Setup & Getting Started (PX4)
Getting started
n this section of the manual, we will cover the basic setup of the units. To setup the RTK units with PX4, you will need QGroundControl installed on your computer or Ground Control Station and PX4 installed on your flight controller. If you are using Ardupilot firmware and Mission Planner ground station software, please refer the Ardupilot setup guide. Using RTK (Real Time Kinematics) greatly increases the accuracy of the GPS positioning. RTK mode requires a base station and a rover station. Either Rover or Helical can be use a rover station. The Helical or the “Base” model, we recommend using the “Base” model should be used as base station since it allows a larger external antenna.
Preparation
To use the H-RTK on a drone, you need the following hardware:
- A flight controller with CAN port for the GPS, a free serial port for the radio telemetry. A Holybro Pixhawk 4 or newer is recommended. This example uses a Pixhawk 6C.
- A pair of radio telemetry radios for data transmission, this example uses Holybro Sik Telemetry Radio V3
- A H-RTK Rover or Helical (UAV side)
- A H-RTK Helical or Base Station H-RTK F9P (base station side)
- Ground Station (Ex: Tablet, Laptop, GCS, etc.)
Connection Diagram
Connect the devices as follow:
Before you start the setup, make sure both RTK units have a good view of the sky so they can receive the best signal from the satellites.
Flight controller Setting with PX4 Firmware
If you are using DroneCAN version, make sure The firmware used for flight control is PX4 V1.12.3 or higher, which automatically allocate 2 node ID for DroneCAN. Older firmware might not be able to automatically allocate 2 node ID. You will need to use newer firmware and perform following operation to manually assigning node ID. Connect the GPS to the flight controller.
If you are using DroneCAN version, connect the flight controller to QGC and Make sure the parameter UAVCAN_ENABLE has been set to “Sensor Automatic Config”. The DroneCAN-F9P will now work.
RTK GPS settings
The RTK GPS settings are specified in the QGroundControl General Settings (opens new window) (Settings View > General Settings > RTK GPS).
These settings define the minimum duration and minimum accuracy for completing the RTK GPS setup process (known as “Survey-In”).
TIP: You can save and reuse a base position to save time: perform Survey-In once, select Use Specified Base Position and press Save Current Base Position to copy in the values for the last survey. The values will then persist across QGC reboots until they are changed.
Flight Controller Setup
The UAVCAN_PUB_RTCM parameter needs to be set to Enabled.
MAVLink2
The MAVLink2 protocol must be used because it makes more efficient use of lower-bandwidth channels. This should be enabled by default on recent builds. Holybro SiK Telemetry Radio uses MAVLink2 protocol by default. But if you are not sure about the status of the data transmission, you can go through the following steps to ensure MAVLink2 is used:
Update the telemetry module firmware to the latest version
Set MAV_PROTO_VER to 2
Tuning
You may also need to tune some parameters of the flight controller as the default parameters are tuned assuming a GPS accuracy in the order of meters, not centimeters. For example, you can decrease EKF2_GPS_V_NOISE and EKF2_GPS_P_NOISE to 0.2.
RTK Connection Process
The RTK GPS connection is essentially plug and play:
1.) Start QGroundControl and attach the base RTK GPS via USB to the ground station. The device is recognized automatically.
2.) Start the vehicle and make sure it is connected to QGroundControl.
3.) QGroundControl then starts the RTK setup process (known as “Survey-In”).
Survey-In is a startup procedure to get an accurate position estimate of the base station. The process typically takes several minutes (it ends after reaching the minimum time and accuracy specified in the RTK settings).
You can track the progress by clicking the RTK GPS status icon.
Once Survey-in completes, the RTK GPS icon changes to white and QGroundControl starts to stream position data to the vehicle.
Vehicle GPS switches to RTK mode. The new mode is displayed in the normal GPS status icon.
Tip: The Orange RTK FIX led on F9P module will blink when receiving RTCM data. And the led will stay on when the Rover module has entered the RTK status.
