN_SUB_RNG	1	Subscribe to DroneCAN range finder messages
EKF2_RNG_QLTY_T	0.2	Range finder quality time
UAVCAN_RNG_MIN	0.08	Min reported range
UAVCAN_RNG_MAX	30	Max reported range
SENS_FLOW_MINHGT	0.08	Min height for optical flow fusion
SENS_FLOW_MAXHGT	25	Max height for optical flow fusion
SENS_FLOW_MAXR	7.4	Max angular flow rate (PAW3902 limit)

Optional

Parameter	Description
UAVCAN_SUB_IMU	Set to 1 to subscribe to DroneCAN RawIMU messages. Requires CANNODE_PUB_IMU to also be set on the ARK Flow
EKF2_GPS_CTRL	Set to 0 to disable GPS aiding (e.g. indoor flight)
EKF2_OF_POS_X / EKF2_OF_POS_Y / EKF2_OF_POS_Z	ARK Flow offset from the vehicle center of gravity (meters)
SENS_FLOW_ROT	Sensor rotation if mounted in a non-default orientation (default 0)

CAN Node Parameters

The node publishes optical flow and range finder data with its default parameters. To terminate the bus, publish IMU data or change the distance sensor mode and rate, see Node Parameters.

Video

PX4 holding position using the ARK Flow sensor for velocity estimation (in Position Mode).