PX4 disarmed automatically

I checked the source code, I found that it was because the remote control signal was interrupted for a period of time and caused the machine to enter the failsafe state, which led to automatic disarm. I want to know, in addition to making a thread that sends control signals regularly, what mavlink message is generally used to guide the robot’s movement when developing automatic cruisers, especially in ALT_HUD and GUIDED modes.