CN111319759B - A method for independently controllable multi-rotor unmanned flight control with six degrees of freedom in space - Google Patents

Abstract

The invention discloses a space six-degree-of-freedom independently controllable multi-rotor unmanned aerial vehicle control method, which comprises a machine body, a horn, a motor and a landing gear; the horn is equally spaced on the fuselage in a horizontal plane; the tail end of each horn is fixed with a driving motor, and the rotor wing is positioned at the other end of the driving motor; the rotation axis of the driving motor is at an angle theta _k Is fixed in an inclined way relative to the plane of the machine body; the six-degree-of-freedom kinetic equation of the multi-rotor unmanned aerial vehicle is generated through the unmanned aerial vehicle linear motion kinetic equation and the angular motion kinetic equation, the six-degree-of-freedom input signals of the space of the unmanned aerial vehicle are converted into rotating speed instructions of a corresponding number of motors, and the rotating speed motions of the rotors are combined, so that the aircraft tracks the six-degree-of-freedom input signals of the space. The invention adopts the layout of multi-rotor arrangement, and the motor and the machine body form a certain inclination angle to form an inward inclination and an outward inclination arrangement, so that the linear movement and the angular movement of the multi-rotor unmanned aerial vehicle are independently controllable, and the control performance of the multi-rotor unmanned aerial vehicle is improved.

Description

A method for independently controllable multi-rotor unmanned flight control with six degrees of freedom in space

Technical field

The invention is designed in the technical field of unmanned aerial vehicles, and in particular relates to a control technology for an independently controllable multi-rotor unmanned aerial vehicle with six degrees of freedom in space, specifically belonging to the technical field of unmanned aerial vehicle flight mechanics and control.

Background technique

Multi-rotor unmanned aerial vehicles use multiple rotors to fly in any direction and hover in the air. They have relatively high maneuverability and can complete a variety of tasks. For example, multi-rotor drones are equipped with cameras, rangefinders, or various special devices to complete tasks such as aerial photography, positioning, terrain scanning, and cargo handling. Today, unmanned aerial vehicles have been widely used in many fields such as agriculture, meteorology, disaster warning, logistics, transportation and rescue.

Currently, most multi-rotor UAVs use a combination of thrust and thrust generated by rotor rotation to provide lift and torque. Since the thrust generated by the rotor rotation of most rotor UAVs is in the same direction, the resultant thrust generated by the rotors is relative to The fuselage has a single fixed direction, so in order to achieve linear motion forward, backward, left and right, it is necessary to change the direction of the thrust resultant force, that is, to change the attitude of the fuselage. When the fuselage needs to be continuously tilted during linear motion, the stability of the flight will be affected, and the instruments and equipment carried on the fuselage will also be affected by shaking. In particular, it will be difficult for the instruments and equipment directly fixed to the fuselage to achieve optimal results. In order to eliminate the influence of fuselage shaking, instruments and equipment are generally mounted on a stabilizing gimbal, and then the stabilizing gimbal is fixed on the fuselage. This increases the complexity of the structure, and the requirements for the control system are relatively high. the complexity of the aircraft. In addition, since the force required for linear motion of the fuselage cannot be directly controlled, the accuracy and timeliness of linear motion of such multi-rotor UAVs are reduced, affecting the use of multi-rotor UAVs in small spaces.

Contents of the invention

In order to realize the problem of multi-dimensional independent control in a small space, the present invention provides a multi-rotor unmanned aerial vehicle with six degrees of freedom in space that is independently controllable and a control method thereof.

The invention discloses a six-degree-of-freedom independent controllable multi-rotor unmanned flight control method in space, including a fuselage, an arm, a motor, and a landing gear;

The arms are distributed on the fuselage at equal intervals on a horizontal plane; a drive motor is fixed at the end of each arm, and the rotor is located at the other end of the drive motor;

The rotation axis of the drive motor is tilted and fixed relative to the plane of the fuselage at an angle θ _k ; by combining the linear motion dynamics equation and the angular motion dynamics equation of the UAV to generate the six-degree-of-freedom dynamics equation of the multi-rotor UAV, the six-degree-of-freedom dynamics equation of the aircraft space is The degree-of-freedom input signal is converted into multiple rotational speed commands of the motors and combined through the rotational speed motion of the rotor, allowing the aircraft to track the six-degree-of-freedom input signal in space.

