  Field trial is very critical and high risk in autonomous UAV development life
cycle. Hardware in the loop (HIL) simulation is a computer simulation that has
the ability to simulate UAV flight characteristic, sensor modeling and actuator
modeling while communicating in real time with the UAV autopilot hardware. HIL
simulation can be used to test the UAV autopilot hardware reliability, test the
closed loop performance of the overall system and tuning the control parameter.
By rigorous testing in the HIL simulator, the risk in the field trial can be
minimized.
