EVTOL single rotor failure disposal method

Abstract

The invention belongs to the technical field of electric vertical take-off and landing aircraft control, and discloses an eVTOL single rotor failure disposal method which comprises the following steps: when single rotor failure occurs, diagonal rotors are closed, meanwhile, the rotating speeds of other front rotors are increased, the maximum value of the total distance of the front rotors is synchronously reduced, and the rotating speed range of rear rotors is increased; and in a certain period of time when failure treatment is started, changing an original control balancing strategy, adding balancing feedforward, converting a control quantity balancing value from an old value into a new value, and sending the new value to the rotor wing for execution. The problem that torque and torque of the aircraft are unbalanced due to failure of a single rotor wing is solved, and the survivability of the electric vertical take-off and landing aircraft can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of electric vertical takeoff and landing (EVTOL) aircraft control technology, specifically relating to a method for handling single rotor failure in an EVTOL aircraft. Background Technology

[0002] In recent years, the global low-altitude economy has developed rapidly, and electric vertical take-off and landing aircraft have been developing vigorously under the impetus of market demand and policy support. In the future, they will have broad application prospects in urban short-distance transportation, logistics, medical transportation and emergency rescue, and short-distance intercity travel.

[0003] However, most eVTOLs currently use multi-rotor designs and operate in densely populated cities. Although the flight control and power systems employ redundant designs, greatly reducing the probability of overall aircraft failure, the failure of a single rotor can cause the aircraft's torque and torque to become unbalanced, tilting or rotating in the direction of the failed rotor. This can cause the aircraft to deviate from its original equilibrium position instantaneously, leading to the risk of crashing and loss of life. Summary of the Invention

[0004] Purpose of the invention: In view of the situation where single rotor failure causes an imbalance of torque and torque in an aircraft, this invention provides a method for handling single rotor failure in eVTOL aircraft, which can effectively improve the survivability of electric vertical take-off and landing aircraft and enhance the safety of electric vertical take-off and landing aircraft in urban low-altitude flight.

[0005] To address the above-mentioned technical issues, the present invention provides the following technical solution: A method for handling single rotor failure in eVTOL includes the following steps: When a single rotor fails, while shutting down the diagonal rotor, increase the speed of the other front rotors, simultaneously reduce the maximum collective pitch of the front rotors, and increase the speed range of the rear rotor; Within a certain period of time after the failure handling begins, the original control trim strategy is changed, and trim feedforward is added to convert the control trim value from the old value to the new value and send it to the rotor for execution.

[0006] As a further technical solution of the present invention: multiple rotors of the aircraft are symmetrically arranged along the longitudinal and transverse axes. After a single rotor fails, in order to ensure longitudinal and transverse balance, the sum of the thrust borne by the front and rear rotors and the left and right rotors is the same as in the normal mode. Due to the torque balance requirement, the remaining rotors often need to redistribute the torque. With the redistribution of thrust and torque, the torque and thrust of each rotor are the same in the normal mode, but there are increases and decreases. Generally, the thrust and torque of the rotors diagonally opposite to the direction of rotation of the failed rotor will decrease. To increase the possibility of trimming after a single rotor failure, all remaining rotors adopt a control method that simultaneously changes collective pitch and rotational speed, so as to increase the adjustable margin of rotor thrust and torque. Number the eight rotors from left to right as front rotors 1-4 and rear rotors 5-8; Among them, rotors 1 and 5 rotate in the same direction, rotors 2 and 6 rotate in the same direction, rotors 3 and 7 rotate in the same direction, and rotors 4 and 8 rotate in the same direction. The four front rotors use a constant speed, variable collective pitch control method, while the four rear rotors use a variable speed control method.

[0007] As a further technical solution of the present invention: if the first rotor fails, the first rotor loses its thrust and torque, and the aircraft will experience attitude fluctuations such as pitching forward, rolling to the left, and yawing to the right. Therefore, the rotational speed of the diagonal rotor, i.e. the eighth rotor, is reduced to 35% to maintain the balance of the aircraft.

[0008] As a further technical solution of the present invention: if the front rotor No. 2 fails, the No. 2 rotor position loses thrust and torque, and the aircraft produces attitude fluctuations of pitching forward, rolling to the left, and yawing to the left. Therefore, the speed of the diagonal rotor, namely the No. 7 rotor, is reduced to 35% to maintain the balance of the aircraft.

