System, a method and a computer program product for maneuvering of an air vehicle with tiltable propulsion unit

A method (1500) for controlling a deceleration process of an air vehicle (100) which comprises at least one tiltable propulsion unit (420), each of the at least one tiltable propulsion unit is tiltable to provide a thrust whose direction is variable at least between a general vertical thrust vector direction and a general longitudinal thrust vector direction with respect to the air vehicle (100);

• the air vehicle further comprises a wing (320) configured to provide lift to the air vehicle;
• the wing being in a fixed position during flight of the air vehicle, the method comprising:
• during a descent of the air vehicle (100), controlling (1510) a descending course of the air vehicle (100) based on at least monitored airspeed and monitored altitude of the air vehicle (100), said controlling comprising carrying out:
• in a first part of the descent, controlling (1520) an operation of the at least one tiltable propulsion unit to provide thrust in the general longitudinal thrust vector direction for propelling the air vehicle (100);
• and
• following a tilting of the at least one tiltable propulsion unit, controlling (1540) in a second part of the descent an operation of the at least one tiltable propulsion unit to provide thrust in the general vertical thrust vector direction for providing lift to the air vehicle (100);
• and
• controlling (1550) a reducing of a groundspeed of the air vehicle (100) substantially to a hover, while the at least one tiltable propulsion unit provides thrust in the general vertical thrust vector direction, at least by:
• controlling (1560) thrust power of the at least one tiltable propulsion unit for reducing a difference between measured groundspeed of the air vehicle (100) and set groundspeed, while restricting reduction of the thrust power based on a lower threshold (1720) that is determined in response to a measured airspeed of the air vehicle;
• controlling the reducing of the groundspeed of the air vehicle during a substantially horizontal flight of the air vehicle, and controlling, during at least the second part of the descent, reduction of the groundspeed below a maximum permitted threshold speed before an end of the descent and before a beginning of the substantially horizontal flight of the air vehicle.

A program storage device readable by machine, tangibly embodying a computer readable code portion executable by the machine for controlling a deceleration process of an air vehicle which comprises at least one tiltable propulsion unit, each of the at least one tiltable propulsion units is tiltable to provide a thrust whose direction is variable at least between a general vertical thrust vector direction and a general longitudinal thrust vector direction with respect to the air vehicle;

• the air vehicle further comprises a wing configured to provide lift to the air vehicle;
• the wing being in a fixed position during flight of the air vehicle, the computer readable code portion comprising instructions for:
• during a descent of the air vehicle, controlling a descending course of the air vehicle based on at least monitored airspeed and monitored altitude of the air vehicle, said controlling comprising carrying out in the following order:
• in a first part of the descent, controlling an operation of the at least one tiltable propulsion unit to provide thrust in the general longitudinal thrust vector direction for propelling the air vehicle;
• and
• following a tilting of the at least one tiltable propulsion unit, controlling in a second part of the descent an operation of the at least one tiltable propulsion unit to provide thrust in the general vertical thrust vector direction for providing lift to the air vehicle;
• and
• controlling a reducing of a groundspeed of the air vehicle substantially to a hover, while the at least one tiltable propulsion unit provides thrust in the general vertical thrust vector direction, at least by:
• controlling thrust power of the at least one tiltable propulsion unit for reducing a difference between measured groundspeed of the air vehicle and set groundspeed, while restricting reduction of the thrust power based on a lower threshold that is determined in response to a measured airspeed of the air vehicle;
• and
• controlling the reducing of the groundspeed of the air vehicle during a substantially horizontal flight of the air vehicle, and controlling, during at least the second part of the descent, reduction of the groundspeed below a maximum permitted threshold speed before an end of the descent and before a beginning of the substantially horizontal flight of the air vehicle.

