Proximity Sensor Bus Address (PRX1_ADDR)

Description

PRX1_ADDR identifies the unique "Hardware Address" of your proximity sensor on the shared I2C or DroneCAN bus.

This allows you to connect multiple sensors of the same type to the same bus without conflict.

• 0: Auto-detection.
• 1-127: Specific hardware address.

Proximity Ignore Angle (PRX1_IGN_ANG1)

Description

PRX1_IGN_ANG1 (and ANG2-ANG4) defines the center of a "Blind Zone" for your proximity sensor.

This is used to prevent the drone from reacting to its own structure (like landing gear, arms, or GPS masts) that might be in the sensor's line of sight. By telling the autopilot to "ignore" a specific angle, you avoid false obstacle detections.

• Units: Degrees (0 to 360).
• Reference: 0 is forward, 90 is right, 180 is back, 270 is left.

Tuning & Behavior

• Default: 0.
• Integration: Use this in combination with PRX1_IGN_WID1 to define the width of the excluded sector.

Proximity sensor ignore angle 2

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 3

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 4

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity Ignore Width (PRX1_IGN_WID1)

Description

PRX1_IGN_WID1 defines the size of the "Blind Zone" sector centered on PRX1_IGN_ANG1.

If you have a 10-degree wide arm in the sensor's path, you would set the center angle to the arm's position and this width to 10. The autopilot will then ignore any data reported within 5 degrees on either side of the center.

Tuning & Behavior

• Default: 0.
• Safety: Do not set the width unnecessarily large, as you might hide real obstacles from the avoidance system.

Proximity sensor ignore width 2

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 3

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 4

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity Maximum Range (PRX1_MAX)

Description

PRX1_MAX defines the "Horizon" for your drone's obstacle avoidance system.

If the sensor reports an object farther away than this value, the autopilot ignores it. This is important to filter out noise at the edge of the sensor's capability or to ignore distant objects that aren't a threat.

• 0: Use sensor default. (Recommended for most digital sensors).
• 1-500: Range in meters.

Tuning & Behavior

• Default: 0.
• Recommendation: If you notice your drone "jerking" or reacting to "ghost" obstacles in the distance, set this to 80% of the sensor's physical max range (e.g., set to 16 for a 20m Lidar).

Proximity Minimum Range (PRX1_MIN)

Description

PRX1_MIN defines the "Blind Spot" around your drone.

If the sensor reports an object closer than this value, the autopilot ignores it. This is critical to prevent the drone from being "scared" of its own frame, propellers, or mounting brackets if they are within the sensor's field of view.

• 0: Use sensor default. (Recommended).
• Value (m): Set this to slightly more than the distance from the sensor to the edge of your drone's props.

Tuning & Behavior

• Default: 0.
• Safety: Setting this too low may cause the drone to detect its own frame as an obstacle, preventing it from moving.

Proximity Orientation (PRX1_ORIENT)

Description

PRX1_ORIENT tells ArduPilot if your 360-degree Lidar is mounted normally or upside down.

• 0: Default (Right-side up).
• 1: Upside Down.

Tuning & Behavior

• Default: 0.
• Action: If your obstacle avoidance seems to react to objects on the wrong side (left instead of right), your sensor might be mounted upside down without this parameter being set correctly.

Proximity MAVLink System ID (PRX1_RECV_ID)

Description

PRX1_RECV_ID specifies the source of the proximity data when using a MAVLink-based sensor (like an OpenMV or a specialized companion computer script).

It tells the autopilot: "Only listen to DISTANCE_SENSOR messages from this specific MAVLink system ID."

• 0 (Default): Listen to all MAVLink proximity sources.
• 1-255: Listen only to this specific System ID.

Proximity type (PRX1_TYPE)

Description

PRX1_TYPE enables a 360-degree Lidar or Radar for Object Avoidance.

Unlike a Rangefinder (which is usually a 1D single-point distance sensor), a Proximity sensor scans a sector or a full circle to build a map of obstacles around the vehicle. This data is used by the AVOID (Object Avoidance) library to stop before hitting objects or path-plan around them.

