Implement PID control on iOS client

[ocb00999]

I want to implement PID control on the iOS client side. From the ios-client-example, I know how to control the thrust output etc, but how can I get the sensor output from crazyflie (yaw,pitch,alt,acceleration.. etc)
I read a post saying I can log those parameters, but I am not very clear how to start. Do I need to modify the firmware?

Thank you very much.

[tobias]

First thing what kind of PID control are you thinking about? Position PID control? I don't think any lower level control will work as the latency is to big over BLE. I know it has been done using the Crazyradio but that has much lower latency.

[ocb00999]

First thing what kind of PID control are you thinking about? Position PID control? I don't think any lower level control will work as the latency is to big over BLE. I know it has been done using the Crazyradio but that has much lower latency.

So what's the typical low latency required to make Positional control? Can I also get the acceleration from the sensor to my ios client?

Actually I want to make an app that can give command as "fly up for x meter and stay still for a couple seconds and come back", the x is given from user input. Is that possible?

[whoenig]

Positional control is possible with BLE, but lower-level control (i.e. trying to hover based on the IMU) is not.
Nevertheless, the drift of the Crazyflie (in fact any quadcopter without optical flow sensors) is so high, that such a high-level controller is only possible if you have some way of external tracking of the Crazyflie. Others used Cameras (such as PS3 Eye), RGBD sensors (MS Kinect, Asus XTION Pro), or professional motion capture systems (such as VICON for researchers) to achieve that.

[Slaxx]

Yes I can confirm that it works pretty nice with a vicon system