DragonOSD+ Autopilot configuration
Posted: Fri 28 May 28 2010 9:57 am
Note: Unless you have GPS home position set - the autopilot will not function under any circumstances.
* If the autopilot is active - this will be indicated on the screen with a message "AUTOPILOT (nnnn )" where nnnn is "HOME" if you're not flying waypoints. If you do not see this message, then you have not activated autopilot successfully.
The keys to successful setting up of the autopilot functon are:-
1. testing a bit at a time
2. testing one part at a time (ie. turning to home, then climbing to cruise altitude)
3. being familiar with the menu settings and able to access them quickly
4. do as much testing on the ground as possible
To do this - the first thing you'd do would be to:-
1. Ensure that you have the Elev. direction and Rudd. direction set correctly in the menu options such that you can navigate the menu in the correct orientation (ie. moving the elevator stick down bring the menu selection down, moving the aileron stick right increases the parameter value.) Note that there are separate direction controls for menu navigation and for actual flight control. The two sets are found in different sub-menus with one set purely for menu navigation, while the second set for autopilot operations.
1b. Ensure that the Elevator and Aileron/Rudder directions are correct. You can do this using the control surface test in the root menu. When you activate it, the surfaces will move in such a way so as to climb and roll/turn right. This means that for a regular plane, the elevators will go up, the rudder will go right (looking from the tail-end of the plane) if connected, and the right aileron will go up while the left aileron will go down. If you are using a wing, the left aileron/elevon will appear to be not moving. If the movements do not correspond to this description, you will need to change the direction settings for the servos in the menu options.
2. Test the autopilot without the stabilizer or IMU working first.
3. Trim out your plane so that it flies more or less straight and level before starting your test.
4. Configure your radio so you can activate or de-activate autopilot mode with a switch.
5. Ensure that you are getting good satellite readings and a solid position fix (HDOP less than 1.3 would be good)
6. We will adjust the turns first so set ROCSTEPGAIN to 0.0 for this test. Also set the Auto and GPS stabilizer gain to 0.0. Remember that changes need to be saved if you want them to persist through a power-cycle.
7. In flight, with the default autopilot settings - fly in a direction away from home. Once you are flying more or less straight (and not in too windy conditions), activate the autopilot. Verify that the autopilot label is printed on screen. Now, without any stick inputs, observe if the plane is attempting to turn in the correct direction.
8. If the autopilot is turning in the right direction, de-activate the autopilot and fly in an opposite direction. Repeat #7 above and see if the autopilot will turn correctly in the opposite direction. Remember that when the autopilot is manually engaged (ie. with the switch), you still retain control over the plane so if you get concerned about the way the plane is going, you can override it with your stick inputs.
9. If the plane is turning the wrong way in #7 or #8, re-do the test to verify it. If it is confirmed, you will need to reverse the Rudd. direction in the menu. After that, try again. Note that reversing this setting will also reverse the way the aileron stick behaves in the menu navigation.
10. Once you have the plane turning in the correct direction, you can now assess if the plane is turning too slow, or too hard. If it is turning too hard, it may start to oscillate hard - ie. turning too hard and then correcting too hard. If this is the case, you may want to reduce APROTGAIN and possibly reduce ROTSTEPGAIN. Normally if it is close to where I want it, I tend to adjust ROTSTEPGAIN. It is preferable to keep ROTSTEPGAIN no more than about 8 but even that could be too much depending on the particular servo and setup. If the plane is turning too weakly, you can increase APROTGAIN and/or ROTSTEPGAIN. Increasing ROTSTEPGAIN too much will result in exaggerated snake-like oscillation movement.
Once you are happy with your settings - turn on the autopilot and see if it brings the plane back properly from about 300m to 500m out (making sure that your radio link can go that far in the first place).
This concludes the adjustment for the turning autopilot. The climbing autopilot will attempt to bring the plane to the cruise altitude which you may want to change in the menu. Other than that, the procedure is pretty much the same except that you are dealing with the Elev. direction, the APROCGAIN and the ROCSTEPGAIN. Instead of turning left or right, you want to observe if the plane is attempting to climb or dive depending on whether you are above or below the cruise altitude. You will need to increase ROCSTEPGAIN to around 3.0 to start with and go from there.
There are other settings for the autopilot but you want to start with these. If the turn direction is correct, the stabilizer should also be working correctly. For that you will need to set the maximum allowable gain, and, optionally, a gain control channel.
Note that you could, technically, perform all these tests on the ground while walking around the field with the plane and observing the movement of the control surfaces. If you choose to do so, you may want to use a very large value for ROTSTEPGAIN so that the servo movements are move easily visible, for when trying to ascertain if the autopilot is turning the right way. Also note that you need to be moving constantly or the GPS will not put out a valid heading which the autopilot needs.
