Flight modes and protection envelopes based on inertial attitude estimates for radio-controlled airplanes

1. A radio-controlled (RC) airplane comprising:

a receiver configured to receive command data corresponding to one or more flight control commands from an RC controller containing a transmitter associated with the RC airplane;

an attitude sensor array comprising one or more accelerometers and one more gyroscopes;

a plurality of servomotors configured to adjust one or more control surfaces of the RC airplane; and

one or more processors configured to (i) estimate an inertial attitude of the RC airplane based on data received from the attitude sensor array, (ii) determine whether the estimated inertial attitude exceeds at least one of a first inertial pitch range or a first inertial roll range corresponding to a first flight envelope of a first flight mode, (iii) in response to determining that the estimated inertial attitude exceeds at least one of the first inertial pitch range or the first inertial roll range, generate at least one control signal for application to at least one of the plurality of servomotors to adjust one or more of the control surfaces; and (iv) in response to receiving command data comprising at least one control stick input, adjusting at least one of a throttle and/or one or more control surfaces of the RC airplane based on an inertial attitude corresponding to the at least one control stick input, wherein the at least one control stick input corresponds to an inertial attitude of the RC airplane rather than a rate of rotation about a corresponding pitch, roll, or yaw axis of the RC airplane.

2. The RC airplane of claim 1 , wherein the first inertial pitch range comprises a minimum inertial pitch angle and a maximum inertial pitch angle, and wherein the first inertial roll range comprises a minimum inertial roll angle and a maximum inertial roll angle.

3. The RC airplane of claim 2 , further comprising:

an engine and a throttle control configured to control a speed of the engine;

at least one altitude sensor, and wherein the first flight envelope further comprises a minimum altitude and a maximum altitude; and

wherein the one or more processors are further configured to (i) determine whether the RC airplane has either exceeded the maximum altitude or fallen below the minimum altitude, and (ii) in response to determining that the RC airplane has either exceeded the maximum altitude or fallen below the minimum altitude, generate at least one control signal for application to at least one of (a) the throttle control to adjust the speed of the engine or (b) at least one of the plurality of servomotors to adjust one or more of the control surfaces.

4. The RC airplane of claim 2 , further comprising:

an engine and a throttle control configured to control a speed of the engine;

at least one airspeed sensor, and wherein the first flight envelope further comprises a minimum airspeed and a maximum airspeed; and

wherein the one or more processors are further configured to (i) determine whether the RC airplane has either exceeded the maximum airspeed or fallen below the minimum airspeed, and (ii) in response to determining that the RC airplane has either exceeded the maximum airspeed or fallen below the minimum airspeed, generate at least one control signal for application to the throttle control to adjust the speed of the engine.

5. The RC airplane of claim 2 , further comprising:

at least one location sensor, and wherein the first flight envelope further comprises a maximum distance between the RC airplane and a predetermined location; and

wherein the one or more processors are further configured to (i) determine whether the RC airplane has exceeded the maximum distance from the predetermined location and (ii) in response to determining that the RC airplane has exceeded the maximum distance from the predetermined location, generate at least one control signal for application to at least one of (a) the throttle control to adjust the speed of the engine or (b) at least one of the plurality of servomotors to adjust one or more of the control surfaces.

6. The RC airplane of claim 1 , wherein the first flight envelope further comprises an inertial yaw range comprising a minimum inertial yaw angle and a maximum inertial yaw angle; and

wherein the one or more processors are further configured to (i) determine whether the RC airplane has exceeded the inertial yaw range, and (ii) in response to determining that the RC airplane has exceeded the inertial yaw range, generate at least one control signal for application to at least one of the plurality of servomotors to adjust one or more of the control surfaces.

7. The RC airplane of claim 1 , wherein the one or more processors are further configured to activate the first flight mode of the plurality of flight modes in response to receiving a flight mode activation command from an RC controller associated with the RC airplane.

8. The RC airplane of claim 1 , wherein the first flight mode is one of a plurality of flight modes comprising:

a panic flight mode comprising a panic flight envelope having corresponding ranges for inertial pitch and inertial roll;

the first flight mode, wherein the first inertial pitch range and the first inertial roll range of the first flight envelope are wider than the corresponding inertial pitch and inertial roll ranges for the panic flight mode; and

a second flight mode comprising a second flight envelope having a second inertial pitch range that is wider than the first inertial pitch range of the first flight envelope of the first flight mode and a second inertial roll range that is wider than the first inertial roll range of the first flight envelope of the first flight mode.