Setup & Getting Started (Ardupilot)
Getting started
In this section of the manual, we will cover the basic setup of the units. To setup the RTK units with Ardupilot, you will need Mission Planner installed on your computer or Ground Control Station and Ardupilot installed on your flight controller.
Using RTK (Real Time Kinematics) greatly increases the accuracy of the GPS positioning. RTK mode requires a base station and a rover station. Either Rover or Helical can be use a rover station. The Helical or the “Base” model, we recommend using the “Base” model should be used as base station since it allows a larger external antenna.
Preparation
To use the H-RTK on a drone, you need the following hardware:
- A flight controller with CAN port for the GPS, a free serial port for the radio telemetry. A Holybro Pixhawk 4 or newer is recommended. This example uses a Pixhawk 6C.
- A pair of radio telemetry radios for data transmission, this example uses Holybro Sik Telemetry Radio V3
- A H-RTK Rover or Helical (UAV side)
- A H-RTK Helical or Base Station H-RTK F9P (base station side)
- Ground Station (Ex: Tablet, Laptop, GCS, etc.)
Connection Diagram
Connect the devices as follow:
Before you start the setup, make sure both RTK units have a good view of the sky so they can receive the best signal from the satellites.
Compass Setting
There is a compass on the GPS Module. After the flight controller connects and recognizes the GPS, you can see that a BusType of UAVCAN or I2C has been added on the SETUP -> Mandatory Hardware -> Compass page. If the priority of this external compass is not 1, you should click the icon on the page and set it to be the highest priority compass.
For any Ardupilot User that uses GPS with IST8310 compass that is unable to preform normal compass calibration “compass dance” for any reason, set parameter COMPASS_ORIENT=6 (Yaw270) for proper compass orientation.
Compass Calibration:
Select the compass you want to use (the default is normally fine). Then click “Start” to begin calibrating the compass, follow the process until the calibration is done.
Ardupilot Parameter Setup
For flight controllers using Ardupilot Firmware
Using one GPS：
Connect the cable connector to the flight controller.
1.) Power the flight controller and connect it to Mission Planner. Go to “CONFIG > Full Parameter List” and modify the following parameters:
If connecting to the CAN1 port:
CAN_D1_PROTOCOL: 1 (set virtual driver of CAN1 to DRONECAN)CAN_P1_DRIVER: 1 (set this parameter to enable CAN 1 bus)
if connecting to the CAN2 port:
CAN_D2_PROTOCOL: 1 (set virtual driver of CAN 2 to DRONECAN)CAN_P2_DRIVER: 1 (set this parameter to enable CAN 2 bus)
2.) Set the following if you are using the DroneCAN version:
GPS_TYPE: 9 set the communication protocol type of GPS 1 to DroneCANNTF_LED_TYPES: 231 Set to DroneCAN for the integrated LED’s type
3.) On the RM3100 version, there is no external safety switch on the GPS unit, so ensure that BRD_SAFETY_DEFLT (BRD_SAFETY_ENABLE on earlier ArduPilot versions) to 0 to disable the safety switch, or connect a external safety switch to the flight controller.
4.) Click “Write Params” when done. CAN functions will be available after rebooting the flight controller.
Using two GPS (Blending or Moving Baseline)：
Refer to Ardupilot guide for the latest information
Two GPS may be used at the same time on a flight controller to either provide redundancy/blending, or moving baseline yaw.
If you are using DroneCAN version, make sure the firmware used for flight controller is ArduCopter 4.1.5 or higher, which automatically allocates 2 node IDs for DroneCAN. Older firmware might not be able to automatically allocate 2 node IDs.
To use two GPS on one flight controller at the same time, in addition to setting the parameters above, the following operations must be performed:
1.) Connect one GPS to the flight controller. If you are using the DroneCAN version, connect one the CAN1 port and another to the CAN2 port.
