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Integration

Technical instructions - how to integrate and set up the system.

Ground unit installation (transmitter)

The device must be installed on a clean surface to avoid any obstacles. The device must be installed in an open area. There must be no obstacles in the radiation field of the transmitting device. If possible, avoid installing the system near vertical surfaces that can strongly reflect infrared radiation. The 4 holes on the bottom of the device can be used to mount the device. For fastening, use M2 screws, thread depth 2 mm.

It is allowed to install the device under a surface that is optically transparent to infrared radiation by more than 95%. Glass or transparent plastic can act as such a surface. In this case, to increase the coverage of the system at low altitudes, it is recommended to install the transmitter below the level of the platform. This will allow you to expand the coverage of the system to a larger area during touchdown.

   

After installation, it is recommended to verify the correctness of the compass reading and, if necessary, correct the compass calibration.

Wiring Transmitter

The transmitter only requires power to operate. The transmitter can be powered either via USB-C or via a 6-pin connector located nearby.

See pinouts info for details

Configure transmitter in ULS-Tools


ParameterDescription
Device nameName of the device displayed in main window
Device low voltageVoltage limit to start indicator flash warning
Device off voltageVoltage limit to disable IR emitters to prevent battery under discharge
Device illumination powerEmitters power correction (100 for normal operation)
Emitter (enable/disable)Disable (for configure) or enable emitter
Compass Override (enable/disable) [deg]Enable in case of module installed on fixed platform. The entered value will be used instead of internal compass data in “Compass mode”. In this way, the transmitter must be turned on the corresponding angle, CW to North.

Compass calibration

This compass is used to calculate an absolute heading of the ground unit. This information is transmitted to the Receiver and used to calculate NED coordinates. To be able to use compass, it needs to be calibrated before. To calibrate compass:

  • Press “Reset calibrations”.
  • Rotate device in different directions until you get 3 circles on charts (see picture below).
  • Press “Apply calibration” & “Apply configuration”.

Compass chart before calibration:

Compass chart after calibration:

Emitters power indicator

On this field, system shows emitter’s state.

Charts Transmitter

Program display several parameters of the device on charts :

  • IMU data.
  • Voltage (not valid when powered from USB).
  • Temperature data.

Led Indicator

You can check the status of the transmitter looking on the LED indicator on the transmitter. LED flashes in sequences of colors, so it can flash green-red-off-off or green-off-blue-off.

Flash colorDescription
GreenNormal operation.
OrangeLow voltage.
RedProblem, check device. If it is first in sequence it can be led malfunctions of power voltage below minimum, second for compass fail detect.
BlueCompass ok and device points to the North (brightness of illumination depends on how precise it is pointed to the North).

On-board unit installation (receiver)

The receiver can be installed both inside and outside the vehicle. However, please note that this version of the system is not equipped with protection against moisture and dust. The orientation of the receiver does not matter - however, when installing the receiver, care should be taken to ensure line-of-sight conditions between the transmitter and receiver throughout the entire field of view of the receiver (100 deg). The receiver sensor zone is indicated in the figure.

Once the receiver is installed, enter the appropriate receiver offset information into the configuration.

Wiring Receiver Pixhawk 4 autopilot connection using UART

See pinouts info for details

Wiring for muliRX mode

See pinouts info for details

Configure Receiver in ULS-Tools


ParameterDescription
Device nameName of the device displayed in main window.
Receiver offset (Front, Right) [m]Location of receiver in the drone (in meters). This configuration used to calculate drone heading in MultiRX mode.
Receiver orientation YAW [deg] (G2 only)Receiver orientation settings relative to drone frame It required to set for DACS system.
Receiver prediction time [s]Prediction time is used to send prediction information of landing position. It is useful to avoid the effect of short terms signal interruptions. Generally, its value can be set from 0.3 up to 1 sec.
Filter responseSet response for internal position filter of receiver. Hi values make lag tame shorter, lower values smooth position information.
Transmitter level compensationUsed to compensate Pan-Tilt rotations of the transmitter. It is used in case of landing on the moving objects.
Noise debugUse this function to check the noise interference with other devices. In this mode, receiver do not receive the signal from the transmitter, but can capture all the other signals. At the time of the test, transmitter must be switched off, and you can see on Signal Viewer the level of noise and detect what devices around affect the receiver. In general, max level of noise needs to be lower than 0.0025 for Beans B channel. NO OPERATIONS CAN BE PERFORMED IF THIS OPTION IS ENABLED - switch off before the normal use.
Compass mode (disable/enable)If settings are disabled - receiver will not perform data calculation based on ground compass data. Multi RX mode and (or) compass mode must be enabled to allow the operation.
MRX mode (disable/enable)If settings are enabled - receiver will use secondary receiver to perform the data calculation. Multi RX mode and (or) compass mode must be enabled to allow the operation.
UART ProtocolSelect corresponding protocol to communicate with autopilot. If protocol “MavlinkV2” is selected, you can enable the corresponding MAV_FRAME message to be sent to the autopilot (Ardupilot - MAV_FARME_BODY_FRD and PX4 MAV_FRAME_LOCAL_NED for now)
UART baud rateSelect UART communication speed.

