CN115783249A - An adaptive landing gear landing control system and method based on touchdown perception - Google Patents

Abstract

The application provides a self-adaptation undercarriage landing control system based on touch down perception, control system includes: a controller for controlling the solenoid valve based on a touchdown sensing landing command; the hydraulic source comprises a high-pressure oil circuit and an oil return circuit, and is used for providing hydraulic oil for the actuator cylinder and the unlocking mechanism of the landing gear; the electromagnetic valve is connected with the controller and arranged on the high-pressure oil path and the oil return path; the displacement sensor is arranged on the retractable actuating cylinder of the undercarriage and is connected with the controller; the ground contact sensing control is based on the condition that the measured ground clearance is not required to be obtained in real time, the interference of environmental factors such as weather, sand and dust, terrain covering objects and the like is basically avoided, the blind landing of the helicopter under the condition of unknown terrain can be realized, the attitude of the landing gear is not required to be preset before landing, and the landing process is more direct and rapid.

Description

An adaptive landing gear landing control system and method based on touchdown perception

technical field

The present application belongs to the technical field of helicopter landing gear, and in particular relates to an adaptive landing gear landing control system and method based on touch sensing.

Background technique

Adaptive landing gear has the ability to take off and land in complex terrain environments. The core is that the attitude of the landing gear can be adaptively adjusted according to the terrain state to ensure the stability of the fuselage during takeoff and landing. Take the patent "Helicopter Quadruped Landing Gear with Terrain Adaptive Takeoff, Landing and Walking Capability" (Application No.: CN202010684516.8) as an example, which uses a laser ranging sensor to pre-measure the distance from each landing gear to the ground before landing, and the control system Calculate the telescopic amount of the actuator according to the distance parameter to adjust the landing attitude of the landing gear and then lock it, so as to meet the landing requirements of different ground steps.

Helicopters rely on laser ranging sensors for adaptive take-off and landing, which belongs to active landing control. The disadvantage is that the attitude of the landing gear only considers the geometric parameters of the terrain to adjust, and the attitude cannot be adjusted after the landing gear touches the ground. Therefore, it has certain requirements for the hardness of the terrain. . In addition, in severe environments such as haze, dust, and high temperature, the measurement accuracy and measurement capability of the sensing device are required to be high, and certain protective measures need to be taken, which increases the difficulty of adding and modifying the landing gear. However, in unstable terrain environments such as sand, snow, shrubs, etc., the helicopter will sink to a certain extent due to its own weight after touching the ground, which will change the landing position step difference. After the landing gear is pre-locked to the landing attitude, it is difficult to ensure the stability of the fuselage. The application of ranging technology has limitations.

Contents of the invention

In view of the above-mentioned technical problems, in the first aspect, the present application provides an adaptive landing gear landing control system based on ground contact perception, and the control system includes:

a controller for controlling the solenoid valve based on the touchdown sensing landing command;

A hydraulic source, including a high-pressure oil circuit and an oil return circuit, the hydraulic source is used to provide hydraulic oil to the actuator cylinder and unlocking mechanism of the landing gear;

A solenoid valve connected to the controller, and the solenoid valve is arranged on the high-pressure oil circuit and the oil return circuit;

The displacement sensor is arranged on the retractable cylinder of the landing gear, and the displacement sensor is connected with the controller.

Preferably, the control system also includes:

The first hydraulically controlled one-way valve is arranged between the retractable cylinder of the landing gear and the hydraulic pressure source;

The second hydraulic control one-way valve is arranged between the unlocking mechanism of the landing gear and the hydraulic pressure source.

Preferably, the first hydraulically controlled one-way valve is arranged on the oil return circuit and connected to the high-pressure oil circuit; the second hydraulically controlled one-way valve is arranged on the oil return circuit and connected to the high-pressure oil circuit; High pressure oil connection.

In a second aspect, the present application also provides a ground-touch sensing-based adaptive landing gear landing control method, the control method comprising:

During the landing and descent process of the body, after the first landing gear first touches the ground, the first landing gear still descends with the body to perform passive attitude adjustment. During the attitude adjustment process, the controller collects the displacement sensor data in real time to obtain the retraction and extension of the first landing gear The extension of the actuator;

After the third landing gear touches the ground, the controller obtains the extension amount of the actuator cylinders of the second landing gear and the third landing gear;

If the extension of the piston rods of all actuators exceeds the first threshold, the controller cuts off the solenoid valve to disconnect the hydraulic control check valve, the landing gear system enters the hydraulic oil circuit to lock, and the attitude does not change any more. The landing gear buffer strut completes the landing energy absorption process.

