Trajectory following in Avoidance

PX4 Autopilot
1

Hi,

From my understanding, there are two trajectory following methods used in the Avoidance repo. Setpoint for Offboard mode and Trajectory_setpoints in Mission Mode.

In Offboard setpoint mode, points are sent sequentially to mavros/setpoint_position/local, while in Mission mode, Mavros::Trajectory is sent to /mavros/trajectory/generated.

My question is, in Offboard mode, if it is using setpoint directly to control the drone, how does it control the drone to fly a smooth flying path? From simulation it seems that the flight was quite smooth, can anyone shed some light here.

Thanks.
Joe

2

Hi,

How do you define smooth?

The setpoints sent to the controller through mavros will be sent with a frequency based on how ros::rate() was initialised. Thus if you have a continuous setpoint signal stored in memory (which isn’t the case, but lets make the assumption) the signal will be sampled at the ros::rate() frequency, resulting in a descretised signal.

The descretised setpoint signal is thus sent to the controller. The controller reacts to this new signal, and your system (the UAV) will have a smooth response, since it is a continuous system.