RU2802978C1 - Unmanned aircraft video surveillance device, video camera assembly for such video surveillance device - Google Patents

Abstract

FIELD: video surveillance.

SUBSTANCE: group of inventions relates to a video surveillance device for an unmanned aircraft and a video camera unit for this device. The device comprises an onboard control unit with a processor module for processing video images. The video camera assembly comprises a visible spectrum module with two sensors and two lenses, a thermal imaging module, a gimbal control module, and a stabilization mechanism.

EFFECT: expansion of the functional properties of the video surveillance device without increasing the payload.

4 cl, 3 dwg

Description

The group of inventions relates to video surveillance devices and can be used for unmanned aircraft (UAV), including those with a maximum take-off weight of less than 1.5 kg.

The invention solves the problem of minimizing the weight and dimensions of a UAV with a video surveillance device installed on it while maintaining the high characteristics of the latter, among which the most important are: a video stream with a resolution of at least 4K and the presence of optical image magnification for a visible spectrum camera, the presence of a thermal imaging camera with a resolution of at least 640 ×512 pixels, mechanical stabilization on three axes. The mass of the UAV directly depends on the mass of the payload (for a given flight duration). With a maximum take-off weight of the UAV less than 1.5 kg and a flight duration of at least 40 minutes, the payload mass should not exceed 120 g.

Currently, four-rotor UAVs with a mass of less than 1.5 kg are known, which are equipped with optical spectrum cameras, for example, infrared, thermal imaging and a visible range camera, however, solutions capable of satisfying all the tasks posed to the invention are not known from the prior art. As a rule, expanding the functionality of a video surveillance device leads to an increase in its weight and size parameters of the payload module and, accordingly, to an increase in the dimensions of the UAV itself when expanding the functionality of the video camera unit.

A bifocal camera, a suspension system and a mobile platform are known (international publication WO2020087697A1 dated 05/07/2020, priority document CN201821798864U · application CN2018122114W · dated 12/19/2018, patent holder: SZ DJI TECHNOLOGY CO LTD (CN)).

The dual light camera includes: a front body, a middle body, a rear body, a first camera module and a second camera module; the front housing, the middle housing and the rear housing are connected in series and enclose a receiving cavity. The anterior shell includes a front wall and a rear wall of the anterior shell located opposite each other. The rear wall of the front shell is located in the receiving cavity, and the rear wall of the front shell is recessed towards the front wall of the receiving cavity of the front shell and the second receiving cavity; the first camera module includes a first circuit board and a first module housing, the first circuit board being mounted on a rear wall of the front housing and/or the middle housing, the first module housing extending into the first receiving space; a second camera module includes a second circuit board and a second module housing, the second circuit board being mounted behind the front housing on a wall and/or middle housing, the second module housing extending into a second receiving space; the middle body is provided with a connecting part, and the connecting part is used to connect the dual optical camera to the gimbal.

The analogue also has a gimbal system that includes a gimbal and the aforementioned camera with two light sources and a mobile platform that includes a housing and a pan/tilt system. In this case, the gimbal system is installed on the body of the mobile platform.

The patent details the mechanical design of the camera unit mounted on a 3-axis gimbal. It also uses two cameras: visible spectrum and infrared spectrum. A separate control board is connected to each camera, after which they are connected to a common board.

The disadvantages of the known analogue in relation to the claimed group of inventions include the complexity of its design, which affects the weight and size parameters of the payload module and limited functionality, since this product uses only one optical system for the visible spectrum.

From the patent CN110730287A - a prototype of the proposed technical solution (Application CN201911018698A, priority dated 10/24/2019, patent holder: Shenzhen Autel Intelligent Aviation Tech Co Ltd) a video surveillance system for an unmanned aerial vehicle and a removable pan-tilt camera of such a system are known.

The video surveillance system of an unmanned aerial vehicle includes an unmanned aerial vehicle, a pan-tilt camera made in the form of a gimbal, a server and an image receiving part, and ensures communication between the UAV and the server and the image receiving means. The removable pan-tilt camera of such a system is made in the form of a suspension to the body of the UAV (payload) and contains a stabilizer including: an image acquisition module, which is located on the rotation/tilt and is used to obtain an image, a static storage module for storing these parameters, and the module The image processing unit is located in the BVS housing and is provided with the ability to communicate with the static storage module to read parameter data stored in the static storage module.

Since the known technical solution has a visible spectrum camera with only one sensor and one lens system, it does not have an optical zoom function, that is, it has a limited range of functionality.

The objective of the claimed group of inventions is to create a new video surveillance device based on a compact folding UAV weighing less than 1.5 kg, the video camera unit of which provides mechanical stabilization in three axes, hybrid magnification of at least ×10 and video resolution no worse than 4K.

