Control distribution method and system for six-rotor tilt-rotor aircraft
By prioritizing the allocation of control amounts of rolling and pitch channels and distributing thrust in the six-rotor tilt wing aircraft, the problem of flight altitude instability is solved, and smooth flight control and efficient power distribution are achieved.
Patent Information
- Application Number
- CN202411675404.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-02-28
AI Technical Summary
The prior art is difficult to effectively allocate the weight of the control channel in a six-rotor tilt-wing aircraft, resulting in unstable flight altitude and long calculation time is not suitable for low-cost flight control solutions.
Based on the characteristics of the tilt rotor configuration, priority is given to the allocation of control amounts of rolling and pitch channels, and the thrust is allocated to ensure the stable flight altitude.
It realizes smooth control of flight altitude, avoids the aircraft falling or rising suddenly, and at the same time, the heading control amount is maximized without the saturation of the actuator, and improves the safety margin of flight control.
Smart Images
Figure CN119527544A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of tilt-rotor aircraft, and in particular to a control distribution method and system for a six-rotor tilt-rotor aircraft. Background Art
[0002] The design of a tilt-wing aircraft usually involves the problem of power distribution between the tilting and non-tilting rotor blades during flight.
[0003] In the prior art, a pseudo-inverse method is usually used to allocate power without considering the control channel allocation weights. However, this method cannot consider the priority of the control channel, or optimize the power control allocation by involving the control channel weights. However, this method has a long operation time and has strict requirements on the flight control hardware and algorithm scheduling cycle, and is not suitable for low-cost flight control solutions. Summary of the invention
[0004] In order to solve the above problems, the present invention provides a control allocation method and system for a six-rotor tilt-rotor aircraft. Based on the characteristics of the tilt-rotor configuration, the control allocation method and system give priority to the control amount allocation of the roll and pitch channels, and at the same time allocate the thrust to perform vertical control to ensure a stable flight altitude, so that the aircraft will not drop or rise suddenly due to giving up part of the vertical control amount.
[0005] The present invention provides the following technical solutions:
[0006] In one aspect, a control allocation method for a six-rotor tilt-wing aircraft is provided, comprising the following steps:
[0007] When rotors 5 and 6 are in multi-rotor mode, the thrust of six rotors 1 to 6 is pre-allocated to obtain the initial allocation control amount thrust_cmd0 corresponding to the six rotors 1 to 6 respectively;
[0008] Allocate control amount to the roll-pitch channel of each rotor;
[0009] Allocate control quantity to the thrust channel of each rotor;
[0010] And distribute the control amount to the yaw channel of each rotor.
[0011] In another aspect, a control distribution system for a six-rotor tilt-wing aircraft is provided, comprising:
[0012] A pre-allocation module is used to pre-allocate the thrust of the six rotors No. 1 to No. 6 when the rotors No. 5 and No. 6 are in the multi-rotor mode, so as to obtain the initial allocation control amount thrust_cmd0 corresponding to the six rotors No. 1 to No. 6 respectively;
[0013] A first control amount distribution module, which is used to distribute the control amount to the roll-pitch channel of each rotor;
[0014] A second control amount distribution module, which is used to distribute the control amount to the thrust channel of each rotor;
[0015] And a third control quantity allocation module, which is used to allocate the control quantity to the yaw channel of each rotor.
[0016] Compared with the prior art, the present invention, based on the characteristics of the tilt-rotor configuration, gives priority to allocating control amounts to the roll and pitch channels to ensure the attitude control effect, and at the same time allocates thrust for vertical control to ensure a stable flight altitude, so that the aircraft will not drop or rise suddenly due to giving up part of the vertical control amount; at the same time, the heading control amount can be allocated to the maximum extent without actuator saturation, so that the unsaturated actuator can be reasonably used to provide lift. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a schematic diagram of the structure of the six-rotor tilt-wing aircraft in the present invention;
[0018] Figure 2 is a flow chart of the steps of the control allocation method of the six-rotor tilt-wing aircraft in the present invention;
[0019] Figure 3 It is a structural schematic diagram of the control distribution system of the six-rotor tilt-wing aircraft in the present invention. DETAILED DESCRIPTION
[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0021] Embodiment 1:
[0022] like Figure 1As shown, the six-rotor tilt-rotor aircraft in this embodiment includes a fuselage 100, two main wings 101 and 102 connected to the fuselage 100, and six rotors No. 1 to No. 6, wherein rotors No. 5 and No. 6 are respectively installed on one main wing, and can be tilted around the axis of the main wing under the drive of the tilt mechanism, so that rotors No. 5 and No. 6 can switch between multi-rotor mode and fixed-wing mode, and can provide a main thrust that is greater than the aircraft's own weight; rotors No. 1, No. 2, No. 3, and No. 4 are all non-tiltable fixed rotors, and their blades are always facing upward. The four rotors all provide partial thrust as an auxiliary lift power system for providing torque for aircraft attitude control and auxiliary lift for vertical movement, and rotors No. 1 and No. 2 are arranged at the front of the fuselage, and rotors No. 3 and No. 4 are arranged at the tail of the fuselage.
