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Glider Airframe Modelling for Flight Controller design

Due to the past 2-3 months of bad rainy weather and gusty winds, I've decided that it was time that I invested in a tool that will be able to give me preliminary understanding the flight control is a scientific way. That means I will have to acquire a mathematical model of the airframe and use the current hardware to form a In-The-Loop Simulation (HILS).

My approach for this will be to use DATCOM to derive aerodynamics parameters then coding the equations in C. This will then be flashed unto a separate Atmega microcontroller and will talk to the the rest of the hardware via the serial interface. The accelerometers and gyroscope values (superimposed with errors and biases) will be then form part of the output from the airframe model which in turn will exercise the flight controller and mission controller.

What's not sure yet is how to test completely the waypoint tracking algorithm without using the GPS hardware. One way was to have a simulated GPS module as part of the output to the Flight control. That might add more computation to the airframe module so it will have to be evaluated once all task are completed.

The aim of this approach is to establish a way to predict and easily analyze the flight control system (servos, transmitter, receiver and the respective algorithms) without having to physically fly the glider. This will mitigate a lot of uncertainty during a flight test programme (which should kickstart again mid February).

So the key is to establish an airframe model that is representative of what will be seen during a typical flight test. What will not be modelled and tested at this point, is the landing and take-off stages of the mission profile.

This is an exciting stage of the project as building such capabilities will only enhance the viability of realising a robust and low-cost UAV solution.

Lookout for upcoming posts!

Comments

  1. I have gone through your post . It is very informative. I would like to share this.

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