The technical result of the claimed group of inventions in relation to technical solutions known from the prior art is the expansion of the functional properties of a video surveillance device without increasing the payload mass.

A video surveillance device for an unmanned aircraft, including an on-board control device and a payload module, differs from the prototype in that the on-board control device contains a processor module for processing video images, the payload module is made in the form of a video camera unit containing a visible spectrum module with two sensors and two lenses, thermal imaging module, gimbal control module and is equipped with a stabilization mechanism; interaction between the video processing processor module and the video camera unit is carried out through a set of micro-coaxial cables and a flexible connecting cable, which may include a USB interface for transmitting a signal from the thermal imaging module, a MIPI CSI interface for transmitting a signal from the module’s sensors visible spectrum, I2C interface for controlling sensors and a CAN interface for controlling the video camera node.

A video camera unit having a visible spectrum module with two sensors and two lenses, containing a visible spectrum sensor board on which lenses with different focal lengths are installed, a thermal imaging module made in the form of a thermal imaging radiometric camera connected to a gimbal control module, and a stabilization mechanism including an electronic stabilization circuit, which is equipped with a gimbal control module, and brushless motors according to the number of stabilization axes.

The stabilization mechanism of the video camera assembly for the video surveillance device of an unmanned aircraft is implemented as follows: the electronic stabilization circuit of the gimbal control module includes a control controller, an inertial system and motor drivers that have feedback to brushless motors through position sensors based on the Hall effect.

In fig. Figure 1 shows a structural block diagram of a video surveillance device for an unmanned aircraft in accordance with the claimed technical solution, where:

1 – video surveillance device for an unmanned aircraft; 2 – on-board control; 3 – processor module for processing video images; 4 – video camera unit; 5 – thermal imaging module; 6 – visible spectrum module; 7 – gimbal control module; 8 – flexible connecting cable; USB, MIPI CSI, I2C – interaction interfaces.

In fig. Figure 2 shows a structural block diagram of a video camera assembly for such a video surveillance device in accordance with the claimed technical solution, where:

4 – video camera unit; 5 – thermal imaging module; 6 – visible spectrum module; 7 – gimbal control module; 9 – sensor board; 10-11 – visible spectrum sensors, 12-13 – lenses; 14 – electronic stabilization circuit; 15-17 - brushless motors; 18 – control controller; 19 - inertial system; 20-22 – motor drivers; 23-25 – position sensors.

In fig. 3 – shows a general view of the payload module with suspension.

The claimed group of inventions solves the problem of expanding the functional properties of a video surveillance device for UAVs with a maximum take-off weight of less than 1.5 kg without increasing the payload weight.

For this purpose, in the proposed new video surveillance device based on a compact folding UAV weighing less than 1.5 kg, the payload module provides a hybrid magnification of at least x10 and a video resolution of at least 4K, as well as mechanical stabilization in three axes due to the implementation of a stabilization mechanism in it .

Payload modules that perform the functions of IR photography and video recording are known from the state of the art, however, these solutions are not applicable for UAVs with a mass of less than 1.5 kg; in addition, payload modules for UAVs with a mass of up to 1.5 kg are known from the prior art , but not having the full range of functionality to perform the tasks assigned to the new video recording device 1 (Fig. 1).

To eliminate these shortcomings, a technical solution is proposed, which is carried out as follows.

Firstly, the processing of video images is carried out on board the UAV, for which the on-board control means 2 is equipped with a processor module 3 for processing video images, which made it possible to eliminate additional boards and reduce the weight and size parameters of the payload module and, accordingly, the video camera unit 4.

The interaction of the processor module 3 for processing video images and the video camera unit 4 is carried out through a set of microcoaxial cables and a flexible connecting cable 8.

Moreover, a set of micro-coaxial cables and a flexible connecting cable 8 include a USB interface for transmitting a signal from the thermal imaging module 5, a MIPI CSI interface for transmitting a signal from the sensors of the visible spectrum module 6, an I2C interface for controlling sensors 10 and 11 and a CAN interface for controlling the position of the node stabilization mechanism video cameras 4.

Thus, image data is transmitted sequentially via separate signal lines directly from the sensor to the processor, without the use of additional converters. The maximum throughput depends on the number of these lines; for example, the implementation can use four differential data pairs and one differential pair for signal clocking, which reduces the number of connecting wires.

Secondly, expansion of functionality due to the presence of optical image magnification. The claimed video camera unit 4 allows you to achieve hybrid x10 entertainment without loss of quality in 720p resolution.

