CUAV C-RTK2 HP is a full-constellation satellite multi-frequency positioning and heading module independently developed by CUAV. Integrated dual-antenna heading system, one module can realize GPS heading. It makes it easy for UAVs to have application scenarios in complex magnetic field environments, such as power line inspections and metal ore inspections. It supports full-system full-band GNSS receivers and provides powerful satellite positioning capabilities. In RTK state, you can get 50+ satellite positioning services and centimeter-level high-precision positioning. C-RTK2 HP also supports UART and Dronecan dual communication interfaces. Dronecan can guarantee higher security and stronger anti-interference for data communication, while UART interface can guarantee compatibility with other non-CAN devices.

CUAV C-RTK2 HP Positioning and Heading is ideal for high precision positioning and haeding, especially for unmanned system applications.

Features

• Full constellation multi-frequency GNSS satellite receiver
• Single module dual antenna haeding system**
• RM3100 Industrial Grade Magnetic Compass (for safety redundancy)
• Safe and reliable Dronecan protocol and better compatible URAT interface
• Automatic switching between USB and URAT
• AP Periph Open Source Firmware，Worry-free custom development

Datasheet

Purchase

World Drone Market

Pinouts

GNSS performance comparison

CUAV C-RTK2 HP User Guide

Hardware connection

CUAV C-RTK2 HP supports connection in the following ways (choose one of the two)

CAN（Recommend）

UART

Enable CUAV C-RTK2 HP

Set the following parameters in the Missionplanner/Configuration Assistant/All Parameters table:

- GPS_TYPE = 9(droncan：9;UART:25）
- EK3_SRC1_YAW = 2 or 3(heading source, 2: use GPS haeding. 3: use GPS first, compass as backup)

Master and slave antenna offset

• GPS_MB1_TYPE=1(GPS1 Moving Baseline master antenna offsets relative to slave antenna, also enables the next parameters to be shown)
• GPS_MB1_OFF_X:offset in meters from the “Slave” to “Master” antenna in the X axis (in direction of 0 deg yaw, positive offsets are if “Master” is in front of the “Slave”.
• GPS_MB1_OFF_Y:offset in meters from the “Slave” to “Master” antenna in the Y axis (in direction 90 deg (right) of 0 deg yaw, positive offsets are if “Master” to the right of the “Slave”.
• GPS_MB1_OFS_Z：offset in meters from the “Slave” to “Master” antenna in the Z axis (in direction up and down, positive offsets are if “Master” below the “Slave”.

Position Offset Compensation

C-RTK2 HP is based on the position of the master antenna. If it cannot be installed at the center of gravity of the unmanned system; you need to set its offset value from the center of gravity for correction.

• GPS_POS1_X：offset in meters from the Center of Gravity to “Master” antenna in the X axis (in direction of 0 deg yaw, positive offsets are if “Master” is in front of the Center of Gravity.
• GPS_POS1_Y：offset in meters from the Center of Gravity to “Master” antenna in the Y axis (in direction 90 deg (right) of 0 deg yaw, positive offsets are if “Master” to the right of the Center of Gravity.
• GPS_POS1_Z：offset in meters from the Center of Gravity to “Master” antenna in the Z axis (in direction up and down, positive offsets are if “Master” below the Center of Gravity.

Example

The following figure is installed as an example:

The main antenna is located on the right side of the center of gravity and the slave antenna, 2 cm above the center of gravity.

Enable CUAV C-RTK2 HP

GPS_TYPE=9(droncan）
EK3_SRC1_YAW =3
GPS_MB1_TYPE=1

Antenna offset setting

GPS_MB1_OFF_X=0
GPS_MB1_OFF_Y=0.58
GPS_MB1_OFS_Z=0

Position offset setting

GPS_POS1_X=0.00
GPS_POS1_Y=0.29
GPS_POS1_Z=-0.02

Check heading

• GPS heading information is in the flight data toolbar of Missin Planner > gpsyaw in the status bar.
• Check if the gpsyaw value is consistent with the real heading.
• Rotate the airframe to check if the gpsyaw value responds correctly to the rotation.

RTK Correction

C-RTK2 HP can be used with C-RTK 9ps base station or Ntrip(CORS )Network RTK base station realizes RTK centimeter-level high-precision positioning, base station configuration:

• Set base station in Mission Planner
• Set base station in QGroundcontrol

Upgrade firmware

This article mainly describes how to upgrade the firmware for C-RTK2 HP.