To go one step further, follow these steps:

Step 1. Establish the thrust model generated by the rotational motion of a single rotor:

In the formula, i is the number of the rotor, θ _k is the inclination angle of the motor relative to the fuselage, f _i (ω _i ) is the thrust generated by the rotor number i when the rotation speed is ω _i , f _il is f _i (ω _i ) The component along the arm direction, f _iv is the component of f _i (ω _i ) perpendicular to the plane of the fuselage;

Step 2. Establish the linear motion dynamics equation, angular motion dynamics equation, and full drive dynamics equation of the independently controllable multi-rotor unmanned aerial vehicle with six degrees of freedom in space.

The linear motion dynamics equation described in step 2.1 is:

_In the ^formula _, The degree of freedom is determined by the structural characteristics of the independently controllable multi-rotor unmanned aerial vehicle, and A is a row full rank matrix;

The angular motion dynamics equation described in step 2.2 is:

In the formula, Y = [p, q, r] ^T , where p, q, r are the angular velocity components under the aircraft body axis system, and B is the structural characteristics of the six-degree-of-freedom independent controllable multi-rotor unmanned aircraft in space. Definite, and B is a row full rank matrix;

The full drive dynamics equation described in step 2.3 is:

In the formula, Z = [X ^T , Y ^T ] ^T , where Z is the linear velocity and angular velocity components under the aircraft body axis system, C = [A ^T , B ^T ] ^T , and C is a row full rank matrix;

Step 3. The relationship equation between the six-degree-of-freedom speed of the multi-rotor unmanned aerial vehicle and the rotor speed is:

In the formula, C ^- is the generalized inverse matrix of C and is a full rank matrix.

Furthermore, two adjacent pairs of motors rotate in opposite directions.

Furthermore, the driving motor tilting methods are divided into inward tilting and outward tilting.

Furthermore, the lift generated by the rotor can be decomposed into lift perpendicular to the plane of the fuselage and thrust parallel to the arm.

Furthermore, the lift generated by all the rotors can be combined to generate thrust for the fuselage to move forward, backward, left, right, and upward.

Compared with the existing technology, the present invention adopts the above technical solution and has the following technical effects:

(1) An 8-rotor layout is adopted, and the motors and the fuselage are arranged at a certain inclination angle and arranged inward and outward, achieving independent controllable linear motion and angular motion of the multi-rotor unmanned aerial vehicle, which improves the performance of the multi-rotor unmanned aerial vehicle. control performance;

(2) All motors are fixed on the machine arm, and no additional device is required to maneuver the attitude of the motor, reducing complexity;

(3). There is no need to use an additional gimbal to carry equipment. It is a stable platform in itself and has the function of being able to carry a variety of equipment and complete a variety of tasks.

Description of the drawings

Figure 1 is a front view of an independently controllable multi-rotor unmanned aerial vehicle with six degrees of freedom in space;

Figure 2 is a top view of an independently controllable multi-rotor unmanned aerial vehicle with six degrees of freedom in space;

Figure 3 shows the tilting modes of the drive motor and the machine arm, which are divided into outward tilting;

Figure 4 shows the tilting modes of the drive motor and the machine arm, which are divided into inward tilting;

Figure 5 is a coordinate diagram of a multi-rotor unmanned aerial vehicle flying from coordinates (0,0,0) to (15,15,15);

Figure 6 is an information diagram of the position (x, y, z) and attitude (φ, θ, ψ) of the multi-rotor unmanned aerial vehicle.

Detailed ways

The technical solutions in the examples of the present invention are clearly and completely described below with reference to the accompanying drawings in the examples of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without any creative work fall within the protection scope of the present invention.

Examples of the present invention will be described in further detail below with reference to the accompanying drawings.