[0009] As a further technical solution of the present invention: if the front rotor No. 3 fails, the No. 3 rotor position loses thrust and torque, and the aircraft produces attitude fluctuations of pitching forward, rolling to the right, and yawing to the right. Therefore, the speed of the diagonal rotor, namely the No. 6 rotor, is reduced to 35% to maintain the balance of the aircraft.

[0010] As a further technical solution of the present invention: if the front rotor No. 4 fails, the No. 4 rotor position loses thrust and torque, and the aircraft produces attitude fluctuations of pitching forward, rolling to the right, and yawing to the left. Therefore, the speed of the diagonal rotor, namely the No. 5 rotor, is reduced to 35% to maintain the balance of the aircraft.

[0011] As a further technical solution of the present invention: if the rear rotor No. 5 fails, the No. 5 rotor position loses thrust and torque, and the aircraft produces attitude fluctuations of pitching backward, rolling to the left, and yawing to the right. Therefore, shutting down the diagonal rotor, i.e., shutting down the No. 4 rotor, allows the aircraft to maintain balance.

[0012] As a further technical solution of the present invention: if the rear rotor No. 6 fails, the No. 6 rotor position loses thrust and torque, and the aircraft produces attitude fluctuations of pitching backward, rolling to the left, and yawing to the left. Therefore, shutting down the diagonal rotor, i.e., shutting down the No. 3 rotor, allows the aircraft to maintain balance.

[0013] As a further technical solution of the present invention: if the rear rotor No. 7 fails, the No. 7 rotor position loses thrust and torque, and the aircraft produces attitude fluctuations of pitching backward, rolling to the right, and yawing to the right. Therefore, shutting down the diagonal rotor, i.e., shutting down the No. 2 rotor, allows the aircraft to maintain balance.

[0014] As a further technical solution of the present invention: if the rear rotor No. 8 fails, the No. 8 rotor position loses thrust and torque, and the aircraft produces attitude fluctuations of pitching backward, rolling to the right, and yawing to the left. Therefore, closing the diagonal rotor, i.e., closing rotor No. 1, allows the aircraft to maintain balance.

[0015] In summary, the beneficial effects of the present invention are as follows: 1. This invention proposes a handling measure for the failure of a single rotor in a multi-rotor electric vertical take-off and landing aircraft. If a single front rotor fails, the rotational speed of the diagonal rear rotor will be reduced to 35%.

[0016] 2. If a single rear rotor fails, the invention will reduce the collective pitch of the diagonal front rotor to 0 degrees.

[0017] 3. This invention increases the front rotor speed, reduces the front rotor collective pitch range, increases the rear rotor speed range, changes the control balance values ​​of each rotor, and softens them.

[0018] 4. This invention enables aircraft to maintain stable flight attitude and return safely when a single rotor failure prevents precise tracking of control commands, effectively improving the aircraft's fault tolerance, enhancing safe return capability, and reducing economic losses.

[0019] 5. The method in this invention is applicable to various multi-rotor configuration aircraft, and the method can be extended to other multi-rotor aircraft.

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of single-rotor failure according to the present invention.

[0022] Figure 2 This is a schematic diagram of the control output before and after single rotor failure in this invention.

[0023] Figure 3 This is a schematic diagram of the balancing manipulation amount softening process of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be described in more detail below with reference to the accompanying drawings.

[0025] In the accompanying drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, of the embodiments of the present invention.

[0026] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0027] The following is in conjunction with the appendix Figure 1-3 The embodiments of the present invention will be described in detail below.

[0028] Example 1 This invention discloses a method for handling single rotor failure in eVTOL, which includes the following steps: When a single rotor fails, while shutting down the diagonal rotor, increase the speed of the other front rotors, simultaneously reduce the maximum collective pitch of the front rotors, and increase the speed range of the rear rotor; Within a certain period of time after the failure handling begins, the original control trim strategy is changed, and trim feedforward is added to convert the control trim value from the old value to the new value and send it to the rotor for execution.

