I have a hexacopter simulink model attached with the controllers and after a particular simulation time my roll pitch and yaw values rapidly increases and simulation stops.

[Sam Chak]

Hi @Agnes

Either the designed controller failed to stabilize the hexacopter or the simulated external disturbance is too strong for the controller to compensate. Without having access to the airworthiness stability proof, we are unable to pinpoint the exact cause.

[Agnes]

Hi @Sam Chak

But the model is reaching upto 1000 m and holding the same for around 20 seconds and then it drops the attained positions and altitude due to the high vlaues of roll pitch yaw which are the main factors to calculate the X Y Z of the hexacopter as per the Equation of motion.I dont have any sensors in my model . So could it be becuase of my controller only ?Since the roll pitch yaw values are high my current X Y Z values also getting high which are the inputs to the controllers along with the desired X Y Z.

Can you please suggest any method to solve this.

Thanking you in Advance.

[Sam Chak]

Hi Agnes, what do you mean by high values of roll pitch yaw? If they are roll rate, pitch rate, and yaw rate, it probably means the UAV is tumbling. Can you show the responses?

What kind of controller do you use to stabilize the UAV?

[Agnes]

Hi Sam, By high values I meant that the values of roll pitch yaw which are the angles integrated from the roll rate, pitch rate and yaw rate and normally the range of these values was between 0 to 1 deg. then this values starts increases gradually .But once the simulation stops due to the previous error the corresponding values will be more than 250 deg and beyond that.

I am using a PI controller for this model.

[Sam Chak]

Hi Agnes,

Something happened at time t = 1246 s. Was the UAV suddenly disturbed by an unknown force? By the way, the PI Controller maybe insufficient to stabilize the 2nd-order UAV motion.

[Agnes]

Hi Sam

Thank you for replying. I will look in the controllers.