A control system (1200) configured to control a deceleration process of an air vehicle (100) which comprises at least one tiltable propulsion unit (420), each of the at least one tiltable propulsion units is tiltable to provide a thrust whose direction is variable at least between a general vertical thrust vector direction and a general longitudinal thrust vector direction with respect to the air vehicle;

• the air vehicle further comprises a wing (320) configured to provide lift to the air vehicle;
• the wing being in a fixed position during flight of the air vehicle the control system comprising:
• at least one input for receiving information indicative of monitored airspeed of the air vehicle and of monitored altitude of the air vehicle;
• and
• a control unit (1220), configured to issue controlling commands to controllers (1410, 1420, 1420, 1440, 1450) of aerodynamic systems (420, 345) of the air vehicle, the aerodynamic systems comprising the at least one tiltable propulsion unit;
• wherein the control unit is configured issue the controlling commands for:
• c. controlling, during a descent of the air vehicle, a descending course of the air vehicle based on at least monitored airspeed and monitored altitude of the air vehicle, at least by controlling in a first part of the descent, an operation of the at least one tiltable propulsion unit to provide thrust in the general longitudinal thrust vector direction for propelling the air vehicle;
• and following a tilting of the at least one tiltable propulsion unit, controlling in a second part of the descent an operation of the at least one tiltable propulsion unit to provide thrust in the general vertical thrust vector direction for providing lift to the air vehicle;
• and
• d. controlling a reducing of a groundspeed of the air vehicle substantially to a hover, while the at least one tiltable propulsion unit provides thrust in the general vertical thrust vector direction, at least by controlling thrust power of the at least one tiltable propulsion unit for reducing a difference between measured groundspeed of the air vehicle and set groundspeed, while restricting reduction of the thrust power based on a lower threshold (1720) that is determined in response to a measured airspeed of the air vehicle;
• wherein the control unit comprises a pitch control module (1224), configured to keep a pitch of the air vehicle within a permitted pitch range when the control unit controls the reducing of the groundspeed, wherein the permitted pitch range is dynamically determined in response to the measured airspeed of the air vehicle.

A method (1500) for controlling a deceleration process of an air vehicle (100) which comprises at least one tiltable propulsion unit (420), each of the at least one tiltable propulsion unit is tiltable to provide a thrust whose direction is variable at least between a general vertical thrust vector direction and a general longitudinal thrust vector direction with respect to the air vehicle (100);

• the air vehicle further comprises a wing (320) configured to provide lift to the air vehicle;
• the wing being in a fixed position during flight of the air vehicle, the method comprising:
• during a descent of the air vehicle (100), controlling (1510) a descending course of the air vehicle (100) based on at least monitored airspeed and monitored altitude of the air vehicle (100), said controlling comprising carrying out:
• in a first part of the descent, controlling (1520) an operation of the at least one tiltable propulsion unit to provide thrust in the general longitudinal thrust vector direction for propelling the air vehicle (100);
• and
• following a tilting of the at least one tiltable propulsion unit, controlling (1540) in a second part of the descent an operation of the at least one tiltable propulsion unit to provide thrust in the general vertical thrust vector direction for providing lift to the air vehicle (100);
• and
• controlling (1550) a reducing of a groundspeed of the air vehicle (100) substantially to a hover, while the at least one tiltable propulsion unit provides thrust in the general vertical thrust vector direction, at least by:
• controlling (1560) thrust power of the at least one tiltable propulsion unit for reducing a difference between measured groundspeed of the air vehicle (100) and set groundspeed, while restricting reduction of the thrust power based on a lower threshold (1720) that is determined in response to a measured airspeed of the air vehicle;
• balancing, during the deceleration process, between aerodynamic effects resulting from the wing and from the at least one tiltable propulsion unit;
• and
• minimizing a vertical deviation of the air vehicle from a set altitude when controlling the reducing of the groundspeed, and restricting the minimizing at least based on the restricting of the reduction of the thrust power based on the lower threshold.

