A method of improving the longitudinal control of a crane helicopter

Abstract

The application belongs to the technical field of helicopters, and particularly relates to a calculation method for improving longitudinal control of a lifting helicopter. The method is applied to a novel helicopter control system, and the helicopter control system comprises a driving rod, a flight control longitudinal control system and a steering engine which are connected in sequence. The method is that the steering engine directly participates in longitudinal control, and improves the gradient of longitudinal control with speed.

Description

Technical Field

[0001] This invention belongs to the field of helicopter technology, and in particular relates to a calculation method for improving the longitudinal control of crane helicopters. Background Technology

[0002] Conventional single-rotor helicopters with a tail rotor have considerable application potential, showing broad prospects in earthquake relief and disaster relief material transport, as well as forest fire fighting and water delivery. Helicopters should have a very low empty weight to carry more supplies. To achieve this, the mid-section of the helicopter can be removed, creating a dedicated lifting helicopter. However, removing the mid-section creates a cross-section behind the cockpit, resulting in significant aerodynamic drag and a substantial increase in drag during forward flight compared to other conventional configurations. During forward flight, to overcome air resistance, the rotor disk tilts forward to generate thrust, leading to a significant nose-down attitude. As forward speed increases, collective pitch is increased to further enhance thrust, resulting in a near-neutral or even inverse slope on the longitudinal control versus speed curve. For helicopter control design, a neutral or inverse slope on the longitudinal control versus speed curve during forward flight is unacceptable to pilots.

[0003] The poor longitudinal control gradient of conventional helicopters differs from that of crane helicopters. While the poor speed-longitudinal control gradient of conventional helicopters can be improved through optimization of fuselage and horizontal stabilizer design, the poor speed-longitudinal control gradient of crane helicopters is caused by their unique fuselage structure, limiting the effectiveness of fuselage design optimization. Given the future deployment of crane helicopters, designing a method to improve longitudinal control is essential. Summary of the Invention

[0004] The present invention provides a calculation method for improving the longitudinal control of a crane helicopter, which solves the problem of poor longitudinal control gradient when the crane helicopter is flying forward. It is used to improve the speed-longitudinal control gradient caused by the large aerodynamic force of the helicopter itself, and can also be used to improve the speed-longitudinal control gradient in the helicopter design process due to other reasons.

[0005] The technical solution of the present invention:

[0006] A calculation method for improving the longitudinal control of a crane helicopter is disclosed. This method is applied to a novel helicopter control system, which includes a control stick, a flight control longitudinal control system, and servos connected in series. The method is as follows:

[0007] The servo motor directly participates in longitudinal control, improving the longitudinal control gradient with speed.

[0008] Furthermore, the method includes:

[0009] S1: Establish a six-degree-of-freedom system of motion equations based on the flight dynamics model of the heavy-lift helicopter;

[0010] S2: By solving the six-degree-of-freedom system of motion equations, the longitudinal control B1 and pitch angle θ of the helicopter at different speeds V are obtained;

[0011] S3: Based on the longitudinal control B1 output by the flight control longitudinal control system, a function related to the helicopter flight speed V and the fuselage pitch angle θ is introduced into the series steering engine, so that the steering engine extension B1s is obtained as the compensation amount for the longitudinal control B1.

[0012] Further,

[0013] The function of the steering engine extension B1s described in S3 is: B1s = K1×V + K2×θ.

[0014] Further,

[0015] The motion logic of the novel helicopter control system is that the steering engine is fully retracted and does not participate in longitudinal control when the flight speed V is less than 60km / h, and the series steering engine extends according to the function of the steering engine extension B1s when the flight speed V is greater than 60km / h.

[0016] Further,

[0017] When the flight speed V < 60km / h, since the forward flight speed is low and the resistance is small, the longitudinal control B1 is proportional to the flight speed V. At this time, K1 = 0, K2 = 0, and the series steering engine extension B1s is 0, which does not participate in longitudinal control.

