I have a plain with a gimbal of all 3 freedoms (tilt ,pan and roll).
I want to fly near a point and Lock on that point with my gimbaled camera while flying.
I know in advance the location o the that point.
Do you know any commend or a script, that does this in the mission planner?
It is similar to Roi commend in Ardu-copter .
Short answer is no.
Target tracking is not yet implemented into APM:Plane, it requires collaboration between the gimbal and the APM. ROI in Arducopter uses the copter yaw to track the target.
when i use code of Ardu Plane, in mission planner, the command DO_SET_ROI doesn't exist, how can i deal with this？I want my 3 axis gimbal to point at ROIs.
It doesn't exist so you can't. You can't get a 3 axis gimbal to point at ROI, with a multirotor the multirotor does the pointing not the gimbal. Maybe it will come eventually but the gimbal will have to interface with the APM/Pixhawk.
Thans very much, Graham.