A control method and system for complete failure of tail rotor of unmanned helicopter

Abstract

The present invention discloses a control method and system for the complete failure of the tail rotor of an unmanned helicopter, and relates to the technical field of unmanned helicopters. The method comprises: when the unmanned helicopter is in a hovering state, judging whether the tail rotor is completely failed according to the sensor data of the unmanned helicopter in the hovering state, and when the tail rotor is completely failed, controlling the height of the unmanned helicopter to drop to a preset height value, and then controlling the unmanned helicopter to autorotate, glide and land; when the unmanned helicopter is in a forward flight state, judging whether the tail rotor is completely failed according to the sensor data of the unmanned helicopter in the forward flight state, and when the tail rotor is completely failed, controlling the height of the unmanned helicopter to drop to a preset height value, and decelerating the forward flight speed to a preset forward flight speed value, and then controlling the unmanned helicopter to autorotate, glide and land. The present invention can realize the control of the unmanned helicopter to land safely when the tail rotor of the unmanned helicopter is completely failed.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned helicopters, and in particular to a control method and system for the complete failure of the tail rotor of an unmanned helicopter. Background Art

[0002] Unmanned helicopters (hereinafter referred to as helicopters) are widely used in many fields of national economic development due to their strong maneuverability and good low-altitude and low-speed flight characteristics, which has a revolutionary impact on economic life. With the gradual opening of low-altitude areas, helicopters have achieved remarkable results in power operations, oil services, maritime rescue, tourism, emergency rescue, aerial inspections, terrain surveys and other fields. With the rapid development of helicopters, corresponding safety issues have also emerged. In the early 20th century, there were many helicopter accidents caused by tail rotor failures in the world. Among the tail rotor failures, the most serious is the complete failure of the tail rotor. If it is not handled properly at this time, it will lead to serious accidents. Therefore, designing a solution to the failure of the tail rotor of a helicopter is of great significance to the flight safety of the helicopter and can accelerate the rapid development of helicopters. Since there is no complete solution for the failure of the tail rotor of a helicopter in the current existing technology, that is, there is no control method for the complete failure of the tail rotor of an unmanned helicopter in the current existing technology, it is impossible to control the safe landing of the unmanned helicopter when the tail rotor of the unmanned helicopter fails completely. Summary of the invention

[0003] The purpose of the present invention is to provide a control method and system for the complete failure of the tail rotor of an unmanned helicopter, which can control the unmanned helicopter to land safely when the tail rotor of the unmanned helicopter completely fails.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A control method for a complete failure of a tail rotor of an unmanned helicopter, the method comprising:

[0006] Step S1: obtaining the current state of the unmanned helicopter; the state includes a hovering state and a forward flight state;

[0007] Step S2: acquiring sensor data of the unmanned helicopter in the state; the sensor data includes yaw angular velocity, roll angular velocity and pitch angular velocity;

[0008] Step S3: judging whether the tail rotor of the unmanned helicopter is completely ineffective according to the sensor data;

[0009] If the output result of step S3 is yes, then execute step S4: obtain the aerial information of the unmanned helicopter at the current moment; when the state is the hovering state, the aerial information includes the height of the unmanned helicopter; when the state is the forward flight state, the aerial information includes the height and forward flight speed of the unmanned helicopter;

[0010] Step S5: Obtaining a preset altitude value and a preset forward flight speed value;

[0011] Step S6: obtaining a control amount of the unmanned helicopter according to the aerial information, the preset height value and the preset forward flight speed value; when the state is a hovering state, the control amount includes a height drop amount; when the state is a forward flight state, the control amount includes a height drop amount and a forward flight speed reduction amount;

[0012] Step S7: according to the control amount, using the implicit model to obtain the control amount of the unmanned helicopter corresponding to the control amount; the control amount includes the rotor collective pitch control amount, the lateral cyclic pitch control amount, the longitudinal cyclic pitch control amount and the tail rotor pitch control amount;

[0013] Step S8: controlling the movement of the unmanned helicopter according to the control amount; when the state is a hovering state, the movement includes descending to the preset height value; when the state is a forward flight state, the movement includes descending to the preset height value and decelerating to the preset forward flight speed value;

[0014] Step S9: After the unmanned helicopter has completed its movement, the unmanned helicopter is controlled to autorotate, glide and land; when the state is a hovering state, the autorotation and glide adopts a vertical descent; when the state is a forward flight state, the autorotation and glide adopts an oblique glide;

[0015] If the output result of step S3 is no, then return to step S1.

[0016] Optionally, judging whether the tail rotor of the unmanned helicopter is completely ineffective according to the sensor data specifically includes:

[0017] When the sensor data meets When , it is determined that the tail rotor of the unmanned helicopter is completely ineffective; where r represents the yaw angular velocity of the unmanned helicopter at the current moment, q represents the roll angular velocity of the unmanned helicopter at the current moment, p represents the pitch angular velocity of the unmanned helicopter at the current moment, and r h represents the yaw angular velocity corresponding to the height of the unmanned helicopter h. When the state is a hovering state, r h =3.5h+3, when the state is forward flight state, r h =-3.025h+189, where h represents the altitude of the unmanned helicopter at the current moment.