[0029] Furthermore, the aircraft's multiple rotors are symmetrically arranged along the longitudinal and transverse axes. When a single rotor fails, in order to ensure longitudinal and transverse balance, the sum of the thrust borne by the front and rear rotors and the left and right rotors is the same as in the normal mode. Due to the torque balance requirement, the remaining rotors often need to redistribute the torque. With the redistribution of thrust and torque, the torque and thrust of each rotor are the same in the normal mode, but some increase and some decrease. Generally, the thrust and torque of the rotors diagonally opposite to the direction of rotation of the failed rotor will decrease. To increase the possibility of trimming after a single rotor failure, all remaining rotors adopt a control method that simultaneously changes collective pitch and rotational speed, so as to increase the adjustable margin of rotor thrust and torque. Number the eight rotors from left to right as front rotors 1-4 and rear rotors 5-8; Among them, rotors 1 and 5 rotate in the same direction, rotors 2 and 6 rotate in the same direction, rotors 3 and 7 rotate in the same direction, and rotors 4 and 8 rotate in the same direction. The four front rotors use a constant speed, variable collective pitch control method, while the four rear rotors use a variable speed control method.

[0030] Furthermore, if the first rotor fails, it loses its thrust and torque, causing the aircraft to pitch forward, roll to the left, and yaw to the right. Therefore, the speed of the diagonal rotor, i.e., the eighth rotor, is reduced to 35% to maintain the aircraft's balance.

[0031] Furthermore, if the No. 2 front rotor fails, the No. 2 rotor position loses thrust and torque, and the aircraft will experience attitude fluctuations such as pitching forward, rolling to the left, and yawing to the left. Therefore, the speed of the diagonal rotor, namely the No. 7 rotor, is reduced to 35% to maintain the balance of the aircraft.

[0032] Furthermore, if the No. 3 front rotor fails, the No. 3 rotor position loses thrust and torque, and the aircraft will experience attitude fluctuations such as pitching forward, rolling to the right, and yawing to the right. Therefore, the speed of the diagonal rotor, namely the No. 6 rotor, is reduced to 35% to maintain the balance of the aircraft.

[0033] Furthermore, if the No. 4 front rotor fails, the No. 4 rotor position loses thrust and torque, and the aircraft will experience attitude fluctuations such as pitching forward, rolling to the right, and yawing to the left. Therefore, the speed of the diagonal rotor, namely the No. 5 rotor, is reduced to 35% to maintain the balance of the aircraft.

[0034] Furthermore, if the No. 5 rear rotor fails, the No. 5 rotor position loses thrust and torque, and the aircraft will experience attitude fluctuations such as pitching backward, rolling to the left, and yawing to the right. Therefore, shutting down the diagonal rotor is equivalent to shutting down the No. 4 rotor, and the aircraft will maintain balance.

[0035] Furthermore, if the rear rotor #6 fails, the position of rotor #6 will lose thrust and torque, and the aircraft will experience attitude fluctuations such as pitching backward, rolling to the left, and yawing to the left. Therefore, shutting down the diagonal rotor, i.e., shutting down rotor #3, will allow the aircraft to maintain balance.

[0036] Furthermore, if the No. 7 rear rotor fails, the No. 7 rotor position loses thrust and torque, and the aircraft will experience attitude fluctuations such as pitching backward, rolling to the right, and yaw to the right. Therefore, shutting down the diagonal rotor, i.e., shutting down the No. 2 rotor, will allow the aircraft to maintain balance.

[0037] Furthermore, if the No. 8 rear rotor fails, the No. 8 rotor position loses thrust and torque, and the aircraft will experience attitude fluctuations such as pitching backward, rolling to the right, and yawing to the left. Therefore, shutting down the diagonal rotor is equivalent to shutting down the No. 1 rotor, and the aircraft will maintain balance.

[0038] Example 2 This invention is designed to address single-rotor failure in vertical takeoff and landing aircraft controlled by eight symmetrical rotors.

[0039] The eight rotors are shown in the appendix. Figure 1 As shown, the rotors are numbered from left to right as follows: front rotors 1-4 and rear rotors 5-8. Rotors 1 and 5 rotate in the same direction; rotors 2 and 6 rotate in the same direction; rotors 3 and 7 rotate in the same direction; and rotors 4 and 8 rotate in the same direction. The four front rotors use a constant speed, variable collective pitch control method, while the four rear rotors use variable speed control.

[0040] In this invention, multiple rotors of the aircraft are symmetrically arranged along the longitudinal and transverse axes. If a single rotor fails, to ensure longitudinal and transverse balance, the sum of the thrust borne by the front and rear rotors and the left and right rotors remains the same as in normal mode. Due to torque balance requirements, the remaining rotors often need torque redistribution. Along with this redistribution of thrust and torque, while the torque and thrust of each rotor are equal in normal mode, some rotors experience increases and others decreases. Generally, the thrust and torque of the rotor diagonally opposite to the direction of rotation of the failed rotor will decrease. To improve the possibility of trimming after a single rotor failure, all remaining rotors employ a control method that simultaneously changes collective pitch and rotational speed to increase the adjustable margin of rotor thrust and torque.