Status Information field

In the status display area, you can check the status of the receiver and visualise the position of the receiver relative to the drone. For XCopter-G2, the YAW orientation of the drone received from the DACS system is displayed.

ParameterDescription
CarrierThe carrier signal from transmitter is detected.
SQ_OKSignal quality of the carrier is ok.
PosRAW sensor position is estimated.
VelRAW sensor velocity.
CompassGround unit orientation is received.
MRXSecondary sensor for MRX mode is connected and sending data.
MRX-YAWYaw orientation is calculated using MRX.
REL-NEDRelative NED position is calculated.
REL-FRDRelative FRD position is calculated.
LLMLat Lon Msl position is available (reserved for future options).
ABS-NEDAbsolute position of transmitter is available.
VEHICLE-NEDAbsolute position of vehicle is provided by the autopilot (used to calculate ABS position data).
BEACONIndicate System Ok state.
PREDICTIONIndicate when system uses predicted information for the calculation.
PLATFORMPosition of landing platform is provided by third party devices.

Setup MRX mode

This option enables to use data from two receivers to calculate position. It allows calculating receiver yaw orientation using triangular method. In this mode, compass data (on ground and on board) is not affecting the position estimation, so it is more durable way to land. In this mode the maximum distance is limited by 10 m and at altitude above, it will use compass mode.

To set up and check MRX mode do the following:

  • Connect receivers on board with CAN BUS (See MRX Wiring).
  • Configure “Receiver offset” for both receivers.
  • Configure “Receiver orientation YAW” for both receivers (XCopter-G2).
  • Enable option “MRX mode”.
  • After set up, hover the drone above the transmitter (1 m - 2 m) and check that TDistance and Distance values (On charts “Distances”) are the same (+/- 20%).
  • Correct “Receiver offset” option in case of TDistance and Distance are not approximately the same. Increasing position between receivers increases TDistace and backwards.
  • Rotate Drove over transmitter (1 m - 2 m) and check the value of the MRX-YAW on chart “GU Orientation”. It needs to be corresponding to the heading of the drone relatively to the transmitter.


DACS

The Distance and Azimuth Correction System allows you to determine the orientation of the receiver relative to the transmitter within +/-90 degrees. This system uses 4 additional LEDs on the transmitter. The presence of this system allows you to clarify the orientation of the receiver with a compass or using MRX technology. In case of using MRX technology, DACS tracks the drone’s rotation. Thus, for a system that works in MRX mode it is enough to get the orientation once and in the future, provided it is in the area of the transmitter, the receiver will track the position of the drone even if approaching the transmitter one of the receivers will be out of range and MRX data will be unavailable.

Receiver Charts

Program display several parameters of the device on charts :

  • Angles, Positions in different coordinate systems
  • Distance
  • Vehicle information (position and velocity)
  • Data from Transmitters IMU.

1 - Ardupilot

Integration instructions for Ardupilot based systems.

Download UAVLAS software and firmware

It is recommended to download the latest version of the ULSTools software. (See download page for details) It is recommended to connect all sensors to PC and update the firmware for all UAVLAS devices in the system. (See ULSTools update page for details)

Autopilot firmware set up

Update autopilot with Arducopter version v4.3.3 or above.

Transmitter Configuration

Configure UAVLAS transmitter See transmitter installation for details

Receiver Configuration

Connect system using UART interface.

Wiring receiver to AP

See pinouts page for details

Configure UAVLAS receiver See receiver integration section for details

Current version of the system can use MavlinkV2 protocol to communicate with Ardupilot autopilots (for now it supports MAV_FRAME_BODY_FRD).