[0018] Optionally, the height drop is -(hh w );where h w Indicates the preset value of height;

[0019] The forward flight speed reduction is -(VV w ), where V represents the forward flight speed of the unmanned helicopter at the current moment, V w Indicates the preset forward flight speed.

[0020] Optionally, the preset height value is 5m.

[0021] Optionally, the oblique downward sliding is an oblique downward sliding at 45°.

[0022] The present invention also provides the following solution:

[0023] A control system for a complete failure of a tail rotor of an unmanned helicopter, the system comprising:

[0024] A state acquisition module is used to acquire the state of the unmanned helicopter at the current moment; the state includes a hovering state and a forward flight state;

[0025] A sensor data acquisition module, used to acquire sensor data of the unmanned helicopter in the above state; the sensor data includes yaw angular velocity, roll angular velocity and pitch angular velocity;

[0026] A failure judgment module, used to judge whether the tail rotor of the unmanned helicopter has completely failed according to the sensor data;

[0027] An air information acquisition module, used for acquiring the air information of the unmanned helicopter at the current moment when the output result of the failure judgment module is yes; when the state is a hovering state, the air information includes the height of the unmanned helicopter; when the state is a forward flight state, the air information includes the height and forward flight speed of the unmanned helicopter;

[0028] A preset value acquisition module is used to acquire a preset value of height and a preset value of forward flight speed;

[0029] A control amount obtaining module is used to obtain the control amount of the unmanned helicopter according to the aerial information, the preset height value and the preset forward flight speed value; when the state is a hovering state, the control amount includes the height drop amount; when the state is a forward flight state, the control amount includes the height drop amount and the forward flight speed reduction amount;

[0030] A control amount obtaining module is used to obtain the control amount of the unmanned helicopter corresponding to the control amount by using an implicit model according to the control amount; the control amount includes the rotor's collective pitch control amount, the lateral cyclic pitch control amount, the longitudinal cyclic pitch control amount and the tail rotor pitch control amount;

[0031] A motion control module, used for controlling the motion of the unmanned helicopter according to the control amount; when the state is a hovering state, the motion includes descending to the preset height value; when the state is a forward flight state, the motion includes descending to the preset height value and decelerating to the preset forward flight speed value;

[0032] The autorotation descent and landing control module is used to control the autorotation descent and landing of the unmanned helicopter after the unmanned helicopter has completed its movement; when the state is a hovering state, the autorotation descent adopts a vertical descent; when the state is a forward flight state, the autorotation descent adopts an oblique descent;

[0033] A return module is used to return to the state acquisition module when the output result of the failure judgment module is no.

[0034] Optionally, the failure judgment module specifically includes:

[0035] A failure judgment unit is used to judge the failure of the sensor data when the sensor data meets the When , it is determined that the tail rotor of the unmanned helicopter is completely ineffective; where r represents the yaw angular velocity of the unmanned helicopter at the current moment, q represents the roll angular velocity of the unmanned helicopter at the current moment, p represents the pitch angular velocity of the unmanned helicopter at the current moment, and r h represents the yaw angular velocity corresponding to the height of the unmanned helicopter h. When the state is a hovering state, r h =3.5h+3, when the state is forward flight state, r h =-3.025h+189, where h represents the altitude of the unmanned helicopter at the current moment.

[0036] Optionally, the height drop is -(hh w );where h w Indicates the preset value of height;

[0037] The forward flight speed reduction is -(VV w ), where V represents the forward flight speed of the unmanned helicopter at the current moment, V w Indicates the preset forward flight speed.

[0038] Optionally, the preset height value is 5m.

[0039] Optionally, the oblique downward sliding is an oblique downward sliding at 45°.

[0040] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0041] The present invention discloses a control method and system for the complete failure of the tail rotor of an unmanned helicopter, and provides a complete solution for the complete failure of the tail rotor of an unmanned helicopter. When the unmanned helicopter is in a hovering state, it is determined whether the tail rotor has completely failed according to the sensor data of the unmanned helicopter in the hovering state. When the tail rotor has completely failed, the height of the unmanned helicopter is controlled to drop to a preset height value, and then the unmanned helicopter is controlled to rotate, glide and land. When the unmanned helicopter is in a forward flight state, it is determined whether the tail rotor has completely failed according to the sensor data of the unmanned helicopter in the forward flight state. When the tail rotor has completely failed, the height of the unmanned helicopter is controlled to drop to a preset height value, and the forward flight speed is decelerated to a preset forward flight speed value, and then the unmanned helicopter is controlled to rotate, glide and land. By determining whether the tail rotor of the unmanned helicopter has completely failed in different states, and making corresponding control for the failure of the tail rotor of the unmanned helicopter in different states when the tail rotor has completely failed, it is possible to control the unmanned helicopter to land safely when the tail rotor of the unmanned helicopter has completely failed. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0043] Figure 1 It is a flow chart of an embodiment of a control method for a complete failure of the tail rotor of an unmanned helicopter according to the present invention;