Example 1

As shown in Figure 1-2, the invention provides a space six-degree-of-freedom independently controllable multi-rotor unmanned aerial vehicle, including a fuselage 4, an arm 3, a motor 2, and a landing gear 5. The arms 3 are spaced 45 are distributed on the fuselage 4, and a drive motor 2 is fixed at the end of each arm 3, and the rotor 1 is connected to the drive motor 2; it is characterized in that: the rotation axis of the drive motor 2 is at a certain angle θ _k relative to the fuselage 4 The plane is tilted and fixed.

As shown in Figure 3-4, the driving motor tilting methods are divided into inward tilting and outward tilting.

The lift generated by the rotor can be decomposed into lift perpendicular to the plane of the fuselage and thrust parallel to the arm.

The lift generated by all the rotors can be combined to generate thrust for the fuselage to move forward, backward, left, right, and upward. Two adjacent pairs of motors have opposite directions of rotation.

The control method of the present invention combines the linear motion dynamics equation and the angular motion dynamics equation of the unmanned aerial vehicle in parallel to generate a six-degree-of-freedom dynamic equation for the multi-rotor unmanned aerial vehicle, and transforms the six-degree-of-freedom input signal of the aircraft space into eight The rotation speed command of the motor is combined with the rotation speed movement of the rotor, allowing the aircraft to completely track the six-degree-of-freedom input signal in space.

The specific steps of the spatial six-degree-of-freedom independent control algorithm are:

Step 1: Establish the thrust model generated by the rotational motion of a single rotor:

In the formula, i is the number of the rotor, θ _k is the inclination angle of the motor relative to the fuselage, f _i (ω _i ) is the thrust generated by the rotor number i when the rotation speed is ω _i , f _il is f _i (ω _i ) The component along the arm 3 direction, f _iv is the component of f _i (ω _i ) perpendicular to the fuselage 4 plane.

Step 2. The linear motion dynamics equation of the independently controllable multi-rotor unmanned aerial vehicle with six degrees of freedom in space is:

_In the ^formula _, The degree of freedom is determined by the structural characteristics of the independently controllable multi-rotor unmanned aerial vehicle, and A is a row full rank matrix.

The angular motion dynamics equation of the independently controllable multi-rotor unmanned aerial vehicle with six degrees of freedom in space is:

In the formula, Y = [p, q, r] ^T , where p, q, r are the angular velocity components under the aircraft body axis system, and B is the structural characteristics of the six-degree-of-freedom independent controllable multi-rotor unmanned aircraft in space. Definite, and B is a row full rank matrix. The full drive dynamics equation of the independently controllable multi-rotor unmanned aerial vehicle with six degrees of freedom in space is:

In the formula, Z = [X ^T , Y ^T ] ^T , where Z is the linear velocity and angular velocity components under the aircraft body axis system, C = [A ^T , B ^T ] ^T , and C is a row full rank matrix.

Step 3. The relationship equation between the six-degree-of-freedom speed of the multi-rotor unmanned aerial vehicle and the rotor speed is:

In the formula, C ^- is the generalized inverse matrix of C and is a full rank matrix.

The method of tilting and fixing the rotors is used in the design of the invention, so that the lift generated by all the rotors on the unmanned aircraft can be combined to independently generate thrust for forward, backward, left, right, upward movement of the fuselage as well as pitch, roll, and Yaw torque. In order to achieve this requirement, the UAV needs at least 6 independent control input channels, such as at least 6 independent controllable motors and rotors, and needs to be matched with the corresponding control algorithm to achieve the six degrees of freedom of the UAV. independently controllable purpose.

The following case demonstrates the flight performance of the multi-rotor unmanned aerial vehicle. As shown in Figure 1-2, (x, y, z) is a fixed inertial coordinate system, and the pitch, roll and yaw angles of the multi-rotor unmanned aerial vehicle are represented by (φ, θ, ψ) respectively. As shown in Figure 5, the multi-rotor unmanned aerial vehicle flies from coordinates (0,0,0) to (15,15,15), and then hovers at a fixed point. During this period, the multi-rotor unmanned aerial vehicle’s position is (x, y, z) and attitude (φ, θ, ψ) information are shown in Figure 6. During the period from 0 to 30 seconds, the position of the UAV changes, but the attitude is not affected; between 30 and 60 seconds, the attitude of the UAV changes, but the position is not affected. It can be seen that the position and attitude control of the multi-rotor unmanned aerial vehicle are independent and can achieve six degrees of freedom independent control.

