Chapter 6: External Control and Trajectory Planning
Unmanned system developers can generally be divided into two categories: low-level developers and high-level developers. Low-level developers work directly with the vehicle's sensors, actuators, and other internal components — their tasks include fuselage structural design, propulsion system selection, and controller design, with a focus on the vehicle's own control and maneuverability. High-level developers, on the other hand, treat the unmanned vehicle as a whole (an agent or controlled object), designing high-level intelligent planning algorithms to generate control commands that are sent to the low-level vehicle system for task execution, with a focus on intelligent perception and decision-making capabilities.
RC (Remote Control) mode is a human-operated UAV control mode, highly effective for UAV acrobatic performances and other demonstration scenarios. The remote controller referred to in this section uses the "Mode 2" (American hand) configuration: the left stick controls throttle and yaw, while the right stick controls roll and pitch. The RflySim Toolchain supports mainstream commercial UAV remote controllers and can achieve both HIL and real flight experiments on this platform.
MAVLink is a communication protocol designed for small unmanned vehicles. It is widely used for communication between ground control stations (GCS) and unmanned vehicles, as well as for internal communication between the onboard computer and Pixhawk. The protocol defines data transmission rules in the form of a message library. The RflySim Toolchain integrates the MAVLink protocol, which can be used directly in SIL, HIL, and real flight.
Offboard mode is a UAV control mode where the onboard computer or ground computer provides real-time control of the aircraft's velocity, position, attitude, etc. In this mode, the aircraft is treated as a whole object, with the focus on high-level vision and swarm algorithm development.
CopterSim communicates with PX4 via UDP, TCP, or serial port, with all packets following the MAVLink protocol. In PX4 SITL mode, CopterSim can use UDP ports to send/receive messages, but the number of vehicles is limited to 50 per session. The RflySim-provided PX4_SITL_RFLY mode supports large-scale swarms of up to 1,000 vehicles without port conflicts. In HIL mode, CopterSim communicates with PX4 via serial port.
Session 5: External Control and Trajectory Planning (Part 1)
Session 5: External Control and Trajectory Planning (Part 2)
Session 5: External Control and Trajectory Planning (Part 3)