[0044] Figure 2 A schematic flow chart of a solution to helicopter tail rotor failure according to the present invention;

[0045] Figure 3 This is a schematic diagram of the change of yaw angular velocity in the hovering state when the tail rotor fails;

[0046] Figure 4 It is a schematic diagram of the change of yaw angular velocity in the forward flight state when the tail rotor fails;

[0047] Figure 5 It is the control structure diagram of the implicit model;

[0048] Figure 6 It is the schematic diagram of the middle loop in the implicit model;

[0049] Figure 7 The present invention is a structural diagram of a control system embodiment for a complete failure of the tail rotor of an unmanned helicopter. DETAILED DESCRIPTION

[0050] 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.

[0051] The purpose of the present invention is to provide a control method and system for the complete failure of the tail rotor of an unmanned helicopter, which can control the unmanned helicopter to land safely when the tail rotor of the unmanned helicopter completely fails.

[0052] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] Figure 1 Flow chart of an embodiment of the control method for the complete failure of the tail rotor of an unmanned helicopter according to the present invention. Figure 1 , the control method for the complete failure of the tail rotor of the unmanned helicopter includes:

[0054] Step S1: Obtain the current state of the unmanned helicopter; the state includes hovering state and forward flight state.

[0055] Step S2: Acquire sensor data of the unmanned helicopter in the state; the sensor data includes yaw angular velocity, roll angular velocity and pitch angular velocity.

[0056] Step S3: Determine whether the tail rotor of the unmanned helicopter is completely ineffective based on the sensor data.

[0057] The step S3 specifically includes:

[0058] When the sensor data meets When , it is determined that the tail rotor of the unmanned helicopter is completely ineffective; where r represents the yaw angular velocity of the unmanned helicopter at the current moment, q represents the roll angular velocity of the unmanned helicopter at the current moment, p represents the pitch angular velocity of the unmanned helicopter at the current moment, and r h It indicates the yaw angular velocity of the unmanned helicopter when its altitude is h. When the state is hovering, r h =3.5h+3, when the state is forward flight state, r h =-3.025h+189, where h represents the altitude of the unmanned helicopter at the current moment.

[0059] If the output result of step S3 is yes, then execute step S4: obtain the aerial information of the unmanned helicopter at the current moment; when the state is a hovering state, the aerial information includes the altitude of the unmanned helicopter; when the state is a forward flight state, the aerial information includes the altitude and forward flight speed of the unmanned helicopter.

[0060] Step S5: Obtaining a preset value of the altitude and a preset value of the forward flight speed.

[0061] In step S5, the preset value of the height is 5 m. The preset value of the height and the height of the unmanned helicopter are both relative to the ground, that is, the height from the ground (vertical height).

[0062] Step S6: According to the aerial information, the preset height value and the preset forward flight speed value, the control amount of the unmanned helicopter is obtained; when the state is a hovering state, the control amount includes the height drop amount; when the state is a forward flight state, the control amount includes the height drop amount and the forward flight speed reduction amount.

[0063] In step S6, the height drop is -(hh w );where h w Indicates the preset altitude; the forward flight speed decreases by -(VV w ), where V represents the forward flight speed of the unmanned helicopter at the current moment, V w Indicates the preset forward flight speed.

[0064] Step S7: According to the control amount, the control amount of the unmanned helicopter corresponding to the control amount is obtained by using the implicit model; the control amount includes the rotor's collective pitch control amount, the lateral cyclic pitch control amount, the longitudinal cyclic pitch control amount and the tail rotor pitch control amount.

[0065] Step S8: Control the movement of the unmanned helicopter according to the control amount; when the state is a hovering state, the movement includes descending to a preset height value; when the state is a forward flight state, the movement includes descending to a preset height value and decelerating to a preset forward flight speed value.

[0066] Step S9: After the unmanned helicopter has completed its movement, the unmanned helicopter is controlled to autorotate, glide and land; when the state is a hovering state, the autorotation and glide adopts a vertical descent; when the state is a forward flight state, the autorotation and glide adopts an oblique glide.

[0067] In step S9, the oblique downward sliding is a 45° oblique downward sliding.

[0068] If the output result of step S3 is no, then return to step S1.