The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can easily think of changes or modifications within the technical scope disclosed in the present invention. All substitutions are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (5)

1. A space six-degree-of-freedom independently controllable multi-rotor unmanned flight control method comprises a fuselage (4), a horn (3), a motor (2) and a landing gear (5);

the machine arms (3) are distributed on the machine body (4) at equal intervals on a horizontal plane; the tail end of each horn (3) is fixed with a driving motor (2), and the rotor wing (1) is positioned at the other end of the driving motor (2);

the method is characterized in that: the rotation axis of the driving motor (2) is at an angle theta _k Is fixed in an inclined way relative to the plane of the machine body (4); generating a six-degree-of-freedom kinetic equation of the multi-rotor unmanned aerial vehicle by using an unmanned aerial vehicle linear motion kinetic equation and an angular motion kinetic equation, converting an aerial vehicle space six-degree-of-freedom input signal into a plurality of rotating speed instructions of the motors, and combining rotating speed motions of the rotors to enable the aerial vehicle to track the space six-degree-of-freedom input signal;

the method comprises the following steps of:

step 1, building a thrust model generated by single rotor rotation movement:

wherein i is the number of the rotor, θ _k F is the inclination angle of the motor relative to the machine body _i (ω _i ) Rotor with number i has a rotational speed of ω _i Thrust force f generated during the process _il Is f _i (ω _i ) Component in the direction of the horn (3), f _iv Is f _i (ω _i ) A component perpendicular to the plane of the fuselage (4);

step 2, establishing a linear motion dynamics equation, an angular motion dynamics equation and a full-drive dynamics equation of the space six-degree-of-freedom independently controllable multi-rotor unmanned aerial vehicle

The linear motion dynamics equation described in the step 2.1 is:

wherein X= [ u, v, w] ^T Wherein u, v, w are linear velocity components under the body axis of the aircraft, F (F) _i ) For all rotor thrust forces f _i The system comprises a space six-degree-of-freedom independently controllable multi-rotor unmanned aerial vehicle, wherein A is determined by the structural characteristics of the space six-degree-of-freedom independently controllable multi-rotor unmanned aerial vehicle, and A is a full-line matrix;

the angular motion dynamics equation described in step 2.2 is:

wherein Y= [ p, q, r] ^T Wherein p, q and r are angular velocity components under the body axis of the aircraft, B is the structural characteristics of the space six-degree-of-freedom independently controllable multi-rotor unmanned aircraft, and B is a full-line order matrix;

the full driving dynamics equation described in the step 2.3 is:

wherein Z= [ X ] ^T ,Y ^T ] ^T Wherein Z is the linear velocity and angular velocity components under the body axis of the aircraft, C= [ A ] ^T ,B ^T ] ^T And C is a full-line matrix;

and 3, a relation equation of the six-degree-of-freedom speed and the rotor rotation speed of the multi-rotor unmanned aerial vehicle is as follows:

wherein C is ^- Is the generalized inverse of C and is the full-line matrix.

2. The spatial six degree-of-freedom independently controllable multi-rotor unmanned aerial vehicle control method of claim 1, wherein: the rotation directions of two adjacent pairs of motors are opposite.

3. The spatial six degree-of-freedom independently controllable multi-rotor unmanned aerial vehicle control method of claim 1, wherein: the driving motor tilting manner is classified into inward tilting and outward tilting.

4. The spatial six degree-of-freedom independently controllable multi-rotor unmanned aerial vehicle control method of claim 1, wherein: the lift force generated by the rotor wing can be divided into a lift force perpendicular to the plane of the fuselage and a thrust force parallel to the horn.

5. The spatial six degree-of-freedom independently controllable multi-rotor unmanned aerial vehicle control method of claim 1, wherein: the lift force generated by all the rotors can generate thrust for forward, backward, leftward, rightward and upward movement of the airframe through combination.