Supplemental attitude with engaged and disengaged input device modes

1. A system, comprising:

a processor; and

a memory coupled with the processor, wherein the memory is configured to provide the processor with instructions which when executed cause the processor to:

receive an input attitude associated with an input device of an aircraft;

generate a supplemental attitude using a switch, including:

comparing a displacement, of the input device from a spring-centered position, against a first threshold;

in the event the displacement exceeds the first threshold, deciding that the input device is engaged;

comparing the displacement against a second threshold, wherein the second threshold is less than the first threshold;

in the event the displacement does not exceed the second threshold, deciding that the input device is disengaged;

selecting a position-based supplemental attitude to be the supplemental attitude in the event the input device is in a disengaged state; and

selecting a velocity-based supplemental attitude to be the supplemental attitude in the event the input device is in an engaged state;

combine, using an adder, the input attitude and the supplemental attitude in order to obtain a combined attitude; and

instruct a controller to control the aircraft using the combined attitude.

2. The system recited in claim 1 , wherein the memory is further configured to provide the processor with instructions which when executed cause the processor to:

obtain a desired velocity which includes a desired direction of movement;

obtain a measured velocity; and

generate the velocity-based supplemental attitude, including by:

determining a difference between the desired velocity and the measured velocity; and

determining a portion of the difference that is perpendicular to the desired direction of movement.

3. The system recited in claim 1 , wherein the input device includes a joystick and the displacement includes a radial displacement.

4. The system recited in claim 1 , wherein the instructions for generating the supplemental attitude include instructions for:

in the event the input device switches from the engaged state to the disengaged state, gradually transition from the velocity-based supplemental attitude to the position-based supplemental attitude as the supplemental attitude; and

in the event the input device switches from the disengaged state to the engaged state, gradually transition from the position-based supplemental attitude to the velocity-based supplemental attitude as the supplemental attitude.

5. A flight control system, comprising:

an input device of an aircraft;

a switch configured to generate a supplemental attitude, including by:

comparing a displacement, of the input device from a spring-centered position, against a first threshold;

in the event the displacement exceeds the first threshold, deciding that the input device is engaged;

comparing the displacement against a second threshold, wherein the second threshold is less than the first threshold;

in the event the displacement does not exceed the second threshold, deciding that the input device is disengaged;

selecting a position-based supplemental attitude to be the supplemental attitude in the event the input device is in a disengaged state; and

selecting a velocity-based supplemental attitude to be the supplemental attitude in the event the input device is in an engaged state;

an adder configured to:

receive an input attitude associated with the input device of the aircraft; and

combine the input attitude and the supplemental attitude in order to obtain a combined attitude; and

a controller configured to control the aircraft using the combined attitude.

6. The system recited in claim 5 , wherein the velocity-based supplemental attitude is generated, including by:

obtain a desired velocity which includes a desired direction of movement;

obtain a measured velocity; and

generate the velocity-based supplemental attitude, including by:

determining a difference between the desired velocity and the measured velocity; and

determining a portion of the difference that is perpendicular to the desired direction of movement.

7. The system recited in claim 5 , wherein the input device includes a joystick and the displacement includes a radial displacement.

8. The system recited in claim 5 , wherein the switch is configured to generate the supplemental attitude, including by:

in the event the input device switches from the engaged state to the disengaged state, gradually transition from the velocity-based supplemental attitude to the position-based supplemental attitude as the supplemental attitude; and

in the event the input device switches from the disengaged state to the engaged state, gradually transition from the position-based supplemental attitude to the velocity-based supplemental attitude as the supplemental attitude.

9. A method, comprising:

receiving an input attitude associated with an input device of an aircraft;

generating a supplemental attitude using a switch, including:

comparing a displacement, of the input device from a spring-centered position, against a first threshold;

in the event the displacement exceeds the first threshold, deciding that the input device is engaged;

comparing the displacement against a second threshold, wherein the second threshold is less than the first threshold;

in the event the displacement does not exceed the second threshold, deciding that the input device is disengaged;

selecting a position-based supplemental attitude to be the supplemental attitude in the event the input device is in a disengaged state; and

selecting a velocity-based supplemental attitude to be the supplemental attitude in the event the input device is in an engaged state;

combining, using an adder, the input attitude and the supplemental attitude in order to obtain a combined attitude; and

controlling the aircraft using the combined attitude.

10. The method recited in claim 9 further comprising:

obtaining a desired velocity which includes a desired direction of movement;

obtaining a measured velocity; and

generating the velocity-based supplemental attitude, including by:

determining a difference between the desired velocity and the measured velocity; and

determining a portion of the difference that is perpendicular to the desired direction of movement.

11. The method recited in claim 9 , wherein the input device includes a joystick and the displacement includes a radial displacement.

12. The method recited in claim 9 , wherein generating the supplemental attitude includes:

in the event the input device switches from the engaged state to the disengaged state, gradually transitioning from the velocity-based supplemental attitude to the position-based supplemental attitude as the supplemental attitude; and

in the event the input device switches from the disengaged state to the engaged state, gradually transitioning from the position-based supplemental attitude to the velocity-based supplemental attitude as the supplemental attitude.

13. A computer program product, the computer program product being embodied in a non-transitory computer readable storage medium and comprising computer instructions for:

receiving an input attitude associated with an input device of an aircraft;

generating a supplemental attitude using a switch, including:

comparing a displacement, of the input device from a spring-centered position, against a first threshold;

in the event the displacement exceeds the first threshold, deciding that the input device is engaged;

comparing the displacement against a second threshold, wherein the second threshold is less than the first threshold;

in the event the displacement does not exceed the second threshold, deciding that the input device is disengaged;

selecting a position-based supplemental attitude to be the supplemental attitude in the event the input device is in a disengaged state; and

selecting a velocity-based supplemental attitude to be the supplemental attitude in the event the input device is in an engaged state;

combining, using an adder, the input attitude and the supplemental attitude in order to obtain a combined attitude; and

instructing a controller to control the aircraft using the combined attitude.

14. The system recited in claim 5 , wherein the controller is configured to control the aircraft using the combined attitude including by actuating control surfaces of the aircraft.