CN106483974A - A kind of fixed-wing unmanned plane closely geometry barrier-avoiding method - Google Patents

Abstract

The invention belongs to the autonomous control technology of unmanned aerial vehicles, and in particular relates to a short-distance geometric obstacle avoidance method for fixed-wing unmanned aerial vehicles. Due to the advantages of fast flight speed, low noise and long battery life of fixed-wing UAVs, the research on autonomous flight technology of fixed-wing UAVs for such complex environments has gradually attracted the attention of the military. This method is mainly used for short-distance obstacle avoidance of fixed-wing UAVs. It uses laser radar and geometric methods to calculate the required deflection angle and yaw angular velocity. It has the advantages of rapid response, high reliability, and easy operation.

Description

A close-range geometric obstacle avoidance method for fixed-wing unmanned aerial vehicles

technical field

The invention belongs to the autonomous control technology of unmanned aerial vehicles, and in particular relates to a short-distance geometric obstacle avoidance method for fixed-wing unmanned aerial vehicles.

Background technique

With the rapid development of UAV technology, it has increasingly wide applications in military and civilian fields such as enemy detection, regional surveillance, agricultural production, meteorological detection, and disaster detection. Faced with complex environments, such as rugged mountainous areas and cities with many buildings, UAVs are required to have a higher level of autonomy and obstacle avoidance functions.

At present, great progress has been made in the research of autonomous flight technology such as small helicopters and quadrotor aircraft for use in urban buildings, forests and mountainous environments. Due to the advantages of fast flight speed, low noise and long battery life of fixed-wing UAVs, the research on autonomous flight technology of fixed-wing UAVs for such complex environments has gradually attracted the attention of the military. The short-distance obstacle avoidance based on the fixed-wing platform faces two problems: 1) real-time performance. Due to the fast flight speed of fixed-wing UAVs, it has high requirements for real-time obstacle avoidance; 2) dynamic constraints. Compared with rotorcraft, fixed-wing UAVs have stronger dynamic constraints, and the dynamic constraints of UAVs need to be considered.

Contents of the invention

The technical problem to be solved by the present invention is to propose a fixed-wing UAV close-range geometric obstacle avoidance method to solve the problem of fixed-wing UAV obstacle avoidance in complex environments.

In order to solve the problems of the technologies described above, the present invention adopts the following steps:

1. Obstacle positioning

Use airborne lidar to detect the position of obstacles in real time.

2. Set the safe area

According to the position, shape and relative distance of the obstacle, set the safe flight area of the UAV, take the center of the obstacle surface as the center, and take the spherical area with r as the radius as the safe flight area of the UAV.

r=max(0.25l, r _obs )

l is the distance from the UAV detected by the lidar to the obstacle surface, and r _obs is the maximum distance from the center of the obstacle surface to its edge.

3. Calculate the yaw angle

Using geometric methods, calculate the required deflection angle and yaw angular velocity according to the current heading and the alternative heading, and draw two tangent lines V ₁ and V ₂ , V ₁ from the current position of the UAV to the safe flight area in the horizontal plane and V ₂ is the alternative heading of the UAV, V _h is the current flight heading of the UAV, and the required deflection angle and yaw angular velocity are calculated;

is the desired deflection angle.

4. Select the flight direction

Select the alternative heading with a smaller deflection angle obtained in step 3 as the flying heading.

5. Solve the roll angle command

According to the coordinated turning conditions, solve the roll angle command that should be flown.

6. Implement obstacle avoidance

When the UAV changes its own position, it updates the roll angle command in real time, and corrects the roll angle command until the UAV crosses the obstacle and completes the obstacle avoidance.

Beneficial effects of the present invention: the method is mainly used for short-distance obstacle avoidance of fixed-wing unmanned aerial vehicles, and has the advantages of rapid response, high reliability, and easy operation. The superior performance of this method is confirmed by a short-distance obstacle avoidance flight test based on a small fixed-wing platform.