Remember, change your values in small steps. It may take slightly longer but your patience will be rewarded. Conversely, impatience will most likely result in an accident. You have been warned.
Daniel
* If the autopilot is active - this will be indicated on the screen with a message "AUTOPILOT (nnnn )" where nnnn is "HOME" if you're not flying waypoints. If you do not see this message, then you have not activated autopilot successfully.
The keys to successful setting up of the autopilot functon are:-
1. testing a bit at a time
2. testing one part at a time (ie. turning to home, then climbing to cruise altitude)
3. being familiar with the menu settings and able to access them quickly
4. do as much testing on the ground as possible
To do this - the first thing you'd do would be to:-
1. Ensure that you have the Elev. direction and Rudd. direction set correctly in the menu options such that you can navigate the menu in the correct orientation (ie. moving the elevator stick down bring the menu selection down, moving the aileron stick right increases the parameter value.) Note that there are separate direction controls for menu navigation and for actual flight control. The two sets are found in different sub-menus with one set purely for menu navigation, while the second set for autopilot operations.
1b. Ensure that the Elevator and Aileron/Rudder directions are correct. You can do this using the control surface test in the root menu. When you activate it, the surfaces will move in such a way so as to climb and roll/turn right. This means that for a regular plane, the elevators will go up, the rudder will go right (looking from the tail-end of the plane) if connected, and the right aileron will go up while the left aileron will go down. If you are using a wing, the left aileron/elevon will appear to be not moving. If the movements do not correspond to this description, you will need to change the direction settings for the servos in the menu options.
2. Test the autopilot without the stabilizer or IMU working first.
3. Trim out your plane so that it flies more or less straight and level before starting your test.
4. Configure your radio so you can activate or de-activate autopilot mode with a switch.
5. Ensure that you are getting good satellite readings and a solid position fix (HDOP less than 1.3 would be good)
6. We will adjust the turns first so set ROCSTEPGAIN to 0.0 for this test. Also set the Auto and GPS stabilizer gain to 0.0. Remember that changes need to be saved if you want them to persist through a power-cycle.
7. In flight, with the default autopilot settings - fly in a direction away from home. Once you are flying more or less straight (and not in too windy conditions), activate the autopilot. Verify that the autopilot label is printed on screen. Now, without any stick inputs, observe if the plane is attempting to turn in the correct direction.
8. If the autopilot is turning in the right direction, de-activate the autopilot and fly in an opposite direction. Repeat #7 above and see if the autopilot will turn correctly in the opposite direction. Remember that when the autopilot is manually engaged (ie. with the switch), you still retain control over the plane so if you get concerned about the way the plane is going, you can override it with your stick inputs.
9. If the plane is turning the wrong way in #7 or #8, re-do the test to verify it. If it is confirmed, you will need to reverse the Rudd. direction in the menu. After that, try again. Note that reversing this setting will also reverse the way the aileron stick behaves in the menu navigation.
10. Once you have the plane turning in the correct direction, you can now assess if the plane is turning too slow, or too hard. If it is turning too hard, it may start to oscillate hard - ie. turning too hard and then correcting too hard. If this is the case, you may want to reduce APROTGAIN and possibly reduce ROTSTEPGAIN. Normally if it is close to where I want it, I tend to adjust ROTSTEPGAIN. It is preferable to keep ROTSTEPGAIN no more than about 8 but even that could be too much depending on the particular servo and setup. If the plane is turning too weakly, you can increase APROTGAIN and/or ROTSTEPGAIN. Increasing ROTSTEPGAIN too much will result in exaggerated snake-like oscillation movement.
Once you are happy with your settings - turn on the autopilot and see if it brings the plane back properly from about 300m to 500m out (making sure that your radio link can go that far in the first place).
This concludes the adjustment for the turning autopilot. The climbing autopilot will attempt to bring the plane to the cruise altitude which you may want to change in the menu. Other than that, the procedure is pretty much the same except that you are dealing with the Elev. direction, the APROCGAIN and the ROCSTEPGAIN. Instead of turning left or right, you want to observe if the plane is attempting to climb or dive depending on whether you are above or below the cruise altitude. You will need to increase ROCSTEPGAIN to around 3.0 to start with and go from there.
There are other settings for the autopilot but you want to start with these. If the turn direction is correct, the stabilizer should also be working correctly. For that you will need to set the maximum allowable gain, and, optionally, a gain control channel.
Note that you could, technically, perform all these tests on the ground while walking around the field with the plane and observing the movement of the control surfaces. If you choose to do so, you may want to use a very large value for ROTSTEPGAIN so that the servo movements are move easily visible, for when trying to ascertain if the autopilot is turning the right way. Also note that you need to be moving constantly or the GPS will not put out a valid heading which the autopilot needs.
Remember, change your values in small steps. It may take slightly longer but your patience will be rewarded. Conversely, impatience will most likely result in an accident. You have been warned.
Daniel