[0069] The technical solution of the present invention is described below with a specific embodiment (this embodiment takes a single-rotor helicopter with a tail rotor as an example, and describes in detail the control method of the present invention for the complete failure of the tail rotor of an unmanned helicopter):

[0070] Aiming at the special situation that the tail rotor of an unmanned helicopter completely fails, the present invention proposes a reasonable and intelligent safe landing plan, that is, a solution to the failure of the helicopter tail rotor, so as to reduce the helicopter accidents caused by the tail rotor failure. Figure 2This is a schematic diagram of a solution flow for a helicopter tail rotor failure provided by the present invention, which is divided into hovering tail rotor failure and forward flight tail rotor failure. Figure 2 The solution to the failure of the helicopter tail rotor of the present invention is a control method for the complete failure of the tail rotor of an unmanned helicopter. The logic is to first obtain the current state of the helicopter, then determine whether the tail rotor fails according to the helicopter state and sensor data, and then issue a corresponding instruction. The control system controls the helicopter according to the instruction. The method scheme is as follows:

[0071] Step 1: For a single-rotor helicopter with a tail rotor, if the tail rotor fails in the hovering state, a large yaw velocity will be generated, and the helicopter will roll and lower its head. If the tail rotor fails in the forward flight state, the yaw velocity will increase, and the helicopter will lower its head and roll. Therefore, based on the real-time data of the helicopter sensor, including the yaw rate (yaw rate) r, the roll rate (roll rate) q, and the pitch rate (pitch rate) p, the hovering mode (hovering state) is determined according to formula (2), and the forward flight mode (forward flight state) is determined according to formula (3). It is determined whether the helicopter has a tail rotor failure. If the tail rotor fails, proceed to step 2, otherwise, it ends.

[0072] When the helicopter tail rotor fails completely, the rotor anti-torque cannot be balanced, and the helicopter accelerates to the opposite direction of the rotor rotation. At this time, the sensor's yaw angular velocity increases rapidly. When the yaw angular velocity is continuously (for 3 seconds or more) greater than 30 degrees per second, the helicopter tail rotor is considered to have failed. At this time, the helicopter will show a trend of yaw, nose down, and roll attitude changes.

[0073] The helicopter status monitor monitors the helicopter sensor data and determines the helicopter status. If it is in hovering status, it is determined as follows:

[0074] The altitude sensor returns the helicopter altitude information (helicopter altitude) h (m). Figure 3 The yaw rate change curve in the hovering state when the tail rotor fails (S-76 helicopter) approximately simulates the following relationship (obtained by fitting the previous experimental values):

[0075] r h =3.5h+3 (1)

[0076] Among them, r h is the yaw rate corresponding to the helicopter when the hovering height is h, where h is the helicopter hovering height. According to formula (1), the corresponding yaw rate r is obtained: h .

[0077] If the helicopter sensor data meets the following conditions, it is determined that the tail rotor has failed:

[0078]

[0079] Among them, r is the real-time yaw rate of the helicopter, q is the real-time roll rate of the helicopter, and p is the real-time pitch rate of the helicopter.

[0080] If it is in forward flight state, it is judged as follows:

[0081] The sensor returns the helicopter altitude information h(m). Figure 4 The yaw rate change curve in forward flight when the tail rotor fails (S-76 helicopter) approximately simulates the following relationship:

[0082] r h =-3.025h+189 (3)

[0083] Among them, r h is the helicopter yaw rate, h is the helicopter hovering height, which is the real-time height of the helicopter in forward flight. The corresponding yaw rate r is obtained according to formula (3). h .

[0084] If the helicopter sensor data meets the following conditions, it is determined that the tail rotor has failed:

[0085]

[0086] Among them, r is the real-time yaw rate of the helicopter, q is the real-time roll rate of the helicopter, and p is the real-time pitch rate of the helicopter.

[0087] After determining that the tail rotor has failed, proceed to the second step.

[0088] Step 2: If the helicopter is in a hovering state and the tail rotor stalls, it needs to quickly release the collective pitch and stabilize the attitude, automatically generate a series of control instructions (a certain height and stable attitude), and implement the instructions through step 3; when the tail rotor fails in the forward flight state, it is necessary to stabilize the helicopter speed and stabilize the attitude, automatically generate a series of control instructions, and implement the instructions through step 3. Step 3 designs the helicopter implicit model control law (implicit model) so that the helicopter can complete the control instructions, so that the helicopter with tail rotor failure can quickly and automatically stabilize the attitude, helicopter height and helicopter speed.

[0089] Among them, the tail rotor fails in hovering:

[0090] Assume that the height when the tail rotor fails is h, and the stable height (height preset value) is h w , the control amount (height descent amount) of the automatically issued command height is -(hh w ), the negative sign represents a decrease hh w (Generally stabilized at 5 meters), the posture will automatically stabilize (i.e. maintain a dynamic balance) through the control law designed in step 3.

[0091] Tail rotor failure in forward flight:

[0092] Assume that the forward flight speed is V, the altitude is h, and the stable forward flight speed (preset forward flight speed) is V when the tail rotor fails. w , the stable height is h w , the control amount for automatically issuing the command height is -(hh w ), the command forward flight speed (forward flight speed reduction) is -(VV w ), the posture will automatically stabilize (i.e. maintain a dynamic balance) through the control law designed in step 3.