[0023] On this basis, this embodiment provides a control allocation method for a six-rotor tilt-wing aircraft, such as Figure 2 As shown, it includes the following steps:
[0024] S1. When rotors No. 5 and No. 6 are in multi-rotor mode, the thrusts of six rotors No. 1 to No. 6 are pre-allocated to obtain initial allocation control quantities thrust_cmd0 corresponding to the six rotors No. 1 to No. 6, respectively, and the initial allocation control quantity thrust_cmd0 of each rotor is the same;
[0025] In this embodiment, the initial allocation control amount thrust_cmd0 is obtained by formula (1):
[0026]
[0027] Wherein, T0 is the initial value of the throttle distribution of the six rotors No. 1 to No. 6, and the initial values of the throttle distribution of the six rotors No. 1 to No. 6 are the same, and the value range is [0, 1]. Preferably, in this embodiment, T0=0.5, so that in the multi-rotor mode, the aircraft as a whole can have the maximum maneuverability and anti-disturbance ability to achieve the best control effect of the aircraft; C 6*4 It is a control allocation matrix with 6 rows and 4 columns;
[0028] S2, allocating the control amount to the roll-pitch channel of each rotor, which specifically includes the following steps:
[0029] S21. Determine the direction vector of the roll-pitch channel of each rotor. Specifically, in this embodiment, the direction vector of the roll-pitch channel of each rotor is obtained by formula (2):
[0030]
[0031] Among them, dir (2,3)(i) (i = 1 to 6, indicating the i-th rotor) is the direction vector of the roll-pitch channel of each rotor, which is a vector with 1 row and 6 columns; C 6*(2) , C 6*(3) are the roll vector (i.e., the second column of matrix C) and the pitch vector (i.e., the third column of matrix C) of the control allocation matrix C respectively; L and M are the virtual control amount of the roll channel and the virtual control amount of the pitch channel of each rotor respectively; abs(L)+abs(M) is the scaling factor of the roll-pitch control amount, which can be determined in advance;
[0032] S22, if dir (2,3) (i) ≥ 0, then the local maximum scaling factor of the roll-pitch control amount is determined according to the local maximum scaling factor of the roll-pitch control amount = throttle upper limit value - thrust_cmd0(i); if dir (2,3) (i)<0, the local maximum scaling factor of the roll-pitch control amount is determined according to the local maximum scaling factor of the roll-pitch control amount=thrust_cmd0(i)-throttle lower limit value;
[0033] S23, taking the minimum value of all local maximum scaling factors of the roll-pitch control amount and the scaling factor abs(L)+abs(M) of the roll-pitch control amount as the global maximum scaling factor of the roll-pitch control amount, and respectively comparing the global maximum scaling factor of the roll-pitch control amount with the direction vector dir of the roll-pitch channel of each rotor (2,3) (i) Multiply, and the product obtained corresponds to the roll-pitch channel throttle commands thrust_cmd1(1) to thrust_cmd1(6) of the six rotors No. 1 to No. 6;
[0034] S24, when the value range of the roll-pitch channel throttle commands thrust_cmd1(1) to thrust_cmd1(6) of the six rotors No. 1 to No. 6 is all [0, 1], it is considered that all actuators are not saturated, and step S4 is directly executed;
[0035] When the value of any one of the roll-pitch channel throttle commands thrust_cmd1(1) to thrust_cmd1(6) of the six rotors No. 1 to No. 6 is not between the throttle upper limit and the throttle lower limit, it is considered that the actuator is saturated, and the roll-pitch control amount scaling factor abs(L)+abs(M) is further revalued, and steps S21-S23 are repeated until all actuators are not saturated;
[0036] S3, distributing the control amount to the thrust channel of each rotor, which specifically includes the following steps:
[0037] S31. Obtain the direction vector of the thrust channel of each rotor based on formula (3):
[0038]
[0039] Among them, dir (1) (i) is the direction vector of the thrust channel of each rotor; C 6*(1) are the thrust vectors of the control allocation matrix C (i.e., the first column of the matrix C); abs(T) is the thrust scaling factor, which can be determined in advance; T is the virtual control amount of the thrust channel of each rotor;
[0040] S32, if dir (1) (i) ≥ 0, the local maximum thrust scaling factor is determined according to the local maximum thrust scaling factor = throttle upper limit value - thrust_cmd1(i); if dir (1) (i)<0, the local maximum thrust scaling factor is determined according to thrust local maximum scaling factor=thrust_cmd1(i)-throttle lower limit value;
