Safe Control for Spiral Recovery of Unmanned Aerial Vehicle
Table 1
Control sequence of spiral recovery.
The sequence
The applied strategies
1
When the UAV is in the spiral, switch to control module of the spiral and give an output of angular rate to execute the control of slowing angular rate of rotation
2
When UAV’s deflection and rolling slow down, give an output of the attack angle to execute the control of reducing the attack angle rapidly
3
When the attack angle is below the critical angle of attack, give an output of attitude angle and then control the rotating attitude angle
4
When UAV stops deflection and rolling, achieve the desired attitude angle and carry on the control of diving and speeding up;
5
When the velocity increases to some degree, carry on the control program of exiting diving