[0093] Step 3: For the helicopter control variables provided in step 2, the helicopter implicit model control law is used to make the helicopter respond quickly to the instructions in step 2 and maintain a stable attitude. The specific steps are as follows:

[0094] Step 1: The helicopter state equation (the following state equation is obtained by linearizing the helicopter kinematic equation obtained by Newton's second law with small perturbations) is as follows:

[0095] x=[uvwpqr φ θ ψ] T (5)

[0096] Using the helicopter state equation to describe the flight state of a helicopter usually requires 9 state quantities, namely: the helicopter's flight speed uvw, roll angular rate, pitch angular rate and heading angular rate pqr, roll angle, pitch angle and yaw angle (heading angle) φ θ ψ. Since the heading angle does not affect the force analysis, only the remaining 8 state quantities need to be considered.

[0097] The control of the helicopter (input command, the helicopter can respond quickly) is mainly achieved through four channels. The collective pitch channel (controls the vertical speed of the helicopter) is controlled by the collective pitch δ of the rotor. c To control, the lateral channel (controls the helicopter pitch angle) is controlled by the lateral cyclic pitch change of the rotor δ a To control, the longitudinal channel (controls the helicopter roll angle) is controlled by the longitudinal cyclic pitch change of the rotor δ e To control, the heading channel (controls the helicopter yaw rate) is controlled by the tail rotor pitch δ r The handling methods for tail rotor failure in hover and forward flight are different.

[0098] The standard state equation of the helicopter system is:

[0099]

[0100] Where A is an 8×8 dynamic state matrix (partial derivatives of force and torque at a certain reference motion point), B is an 8×4 control matrix (same as above), and the AB matrix is ​​obtained by small perturbation linearization.

[0101] State control vector Δx = [uvwpqr φ θ] T , which are the changes of forward speed (m / s), lateral speed (m / s), vertical speed (m / s), roll angular rate (° / s), pitch angular rate (° / s), yaw angular rate (° / s), roll angle (° / s), and pitch angle (° / s).

[0102] Control matrix Δu=[Δδ c Δδ a Δδ e Δδ r ] T , respectively, are total pitch (°), lateral cyclic pitch (°), longitudinal cyclic pitch (°), and change in tail rotor pitch (°).

[0103] Step 2: Design the implicit model to achieve fast and stable response of the helicopter command (by decoupling to achieve single-channel response of the helicopter). The implicit model is the control method, that is, Figure 5 The control structure diagram shown.

[0104] Hidden model such as Figure 5 As shown in the structure diagram, Figure 5 The flow of the control method is shown:

[0105] Step ①: The input is the control variable, the collective pitch channel input corresponds to the helicopter vertical speed command, and the output is the response of the helicopter vertical speed command; the heading channel input corresponds to the helicopter yaw angular velocity command, and the output is the response of the helicopter yaw angular velocity command; the roll channel input corresponds to the helicopter roll angular rate command, and the output is the response of the helicopter roll angular rate command; the pitch channel input corresponds to the helicopter pitch angular rate command, and the output is the response of the helicopter pitch angular rate command;

[0106] Among them, the control variable is the state control vector. The collective pitch channel controls several state quantities of the helicopter separately. This channel controls the vertical speed of the helicopter, the heading channel controls the yaw angular velocity of the helicopter, the roll channel controls the roll angular rate of the helicopter, and the pitch channel controls the pitch angular rate of the helicopter.

[0107] Step ②: The four input instructions are decoupled by the matrix B d , achieving operational decoupling, and each input will not affect each other.

[0108] Decoupling means making several quantities independent of each other, and the change of one quantity will not affect the change of other quantities. Decoupling matrix Bd From the structure diagram Figure 5 It is composed of H and B, and the decoupling matrix is ​​specifically H*B.

[0109] Step ③: State A is converted to the desired state matrix A through K. d (Set according to your own needs) to make it meet the quality standards of helicopters.

[0110] Among them, the conversion is A-BK.

[0111] Step ④: Expected state matrix A d The result of multiplication with the state quantity x is then added to the decoupled control input of step ② to obtain four output instructions after response.

[0112] Here, response refers to the actual change in the helicopter state quantity.

[0113] Through decoupling and feedback, the helicopter can respond quickly to the command value. The control result is the best way to control the helicopter to deal with tail rotor failure, providing a control basis for solving the problem.

[0114] The coupling reflected in the system matrix A is dynamic coupling, and the coupling reflected in the system matrix B is control coupling, such as Figure 5 As shown in the inner loop design of the control matrix, the dynamic coupling is released through the state feedback matrix K, and the control coupling is released through the feedforward compensation matrix H.

[0115] The desired closed-loop characteristic of the inner loop is as follows:

[0116]

[0117] In the formula, A d is the desired state matrix (A in the above step ③ d ), B d is the desired control allocation matrix (the decoupling matrix B in step ② above) d ).