[0041] If the first front rotor fails, the first rotor loses its thrust and torque, and the aircraft will experience attitude fluctuations such as pitching forward, rolling to the left, and yawing to the right. Therefore, the speed of the diagonal rotor, i.e. the eighth rotor, is reduced to 35% to maintain the balance of the aircraft. If the No. 2 front rotor fails, the No. 2 rotor position loses thrust and torque, and the aircraft will produce attitude fluctuations of pitching forward, rolling to the left, and yawing to the left. Therefore, the speed of the diagonal rotor, namely the No. 7 rotor, is reduced to 35% to maintain the balance of the aircraft. If the No. 3 front rotor fails, the No. 3 rotor position loses thrust and torque, and the aircraft will produce attitude fluctuations of pitching forward, rolling to the right, and yaw to the right. Therefore, the speed of the diagonal rotor, namely the No. 6 rotor, is reduced to 35% to maintain the balance of the aircraft. If the No. 4 front rotor fails, the No. 4 rotor position loses thrust and torque, and the aircraft will produce attitude fluctuations of pitching forward, rolling to the right, and yawing to the left. Therefore, the speed of the diagonal rotor, namely the No. 5 rotor, is reduced to 35% to maintain the balance of the aircraft. If the No. 5 rear rotor fails, the No. 5 rotor position loses thrust and torque, and the aircraft will experience attitude fluctuations such as pitching backward, rolling to the left, and yawing to the right. Therefore, closing the diagonal rotor is equivalent to closing the No. 4 rotor, and the aircraft will maintain balance. If the rear rotor No. 6 fails, the No. 6 rotor position loses thrust and torque, and the aircraft will produce attitude fluctuations of pitching backward, rolling to the left, and yaw to the left. Therefore, shutting down the diagonal rotor means shutting down the No. 3 rotor, and the aircraft will maintain balance. If the No. 7 rear rotor fails, the No. 7 rotor position loses thrust and torque, and the aircraft will experience attitude fluctuations such as pitching backward, rolling to the right, and yaw to the right. Therefore, shutting down the diagonal rotor means shutting down the No. 2 rotor, and the aircraft will maintain balance. If the No. 8 rear rotor fails, the No. 8 rotor position loses thrust and torque, and the aircraft will experience attitude fluctuations such as pitching backward, rolling to the right, and yawing to the left. Therefore, closing the diagonal rotor is equivalent to closing the No. 1 rotor, and the aircraft will maintain balance. Since the motor power is limited to the normal operating range during normal flight, if a single rotor fails, it is necessary to increase the power of the other non-failed rotors in order to maintain the stability of the aircraft attitude. Therefore, this invention proposes to increase the speed of the other front rotors while shutting down the diagonal rotors, and simultaneously reduce the maximum collective pitch of the front rotors to increase the speed range of the rear rotor.

[0042] To improve the speed at which an aircraft can recover its balance position after a single rotor failure, and to avoid abrupt changes in control values ​​during single rotor failure handling, this invention proposes a control value trimming + softening approach.

[0043] During the period before failure handling is implemented after a single rotor failure, the aircraft deviates from its original equilibrium position under the control of the seven rotors. Therefore, while the failure handling is implemented by shutting down / reducing the collective pitch / speed of the diagonal rotors, the original control trim strategy is changed and trim feedforward is added to quickly stabilize the aircraft back to the vicinity of the equilibrium position.

[0044] Since large trim can cause significant attitude fluctuations in the aircraft due to sudden changes in control values, this invention proposes a 2s softening method after considering motor capabilities, theoretical calculations, and simulations. This method involves linearly transitioning the allocation coefficient of the old control trim value from 1 to 0 and the allocation coefficient of the new control trim value from 0 to 1 within 2 seconds of starting the failure handling process, and then outputting the command to the rotor.

[0045] Key points of this invention: This invention addresses the handling measures for single rotor failure in multi-rotor electric vertical takeoff and landing aircraft. If a single front rotor fails, the rotational speed of the diagonal rear rotor is reduced to 35%; if a single rear rotor fails, the collective pitch of the diagonal front rotor is reduced to 0 degrees; the rotational speed of the front rotor is increased, the range of the collective pitch of the front rotor is reduced, the range of the rotational speed of the rear rotor is increased, the trim values ​​of the control parameters of each rotor are changed and softened.

