CN104569993B - A kind of all-around ultrasonic wave obstacle detector for four-axle aircraft - Google Patents

Abstract

The invention belongs to the field of flight environment obstacle detection, and in particular relates to an omnidirectional ultrasonic obstacle detector for a four-axis aircraft that realizes omnidirectional distance measurement, collision detection and early warning. An omnidirectional ultrasonic obstacle detector for a quadcopter, including a single-chip microcomputer, a multi-way selector switch, a boost circuit, an amplifier circuit, an ultrasonic transmitting probe, an ultrasonic receiving probe, a temperature compensation circuit, and an interface. Because the present invention adopts the omnidirectional ultrasonic probe, it can carry out all-round detection to the surrounding environment. At a certain moment, the relative distance measurement between the quadrotor aircraft and the surrounding environment, collision threat detection and early warning can be realized at the same time. It greatly reduces the time used for military investigation and has the advantage of investigation speed. Moreover, the omnidirectional ultrasonic detector does not require the quadcopter to adjust its attitude during operation, which greatly reduces the complexity of operation and improves detection efficiency and real-time performance.

Description

An Omnidirectional Ultrasonic Obstacle Detector for Quadcopters

technical field

The invention belongs to the field of flight environment obstacle detection, and in particular relates to an omnidirectional ultrasonic obstacle detector for a four-axis aircraft that realizes omnidirectional distance measurement, collision detection and early warning.

Background technique

As the urban environment in which unmanned aerial vehicles fly is becoming more and more complex, the difficulty of UAV data collection is greatly increased, and higher requirements are put forward for the detection of airborne ultrasonic sensors. Conventional airborne ultrasonic detectors use a fixed single ultrasonic transmitter and receiver to collect data, and process the data through a single-chip microcomputer. This makes the aircraft only obtain obstacles in a single direction at a certain moment; at the same time, when the traditional airborne ultrasonic detector measures the distance of the surrounding environment, it needs to adjust the attitude of the aircraft, which not only increases the difficulty of operation, but also lacks reliability. sex. Conventional ultrasonic detectors find targets by adjusting the attitude of the aircraft many times, which is poor in operability.

Contents of the invention

The purpose of the present invention is to solve the problem of poor operability of a single fixed airborne ultrasonic detector in fault detection, distance measurement, and target finding, and provide an omnidirectional ultrasonic obstacle detector for quadcopters.

The purpose of the present invention is achieved like this:

Omni-directional ultrasonic obstacle detector for quadcopter, including single-chip microcomputer, multi-way selection switch, boost circuit, amplifier circuit, ultrasonic transmitting probe, ultrasonic receiving probe, temperature compensation circuit, interface:

The input terminal of the single-chip microcomputer 1 is connected with the multi-channel selection switch 2 and the temperature compensation meter 7; the output terminal is connected with the multi-channel selection switch 2 and the interface 6; The input end of the circuit 3 is connected with the multi-way selection switch 2; the output end is connected with the ultrasonic transmitting probe 4; the input end of the ultrasonic transmitting probe 4 is connected with the boost circuit 3; the output end of the ultrasonic receiving probe 5 is connected with the amplifier circuit 8; the interface The input end of 6 is connected with single-chip microcomputer 1; the output end of temperature compensation meter 7 is connected with single-chip microcomputer 1; the input end of amplifier circuit 8 is connected with ultrasonic receiving probe 5;

There are 12 ultrasonic transmitting probes and ultrasonic receiving probes. The multi-channel selection includes 24 switches, of which 11 switches are respectively connected to the output end of the amplifier circuit, 11 switches are connected to the input end of the boost circuit, and the input and output ends of the single-chip microcomputer Connected with the multi-way selector switch; the single-chip microcomputer control sends out a weak signal, which enters the booster circuit through the multi-way selector switch, and the booster circuit converts the weak signal into a strong electric signal, and the strong electric signal enters 12 ultrasonic transmitting probes, and transforms into ultrasonic waves to the surroundings Transmitting in the environment; the ultrasonic waves are reflected by obstacles in the surrounding environment, and the 12 receiving probes corresponding to the 12 transmitting probes receive the reflected waves, convert the ultrasonic waves into weak electrical signals, and the electrical signals enter the amplification circuit to amplify the electrical signals , the amplified electrical signal enters the single-chip microcomputer through the multi-way selection switch, and the single-chip microcomputer processes the collected data, judges those directions where ultrasonic waves are reflected back, proves that there are obstacles in the environment in this direction, and calculates environmental obstacles through the propagation time of ultrasonic waves Distance from aircraft:

s _i =165.75t _i i =1,2,...,n

In the formula, s _i is the sampling point, with the aircraft as the center and the north as the starting point, n+1 points are collected in a 360° direction, respectively

s ₀ , s ₁ , s ₂ ,…s _n , use Lagrangian interpolation method to perform function fitting on n+1 discrete points, and get the distance around the aircraft:

