Problem tunning PID in Quadcopter proyect

Hi to everyone

Im trying to control a quadcopter model by using some PIDs. Im using a step imput and the accelerations of the body as a feedback (I attach the file). The problem comes when trying to tune the PIDs: Im not able to do that. I have tried PID tuner, but the plant cannot be linnearized. I have tried a estimation of the plant, but it didn´t work. Finally I have tried with System Control Designer, but the PIDs cannot be tuned automaticaly. Since I´m not experienced with Simulink I would thank any suggestion or indication.

Thank you