[0041] S33, taking the minimum value of all local maximum thrust scaling multiples and thrust scaling multiples as the global maximum thrust scaling multiple, and respectively comparing the global maximum thrust scaling multiple with the direction vector dir of the thrust channel of each rotor (1) (i) multiply, and the product obtained corresponds to the thrust channel throttle commands thrust_cmd2(1) to thrust_cmd2(6) of the six rotors No. 1 to No. 6;
[0042] S4, allocating the control amount to the yaw channel of each rotor, which specifically includes the following steps:
[0043] S41. Obtain the direction vector of the yaw channel of each rotor based on formula (4):
[0044]
[0045] Among them, dir (4) (i) is the direction vector of the yaw channel of each rotor; C 6*(4) are the yaw vectors of the control allocation matrix C (i.e., the fourth column of the matrix C); abs(N) is the scaling factor of the yaw channel control quantity, which can be determined in advance; N is the virtual control quantity of the yaw channel of each rotor;
[0046] S42, if dir (4) (i) ≥ 0, then the local maximum scaling factor of the yaw channel control amount is determined according to the local maximum scaling factor of the yaw channel control amount = throttle upper limit value - thrust_cmd2(i); if dir (4)(i)<0, the local maximum scaling factor of the yaw channel control amount is determined according to the local maximum scaling factor of the yaw channel control amount=thrust_cmd2(i)-throttle lower limit value;
[0047] S43, taking the minimum value of all the local maximum scaling factors of the yaw channel control amount and the yaw channel control amount scaling factor abs(N) as the global maximum scaling factor of the yaw channel control amount, and respectively comparing the global maximum scaling factor of the yaw channel control amount with the direction vector dir of the yaw channel of each rotor (4) The product obtained by multiplying (i) corresponds to the yaw channel throttle commands thrust_cmd3(1) to thrust_cmd3(6) of the six rotors No. 1 to No. 6.
[0048] Therefore, the control method algorithm in this embodiment is simple and suitable for low-cost flight control needs of ordinary computing power. Based on the characteristics of the tilt-rotor configuration, it gives priority to allocating control amounts to the roll and pitch channels to prioritize the attitude control effect, and at the same time allocates thrust for vertical control to ensure a stable flight altitude, so that the aircraft will not drop or rise suddenly due to giving up part of the vertical control amount. Furthermore, this embodiment maximizes the allocation of heading control amounts without actuator saturation, so that unsaturated actuators can be reasonably used to provide lift, which can solve the problem of low control allocation efficiency in the current method and improve the flight control safety margin.
[0049] Embodiment 2:
[0050] The difference between this embodiment and the first embodiment is that the step S3 includes, when any one of the four rotors No. 1 to No. 4 has an actuator saturation, the thrust throttle command of the rotor No. 5 and No. 6 is obtained according to the following formula:
[0051]
[0052] Among them, thrust_cmd2(5,6) is the thrust channel throttle command of rotors 5 and 6; b1 and b2 are the maximum thrust of a single rotor of rotors 1-4 and 5-6 respectively; ΔT is the difference between the expected thrust T and the actual thrust T of rotors 5 and 6. ACT Difference, that is, ΔT = TT ACT ; thrust_cmd1(5,6) is the roll-pitch channel throttle command of rotors 5 and 6; In this embodiment, the maximum thrust b1 of each rotor of rotors 1 to 4 is the same, the maximum thrust b2 of each rotor of rotors 5 to 6 is the same, the expected thrust T of rotors 5 and 6 is the same, and the actual thrust T of rotors 5 and 6 is the same. ACT The roll-pitch channel throttle commands of rotors 5 and 6 are the same.
[0053] In this embodiment, after the direction vector of the thrust channel is determined, and when the actuators of the auxiliary rotors (i.e., rotors 1 to 4) are saturated, the desired thrust T of rotors 5 and 6 and the actual thrust T ACT The difference adjusts the thrust channel throttle command of the main power rotor (i.e. rotors No. 5 and 6), thereby further improving the power distribution efficiency and maximizing the actuator performance.