A control system (1200) configured to control a deceleration process of an air vehicle (100) which comprises at least one tiltable propulsion unit (420), each of the at least one tiltable propulsion units is tiltable to provide a thrust whose direction is variable at least between a general vertical thrust vector direction and a general longitudinal thrust vector direction with respect to the air vehicle;

• the air vehicle further comprises a wing (320) configured to provide lift to the air vehicle;
• the wing being in a fixed position during flight of the air vehicle the control system comprising:
• at least one input for receiving information indicative of monitored airspeed of the air vehicle and of monitored altitude of the air vehicle;
• and
• a control unit (1220), configured to issue controlling commands to controllers (1410, 1420, 1420, 1440, 1450) of aerodynamic systems (420, 345) of the air vehicle, the aerodynamic systems comprising the at least one tiltable propulsion unit;
• wherein the control unit is configured issue the controlling commands for:
• a. controlling, during a descent of the air vehicle, a descending course of the air vehicle based on at least monitored airspeed and monitored altitude of the air vehicle, at least by controlling in a first part of the descent, an operation of the at least one tiltable propulsion unit to provide thrust in the general longitudinal thrust vector direction for propelling the air vehicle;
• and
• following a tilting of the at least one tiltable propulsion unit, controlling in a second part of the descent an operation of the at least one tiltable propulsion unit to provide thrust in the general vertical thrust vector direction for providing lift to the air vehicle;
• and
• b. controlling a reducing of a groundspeed of the air vehicle substantially to a hover, while the at least one tiltable propulsion unit provides thrust in the general vertical thrust vector direction, at least by controlling thrust power of the at least one tiltable propulsion unit for reducing a difference between measured groundspeed of the air vehicle and set groundspeed, while restricting reduction of the thrust power based on a lower threshold (1720) that is determined in response to a measured airspeed of the air vehicle,
• wherein the control unit comprises an altitude control module (1221) configured to minimize a vertical deviation of the air vehicle from a set altitude when the control unit controls the reducing of the groundspeed, and to restrict the minimizing at least based on the restricting of the reduction of the thrust power based on the lower threshold.

A control system (1200) configured to control a deceleration process of an air vehicle (100) which comprises at least one tiltable propulsion unit (420), each of the at least one tiltable propulsion units is tiltable to provide a thrust whose direction is variable at least between a general vertical thrust vector direction and a general longitudinal thrust vector direction with respect to the air vehicle;

• the air vehicle further comprises a wing (320) configured to provide lift to the air vehicle;
• the wing being in a fixed position during flight of the air vehicle the control system comprising:
• at least one input for receiving information indicative of monitored airspeed of the air vehicle and of monitored altitude of the air vehicle;
• and
• a control unit (1220), configured to issue controlling commands to controllers (1410, 1420, 1420, 1440, 1450) of aerodynamic systems (420, 345) of the air vehicle, the aerodynamic systems comprising the at least one tiltable propulsion unit;
• wherein the control unit is configured issue the controlling commands for:
• a. controlling, during a descent of the air vehicle, a descending course of the air vehicle based on at least monitored airspeed and monitored altitude of the air vehicle, at least by controlling in a first part of the descent, an operation of the at least one tiltable propulsion unit to provide thrust in the general longitudinal thrust vector direction for propelling the air vehicle;
• and
• following a tilting of the at least one tiltable propulsion unit, controlling in a second part of the descent an operation of the at least one tiltable propulsion unit to provide thrust in the general vertical thrust vector direction for providing lift to the air vehicle;
• and
• b. controlling a reducing of a groundspeed of the air vehicle substantially to a hover, while the at least one tiltable propulsion unit provides thrust in the general vertical thrust vector direction, at least by controlling thrust power of the at least one tiltable propulsion unit for reducing a difference between measured groundspeed of the air vehicle and set groundspeed, while restricting reduction of the thrust power based on a lower threshold (1720) that is determined in response to a measured airspeed of the air vehicle,
• wherein the control unit further includes a monitor, configured to repeatedly check, starting at the first part of the descent and at least until a first occurrence of an event selected from (a) receiving a negative result and (b) reduction of the groundspeed to substantially hovering, whether flight parameters are within an envelope permitting deceleration to hover at a predetermined hover destination position, and
• wherein the control unit is configured to selectively instruct tilting of the at least one tiltable propulsion unit to provide thrust in the general longitudinal thrust vector direction if a result of the checking was negative, and to further control a directing of the air vehicle to a position and a state in which the flight parameters are within the envelope.