机载计算机外设
This section contains information about companion computer peripherals. These include both components that might be connected to a companion computer (potentially triggered/accessed by PX4), and for connecting the computer to the flight controller.
Companion/Pixhawk Communication
Typical companion computer work with Pixhawk requires a companion link to transmit/receive the data between the companion computer and Pixhawk hardware (e.g. Intel NUC and Pixhawk 4).
有一些构建这种通信桥的设备，如 FTDI USB 接口和电平移位器(见下文)。
FTDI 设备
The FTDI USB adapters are the most common way of communicating between companion computer and Pixhawk. They are usually plug and play as long as the IO of the adapter is set to 3.3V. In order to utilize the full capability/reliability of the serial link offered on the Pixhawk hardware, flow control is recommended.
A few "turnkey" options are listed below:
| 设备 | 3.3v IO (默认) | 流控 | Tx/Rx LEDs | JST-GH接插件 |
|---|---|---|---|---|
Capable | Capable | No | Yes | |
Yes | No | Yes | No |
You can also use an off-the-shelf FTDI cable like this one and connect it to flight controller using the appropriate header adaptor (JST-GH connectors are specified in the Pixhawk standard, but you should confirm the connectors for your flight controller).
逻辑电平移位器
On occasion a companion computer may expose hardware level IO that is often run at 1.8v or 5v, while the Pixhawk hardware operates at 3.3v IO. In order to resolve this, a level shifter can be implemented to safely convert the transmitting/receiving signal voltage.
Options include:
相机
Cameras are used image and video capture, and more generally to provide data for computer vision applications (in this case the "cameras" may only provide processed data, not raw images)
立体摄像机
Stereo cameras are typically used for depth perception, path planning and SLAM. They are in no way guaranteed to be plug and play with your companion computer.
Popular stereo cameras include:
VIO Cameras/Sensors
The following sensors can be used for Visual Inertial Odometry (VIO):
Data Telephony (LTE)
An LTE USB module can be attached to a companion computer and used to route MAVLink traffic between the flight controller and the Internet.
There is no "standard method" for a ground station and companion to connect over the Internet. Generally you can't connect them directly because neither of them will have a public/static IP on the Internet.
A common approach is to set up a virtual private network between the companion and GCS computer (i.e. install a VPN system like zerotier on both computers). The companion then uses mavlink-router to route traffic between the serial interface (flight controller) and GCS computer on the VPN network.
This method has the benefit that the GCS computer address can be static within the VPN, so the configuration of the mavlink router does not need to change over time. In addition, the communication link is secure because all VPN traffic is encrypted (MAVLink 2 itself does not support encryption).
Some USB modules that are known to work include:
The E8372 includes WiFi which you can use to configure the SIM while it is plugged into the companion (making the development workflow a little easier). The E3372 lacks WiFi, so you have to configure it by plugging the stick into a laptop.
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