Flat Trim

[devmax]

I noticed that doing a flat trim before every take-off sometimes drastically improves the accuracy of the sonar data(as it is now calibrated to zero) and leads to more stable take-offs...Unfortunately I don't have the time now to figure out how pull requests work, so please consider adding this code to enable flat trims!

in ardrone_driver.cpp add

flatTrim_sub = node_handle.subscribe("ardrone/flatTrim",1,&flatTrimCallback);

in ardrone_driver.h add

ros::Subscriber flatTrim_sub;

in `teleop_twist.cpp` add

void flatTrimCallback(const std_msgs::Empty &msg)
{
    vp_os_mutex_lock(&twist_lock);
    ROS_INFO("Setting flat trim now!");
    ardrone_at_set_flat_trim();
    ROS_INFO("Flat trim Set!");
    vp_os_mutex_unlock(&twist_lock);
}

user then publishes empty message to 'ardrone/flatTrim' topic to do a flat trim!

[mmyself]

sounds good to me.

[mani-monaj]

Thanks for the code @devmax .

My previous attempts to use flat-trim was not successful. Once I put a printf in the actual function in ARDroneLib to see if it catches and executes flat-trim. I noticed that the printf seemed to get executed when the program exits. I did not go further, so I want to ask if you are completely sure that the command gets executed and has an effect?

[devmax]

Hi Mani,

I didn't actually do the printf test like you, but what I did was to do a flat trim while echo-ing the navdata from the drone. In the landed state the altitude is automatically zero, but the rotXYZ values seem to be reset everytime I gave the command. More concretely, I did a flat trim a couple of times while the drone was in the air, and it crashed as expected..So there is something definitely going on!

The other ARDrone tool commands (set_ui_pad and set_Progressive_cmd) seem to work fine, so I see no reason why this shouldn't!

[mani-monaj]

I didn't actually do the printf test like you, but what I did was to do a flat trim while echo-ing the navdata from the drone. In the landed state the altitude is automatically zero, but the rotXYZ values seem to be reset everytime I gave the command. More concretely, I did a flat trim a couple of times while the drone was in the air, and it crashed as expected..So there is something definitely going on!

That's the correct way to testing of course.

[devmax]

@mani-monaj did you put the printf commands in ardrone_at_mutex.c? I did that and they didn't get executed..however even when i put the print commands in ardrone_at_set_ui_pad_value, they didn't get executed, although of course the drone takes off and lands just fine..any idea what the problem could be? I'm not very well versed with mutexes!

[mani-monaj]

@devmax I think the whole idea of putting printf in ARDroneLib's low level functions is wrong and misleading. However I have no explanation about the reason 😔

[devmax]

@mani-monaj I agree...but you said that's the correct way of testing it...what did you mean then?

[mani-monaj]

I meant the method that you used which tested the functionality rather than execution. Sorry for being vague.

[devmax]

oh I see, in that case do you want to commit the changes?

[mani-monaj]

oh I see, in that case do you want to commit the changes?

Sure. As soon as I can.

[mani-monaj]

Thanks for the contribution.

Note: flattrim has been implemented as a service.