Link Search Menu Expand Document

Sentinel Connect to GCS

  1. Connecting to over Wi-Fi
  2. Connecting to QGC over 5G
  3. Tailscale VPN Setup
  4. Confirm Connection

Connecting to over Wi-Fi

If using Wi-Fi and you haven’t already connected to you network, see here.

In order to connect to QGC, ensure that your host computer is connected to the same network as your Sentinel.

If PX4 is running and both devices are connected to the network then Sentinel should automatically detect the host PC running QGC and connect.


Connecting to QGC over 5G

First follow the steps to connect to the 5G network.

In order to connect QGC over the LTE or 5G network, a VPN will be needed in order to complete the bridge from the cellular network to the drone.

A typical use case of an LTE connection is to connect a drone to a Ground Control Station (GCS) such as QGroundControl. Typically the GCS is also connected to an LTE network. In this case, both the drone and the GCS have been assigned IP addresses on the LTE network that are private to the carrier network. This prevents the drone from directly connecting to the GCS since their IP addresses are not visible to each other over the internet.

There are a variety of ways to solve this issue. ModalAI uses a VPN as the preferred solution.

LTE data flow

This diagram shows how the VPN solution works. In this example a server is allocated with a static IP address, For VOXL2 based devices, we prefer to use Tailscale as our VPN provider.

If you prefer to host your own server, you can do so with Google Cloud Platform, Amazon Web Services, Microsoft Azure, etc. Ubuntu is our preferred OS for our servers. Our self-hosted VPN server is setup using the OpenVPN software package.

In the example above, once the drone has connected to the AT&T network, it obtains the IP address 10.47.x.y and the GCS, once connected, obtains the address 10.47.x.z.

With the VPN server software running on the cloud server and VPN client software on both the drone and the GCS, the devices can now connect and get VPN IP address assignments. In this diagram, the drone is assigned and the GCS is assigned The drone can now communicate directly to the GCS using the IP address.

It is desirable for the drone and the GCS to always get the same IP address when connecting to the VPN. This is possible by assigning each separate network endpoint a unique security certificate. When each endpoint connects using it’s certificate it can be configured to receive the same address every time.

Tailscale VPN Setup

In order to install the Tailscale client on VOXL2, follow these instructions: Installing Tailscale on Ubuntu 18.04

Tailscale is extremely simple, fast, and straight-forward to setup. It’s free tier is a solid choice for robotics use cases.

Confirm Connection

If connection succeeds, you should get a connected status in QGC.

Next Step: Pre-Flight Setup