[0018] Further,

[0019] When 60km / h < V < 160km / h, a set of K1 and K2 is obtained, and the steering engine extension B1s is calculated to compensate the longitudinal control.

[0020] Further,

[0021] When 160km / h < V, a set of K1 and K2 is obtained, and the steering engine extension B1s is calculated to compensate the longitudinal control.

[0022] Further,

[0023] When 60km / h<V<160km / h, V1 and V2 are obtained at 20km / h speed intervals, the initial values of K1 are set as [a1, b1], and the initial values of K2 are set as [a2, b2]. A set of initial values of K1 and K2 is selected, and the sum of the longitudinal control and the actuator compensation amount is obtained as B1S1 and B1S2 respectively through trim calculation. With 0.1<(V1-V2) / (B1S1-B1S2)<0.15 as the convergence boundary, K1 and K2 for this speed range are obtained through bi-objective optimization.

[0024] The present invention proposes a calculation method for improving the longitudinal control of a heavy-lift helicopter. This method can effectively improve the slope of the relationship curve between longitudinal control and speed during forward flight. Analysis shows that during the forward flight of the helicopter, the cyclic stick is pushed forward when the speed increases, and pulled backward when decelerating, which meets ergonomics and the pilot's driving habits, and reduces the pilot's control workload. Brief Description of the Drawings

[0025] Figure 1 is a schematic diagram of the control system structure;

[0026] Figure 2 is a schematic diagram of the longitudinal control improvement effect. Detailed Description of the Embodiments

[0027] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] In the calculation method for improving the longitudinal control of a heavy-lift helicopter provided by the embodiment of the present invention, correction coefficients are added to the aerodynamic model to solve for the speed V, the longitudinal control quantity B1 and the pitch angle θ in the forward flight trim of the helicopter, and speed and pitch angle are introduced as compensation quantities in the trimmed longitudinal control.

[0029] Specifically, the method includes:

[0030] 1) Establish a six-degree-of-freedom system of motion equations based on the flight dynamics model of the heavy-lift helicopter;

[0031] 2) Solve the equations to obtain the longitudinal control B1 and the pitch angle θ of the helicopter at different speeds;

[0032] 3) Add a tandem actuator to the helicopter longitudinal control system, which directly participates in longitudinal control to enhance the gradient of longitudinal control with respect to speed. The schematic diagram of the control system is shown in Figure 1 .

[0033] 4) Based on the longitudinal control B1 output by the flight control longitudinal control system, a function related to the helicopter flight speed V and the fuselage pitch angle θ is introduced into the tandem actuator, so that the actuator extension B1s is obtained as the compensation amount for the longitudinal control B1;

[0034] 5) The motion logic of the series-type actuator is as follows: when the speed V is less than 60km / h, it is fully retracted and does not participate in longitudinal control; when the speed V is greater than 60km / h, the series-type actuator extends according to the input function command;

[0035] 6) The functional relationship input in the series-type actuator is:

[0036] B1s=K1*V+K2θ

[0037] When the speed V is less than 60km / h, due to the low forward flight speed and low resistance, the longitudinal control B1 is proportional to the flight speed V. At this time, K1=0, K2=0, the extension amount B1s of the series actuator is 0, and it does not participate in longitudinal control;

[0038] When 60km / h<V<160km / h, a set of K1 and K2 is obtained, and the calculated actuator extension amount B1s is used to compensate the longitudinal control;

[0039] When V>160km / h, the speed value is relatively large at this time, which leads to an excessively large actuator extension amount B1s caused by the speed, so the values need to be adjusted appropriately to obtain a set of K1 and K2;

[0040] 7) In order to obtain a remarkable effect without causing inappropriate longitudinal control, it is necessary to use the values of K1 and K2 in different speed ranges, so as to obtain different control compensation effects to improve the longitudinal control gradient during forward flight.

