https://ardupilot.org/copter/docs/parameters.html#frame-class
git submodule update --init --recursive
参数RTL_ALT 回家时高度
https://ardupilot.org/copter/docs/parameters.html#rc9-option-rc-input-option
https://ardupilot.org/copter/docs/parameters-Copter-stable-V4.0.3.html?highlight=parameters