Preferably, the control method also includes:

The controller obtains the compression amount of the first landing gear actuator, the compression amount of the second landing gear actuator, and the compression amount of the third landing gear actuator;

If the compression amount of any landing gear exceeds the second threshold, the controller immediately cuts off the solenoid valve to disconnect the hydraulic control check valve, the landing gear system enters the hydraulic oil circuit lock, the attitude does not change, and the landing is completed by the landing gear buffer strut Energy absorption process.

Preferably, during the landing and descent process of the airframe, after the first landing gear first touches the ground, the first landing gear still descends with the body to perform passive attitude adjustment. During the attitude adjustment process, the controller collects the displacement sensor data in real time to obtain the second Before the extension of the retractable actuator of the landing gear, it also includes:

A helicopter hovers over a landing site; wherein the landing site includes rough terrain.

Preferably, the first threshold includes 5-300mm.

Preferably, the second threshold includes 5-200mm.

Beneficial technical effect of the application:

Ground-based sensing control does not require real-time acquisition of the measured distance from the ground, and is basically not disturbed by environmental factors such as weather, sand, and terrain cover (such as grass, shrubs, and snow). With blind landing, there is no need to pre-adjust the attitude of the landing gear before landing, and the landing process is more direct and faster.

Description of drawings

FIG. 1 is a block diagram of an adaptive landing gear landing control system based on ground contact perception provided by an embodiment of the present application;

Fig. 2 is a flowchart of an adaptive landing gear landing based on ground contact perception provided by an embodiment of the present application.

Detailed ways

In the embodiment of this application, a landing control system for adaptive landing gear is proposed, as shown in FIG. 1 . It includes a controller 1 , a solenoid valve 2 , a hydraulic control check valve 3 , a retractable actuator 4 , a displacement sensor 5 , an unlocking mechanism 6 and a hydraulic pressure source 7 .

Among them, the hydraulic servo system is an important part of the adaptive landing gear control system. The hydraulic servo system receives the control signal of the controller, controls the working state of the solenoid valve and the hydraulic control check valve in the hydraulic circuit, and controls the input actuator. The hydraulic flow direction and flow are controlled to realize the attitude adjustment control of the landing gear. The control circuit of the hydraulic servo system adopts a distributed architecture design, and the three landing gear actuators are divided into three independent control channels, and the solenoid valve and hydraulic control check valve of each hydraulic control form an independent combined valve.

Further, the implementation process of adaptive landing based on touchdown perception is shown in Figure 2. After the helicopter is in the hovering position, the controller 1 sends out a landing command based on touch-to-ground sensing and then turns on the solenoid valve 2, and the unlocking mechanism 6 opens the mechanical lock of the retractable actuator 4 under the pressure of the hydraulic source 7, so that the landing gear system enters a random position. In the dynamic state, that is, the retractable actuator 4 can be stretched or compressed freely, and will not be locked at the extreme compression position.

In a feasible implementation, during the landing process of the body, when a landing gear first touches the ground, the landing gear still descends with the body to perform passive attitude adjustment. During the attitude adjustment process, the controller 1 collects the data of the displacement sensor 5 in real time to obtain The stretching amount of retractable actuator 4. When the last landing gear touches the ground, the controller 1 obtains the extension of all landing gear actuators 4, and the extension of the piston rods of all actuators 5 exceeds the threshold 1 or the piston of any landing gear actuator 5 When the rod compression exceeds the threshold 2, the controller 1 immediately cuts off the solenoid valve 2 to disconnect the hydraulic control check valve 3, the hydraulic oil circuit of the landing gear system is locked, and the attitude does not change any more. process.

It should be noted:

1) The present invention proposes an adaptive landing gear control method, the key point of which is to adjust the pose height of the landing gear by sensing the ground contact state. The height difference of the terrain surface does not need to be measured in advance, so no terrain data is required Acquisition-processing-calculation and other intermediate links process, improve the response ability of landing attitude control.

2) The method based on touch sensing control does not need to pre-adjust the attitude of the landing gear to match the terrain before landing. The controller connects the hydraulic valve to make the landing gear system enter the follow-up state after touching the ground, and the landing gear itself has terrain self-control. Adaptive function, the control system is optimized from the previous active control of measurement sensing to the passive control of sensing the ground contact state, improving the accuracy of attitude adjustment.

