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PX4 / PX4-Autopilot

PX4 Autopilot Software
https://px4.io
BSD 3-Clause "New" or "Revised" License
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Trajectory Setpoint - yawspeed #21621

Open fbenti opened 1 year ago

fbenti commented 1 year ago

I'm sending TrajectorySetpoint to the drone in order to rotate around its z axis, with low yaw speed, I set yawspeed to 0.1. However, it seems like the yawspeed parameter is not considered.

Screenshot from 2023-05-22 09-06-23 06_57_44.zip

I'm sending TrajectorySetpoint and OffboarddControlMode with only position set to True (but I also tried with attitude true, but nothing changed.

bresch commented 1 year ago

Do you also set an attitude or just a yawrate? Could you upload the log to https://logs.px4.io/ and share the link here please

fbenti commented 1 year ago

I've also set the attitude. https://logs.px4.io/plot_app?log=9e036756-6219-4e61-8f88-1aa75e3c9383

bresch commented 1 year ago

The yawspeed is a feedforward, so you need to send a yaw setpoint that is the integral of that 0.1 rad/s if you want a ramp with constant speed.

fbenti commented 1 year ago

Ok, I cannot just set the desired yaw only once, but I have to change it at every sampling step according to the sampling time, right?

I mean, if I start at yaw=0 and set the yaw_setpoint =1 (rad) and yawspeed = 0.1 (rad/s), it wouldn't reach the target in 10 seconds ?

fbenti commented 1 year ago

In the first log attached, in the TrajectorySetpoint msg, I was giving yaw = desired_yaw and yawspeed = yawspeed.

Now, instead https://review.px4.io/plot_app?log=3e32b266-4225-47ba-8ba9-cbd9dfb27adb? So now in the trajectory msg, at every iteration I'm giving a yaw setpoint as yaw = curr_yaw + yawspeed and set yawspeed = yawspeed. Is this the right way of doing it? If so, what the purpose of setting the yawspeed?

bresch commented 1 year ago

Ok, I cannot just set the desired yaw only once, but I have to change it at every sampling step according to the sampling time, right?

Yes.

I'm giving a yaw setpoint as yaw = curr_yaw + yawspeed and set yawspeed = yawspeed . Is this the right way of doing it?

Yes, but you should also consider the sampling time and use the previous yaw setpoint, not the current value: yaw = yaw + yawspeed * dt

If so, what the purpose of setting the yawspeed?

Yawspeed is a feedforward, it helps to have a better tracking. If you just set the yaw, the drone will slightly lag behind the setpoint.

BTW, if you just want to control the yaw rate, you can also send yaw = NAN and yawspeed = yawspeed. This will open the yaw loop and only control the yaw rate.