[0046] Thus, the objective of this invention has been achieved.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An eVTOL single rotor failure handling method, characterized by, Comprising the following steps: When a single rotor fails, increase the speed of the other front rotors while closing the diagonal rotors, simultaneously reduce the maximum total pitch of the front rotors, and increase the speed range of the rear rotors. Within a certain time after starting the failure handling, change the original control trim strategy, add trim feedforward, and convert the control amount trim value from the old value to the new value and send it to the rotor for execution.

2. The eVTOL single rotor failure handling method of claim 1, wherein, The multiple rotors of the aircraft are symmetrically arranged along the longitudinal and transverse axes. After a single rotor fails, to ensure longitudinal and transverse balance, the sum of the pulling forces borne by the front and rear rotors is the same as in the normal mode. Due to the torque balance requirement, the remaining rotors often need to be redistributed in torque, accompanied by the redistribution of pulling force and torque. Based on the same torque and pulling force of each rotor in the normal mode, some increase and some decrease, the pulling force and torque of the rotor opposite to the failed rotor will decrease. To improve the trim possibility after a single rotor fails, all remaining rotors use the control mode of simultaneous total pitch and speed change to increase the adjustable margin of rotor pulling force and torque. The eight rotors are numbered from left to right as front rotors 1-4 and rear rotors 5-8. Among them, rotor No. 1 and rotor No. 5 rotate in the same direction, rotor No. 2 and rotor No. 6 rotate in the same direction, rotor No. 3 and rotor No. 7 rotate in the same direction, and rotor No. 4 and rotor No. 8 rotate in the same direction. The four front rotors are controlled by constant speed variable total pitch, and the four rear rotors are controlled by variable speed.

3. The eVTOL single rotor failure handling method of claim 2, wherein, If front rotor No. 1 fails, the position of rotor No. 1 loses pulling force and torque, the aircraft produces forward pitch, left roll, and right yaw attitude fluctuations, so the speed of the diagonal rotor, rotor No. 8, is reduced to 35%, and the aircraft maintains balance.

4. The eVTOL single rotor failure handling method of claim 2, wherein, If front rotor No. 2 fails, the position of rotor No. 2 loses pulling force and torque, the aircraft produces forward pitch, left roll, and left yaw attitude fluctuations, so the speed of the diagonal rotor, rotor No. 7, is reduced to 35%, and the aircraft maintains balance.

5. The eVTOL single rotor failure handling method of claim 2, wherein, If front rotor No. 3 fails, the position of rotor No. 3 loses pulling force and torque, the aircraft produces forward pitch, right roll, and right yaw attitude fluctuations, so the speed of the diagonal rotor, rotor No. 6, is reduced to 35%, and the aircraft maintains balance.

6. The eVTOL single rotor failure handling method of claim 2, wherein, If front rotor No. 4 fails, the position of rotor No. 4 loses pulling force and torque, the aircraft produces forward pitch, right roll, and left yaw attitude fluctuations, so the speed of the diagonal rotor, rotor No. 5, is reduced to 35%, and the aircraft maintains balance.

7. The eVTOL single rotor failure handling method of claim 2, wherein, If rear rotor No. 5 fails, the position of rotor No. 5 loses pulling force and torque, the aircraft produces backward pitch, left roll, and right yaw attitude fluctuations, so the diagonal rotor, rotor No. 4, is closed, and the aircraft maintains balance.

8. The eVTOL single rotor failure handling method of claim 2, wherein, If rear rotor No. 6 fails, the position of rotor No. 6 loses pulling force and torque, the aircraft produces backward pitch, left roll, and left yaw attitude fluctuations, so the diagonal rotor, rotor No. 3, is closed, and the aircraft maintains balance.

9. The eVTOL single rotor failure handling method of claim 2, wherein, If rear rotor No. 7 fails, the position of rotor No. 7 loses pulling force and torque, the aircraft produces backward pitch, right roll, and right yaw attitude fluctuations, so the diagonal rotor, rotor No. 2, is closed, and the aircraft maintains balance.

10. The eVTOL single rotor failure handling method of claim 2, wherein, If the back rotor 8 fails, the 8 rotor position loss of tension and torque, the aircraft produces a rear pitch, right roll, left yaw attitude fluctuation, so close to the diagonal rotor, that is, close to the 1 rotor, the aircraft maintains balance.

Images