• 0: None.
• 2: MAVLink. Data sent from a Companion Computer.
• 4: RangeFinder. Uses an existing RNGFND instance (turned into a proximity sensor).
• 5: RPLidarA2. Common 360 Lidar.
• 6: TeraRangerTowerEvo. 8-zone ToF array.
• 14: DroneCAN.
• 16: LD06. Inexpensive 360 Lidar.

The Engineer's View

Defined in AP_Proximity.
Enabling this allocates the driver. The driver then populates the AP_Proximity_Boundary_3D structure, which the Avoidance library (AC_Avoid) queries during flight.

Tuning & Behavior

• Default Value: 0 (Disabled).
• Reboot Required: Yes.
• Orientation: 360-degree Lidars must be mounted flat. Check PRX1_ORIENT if mounted upside down.

Proximity Sensor Yaw Correction (PRX1_YAW_CORR)

Description

PRX1_YAW_CORR allows you to digitally "Rotate" your proximity sensor if it wasn't mounted perfectly straight.

For obstacle avoidance to work, the autopilot must know exactly which direction each sensor reading corresponds to. If your Lidar is mounted 90 degrees to the right, you set this to 90 so the autopilot knows to shift all incoming data accordingly.

Tuning & Behavior

• Default: 0.
• Calibration: Point your drone at a known obstacle (like a wall) and check the proximity radar in your GCS. If the wall appears to the side instead of directly in front, adjust this parameter until they match.
• Significance: Critical for accurate avoidance maneuvers; if this is off, the drone might steer into an obstacle while trying to avoid it.

Bus address of sensor

Note: This parameter functions identically to PRX1_ADDR.

Proximity sensor ignore angle 1

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 2

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 3

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 4

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore width 1

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 2

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 3

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 4

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity maximum range

Note: This parameter functions identically to PRX1_MAX.

Proximity minimum range

Note: This parameter functions identically to PRX1_MIN.

Proximity sensor orientation

Note: This parameter functions identically to PRX1_ORIENT.

Proximity type

Note: This parameter functions identically to PRX1_TYPE.

Proximity sensor yaw correction

Note: This parameter functions identically to PRX1_YAW_CORR.

Bus address of sensor

Note: This parameter functions identically to PRX1_ADDR.

Proximity sensor ignore angle 1

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 2

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 3

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 4

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore width 1

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 2

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 3

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 4

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity maximum range

Note: This parameter functions identically to PRX1_MAX.

Proximity minimum range

Note: This parameter functions identically to PRX1_MIN.

Proximity sensor orientation

Note: This parameter functions identically to PRX1_ORIENT.

Proximity type

Note: This parameter functions identically to PRX1_TYPE.

Proximity sensor yaw correction

Note: This parameter functions identically to PRX1_YAW_CORR.

Bus address of sensor

Note: This parameter functions identically to PRX1_ADDR.

Proximity sensor ignore angle 1

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 2

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 3

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 4

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore width 1

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 2

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 3

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 4

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity maximum range

Note: This parameter functions identically to PRX1_MAX.

Proximity minimum range

Note: This parameter functions identically to PRX1_MIN.

Proximity sensor orientation

Note: This parameter functions identically to PRX1_ORIENT.

Proximity type

Note: This parameter functions identically to PRX1_TYPE.

Proximity sensor yaw correction

Note: This parameter functions identically to PRX1_YAW_CORR.

Bus address of sensor

Note: This parameter functions identically to PRX1_ADDR.

Proximity sensor ignore angle 1

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 2

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 3

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore angle 4

Note: This parameter functions identically to PRX1_IGN_ANG1.

Proximity sensor ignore width 1

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 2

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 3

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity sensor ignore width 4

Note: This parameter functions identically to PRX1_IGN_WID1.

Proximity maximum range

Note: This parameter functions identically to PRX1_MAX.

Proximity minimum range

Note: This parameter functions identically to PRX1_MIN.

Proximity sensor orientation

Note: This parameter functions identically to PRX1_ORIENT.

Proximity type

Note: This parameter functions identically to PRX1_TYPE.

Proximity sensor yaw correction

Note: This parameter functions identically to PRX1_YAW_CORR.

