Setup Instructions

Connection Diagram

First, Twist the provided 4 pin CAN cables as this will cancels out electromagnetic interference (noise) and reduces crosstalk by ensuring external fields affect both wires equally, allowing receivers to filter it out, leading to cleaner signals, better reliability, and efficient data transmission in noisy environments. It also helps manage physical aspects like stability, preventing tangles, and ensuring even stress distribution.

Mounting

Below is the recommended mounting orientation. The connectors on the board should point towards the back of the vehicle with the sensors facing downwards.

The above mounting is the default value (0) of the parameter SENS_FLOW_ROT. If you want to mount in a different orientation, change this parameter accordingly.

PX4 Configuration

Agam FloRange Sensor is a CAN based device. The CAN device needs to be powered for certain parameters to show up. So, the recommended way is to power the device through USB port from Autopilot or external battery and then open QGroundControl.

• Enable the UAVCAN driver by setting parameter UAVCAN_ENABLE to 2 for dynamic node allocation (or 3 if using DroneCAN ESCs)

• Connect Agam Florange Sensor to CAN port

  • Set the following parameters

  • Enable EKF2_OF_CTRL

    • To optionally disable GPS aiding, set EKF2_GPS_CTRL to 0

  • Set EKF2_RNG_CTRL to Enable(Conditional mode). This enables the range finder to be used during low speed (< EKF2_RNG_A_VMAX) and low altitude (< EKF2_RNG_A_HMAX) operation, eg takeoff and landing, where baro interference from rotor wash is excessive and can corrupt EKF state estimates. It is intended to be used where a vertical takeoff and landing is performed, and horizontal flight does not occur until above EKF2_RNG_A_HMAX.

  • Enable UAVCAN_SUB_FLOW

  • Enable UAVCAN_SUB_RNG

  • Set UAVCAN_RNG_MIN to 0.08 (minimum range is 80mm)

  • Set UAVCAN_RNG_MAX to 30 (max range is 30m)

  • Set EKF2_RNG_A_HMAX to 10

  • Set EKF2_RNG_QLTY_T to 0.2

  • Set SENS_FLOW_MINHGT to 0.08

  • Set SENS_FLOW_MAXHGT to 30

  • Set SENS_FLOW_MAXR to 7.4 to match the PAW3902 maximum angular flow rate

  • The sensor can be mounted anywhere on the frame, but you will need to specify the focal point position, relative to the vehicle's center of gravity, during PX4 configuration. The below parameters can be set to account for the offset of the Agam FloRange Sensor from the vehicle center of gravity.

    • EKF2_OF_POS_X, EKF2_OF_POS_Y, and EKF2_OF_POS_Z

    • EKF2_RNG_POS_X, EKF2_RNG_POS_Y, and EKF2_RNG_POS_Z

  • When optical flow is the only source of horizontal position/velocity, then lowering the gain for controller response to horizontal position error MPC_XY_P (e.g. to 0.5) is recommended to reduce oscillations.

• Reboot

After connecting the sensor to the autopilot, connect the autopilot using QGroundControl. Open the MAVLink Inspector screen for DISTANCE_SENSOR. If the sensor is OK, you can see that the current_distance number is non-zero.

Refer the latest PX4 Optical Flow sensor setup in the link below:

https://docs.px4.io/main/en/sensor/optical_flow.html

Ardupilot Configuration

Connect Agam Florange to CAN port. Set the following parameters:

• Set FLOW_TYPE = 6

• Set CAN_P1_DRIVER = 1

• Set CAN_D1_PROTOCOL = 1

To use the onboard lidar:

• Set RNGFND1_TYPE = 24

• Set RNGFND1_MAX = 3000

• EK3_SRC_OPTIONS = 0

• EK3_FLOW_DELAY

• EK3_SRC1_POSXY = 0 (use optical flow)

• EK3_SRC1_VELXY = 5

• EK3_SRC1_POSZ = 1

• EK3_SRC1_VELZ = 0

• EK3_SRC1_YAW = 1

• The sensor can be mounted anywhere on the frame, but you will need to specify the focal point position, relative to the vehicle's center of gravity, during PX4 configuration. The below parameters can be set to account for the offset of the Agam FloRange Sensor from the vehicle center of gravity.

  • FLOW_POS_X, FLOW_POS_Y, FLOW_POS_Z

UART Version Setup

• Set MAV_X_CONFIG to the port the sensor is connected to(eg: TELEM 3)

• Reboot

• Set MAV_X_FORWARD to Disabled

• Set MAV_X_MODE to Minimal or Low Bandwidth

• Reboot

• Set SER_TELx_BAUD to 115200 8N1

• Set EKF2_RNG_A_HMAX to 10

• Set EKF2_RNG_QLTY_T to 0.2

• Set SENS_FLOW_MINHGT to 0.08

• Set SENS_FLOW_MAXHGT to 30

• Set SENS_FLOW_MAXR to 7.4

• The sensor can be mounted anywhere on the frame, but you will need to specify the focal point position, relative to the vehicle's center of gravity, during PX4 configuration. The below parameters can be set to account for the offset of the Agam FloRange Sensor from the vehicle center of gravity.

  • EKF2_OF_POS_X, EKF2_OF_POS_Y, and EKF2_OF_POS_Z

  • EKF2_RNG_POS_X, EKF2_RNG_POS_Y, and EKF2_RNG_POS_Z

• When optical flow is the only source of horizontal position/velocity, then lowering the gain for controller response to horizontal position error MPC_XY_P (e.g. to 0.5) is recommended to reduce oscillations.

• Reboot