Example of receiver configuration:

Autopilot configuration

Setup PLND section

ParamValueComment
PLND_ENABLED1Enable precision landing module
PLND_TYPE1Use type = 1 to enable UAVLAS sensor over Companion computer driver

All other parameters in PLND section defaults or use accordingly to your vehicle set up requirements.

On a picture example configuration provided.

Set up serial communication in SERIALx Section.

ParamValueComment
SERIAL2_BAUD230Select baud rate - it needs to be same as in receiver’s configuration.
SERIAL2_OPTIONS0Default
SERIAL2_PROTOCOL2MAVlink2 protocol support.

Set up serial communication messages in SRx Section. Sensor requires some data from autopilot to work in different modes.

ParamValueComment
SR2_EXTRA120Stream Attitude information (20Hz) (YAW Orientation is required for sensor in compass mode)
SR2_POSITION20Optional - Stream Vehicle position (20Hz) (LOCAL_POSITION_NED is required for sensor to provide LOCAL position for the target)

Check setup.

If all settings are done correct, autopilot has GPS data and receiver in the field of view of the transmitter, you can find LANDING_TARGET message in mavlink inspector (a screenshot from Mission Planner)

Setup Precision loiter mode.

To enable precision loiter mode you need attach any unused switch to PrecLoiter option see picture below:

Try to use this switch and you must get messages: “PrecLoiter: LOW” and “PrecLoiter: HIGH” After test flight above target check telemetry - you will find PL data contains offsets form landing target.

PID tuning

In case of oscillations and other issues at landing stage, pls, check PID parameters of Ardupilot.

It is recommended to check the Position XY, Velocity XY and Loiter speed parameters in “Extended tuning” section to achieve the best performance.

For additional information, see Ardupilot manual.

Troubleshooting

Before of all check:

  • You are using lates version od ULS-Tools, lates firmware on USL-XCOPTER transmitter and receiver, and latest Ardupilot firmware.
  • Check common Troubleshooting section
  • ULS-XCopter transmitter are switched on and receiver in field of view of transmitter.
  • Red light on receiver flashes fast ( > 5 times per second ). If it flash 2 times per sec it mean that transmitter not switched on, or not in field of view. If it not flash - check power.
  • Check Serial setting on AP params and on receiver be sure you are set EXTRA params for corresponding serial port on AP.
  • Check wiring power and RX, TX (see pinouts and wiring diagram)
  • Check on receiver that MAV_FRAME_BODY_FRD enabled.

2 - PX4

Integration instructions for PX4 based systems.

Download UAVLAS software and firmware

It is recommended to download the latest version of the ULSTools software (See download page for details) It is recommended to connect all sensor to the PC and update the firmware for all UAVLAS devices in the system. (See ULSTools page for details)

Transmitter Configuration

Configure UAVLAS transmitter See transmitter installation for details

Receiver Configuration

Connect the system using UART interface.

Wiring receiver to AP

See pinouts page for details

Configure UAVLAS receiver See receiver integration section for details

Current version of the system can use MavlinkV2 protocol to communicate with PX4 autopilots (for now it supports MAV_FRAME_LOCAL_NED).

Example of receiver configuration:

Download Firmware for PX4

UAVLAS device is working using a standard Mavlink messages protocol.

But in PX4 v1.13 and lower there are some issues related to precision landing capability, so it is required to flash the patched firmware file.

Download firmware binary files (based on V1.13.2)

or, for developing and building custom platforms, refer to source based on the current version of the PX4 project.

Clone modified version of PX4 stack

Before building, switch to uls-alpha branch.

Configure PX4 autopilot.

Values are provided as example (in our case, Pixhawk4-mini AP)

PX4 ParameterValue
MAV_1_CONFIGTELEM/SERIAL4 (require reboot to set next params)
MAV_1_FORWARDEnabled.
MAV_1_MODEOnboard.
SER_TEL4_BAUD460800_8N1 (It needs to be corresponding to the setting of UART in Receiver ULS-QR1-R1 connected to PX4 AP)

Running and testing

After configuration and wiring, power up drone and transmitter. On QGround control, go “Analyze Tools” -> MAVLINK Inspector. Check LANDING_TARGET MAVLINK message

In case the vehicle provide LOCAL_POSITION_NED message to UAVLAS system, and it hovers over beacon, you get “position_valid = 1” in LANDING_TARGET

To perform precision landing, you need to create a flight plan and enable Precision Landing option on the landing point.

Have a good flights !