L _n (θ) = s ₀ L ₀ (θ) + s ₁ L ₁ (θ) + . . . + s _n L _n (θ).

The output end of the temperature compensation circuit 7 is connected with the single-chip microcomputer 1, and the ultrasonic transmitting probe and the ultrasonic receiving probe consist of 12, and the multi-channel selection includes 24 switches, wherein 11 switches are connected with the output end of the amplifying circuit respectively, and 11 switches are connected with the output end of the amplifier circuit. The input terminal of the boost circuit is connected, and the input and output terminals of the single-chip microcomputer are connected with the multi-channel selector switch; the single-chip microcomputer controls to send out a weak signal, which enters the boost circuit through the multi-channel selector switch, and the boost circuit converts the weak signal into a strong electric signal, which is strong The electrical signal enters 12 ultrasonic transmitting probes and is transformed into ultrasonic waves and is transmitted to the surrounding environment; the ultrasonic waves are reflected by obstacles in the surrounding environment, and the 12 receiving probes corresponding to the 12 transmitting probes receive the reflected waves and convert the ultrasonic waves into It is a weak electrical signal, and the electrical signal enters the amplification circuit to amplify the electrical signal, and the amplified electrical signal enters the single-chip microcomputer through the multi-way selection switch. Obstacles, and through the propagation time of ultrasonic waves, calculate the distance between the environmental obstacles and the aircraft:

In the formula, s _i is the sampling point, with the aircraft as the center of the circle, n+1 points are collected in a 360° direction starting from the true north direction, which are respectively s ₀ , s ₁ , s ₂ ,…s _n , using Lagrangian The interpolation method performs function fitting on n+1 discrete points to obtain the distance around the aircraft:

L _n (θ) = s ₀ L ₀ (θ) + s ₁ L ₁ (θ) + . . . + s _n L _n (θ).

The beneficial effect of the present invention lies in that: the present invention can perform omnidirectional detection of the surrounding environment due to the use of the omnidirectional ultrasonic probe. At a certain moment, the relative distance measurement between the quadrotor aircraft and the surrounding environment, collision threat detection and early warning can be realized at the same time. It greatly reduces the time used for military investigation and has the advantage of investigation speed. Moreover, the omnidirectional ultrasonic detector does not require the quadcopter to adjust its attitude during operation, which greatly reduces the complexity of operation and improves detection efficiency and real-time performance.

Description of drawings

Accompanying drawing 1 is the composition diagram of detection system of the present invention.

Accompanying drawing 2 is the top view structure diagram of the present invention.

Accompanying drawing 3 is the side view structure diagram of the present invention.

Accompanying drawing 4 is the schematic diagram of the temperature compensation circuit of the present invention.

Accompanying drawing 5 is obstacle situation around aircraft and omnidirectional distance function curve.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

The invention relates to a flight environment obstacle detection, which can be applied to small and medium-sized unmanned aerial vehicles and four-rotor aircraft autonomous flight, omnidirectional distance measurement, collision detection and early warning omnidirectional ultrasonic detector and its implementation method, belonging to unmanned Data acquisition and processing technology field of aircraft.

In Figure 2, eight ultrasonic probes are evenly distributed on the first layer at intervals of 45°; on the second layer, three ultrasonic probes are evenly distributed at intervals of 120°, and the direction of the probes is maintained at an angle of 45° to the horizontal plane. The third layer is equipped with a detection head, the angle with the horizontal plane is 90 degrees.

The two structural drawings of accompanying drawings 2 and 3 show half of the structure of the omnidirectional ultrasonic detector. Since the structure is symmetrical up and down, the layout of the upper part of the lower structural domain is the same, so it is not listed separately.

The invention includes a single-chip microcomputer, a multi-way selection switch, a boost circuit, an amplifying circuit, an ultrasonic transmitting probe, an ultrasonic receiving probe, a temperature compensation circuit and an interface.

