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.

If you are using PX4 firmware and QGroundControl ground station software, please refer to the link for more information: https://docs.px4.io/en/advanced_features/rtk-gps.html Using RTK (Real Time Kinematics) greatly increases the accuracy of the GPS positioning. RTK mode requires a base station and a rover station. Either DroneCAN F9P Rover or Helical can be use a rover station. The DroneCAN F9P Helical or the Standard F9P Helical/Base should be used as base station since it allows a larger external antenna.

Preparation

To use the DroneCAN H-RTK F9P 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 DroneCAN F9P Rover or Helical (UAV side)

• A DroneCAN H-RTK F9P or Station H-RTK F9P (base side)

• Ground Station (Ex: Tablet, Laptop, etc.)

Connection Diagram

Connect the devices as follow:

Compass Setting

There is a BMM150 compass on the DroneCAN-F9P. After the flight controller connects and recognizes the DroneCAN-F9P, you can see that a BusType of UAVCAN has been added on the SETUP-> Mandatory Hardware ->Compass page. If the priority of this compass is not 1, you should click the icon on the page and set it to be the highest priority compass.

Compass Calibration:

Select the compass you want to use (the default is normally ok). 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 DroneCAN F9P：

Connect the 4 pin CAN cable connector to CAN1 (or CAN2) port on 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:

• GPS_TYPE: 9 set the communication protocol type of GPS 1 to DroneCAN

• NTF_LED_TYPES: 231 Set to DroneCAN for the integrated LED’s type

3.) There is no external safety switch on the GPS unit, so either set BRD_SAFETY_DEFLT (BRD_SAFETY_ENABLE on earlier ArduPilot versions) to 0 to disable the safety switch, or connect a safety switch to the flight controller.

4.) Click "Write Params" when done. CAN functions will be available after rebooting the flight controller.

Using two DroneCAN F9P (Blending or Moving Baseline)：

Two DroneCAN F9Ps may be used at the same time on a flight controller to either provide redundancy/blending, or moving baseline yaw.

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 DroneCAN F9P on one flight controller at the same time, in addition to setting the parameters above, the following operations must be performed:

1.）Connect one DroneCAN-F9P to the CAN1 port of the flight controller, 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_TYPE2：9 set the communication protocol type of GPS 2 to DroneCAN.

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.

To setup Moving Baseline for Yaw:

Instead of using different CAN ports for the two GPS, they must be on the same CAN bus to allow the fast data transfer required between the two GPS for Moving Baseline YAW (you may need a CAN/I2C bus splitter board to do this), and instead of setting GPS_TYPE and GPS2_TYPE to 9, set:

• GPS_TYPE: 22

• GPS_TYPE2: 23

• GPS_AUTO_CONFIG: 2 for DroneCAN Moving Baseline configuration

For Moving Baseline Yaw to be computed, the positions, relative to vehicle motion, of the two GPS must be specified. Since they are connected to the same CAN bus, the identity of which is the “first” GPS and which is the “second” GPS is a bit of a problem since they get assigned on a first detected, first assigned basis. The most practical approach is to just unplug one of the GPS and see in the GCS which no longer is present, in order to identify which is GPS1 and which is GPS2.

Then the GPS_POS1_X, GPS_POS1_Y, and GPS_POS1_Z parameters can be entered for GPS1 and, similarly for the second GPS, the GPS_POS2_X, GPS_POS2_Y, and GPS_POS2_Z parameters. The X direction is in the direction of forward motion, offset from the centroid of the vehicle, the Y is to the right, and Z is down from the centroid.

Also set:

• GPS_AUTO_SWITCH: 1

• AHRS_EKF_TYPE: 3 (to use EKF3)

• EK2_ENABLE: 0 (to disable EKF2)

• EK3_ENABLE: 1 (to enable EKF3)

• EK3_SRC1_YAW: 2 (“GPS”) or 3 (“GPS with Compass Fallback”) if a compass(es) is also in the system

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 DroneCAN-F9P 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

Mission Planner Software Configuration of F9P Parameters

Parameters change

In the previous steps, the Flight Controller (Pixhawk 6C) was able to connect to the DroneCAN F9P module. To change the internal parameters of the DroneCAN 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 DroneCAN F9P. If you change something, click "Commit Params" to save the changes。