[0118] The following is the derivation of the solution of H and K. The purpose of the following derivation is to transform formula (6) into formula (7) through K and B:

[0119] Depend on Figure 5 From the structure diagram, we can see that:

[0120]

[0121] but:

[0122]

[0123] Wherein, formula (9) is obtained by the matrix transformation formula.

[0124] Through the implicit model control law (the above-mentioned control structure), after decoupling, the implicit model of each channel is linearly independent, and the operation of one channel will not affect other channels. Then the four instructions of the inner loop can be realized to control the four state quantities of the helicopter separately.

[0125] On the basis of the inner loop, build the middle loop, and input the height instruction of step 2, that is, the height drop amount - (hh w ) and the forward flight speed command, that is, the forward flight speed reduction amount - (VV w ), the posture will automatically stabilize (if the middle circuit is stable, the inner circuit will automatically stabilize).

[0126] The middle circuit Figure 6 As shown, the input is the hovering height command of step 2, which responds to the vertical velocity through the inner loop, and then the integral of the vertical velocity is the vertical height response (i.e., the hovering height); the forward flight speed and height command of step 2 are input, and after the response of the inner loop, the integral is the vertical height response (the vertical height response is different from the vertical velocity response, and the integral of the vertical velocity is the vertical height), and the forward flight speed still needs to be converted through the longitudinal kinematic link to obtain the final forward flight speed response. The inner loop will automatically adjust during the whole process (the control structure is a feedback process).

[0127] Step 3 describes the control system workflow inside the helicopter, which is the instructions of step 2, including the height descent amount - (hh w ) and the forward speed reduction - (VV w ) is input into the helicopter, and then how the helicopter descends to the preset altitude and decelerates to the preset forward flight speed. Step 3 introduces how the existing latent model decoupling control system (latent model control system) converts the input command into the four control variables for actually controlling the helicopter: the rotor collective pitch δ c , lateral periodic variation δ a 、Longitudinal periodic pitch δ e and tail rotor pitch δ r , with the rotor's total pitch δ c , lateral periodic variation δ a 、Longitudinal periodic pitch δ e and tail rotor pitch δ r The helicopter is manipulated to descend to a preset altitude and decelerate to a preset forward flight speed. The formulas and parameters involved in step 3 are all existing formulas and parameters known to those skilled in the art.

[0128] Step 4: When the tail rotor fails during hovering, after stabilizing the helicopter's attitude and hovering altitude (Step 3 is the process of stabilizing the attitude and hovering altitude), proceed to Step 4; when the tail rotor fails during forward flight, after stabilizing the helicopter's attitude and forward flight speed (achieved by Step 3), automatically plan its flight to a suitable geographical location and flight altitude based on the geographic information fed back from the surrounding area (mainly terrain information, flat land, mountains, etc.) (achieved by Step 3), and proceed to Step 4.

[0129] Step 4: Make the next decision:

[0130] The tail rotor fails when hovering, and the helicopter is controlled to hover at a stable altitude of about 5m, at which point it is controllable.

[0131] When the tail rotor fails during forward flight, the helicopter should be properly distanced, the yaw rate should be reduced, the helicopter attitude should be stabilized, and the flight path should be planned to the nearest flat ground suitable for autorotation and gliding (about 5 meters above the ground). The flat ground suitable for autorotation and gliding is the position where there are no obstacles and the helicopter can be glided very quickly.

[0132] Step 5: When hovering, the tail rotor fails. The helicopter autorotates and descends after completing the command in step 3 (the engine is shut down for autorotation and descent is completed by itself) and descends vertically. When flying forward, the tail rotor fails. After completing the command in step 3, the engine is shut down (the engine is shut down for autorotation and descent after the command response in step 3 is completed). The helicopter autorotates and descends at an angle downward (forty-five degrees downward) and lands safely.

[0133] The helicopter autorotation glide emergency landing only needs a short runway. Autorotation glide flight refers to the process of emergency control of the helicopter when the engine or tail rotor fails during flight, making full use of the conversion between kinetic energy and gravitational potential energy, so that the helicopter can enter the autorotation glide state stably and finally achieve a safe landing.

[0134] Steps 4 and 5 describe a method for controlling the helicopter to land safely after the helicopter descends to a preset altitude and decelerates to a preset forward flight speed. The method for controlling the helicopter to land safely (including autorotation gliding and landing) described in steps 4 and 5 is an existing method for controlling the autorotation gliding and landing of an unmanned helicopter.

[0135] Compared with the prior art, the advantages of the present invention are:

[0136] First, a method for judging the failure of a helicopter tail rotor is provided, which can detect the occurrence of a tail rotor failure in a timely manner, and is of great significance for the subsequent timely handling of the tail rotor failure.

[0137] Second, a control method for stabilizing the helicopter's attitude, hovering altitude and flight speed is provided.