2.) Power up the flight controller and connect to Mission Planner. Go to “CONFIG > Full Parameter List” and modify the following parameters:
GPS_TYPE2：set to 9 (If the communication protocol type of GPS 2 is DroneCAN)GPS_TYPE2：set to 1 (If the communication protocol type of GPS 2 is UART)
To setup dual GPS Blending or GPS priority:
GPS_AUTO_SWITCH: 2 for blending, 1 to use best GPS (self-judged)GPS_BLEND_MASK: bitmask for which elements are blended between the two GPS: bit 0, Horizontal Position, bit 1, Vertical Position, bit 2, Speed. A value of 7 (first three bits set) is suggested.
Refer to Ardupilot guide for the latest information
RTK Survey by Mission Planner
Base Module Setting using Mission Planner
Start with a base station setup first. During the base station setup, the rover and the UAV do not need to be turned on.
Open the Mission Planner ground station software on your computer and go to the “SETUP→ Optional Hardware → RTK/GPS Inject”. You will see the following page:
Select the correct COM port that the base RTK module is connected to in the top right corner and click connect.
In the SurveyIn Acc section, enter the absolute geographic accuracy that you expect your base station to achieve (2m or better is typical). In the Time column, enter the minimum survey time you expect (60sec or longer is typical).
Click on Restart, the ground station will transfer the data you have entered to the base module, the base module will start a new round of surveying. You will see the following page:
During the survey process, the right box will show the current survey status:
- The Position is invalid: The base station has not yet reached a valid location.
- In Progress: The survey is still in progress.
- Duration: The number of seconds that the current surveying task has been executed.
- Observation: the number of observations acquired.
- Current Acc: Absolute geographic accuracy that the current base station can achieve.
The Green bar at the lower part of the Mission Planner page shows the current satellites being detected and the signal strength related to each satellite. At least eight or more satellite signals need to be guaranteed to exceed the red line (Only when the satellite signal exceeds the red line is the effective number of satellites).
The base station needs a certain amount of time to meet the accuracy requirements of your input. Testing shows that in an open area without shelter, to achieve the absolute accuracy of 2m takes a few minutes; to reach the absolute accuracy of less than 30cm takes around an hour; to reach the accuracy of 1cm takes around 24 hours.
Even if the accuracy of the base station is 1.5 to 2 m, the position accuracy of the rover module relative to the base station can still reach the centimeter level.
After the survey is complete, the Mission Planner will display the following page:
In the RTCM box it shows that the base status indicator is green, and the GPS/Glonas/BeiDou/Galileo satellite systems are all green. The Survey In box on the right says, Position is valid.
To store the current location in the Mission Planner: Click Save Current Pos, enter a name in the dialogue box, and click “OK”. As shown below, you can see your saved location in the list. Click the Use button for the location you saved. The base station will enter the fixed mode and the status will show “Using FixedLLA”.
In the future, if you set the base station in the same location, you do not need to conduct the survey again, just click the “Use” button that corresponds to the location you have saved.
Rover Module and Flight Controller Setup
After the base station is set up, you can turn on the UAV. The base station data will be transmitted through the telemetry module to the GPS module on the UAV. In the Mission Planner main page, you can see the current GPS status displayed as RTK Float / RTK Fixed / 3D RTK, indicating that the positioning of the UAV has entered RTK mode.
- RTK Float is a floating-point solution。
- RTK Fixed is a fixed solution. RTK Fixed mode has higher accuracy and requires better signal strength.
- 3D RTK is unified saying of RTK Float / RTK in the Mission Planner Chinese version
Tip: The Orange RTK FIX led on F9P module will blink when receiving RTCM data. And the RTK FIX led will stay on when the Rover module has entered the RTK status.
Mission Planner Software Configuration of F9P Parameters (DroneCAN Version)
Parameters change
To change the internal parameters of the F9P module through Mission Planner, connect to the autopilot normally and go to the SETUP->Optional Hardware->DroneCAN/UAVCAN screen. Press the MAVLink CAN1 (or MAVLink CAN2 if on CAN port 2) button and you will see the GPS by name:
Press the “Menu” button and then click “Parameters” from the right drop down menu.
In the parameter setting page, you can see all the parameters of F9P. If you change something, click “Commit Params” to save the changes.
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