9. A flight control unit for a radio-controlled (RC) airplane comprising:

a receiver configured to receive command data corresponding to one or more flight control commands from an RC controller containing a transmitter associated with the RC airplane;

an attitude sensor array comprising one or more accelerometers and one more gyroscopes; and

one or more processors configured to (i) estimate an inertial attitude of the RC airplane based on data received from the attitude sensor array, (ii) determine whether the estimated inertial attitude exceeds at least one of a first inertial pitch range or a first inertial roll range corresponding to a first flight envelope of a first flight mode, (iii) in response to determining that the estimated inertial attitude exceeds at least one of the first inertial pitch range or the first inertial roll range, generate at least one control signal for application to at least one of a plurality or servomotors to adjust one or more of the control surfaces, wherein the plurality of servomotor are configured to adjust one or more control surfaces of the RC airplane; and (iv) in response to receiving command data comprising at least one control stick input, adjusting at least one of a throttle and/or one or more control surfaces of the RC airplane based on an inertial attitude corresponding to the at least one control stick input, wherein the at least one control stick input corresponds to an inertial attitude of the RC airplane rather than a rate of rotation about a corresponding pitch, roll, or yaw axis of the RC airplane.

10. The flight control unit of claim 9 , wherein the first inertial pitch range comprises a minimum inertial pitch angle and a maximum inertial pitch angle, and wherein the first inertial roll range comprises a minimum inertial roll angle and a maximum inertial roll angle.

11. The flight control unit of claim 10 , further comprising:

at least one altitude sensor,

wherein the first flight envelope further comprises a minimum altitude and a maximum altitude; and

wherein the one or more processors are further configured to (i) control a speed of an engine via a throttle control, (ii) determine whether the RC airplane has either exceeded the maximum altitude or fallen below the minimum altitude, and (iii) in response to determining that the RC airplane has either exceeded the maximum altitude or fallen below the minimum altitude, generate at least one control signal for application to at least one of (a) the throttle control to adjust the speed of the engine or (b) at least one of the plurality of servomotors to adjust one or more of the control surfaces.

12. The flight control unit of claim 10 , further comprising:

at least one airspeed sensor,

wherein the first flight envelope further comprises a minimum airspeed and a maximum airspeed; and

wherein the one or more processors are further configured to (i) control a speed of an engine via a throttle control, (ii) determine whether the RC airplane has either exceeded the maximum airspeed or fallen below the minimum airspeed, and (iii) in response to determining that the RC airplane has either exceeded the maximum airspeed or fallen below the minimum airspeed, generate at least one control signal for application to the throttle control to adjust the speed of the engine.

13. The flight control unit of claim 10 , further comprising:

at least one location sensor, and wherein the first flight envelope further comprises a maximum distance between the RC airplane and a predetermined location; and

wherein the one or more processors are further configured to (i) determine whether the RC airplane has exceeded the maximum distance from the predetermined location and (ii) in response to determining that the RC airplane has exceeded the maximum distance from the predetermined location, generate at least one control signal for application to at least one of (a) the throttle control to adjust the speed of the engine or (b) at least one of the plurality of servomotors to adjust one or more of the control surfaces.

14. The flight control unit of claim 9 , wherein the first flight envelope further comprises an inertial yaw range comprising a minimum inertial yaw angle and a maximum inertial yaw angle; and

wherein the one or more processors are further configured to (i) determine whether the RC airplane has exceeded the inertial yaw range, and (ii) in response to determining that the RC airplane has exceeded the inertial yaw range, generate at least one control signal for application to at least one of the plurality of servomotors to adjust one or more of the control surfaces.

15. The flight control unit of claim 9 , wherein the one or more processors are further configured to activate the first flight mode of the plurality of flight modes in response to receiving a flight mode activation command from an RC controller associated with the RC airplane.

16. The flight control unit of claim 9 , wherein the first flight mode is one of a plurality of flight modes comprising:

a panic flight mode comprising a panic flight envelope having corresponding ranges for inertial pitch and inertial roll;

the first flight mode, wherein the first inertial pitch range and the first inertial roll range of the first flight envelope are wider than the corresponding inertial pitch and inertial roll ranges for the panic flight mode; and

a second flight mode comprising a second flight envelope having a second inertial pitch range that is wider than the first inertial pitch range of the first flight envelope of the first flight mode and a second inertial roll range that is wider than the first inertial roll range of the first flight envelope of the first flight mode.