Preparations before upgrade

• Flight controller running ArduPilot firmware
• Download Dronecan GUI/Mission Planner
• Connect C-RTK2 HP to flight controller
• Download firmware file

Set flight controller parameters

To upgrade the C-RTK2 HP firmware through the flight controller, you also need to set the following parameters in the Mission plannerd ground station”All parameter table:

For flight controllers using STMF7XX/STMH7XX as MCU:

"CAN_SLCAN_CPORT set to 2
'Serial7_Protocol set to 22

• Reboot

NOTE These flight controllers will have two usb driver ports in AP4.0/AP4.0 and above firmware, one is the flight controller mavlink output port, and the other is the slcan port; if there are no two ports, please uninstall the driver and reinstall)

For flight control using STM32F4xx as MCU

CAN_SLCAN_CPORT set to`1`
CAN_SLCAN_TIMEOUT set to 130000
CAN_SLCAN_SERNUM set to 0

Do not reboot until the upgrade is complete.

Load firmware

Upgrade using Droncan GUI

• Select the device port corresponding to slcan and click ok

• Click “√”; then double-click the device information
• Click “update firmware”, pop up a message box and click “yes”

• The mode/heakth/uptime item becomes “SOftware_update”

FAQ

1、Can C-RTK 2 HP be used as a RTK base?

• C-RTK2 HP is not designed as a base station, and it is complex to use as a base station; it is recommended to use the C-RTK 9Ps base station or use it in conjunction with other base stations.

2、Why do you need GPS Haeding?

• The GPS haeding system can replace the magnetic compass and solve the magnetic compass interference problem caused by the magnetic field generated by the internal circuit of the drone or the external complex magnetic field environment. It can be widely used in unmanned system power inspection, ship take-off and landing, mine inspection and other application scenarios.

3、I only use haeding, do I need an RTK base station?

• C-RTK2 HP obtains heading data in single-point positioning and RTK state; RTK base station is not required, but RTK base station can be added to obtain accurate centimeter-level positioning.

4、How far apart do the master and slave antennas need to be?

• There is no mandatory requirement. It is generally recommended that the installation distance be greater than 30cm. The larger the distance, the better the directional stability.

5、Can only one antenna be installed?

• If you don’t need haeding date, you can install only the main antenna (ANT1).

6、C-RTK2 has two antennas, which antenna is the location for positioning?

• The latitude and longitude reported by C-RTK2 is the positioning data of the main antenna (if no GPS offset is set).

Set rtkbase in Mission Planner

If you use Ardupilot firmware to build an RTK differential system, you need to perform base station-side positioning configuration and data forwarding through the missionplanner. During the positioning configuration of the base station, there is no need to start the mobile station and drone.

• Open the Mission Planner
• Enter the initial settings
• Click on optional hardware
• Click on RTK/GPS Inject you will see the following page:

• Set the base station port in the upper left corner
• Click connect
• In the SurveyIn Acc section, enter the absolute geographic accuracy that you expect your C-RTK base station to achieve. In the Time field, enter the shortest search time you want.
• Click Restart (the ground station will transfer the data you input to the C-RTK base station, and the base station will start a new round of search star positioning)
• You will see the following page: During the search process, the current search star positioning will be displayed in the box on the right side of the Mission Planner page:

• Position is invalid: The base station has not yet reached a valid location;
• In Progress: Search Star is still in progress;
• Duration: The number of seconds the current search star has been executed;
• Observation: the number of observations obtained;
• Current Acc: The absolute geographic accuracy that the current base station can achieve.
• The green vertical bar below Mission Planner shows the satellite and satellite signal strengths currently searched by the base station. The base station requires a certain amount of convergence time to meet your desired accuracy requirements. After testing, in an unobstructed area, it takes a few minutes to reach an absolute accuracy of 2m, and an absolute accuracy of less than 30cm takes about one hour, and it takes several hours (under ideal conditions) to achieve an accuracy of less than 10cm.

After the base station search star is completed, the Mission Planner will display the following page:

Using NTRIP Network RTK Base Station

Missionplanner supports NTRIP protocol to access CORS network RTK base station service instead of RTK base.

Setup Tutorial:

• Set to NTRIP in MP Ground Station>Initial Settings>Optional Hardware>RTK/GPS Inject
• Click “Connect” to enter the URL.

 Note : 

RTK positioning status

Using the paired digital transmission module to connect to the same Mission Planner ground station, the data of the base station will be transmitted to the C-RTK mobile station on the drone through the data transmission module. On the main page of Mission Planner, you can see that the current GPS status of the drone is displayed as RTK Float/RTK Fixed/3D RTK, indicating that the UAV’s positioning has entered the RTK state.

• RTK Float is a floating point solution.
• RTK Fixed is a fixed solution.

RTK Fixed has higher accuracy and is extremely environmentally demanding, and positioning can enter the RTK Fixed state when the signal is good enough.

Set rtkbase in QGoundcontrol

follow-up update

CUAV C-RTK2 HP Positioning and Heading Module Manual（inPDF）

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