3) By controlling the working status of various hydraulic components (solenoid valve, hydraulic control check valve, unlocking mechanism) in the hydraulic circuit, the hydraulic flow direction and flow of the landing gear actuator are controlled to realize the self-adaptive adjustment of the attitude of the landing gear control.

4) The principle of adaptive landing control based on touch-down perception, that is, before landing, the actuator unlocks and releases the degree of freedom (from structure to mechanism) to realize the attitude follow-up function of the landing gear. When landing, the three landing gears touch the ground one after another. The attitude of the landing gear that touches the ground adapts to changes with the terrain, and the attitude change information of the landing gear is obtained through the displacement sensor. After detecting that all three landing gears touch the ground, all actuators are locked and closed at the same time. The landing gear bears the impact of landing in an attitude that matches the terrain adaptation, ensuring that the attitude of the fuselage remains horizontal throughout the landing process.

5) In order to prevent the failure of the adaptive landing function caused by the failure of the touchdown signal, a safety design has been added to the control logic. When the control system detects that any change in the vertical attitude of the landing gear exceeds the threshold, it will issue a mandatory locking command to prevent the landing gear from landing. The structure suffered a hard impact and the attitude of the fuselage tilted.

This application is based on touch sensing control without real-time acquisition of the measured distance from the ground, and is basically not disturbed by environmental factors such as weather, sand and terrain cover (such as grass, shrubs, snow) and other environmental factors, and can realize helicopters in "unknown terrain" conditions In the blind landing, there is no need to measure the terrain before landing, and there is no need to pre-adjust the attitude of the landing gear. The landing process is more direct and faster.

Claims (8)

1. An adaptive landing gear landing control system based on touchdown sensing, the control system comprising:

the controller is used for controlling the electromagnetic valve based on the touchdown sensing landing instruction;

the hydraulic source comprises a high-pressure oil way and an oil return way, and is used for providing hydraulic oil for the actuating cylinder and the unlocking mechanism of the landing gear;

the electromagnetic valve is connected with the controller and arranged on the high-pressure oil path and the oil return path;

and the displacement sensor is arranged on the retractable actuator cylinder of the undercarriage and is connected with the controller.

2. The control system of claim 1, further comprising:

the first hydraulic control one-way valve is arranged between the retractable actuator cylinder of the undercarriage and the hydraulic source;

and the second hydraulic control one-way valve is arranged between the unlocking mechanism of the landing gear and the hydraulic source.

3. The control system according to claim 2, wherein the first pilot-operated check valve is provided in the return oil passage and connected to the high-pressure oil passage; and the second hydraulic control one-way valve is arranged on the oil return path and is connected with the high-pressure oil path.

4. An adaptive landing gear landing control method based on touchdown sensing, the control method comprising:

in the landing and descending process of the engine body, after a first lifting frame contacts the ground firstly, the first lifting frame still descends along with the engine body to perform passive posture adjustment, and in the posture adjustment process, the controller collects data of the displacement sensor in real time to acquire the extension amount of a retractable actuator cylinder of the first lifting frame;

after the third landing gear is grounded, the controller obtains the extension of the second landing gear and the third landing gear actuator cylinder;

if the extension amounts of the piston rods of all the actuating cylinders exceed a first threshold value, the controller cuts off the electromagnetic valves to disconnect the hydraulic control one-way valves, the undercarriage system enters a hydraulic oil circuit to be locked, the posture is not changed any more, and the undercarriage buffer support completes the landing energy absorption process.

5. The control method according to claim 4, characterized by further comprising:

the controller obtains the compression amount of the first landing gear actuator cylinder, the compression amount of the second landing gear actuator cylinder and the compression amount of the third landing gear actuator cylinder;

if the compression amount of any undercarriage exceeds a second threshold value, the controller immediately cuts off the electromagnetic valve to disconnect the hydraulic control one-way valve, the undercarriage system enters a hydraulic oil way to be locked, the posture is not changed any more, and the undercarriage buffer strut finishes the landing energy absorption process.

6. The control method according to claim 5, wherein in the landing and descending process of the engine body, after a first landing frame is grounded first, the first landing frame is still descended randomly to perform passive posture adjustment, and before the controller acquires data of the displacement sensor in real time in the posture adjustment process to acquire the extension amount of the retractable actuator cylinder of the first landing frame, the method further comprises:

the helicopter hovers above the landing site; wherein the landing site comprises rugged terrain.

7. The control method of claim 4, wherein the first threshold comprises 5-300mm.

8. The control method of claim 5, wherein the second threshold comprises 5-200mm.

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