Proximity Minimum Altitude (PRX_ALT_MIN)

Description

PRX_ALT_MIN defines the "Activation Floor" for object avoidance.

Proximity sensors (like 360-degree Lidars) can sometimes "see" the ground when the drone is very low or during takeoff/landing, causing false obstacle detections. This parameter tells the autopilot to ignore all proximity data until the drone has climbed above this altitude.

• Default Value: 1.0 meter.
• Safety: This ensures the drone doesn't try to "dodge" the grass or its own landing pad during the critical phases of flight.

Tuning & Behavior

• Default: 1.0.
• Note: This requires a valid downward-facing Rangefinder (Lidar/Sonar) to know the altitude accurately. If no rangefinder is present, this parameter may not function as expected.

Proximity Sensor Baud Rate (PRX_BAUDRATE)

Description

PRX_BAUDRATE sets the communication speed for proximity sensors (like Lidars) that connect via a Serial (UART) port.

This parameter is primarily found on AP_Periph nodes that are being used as CAN bridges for serial sensors.

Tuning & Behavior

• Default: 0 (Use driver default).
• Common Values: 115200 (Most common), 921600 (High speed).
• Reboot Required: Yes.

Proximity Data Low-Pass Filter (PRX_FILT)

Description

PRX_FILT smooths out the "noisy" data from proximity sensors (like Lidars).

Lidars often report small, random fluctuations in distance. Without filtering, these fluctuations can cause the drone to twitch or make small steering corrections even when stationary. This filter removes that high-frequency noise, providing a stable "Boundary" for the obstacle avoidance algorithm to work with.

• Higher Frequency: Faster reaction to obstacles, but more twitchy.
• Lower Frequency (Default): Very smooth movement, but may react slightly slower to a fast-moving object.

Tuning & Behavior

• Default: 0.25 Hz.
• Recommendation: Leave at 0.25 Hz for most setups. If you find your drone is too slow to stop for obstacles, try increasing to 1.0 Hz.

Proximity Ignore Ground (PRX_IGN_GND)

Description

PRX_IGN_GND prevents the drone from being "Scared" of the floor.

When a drone is close to the ground, its Lidar often sees reflections from the dirt, grass, or landing pad as "Obstacles." This can prevent the drone from landing or cause it to jump away during takeoff. When enabled, this feature uses a downward rangefinder to determine exactly where the ground is and ignores any proximity data that is too close to that surface.

Proximity Raw Data Logging (PRX_LOG_RAW)

Description

PRX_LOG_RAW is a developer and troubleshooting tool.

When enabled, the autopilot records every individual measurement from the proximity sensor (e.g. all 360 degrees of data from a Lidar) into the internal DataFlash log.

• 0: Disabled (Default). Only the processed "Boundary" data is logged.
• 1: Enabled. Logs the full raw data stream.

Tuning & Behavior

• Warning: This creates extremely large log files.
• Usage: Only enable this if you are debugging a sensor issue or verifying that your ignore sectors (PRX1_IGN_ANG1) are correctly configured.

Proximity Sensor Port (PRX_PORT)

Description

PRX_PORT is used on AP_Periph nodes to map a physical UART port to the proximity sensor driver.

If you are using a CAN-based peripheral node to bridge a serial Lidar to the main flight controller, this parameter tells the peripheral node which of its own serial ports is connected to the Lidar.

Tuning & Behavior

• Default: 0.
• Setup: Refer to the wiring diagram for your specific AP_Periph hardware (e.g., Matek or CUAV CAN nodes) to find the correct port number.
• Reboot Required: Yes.

PRX_MAX_RATE: Proximity Sensor max rate

Description

This is the maximum rate we send Proximity Sensor data in Hz. Zero means no limit.

Values

• Range: 0 to 200
• Units: Hz
• Default: 50

Description

This parameter limits the frequency of proximity data messages sent by the AP_Periph device.

• Purpose: Prevents high-speed Lidar sensors from flooding the CAN bus or telemetry link with too much data.
• 50Hz (Default): A good balance for obstacle avoidance.
• 0: Sends data as fast as the sensor can read (can be >1000Hz for some Lidars, which may choke the bus).

Source Code

ardupilot/Tools/AP_Periph/Parameters.cpp