The input end of the single chip microcomputer 1 is connected with the multi-way selection switch 2 and the temperature compensation meter 7 ; the output end is connected with the multi-way selection switch 2 and the interface 6 .

The multi-way selector switch 2 is connected with the single chip microcomputer 1, the voltage boosting circuit 3 and the amplifying circuit 8.

The input end of the boost circuit 3 is connected with the multi-way selector switch 2 ; the output end is connected with the ultrasonic transmitting probe 4 .

The input end of the ultrasonic transmitting probe 4 is connected with the boost circuit 3 .

The output end of the ultrasonic receiving probe 5 is connected with the amplifier circuit 8 .

The input end of the interface 6 is connected with the single-chip microcomputer 1 .

The output terminal of the temperature compensation meter 7 is connected with the single chip microcomputer 1 .

The input end of the amplifying circuit 8 is connected with the ultrasonic receiving probe 5 ; the output end is connected with the multiplex switch 2 .

Specific embodiment one: the present embodiment is described below in conjunction with Fig. 1, and present embodiment comprises single-chip microcomputer, multi-way selection switch, booster circuit, amplifying circuit, 12 ultrasonic transmitting probes, 12 ultrasonic receiving probes.

The multi-way selection includes 24 switches, which are respectively switch 21, switch 22 ... switch 224, the switch 21 is connected to the input end of the booster circuit 31, the switch 22 is connected to the output end of the amplifier circuit 81, and the switch 23 is connected to the booster circuit 32 The input terminal is connected, the switch 24 is connected with the output terminal of the amplifying circuit 82, ... the switch 223 is connected with the input terminal of the boost circuit 312, and the switch 224 is connected with the output terminal of the amplifying circuit.

The input and output terminals of the single chip microcomputer are connected with the multi-way selection switch.

The omnidirectional ultrasonic detector used for data collection and processing will use the principle of ultrasonic reflection to detect the distance between the aircraft and surrounding obstacles or to detect target objects around the aircraft. The omnidirectional ultrasonic detector sends a weak signal through the control of the single-chip microcomputer 1, and enters the boost circuit 3 through the multi-way selector switch 2, and the boost circuit 3 converts the weak signal into a strong electric signal, and the strong electric signal enters 12 ultrasonic transmitting probes with different directions 41, 42...412, converted into ultrasonic waves and transmitted to the surrounding environment; the ultrasonic waves are reflected when encountering obstacles in the surrounding environment, and the 12 receiving probes 51, 52...512 corresponding to the 12 transmitting probes receive the reflected waves , the ultrasonic wave is converted into a weak electrical signal, and the electrical signal enters the amplifying circuit 8 to amplify the electrical signal, and the amplified electrical signal enters the single-chip microcomputer through the multi-way selector switch 2.

The single-chip microcomputer processes the collected data, judges which directions have ultrasonic waves reflected back, proves that there are obstacles in the environment in this direction, and calculates the distance between the environmental obstacles and the aircraft through the propagation time of the ultrasonic waves.

The distance calculation formula is:

s _i =165.75t _i (i=1,2,...,n)

In the formula, _si is the sampling point, which represents the distance in any direction around the aircraft. The present invention collects n+1 points omnidirectionally in a 360° direction with the aircraft as the center and the true north as the starting point, which are respectively s ₀ , s ₁ , s ₂ ,...s _n , and uses the Lagrangian interpolation method to n+1 discrete points are used for function fitting, and the continuity equation of the distance around the aircraft is obtained:

L _n (θ)＝s ₀ L ₀ (θ)+s ₁ L ₁ (θ)+…+s _n L _n (θ)

According to the continuous function, draw the form shown in the accompanying drawing 5 of the omnidirectional distance curve around the aircraft. If there is no obstacle in a certain direction around the aircraft, that is, the distance is infinite, then define the distance in this direction as a maximum value, so as to ensure that the obtained curve does not have an infinite value.

Specific embodiment two: the difference between this embodiment and embodiment one is that it also includes a temperature compensation circuit 7, and a temperature compensation algorithm and a Kalman filter algorithm are added in the single-chip microcomputer 1, and the output terminal of the temperature compensation circuit 7 is connected to the single-chip microcomputer 1 connected.

The composition of temperature compensation circuit 7 is shown in accompanying drawing 4, is made up of PT100 temperature-sensitive resistor 71, amplifying circuit one 72, amplifying circuit two 73, AD circuit 74, filter algorithm 75, temperature compensation algorithm 76.