[0054] Embodiment three:
[0055] This embodiment provides a control distribution system for a six-rotor tilt-wing aircraft, which can implement the control distribution method in the first or second embodiment, such as Figure 3 As shown, it includes:
[0056] Pre-allocation module 1 is used to pre-allocate the thrust of six rotors No. 1 to No. 6 when rotors No. 5 and No. 6 are in multi-rotor mode, so as to obtain initial allocation control quantities thrust_cmd0 corresponding to the six rotors No. 1 to No. 6, respectively, and the process is the same as step S1;
[0057] A first control amount distribution module 2, which is used to distribute the control amount to the roll-pitch channel of each rotor, and its process is the same as step S2;
[0058] A second control amount distribution module 3 is used to distribute the control amount to the thrust channel of each rotor, and its process is the same as step S3;
[0059] The third control amount distribution module 4 is used to distribute the control amount to the yaw channel of each rotor, and its process is the same as step S4.
[0060] To sum up, the control method algorithm in the present invention is simple and suitable for low-cost flight control needs of ordinary computing power. Based on the characteristics of the tilt-rotor configuration, it gives priority to allocating control amounts to the roll and pitch channels to prioritize the attitude control effect, and at the same time allocates thrust for vertical control to ensure a stable flight altitude, so that the aircraft will not drop or rise suddenly due to giving up part of the vertical control amount; at the same time, the heading control amount can be maximized without actuator saturation, so that the unsaturated actuator can be reasonably used to provide lift.
[0061] It should be noted that the technical features in the above two embodiments can be combined arbitrarily, and the combined technical solutions all belong to the protection scope of the present application. And in this article, terms such as "including", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.
[0062] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A control allocation method for a six-rotor tilt-rotor aircraft, wherein the six-rotor tilt-rotor aircraft comprises a fuselage, two main wings connected to the fuselage, and six rotors No. 1 to No. 6, wherein: Rotors No. 5 and No. 6 are respectively installed on a main wing, and can be tilted around the main wing axis under the drive of the tilt mechanism; rotors No. 1, No. 2, No. 3, and No. 4 are fixed rotors that cannot be tilted, and their blades are always facing upward. It is characterized in that the control distribution method includes the following steps: When rotors 5 and 6 are in multi-rotor mode, the thrust of six rotors 1 to 6 is pre-allocated to obtain the initial allocation control amount thrust_cmd0 corresponding to the six rotors 1 to 6 respectively; Allocate control amount to the roll-pitch channel of each rotor; Allocate control quantity to the thrust channel of each rotor; And distribute the control amount to the yaw channel of each rotor.
2. The control allocation method according to claim 1, characterized in that: The initial allocation control amount thrust_cmd0 is obtained by the following formula: Among them, T0 is the initial value of the throttle distribution of the six rotors 1 to 6, and the initial values of the throttle distribution of the six rotors 1 to 6 are the same, and the value range is [0,1]; C 6*4 It is a control allocation matrix with 6 rows and 4 columns.
3. The control allocation method according to claim 1, characterized in that: The control amount is distributed to the roll-pitch channel of each rotor, which specifically includes the following steps: The direction vector of the roll-pitch channel of each rotor is determined by the following formula: Among them, dir (2,3) (i) is the direction vector of the roll-pitch channel of each rotor, i=1-6, representing the i-th rotor; C 6*(2) , C 6*(3) are the roll vector and pitch vector of the control allocation matrix C respectively; L and M are the virtual control amount of the roll channel and the virtual control amount of the pitch channel of each rotor respectively; abs(L)+abs(M) is the scaling factor of the roll-pitch control amount; If dir (2,3) (i) ≥ 0, then the local maximum scaling factor of the roll-pitch control amount is determined according to the local maximum scaling factor of the roll-pitch control amount = throttle upper limit value - thrust_cmd0(i); if dir (2,3) (i)<0, the local maximum scaling factor of the roll-pitch control amount is determined according to the local maximum scaling factor of the roll-pitch control amount=thrust_cmd0(i)-throttle lower limit value; Take the minimum value of all local maximum scaling factors of the roll-pitch control amount and the scaling factor abs(L)+abs(M) of the roll-pitch control amount as the global maximum scaling factor of the roll-pitch control amount, and add the global maximum scaling factor of the roll-pitch control amount to the direction vector dir of the roll-pitch channel of each rotor. (2,3) The product obtained by multiplying (i) corresponds to the roll-pitch channel throttle commands thrust_cmd1(1) to thrust_cmd1(6) of the six rotors No. 1 to No.
6.
4. The control allocation method according to claim 3, characterized in that: When the value range of the roll-pitch channel throttle commands thrust_cmd1(1) to thrust_cmd1(6) of the six rotors 1 to 6 is all [0,1], it is considered that all actuators are not saturated, and the control amount is directly allocated to the yaw channel of each rotor.