[0138] Figure 7FIG. 1 is a structural diagram of an embodiment of a control system for a complete failure of the tail rotor of an unmanned helicopter according to the present invention. Figure 7 The control system for the complete failure of the tail rotor of the unmanned helicopter includes:

[0139] The state acquisition module 701 is used to acquire the state of the unmanned helicopter at the current moment; the state includes the hovering state and the forward flight state.

[0140] The sensor data acquisition module 702 is used to acquire sensor data of the unmanned helicopter in a certain state; the sensor data includes yaw angular velocity, roll angular velocity and pitch angular velocity.

[0141] The failure judgment module 703 is used to judge whether the tail rotor of the unmanned helicopter has completely failed according to the sensor data.

[0142] The failure judgment module 703 specifically includes:

[0143] Failure judgment unit, used when the sensor data meets When , it is determined that the tail rotor of the unmanned helicopter is completely ineffective; where r represents the yaw angular velocity of the unmanned helicopter at the current moment, q represents the roll angular velocity of the unmanned helicopter at the current moment, p represents the pitch angular velocity of the unmanned helicopter at the current moment, and r h It indicates the yaw angular velocity of the unmanned helicopter when its altitude is h. When the state is hovering, r h =3.5h+3, when the state is forward flight state, r h =-3.025h+189, where h represents the altitude of the unmanned helicopter at the current moment.

[0144] The air information acquisition module 704 is used to obtain the air information of the unmanned helicopter at the current moment when the output result of the failure judgment module is yes; when the state is a hovering state, the air information includes the height of the unmanned helicopter; when the state is a forward flight state, the air information includes the height and forward flight speed of the unmanned helicopter.

[0145] The preset value acquisition module 705 is used to acquire a preset value of the altitude and a preset value of the forward flight speed.

[0146] The control quantity obtaining module 706 is used to obtain the control quantity of the unmanned helicopter according to the air information, the preset height value and the preset forward flight speed value; when the state is the hovering state, the control quantity includes the height decrease amount; when the state is the forward flight state, the control quantity includes the height decrease amount and the forward flight speed reduction amount.

[0147] The height decrease is -(hh w );where h w Indicates the preset value of height.

[0148] The forward flight speed decreases by -(VVw ), where V represents the forward flight speed of the unmanned helicopter at the current moment, V w Indicates the preset forward flight speed.

[0149] The default height is 5m.

[0150] The control variable obtaining module 707 is used to obtain the control variable of the unmanned helicopter corresponding to the control variable using an implicit model according to the control variable; the control variable includes the rotor's collective pitch control variable, the lateral cyclic pitch control variable, the longitudinal cyclic pitch control variable and the tail rotor pitch control variable.

[0151] The motion control module 708 is used to control the motion of the unmanned helicopter according to the control amount; when the state is the hovering state, the motion includes descending to the preset height value; when the state is the forward flight state, the motion includes descending to the preset height value and decelerating to the preset forward flight speed value.

[0152] The autorotation descent and landing control module 709 is used to control the autorotation descent and landing of the unmanned helicopter after the unmanned helicopter completes its movement; when the state is a hovering state, the autorotation descent adopts a vertical descent; when the state is a forward flight state, the autorotation descent adopts an oblique descent.

[0153] Among them, the oblique descent is a 45° oblique descent.

[0154] The return module 710 is used to return to the status acquisition module 701 when the output result of the failure judgment module 703 is no.

[0155] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0156] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A control method for the complete failure of the tail rotor of an unmanned helicopter, characterized in that: The method comprises: Step S1: obtaining the current state of the unmanned helicopter; the state includes a hovering state and a forward flight state; Step S2: acquiring sensor data of the unmanned helicopter in the state; the sensor data includes yaw angular velocity, roll angular velocity and pitch angular velocity; Step S3: judging whether the tail rotor of the unmanned helicopter is completely inoperative according to the sensor data, specifically comprising: when the sensor data satisfies When , it is determined that the tail rotor of the unmanned helicopter is completely ineffective; where r represents the yaw angular velocity of the unmanned helicopter at the current moment, q represents the roll angular velocity of the unmanned helicopter at the current moment, p represents the pitch angular velocity of the unmanned helicopter at the current moment, and r h It indicates the yaw angular velocity of the unmanned helicopter when its altitude is h. When the state is hovering, r h =3.5h+3, when the state is forward flight state, r h =-3.025h+189, where h represents the altitude of the unmanned helicopter at the current moment; If the output result of step S3 is yes, then execute step S4: obtain the aerial information of the unmanned helicopter at the current moment; when the state is the hovering state, the aerial information includes the height of the unmanned helicopter; when the state is the forward flight state, the aerial information includes the height and forward flight speed of the unmanned helicopter; Step S5: Obtaining a preset altitude value and a preset forward flight speed value; Step S6: obtaining a control amount of the unmanned helicopter according to the aerial information, the preset height value and the preset forward flight speed value; when the state is a hovering state, the control amount includes a height drop amount; when the state is a forward flight state, the control amount includes a height drop amount and a forward flight speed reduction amount; Step S7: according to the control amount, using the implicit model to obtain the control amount of the unmanned helicopter corresponding to the control amount; the control amount includes the rotor collective pitch control amount, the lateral cyclic pitch control amount, the longitudinal cyclic pitch control amount and the tail rotor pitch control amount; Step S8: controlling the movement of the unmanned helicopter according to the control amount; when the state is a hovering state, the movement includes descending to the preset height value; when the state is a forward flight state, the movement includes descending to the preset height value and decelerating to the preset forward flight speed value; Step S9: After the unmanned helicopter has completed its movement, the unmanned helicopter is controlled to autorotate, glide and land; when the state is a hovering state, the autorotation and glide adopts a vertical descent; when the state is a forward flight state, the autorotation and glide adopts an oblique glide; If the output result of step S3 is no, then return to step S1.