Since the ambient temperature generally does not change much when disturbed, the present invention uses a PT100 temperature sensitive resistor. The PT100 is characterized by a small range of measurable temperature changes, and has the advantages of good linearization, accurate measurement values and low price.

The temperature-sensitive resistor 71 is affected by the change of ambient temperature, and the resistance changes, which leads to the change of the electrical signal of the temperature compensation circuit. The electrical signal passes through the two-wire bridge circuit, that is, the amplifier circuit 1 and the amplifier circuit 2, and enters the A/D in the microcontroller. Converter circuits convert electrical signals into digital signals. Because the disturbance of the ambient temperature of the aircraft will cause the temperature value to drift too much, the present invention will also use the filter circuit 75 to process the digital signal, so that the signal value tends to a stable estimated value, and the measurement error is accurate to 1 digit after the decimal point, thereby making the environment The error caused by the influence of temperature on the ultrasonic velocity is minimized.

The distance measurement formula for temperature compensation is:

Specific embodiment three: the difference between this embodiment and embodiment two is that it also includes an interface 6 connected to the early warning system, and an early warning algorithm is added in the single-chip microcomputer, and the input and output ends of the interface 6 are connected with the single-chip microcomputer 1.

In order to prevent the aircraft from colliding with environmental obstacles during flight and cause aircraft failure, a flight warning system is added to avoid collisions between the aircraft and surrounding environmental obstacles. When the distance between the aircraft and the environmental obstacles in a certain direction is less than the critical value, the early warning system sends out an alarm and proposes the best avoidance plan.

The single-chip microcomputer 1 receives the electrical signal sent back by the ultrasonic receiving probe 2, calculates the distance between the surrounding environment obstacles and the aircraft through the temperature compensation algorithm, and judges whether the minimum distance is less than the collision critical value according to the distance between the two. If the distance is less than the critical value, the single chip microcomputer 1 sends a collision warning signal and the best avoidance signal, and enters the early warning system through the interface 6. The early warning system sends out an alarm and reports the direction of the dangerous distance, and proposes the best avoidance plan for the aircraft:

According to the distance function image, if the flight direction s _θ of the aircraft satisfies the condition:

s _θ < s _critical

Then judge whether the distance s _θ +Δθ in the direction of θ+Δθ reaches the avoidance distance value s _{to avoid} , if so, the aircraft avoids in the direction of θ+Δθ, if the requirement is not met, then continue to judge the direction of θ+2·Δθ until the requirement is met .

Claims (1)