5. The control allocation method according to claim 3, characterized in that: When the value of any of the roll-pitch channel throttle commands thrust_cmd1(1) to thrust_cmd1(6) of the six rotors 1 to 6 is not between the throttle upper limit and the throttle lower limit, it is considered that the actuator is saturated. The roll-pitch control value scaling factor abs(L)+abs(M) is revalued, and the process of determining the direction vector of the roll-pitch channel, determining the global maximum scaling factor of the roll-pitch control value, and calculating the roll-pitch channel throttle command is repeated until all actuators are unsaturated.
6. The control allocation method according to claim 1, characterized in that: The control amount distribution is performed on the thrust channel of each rotor, which specifically includes the following steps: The direction vector of the thrust channel of each rotor is obtained based on the following formula: Among them, dir (1) (i) is the direction vector of the thrust channel of each rotor; C 6*(1) are the thrust vectors of the control allocation matrix C; abs(T) is the thrust scaling factor; T is the virtual control amount of the thrust channel of each rotor; If dir (1) (i) ≥ 0, the local maximum thrust scaling factor is determined according to the local maximum thrust scaling factor = throttle upper limit value - thrust_cmd1(i); if dir (1) (i)<0, the local maximum thrust scaling factor is determined according to thrust local maximum scaling factor=thrust_cmd1(i)-throttle lower limit value; Take the minimum value of all local maximum thrust scaling multiples and thrust scaling multiples as the global maximum thrust scaling multiple, and compare the global maximum thrust scaling multiple with the direction vector dir of the thrust channel of each rotor (1) The product obtained by multiplying (i) corresponds to the thrust channel throttle commands thrust_cmd2(1) to thrust_cmd2(6) for the six rotors No. 1 to No.
6.
7. The control allocation method according to claim 6, characterized in that: The control amount is distributed to the thrust channel of each rotor, which also includes the following steps: When any of the four rotors 1 to 4 has an actuator saturation, the thrust throttle command of rotors 5 and 6 is obtained according to the following formula: Among them, thrust_cmd2(5,6) is the thrust channel throttle command of rotors 5 and 6; b1 and b2 are the maximum thrust of a single rotor of rotors 1-4 and 5-6 respectively; ΔT is the difference between the expected thrust T and the actual thrust T of rotors 5 and 6. ACT Difference, that is, ΔT = TT ACT ; thrust_cmd1(5,6) is the throttle command for the roll-pitch channel of rotors 5 and 6.
8. The control allocation method according to claim 1, characterized in that: The control amount is distributed to the yaw channel of each rotor, which specifically includes the following steps: The direction vector of the yaw channel of each rotor is obtained based on the following formula: Among them, dir (4) (i) is the direction vector of the yaw channel of each rotor; C 6*(4) are the yaw vectors of the control allocation matrix C respectively; abs(N) is the scaling factor of the yaw channel control quantity; N is the virtual control quantity of the yaw channel of each rotor; If dir (4) (i) ≥ 0, then the local maximum scaling factor of the yaw channel control amount is determined according to the local maximum scaling factor of the yaw channel control amount = throttle upper limit value - thrust_cmd2(i); if dir (4) (i)<0, the local maximum scaling factor of the yaw channel control amount is determined according to the local maximum scaling factor of the yaw channel control amount=thrust_cmd2(i)-throttle lower limit value; Take the minimum value of the local maximum scaling multiples of all yaw channel control quantities and the yaw channel control quantity scaling multiples abs(N) as the global maximum scaling multiple of the yaw channel control quantity, and compare the global maximum scaling multiple of the yaw channel control quantity with the direction vector dir of the yaw channel of each rotor. (4) The product obtained by multiplying (i) corresponds to the yaw channel throttle commands thrust_cmd3(1) to thrust_cmd3(6) of the six rotors No. 1 to No.
6.
9. A control distribution system for a six-rotor tilt-wing aircraft, characterized in that: include: A pre-allocation module is used to pre-allocate the thrust of the six rotors No. 1 to No. 6 when the rotors No. 5 and No. 6 are in the multi-rotor mode, so as to obtain the initial allocation control amount thrust_cmd0 corresponding to the six rotors No. 1 to No. 6 respectively; A first control amount distribution module, which is used to distribute the control amount to the roll-pitch channel of each rotor; A second control amount distribution module, which is used to distribute the control amount to the thrust channel of each rotor; And a third control quantity allocation module, which is used to allocate the control quantity to the yaw channel of each rotor.