[0041] 8) By applying a function proportional to the airspeed V and the pitch angle θ, when the helicopter pilot pushes the control stick forward during forward flight, the series actuator is introduced into the longitudinal control system, which eliminates the control stick displacement of longitudinal control, and improves the speed-longitudinal control gradient of the heavy-lift helicopter without affecting the longitudinal cyclic pitch.

[0042] After applying a function proportional to the airspeed and the pitch angle in the flight control system, the speed-longitudinal control gradient is significantly improved, Figure 2 which is the improved longitudinal control.

[0043] The present invention proposes a method for improving the longitudinal control of a heavy-lift helicopter. This method can effectively improve the slope of the relational curve between longitudinal control and speed during forward flight. Through analysis, during the forward flight of the helicopter, the control stick is pushed forward when the speed increases, and pulled backward when decelerating, which meets ergonomics and pilot driving habits, and reduces the pilot's control workload.

Claims

1. A calculation method for improving the longitudinal control of a crane helicopter, characterized in that, The method is applied to a novel helicopter control system, which comprises a control stick, a flight control longitudinal control system, and a steering gear connected in sequence in series; the method is as follows: The steering gear directly participates in longitudinal control to improve the gradient of longitudinal control with respect to speed.

2. The calculation method for improving the longitudinal control of a crane helicopter according to claim 1, characterized in that, The method comprises: S1, establishing a six-degree-of-freedom system of motion equations based on the flight mechanics model of the heavy-lift helicopter; S2, obtaining the longitudinal control B1 and the pitch angle θ of the helicopter at different speeds V by solving the six-degree-of-freedom system of motion equations; S3, on the basis of the longitudinal control B1 output by the flight control longitudinal control system, introducing a function related to the helicopter flight speed V and the fuselage pitch angle θ in the series steering gear, and obtaining the steering gear extension amount B1s as a compensation amount for the longitudinal control B1.

3. The calculation method for improving the longitudinal control of a heavy-lift helicopter according to claim 2, characterized in that, the function of the steering gear extension amount B1s in S3 is: B1s=K1×V+K2×θ.

4. The calculation method for improving the longitudinal control of a heavy-lift helicopter according to claim 3, characterized in that, The motion logic of the novel helicopter control system is that when the flight speed V is less than 60km / h, the steering gear is fully retracted and does not participate in longitudinal control, and when the flight speed V is greater than 60km / h, the series steering gear extends according to the function of the steering gear extension amount B1s.

5. The calculation method for improving the longitudinal control of a heavy-lift helicopter according to claim 3, characterized in that, When the flight speed V<60km / h, due to the low forward flight speed and low resistance, the longitudinal control B1 is proportional to the flight speed V, at this time K1=0, K2=0, the series steering gear extension amount B1s is 0, and does not participate in longitudinal control.

6. The calculation method for improving the longitudinal control of a heavy-lift helicopter according to claim 3, characterized in that, When 60km / h<V<160km / h, a set of K1 and K2 is obtained, and the steering gear extension amount B1s is calculated to compensate the longitudinal control.

7. The calculation method for improving the longitudinal control of a heavy-lift helicopter according to claim 6, characterized in that, When 160km / h<V, a set of K1 and K2 is obtained, and the steering gear extension amount B1s is calculated to compensate the longitudinal control.

8. The calculation method for improving the longitudinal control of a heavy-lift helicopter according to claim 7, characterized in that, When 60km / h<V<160km / h, V1 and V2 are obtained at an interval of 20km / h, the initial values of K1 are set as [a1, b1], the initial values of K2 are set as [a2, b2], a set of initial values of K1 and K2 is taken, the sum of the longitudinal control and the steering gear compensation amount obtained through trim calculation is B1S1 and B1S2 respectively, with 0.1<(V1-V2) / (B1S1-B1S2)<0.15 as the convergence boundary, and K1 and K2 for this speed range are obtained through bi-objective optimization.

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