1. a kind of omnidirectional ultrasonic obstacle detector that is used for quadcopter, comprises single-chip microcomputer, multi-way selector switch, step-up circuit, amplifying circuit, ultrasonic emission probe, ultrasonic receiving probe, temperature compensation circuit, interface, it is characterized in that: The input end of the single-chip microcomputer (1) is connected with the multi-way selection switch (2) and the temperature compensation meter (7); the output end is connected with the multi-way selection switch (2) and the interface (6); the multi-way selection switch (2) is connected with the single-chip microcomputer (1 ), the booster circuit (3), and the amplifier circuit (8) are connected; the input end of the booster circuit (3) is connected with the multi-way selector switch (2); the output end is connected with the ultrasonic emission probe (4); the ultrasonic emission probe ( The input end of 4) is connected with the boost circuit (3); the output end of the ultrasonic receiving probe (5) is connected with the amplifier circuit (8); the input end of the interface (6) is connected with the single-chip microcomputer (1); the temperature compensation meter (7 ) is connected to the single-chip microcomputer (1); the input of the amplifying circuit (8) is connected to the ultrasonic receiving probe (5); the output is connected to the multi-way selector switch (2); There are 12 described ultrasonic transmitting probes and ultrasonic receiving probes, and the multi-channel selection includes 24 switches, wherein 11 switches are respectively connected with the output terminals of the amplifying circuit, 11 switches are connected with the input terminals of the booster circuit, and the input of the single-chip microcomputer , The output terminal is connected with the multi-way selector switch; the single-chip microcomputer control sends out a weak signal, which enters the boost circuit through the multi-way selector switch, and the boost circuit converts the weak signal into a strong electric signal, and the strong electric signal enters 12 ultrasonic transmitting probes, which is transformed into Ultrasonic waves are emitted to the surrounding environment; the ultrasonic waves are reflected by obstacles in the surrounding environment, and the 12 receiving probes corresponding to the 12 transmitting probes receive the reflected waves, convert the reflected waves into weak electrical signals, and the electrical signals enter the amplification circuit The electrical signal is amplified, and the amplified electrical signal enters the single-chip microcomputer through the multi-way selector switch. The single-chip microcomputer processes the collected data, judges which directions have ultrasonic waves reflected back, and proves that there are obstacles in the environment in this direction, and through the propagation time of ultrasonic waves, Calculate the distance between environmental obstacles and the aircraft: s _i =165.75t _i i =1,2,...,n In the formula, s _i is the sampling point, and t _i is the propagation time of the ultrasonic wave. With the aircraft as the center and the north direction as the starting point, n+1 points are collected in a 360 ^° direction, which are respectively s ₀ , s ₁ , s ₂ ,…s _n , use the Lagrange interpolation method to perform function fitting on n+1 discrete points, and get the distance around the aircraft: L _n (θ)＝s ₀ L ₀ (θ)+s ₁ L ₁ (θ)+…+s _n L _n (θ); The output end of described temperature compensation circuit (7) and single-chip microcomputer (1), described ultrasonic transmitting probe, ultrasonic receiving probe are by 12, multi-channel selection comprises 24 switches, and wherein 11 switches are connected with the output of amplifying circuit respectively The 11 switches are connected to the input terminals of the boost circuit, and the input and output terminals of the single-chip microcomputer are connected to the multi-way selector switch; the single-chip microcomputer control sends out a weak signal, which enters the boost circuit through the multi-way selector switch, and the booster circuit converts the weak signal It is converted into a strong electrical signal, and the strong electrical signal enters 12 ultrasonic transmitting probes, which are converted into ultrasonic waves and transmitted to the surrounding environment; the ultrasonic waves are reflected by obstacles in the surrounding environment, and the 12 receiving probes corresponding to the 12 transmitting probes receive To the reflected wave, the ultrasonic wave is converted into a weak electrical signal, and the electrical signal enters the amplification circuit to amplify the electrical signal, and the amplified electrical signal enters the single-chip microcomputer through the multi-way selector switch, and the single-chip microcomputer processes the collected data, and judges which directions have ultrasonic waves reflected back , to prove that there is an obstacle in the environment in this direction, and calculate the distance between the environmental obstacle and the aircraft through the propagation time of the ultrasonic wave: <mrow><msub><mi>s</mi><mi>i</mi></msub><mo>=</mo><mfrac><mrow><mn>331.5</mn><mo>+</mo><mn>0.607</mn><mi>T</mi></mrow><mn>2</mn></mfrac><msub><mi>t</mi><mi>i</mi></msub><mo>,</mo><mi>i</mi><mo>=</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo>,</mo><mo>...</mo><mo>,</mo><mi>n</mi></mrow> In the formula, s _i is the sampling point, T is the ambient temperature of the aircraft, and n+1 points are collected in a 360 ^° direction with the aircraft as the center and the true north as the starting point, respectively s ₀ , s ₁ , s ₂ ,…s _n , use the Lagrange interpolation method to perform function fitting on n+1 discrete points, and get the distance around the aircraft: L _n (θ)＝s ₀ L ₀ (θ)+s ₁ L ₁ (θ)+…+s _n L _n (θ); It also includes an interface (6) connected to the early warning system, and an early warning algorithm is added in the single-chip microcomputer, and the input and output ends of the interface (6) are connected with the single-chip microcomputer (1); The temperature compensation algorithm calculates the distance between the surrounding environment obstacles and the aircraft, and judges whether the minimum distance is less than the collision critical value according to the distance between the two. If the distance in a certain direction is less than the critical value, the single-chip microcomputer sends a collision warning signal and the best avoidance The signal enters the early warning system through the interface (6), the early warning system sends out an alarm and reports the position of the dangerous distance, and proposes the best avoidance plan for the aircraft: According to the distance function image, if the flight distance s _θ of the aircraft satisfies the condition: s _θ < s _critical Then judge whether the distance s _θ +Δθ in the direction of θ+Δθ reaches the avoidance distance value s _{to avoid} , if so, the aircraft avoids in the direction of θ+Δθ, if the requirement is not met, then continue to judge the direction of θ+2·Δθ until the requirement is met .