Description of drawings

Fig. 1 is a schematic diagram of the geometric obstacle avoidance method of the present invention.

detailed description

A specific embodiment of the short-distance geometric obstacle avoidance method for the fixed-wing unmanned aerial vehicle of the present invention,

1. Obstacle positioning

For short-distance obstacle avoidance, higher precision is required for obstacle detection. This test uses the UTM-30LX laser radar of Japan HOKUYO company. The laser radar has a range of 30 meters, a horizontal viewing angle of 270°, an angular resolution of 0.25°, and an accuracy of 3cm, which can meet the requirements of this method. The lidar is installed at the nose of the drone. In this method, the laser radar is used to detect surrounding obstacles, and the position of the obstacle is calculated through the relative position of the UAV and the obstacle and the current position of the UAV. At the same time, the size of the obstacle can be obtained.

2. Set the safe area

Since the small fixed-wing UAV may be affected by the external environment during flight, and the flight path has a certain error and hits obstacles, it is necessary to set a safe flight area for the UAV. As shown in Figure 1, this method uses the center of the obstacle surface as the center and the spherical area with r as the radius as the safe flight area of the UAV.

r=max(0.25l, r _obs )

l is the distance from the UAV detected by the lidar to the obstacle surface, and r _obs is the maximum distance from the center of the obstacle surface to its edge.

3. Calculate the yaw angle

In the horizontal plane, two tangent lines V ₁ and V ₂ are drawn from the current position of the UAV to the safe flight area, and V ₁ and V ₂ are the alternative headings of the UAV. V _h is the current flight heading of the UAV, and the required deflection angle and yaw angular velocity are calculated;

is the desired deflection angle.

4. Select the flight direction

like Adopting the principle of proximity, select V ₁ as the heading to be flown.

5. Solve the roll angle command

In order to ensure the flight safety of fixed-wing UAVs during obstacle avoidance, the conditions for coordinated turning should be met when avoiding obstacles in the horizontal plane, and the UAV roll angle limit should not be exceeded. According to coordinated turn conditions:

From this we get

l is the distance from the current position of the UAV to the position of the obstacle, and the flying speed of the UAV is V, and the time it takes for the UAV to fly to the obstacle is obtained

The maximum roll angle of the fixed-wing UAV used in this flight test is limited to 50°.

Thus, the roll angle command for obstacle avoidance is obtained.

6. Implement obstacle avoidance

Input the flying and rolling angle command to the UAV to avoid obstacles. During this process, the UAV updates the roll angle command in real time while its own position changes, and corrects the previously calculated roll angle command until the UAV crosses the obstacle and completes obstacle avoidance.

Claims (1)

1. a kind of fixed-wing unmanned plane closely geometry barrier-avoiding method it is characterised in that the method include following Step：

First, barrier positioning

Position using airborne laser radar real-time detection barrier；

2nd, set safety zone

According to the position of barrier, shape and relative distance, set unmanned plane safe flight region, to hinder The center hindering thing surface is the center of circle, and the spheric region with r as radius, as the Flight Safety Region of unmanned plane Domain,

R=max (0.25l, r_obs)

L is the distance to blocking surfaces for the unmanned plane that measures of Airborne Lidar, r_obsFor blocking surfaces center extremely The ultimate range at its edge；

3rd, calculate yaw angle

According to current course and alternative course, calculate required deflection angle and yaw rate, in horizontal plane Interior, with unmanned plane current location, make two tangent line V to safe flight region₁With V₂, V₁With V₂For no Man-machine alternative course, V_hFor unmanned plane current flight course, calculate required deflection angle and yaw angle speed Degree；

It is required deflection angle；

4th, select desired heading

The alternative course of the relatively primary deflector obtaining in step 3 angle is chosen to be desired heading；

5th, resolve roll angle instruction

According to coordinate turn condition, resolve the roll angle instruction that should fly；

6th, implement avoidance

While self-position changes, real-time update roll angle instructs unmanned plane, and roll angle instruction is carried out Revise, until unmanned plane clears the jumps, complete avoidance.