2. The control method for the complete failure of the tail rotor of an unmanned helicopter according to claim 1 is characterized in that: The height drop is -(hh w );where h w Indicates the preset value of height; The forward flight speed reduction is -(VV w ), where V represents the forward flight speed of the unmanned helicopter at the current moment, V w Indicates the preset forward flight speed.

3. The control method for the complete failure of the tail rotor of an unmanned helicopter according to claim 1 is characterized in that: The preset height value is 5m.

4. The control method for the complete failure of the tail rotor of an unmanned helicopter according to claim 1 is characterized in that: The oblique downward sliding is a 45° oblique downward sliding.

5. A control system for the complete failure of the tail rotor of an unmanned helicopter, characterized in that: The system comprises: A state acquisition module is used to acquire the state of the unmanned helicopter at the current moment; the state includes a hovering state and a forward flight state; A sensor data acquisition module, used to acquire sensor data of the unmanned helicopter in the above state; the sensor data includes yaw angular velocity, roll angular velocity and pitch angular velocity; The failure judgment module is used to judge whether the tail rotor of the unmanned helicopter is completely failed according to the sensor data; the failure judgment module specifically includes: a failure judgment unit, which is used to judge whether the tail rotor of the unmanned helicopter is completely failed when the sensor data meets the requirements; When , it is determined that the tail rotor of the unmanned helicopter is completely ineffective; where r represents the yaw angular velocity of the unmanned helicopter at the current moment, q represents the roll angular velocity of the unmanned helicopter at the current moment, p represents the pitch angular velocity of the unmanned helicopter at the current moment, and r h It indicates the yaw angular velocity of the unmanned helicopter when its altitude is h. When the state is hovering, r h =3.5h+3, when the state is forward flight state, r h =-3.025h+189, where h represents the altitude of the unmanned helicopter at the current moment; An air information acquisition module, used for acquiring the air information of the unmanned helicopter at the current moment when the output result of the failure judgment module is yes; when the state is a hovering state, the air information includes the height of the unmanned helicopter; when the state is a forward flight state, the air information includes the height and forward flight speed of the unmanned helicopter; A preset value acquisition module is used to acquire a preset value of height and a preset value of forward flight speed; A control amount obtaining module is used to obtain the control amount of the unmanned helicopter according to the aerial information, the preset height value and the preset forward flight speed value; when the state is a hovering state, the control amount includes the height drop amount; when the state is a forward flight state, the control amount includes the height drop amount and the forward flight speed reduction amount; A control amount obtaining module is used to obtain the control amount of the unmanned helicopter corresponding to the control amount by using an implicit model according to the control amount; the control amount includes the rotor's collective pitch control amount, the lateral cyclic pitch control amount, the longitudinal cyclic pitch control amount and the tail rotor pitch control amount; A motion control module, used for controlling the motion of the unmanned helicopter according to the control amount; when the state is a hovering state, the motion includes descending to the preset height value; when the state is a forward flight state, the motion includes descending to the preset height value and decelerating to the preset forward flight speed value; The autorotation descent and landing control module is used to control the autorotation descent and landing of the unmanned helicopter after the unmanned helicopter has completed its movement; when the state is a hovering state, the autorotation descent adopts a vertical descent; when the state is a forward flight state, the autorotation descent adopts an oblique descent; A return module is used to return to the state acquisition module when the output result of the failure judgment module is no.

6. The control system for the complete failure of the tail rotor of an unmanned helicopter according to claim 5, characterized in that: The height drop is -(hh w );where h w Indicates the preset value of height; The forward flight speed reduction is -(VV w ), where V represents the forward flight speed of the unmanned helicopter at the current moment, V w Indicates the preset forward flight speed.

7. The control system for the complete failure of the tail rotor of an unmanned helicopter according to claim 5, characterized in that: The preset height value is 5m.

8. The control system for the complete failure of the tail rotor of an unmanned helicopter according to claim 5, characterized in that: The oblique downward sliding is a 45° oblique downward sliding.

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