For this, the video camera unit 4 has a visible spectrum module 2 with two sensors 10 and 11 and two lenses 12 and 13 mounted on the sensors, for which sensors 10 and 11, in turn, are placed on a visible spectrum sensor board 9. Moreover, lenses 12 and 13 have different focal lengths, for example, 16 mm and 4.35 mm.

Hybrid augmentation means the following. Due to different focal lengths and excess resolution (more than the target). Switching sensors gives an increase of 3.7 times. This is “honest” optical magnification, since it is achieved by changing the optics. 10x, respectively, is achieved by digital zoom according to the principle: digital zoom -> change the sensor -> digital zoom.

It should be noted that the placement of two sensors on one printed circuit assembly - sensor board 9 - made it possible to abandon the optical zoom for optical zoom, since it has a large mass and dimensions, which also had a positive effect on the weight and size parameters of the payload module.

The thermal imaging module 5 is made in the form of a thermal imaging radiometric camera and is connected to the gimbal control module 7, since it controls the stabilization mechanism equipped with the video camera unit 4 to ensure the quality of transmitted images, which, among other things, provides design convenience.

The stabilization mechanism of the video camera assembly 4 in three axes is implemented as follows: the gimbal control module 7 has an electronic stabilization circuit 14, which includes a control controller 18 (computing tool), an inertial system 19 for determining angular velocities and accelerations, and a motor driver 20 - 22 that converts control low power signals into currents sufficient to control motors. Moreover, the motor drivers 20 – 22 are connected to the brushless motors 15 – 17 via position sensors 23 – 25, based on the Hall effect to determine the position and synchronize the operation of the brushless motors 15 – 17 of the stabilization mechanism.

This solution made it possible to locate the center of mass of the video camera assembly 4 in the center of the stabilization axes, which made it possible not to create a constant torque to maintain the video camera assembly 4 in a certain position, but only to compensate for deviations.

To summarize the above.

To implement the proposed technical solution, a new video surveillance device for an unmanned aircraft, a video camera unit for such a video surveillance device and a stabilization mechanism for such a video camera unit are proposed, which together have the following characteristics:

- Video resolution – 4K;

- Availability of optical zoom for a visible spectrum camera;

- Availability of a thermal imaging camera;

- Mechanical stabilization on 3 axes.

If the condition of the total mass of the UAV is 1500 g and the payload mass is no more than 120 g, that is, the functional properties of the video surveillance device are expanded without increasing the mass of the payload module.

Thus, the claimed group of inventions with the specified set of essential features allows us to solve the assigned problems and, as a result, achieve the declared technical result.

The operation of a video surveillance device for an unmanned aircraft, a video camera assembly for such a video surveillance device, and a stabilization mechanism for such a video camera assembly is carried out as follows.

The main purpose of UAV video surveillance devices is photo and video recording of various objects, so they are usually equipped with controlled camera gimbals. The UAV flight is controlled via a remote control - a remote control or a mobile device (smartphone or tablet). The camera and gimbal (payload of Fig. 3) are also controlled by the pilot (or a second operator through a slave console), since their control system is integrated into the overall control system of the UAV and represents a video surveillance device 1. The operation of the entire video surveillance device 1 is controlled by the onboard control processor 2, located on the processor module of the BVS base board.

A suspension with a payload module (Fig. 1) is placed on the fuselage of the UAV. 3, which is made in the form of a video camera unit 4 of FIG. 2. Using a flexible connecting cable 8, the video camera unit 4 is connected to the on-board control unit 2. Thus, the gimbal control controller 18, located in the gimbal control module 7 of the video camera unit 4, is connected to the common on-board CAN bus, and interacts not only with the processor processing module image 3, but also with the flight controller of the on-board control unit 2 to adjust the movement of the UAV.

Thanks to the presence of two video modules - a visible spectrum module 6 and a thermal imaging module 5 - the video camera unit 4 allows not only to detect movement (people and/or vehicles) in the mid-IR range, but also to obtain a traditional color image.

Via the USB interface, the video image processing processor module 3 of the on-board control unit 2 configures the parameters of the thermal imaging module 5 and receives the video image for further processing. Video images from the visible spectrum module 6 are received via the MIPI CSI interface.

Due to the fact that in the video camera assembly 4, the visible spectrum module 6 is equipped with two visible spectrum sensors 10 and 11 and two lenses 12 and 13 with different focal lengths, the video surveillance device 1 has a higher resolution and an increased focal length, and the images received by the pilot are more detailed. Visible spectrum sensors 10 and 11 are configured via the I2C interface (both sensors via one interface) and connected as “Master” and “Slave”. In this case, sensors 10 and 11 operate alternately: in normal mode, one sensor works, with an increase of more than 3.7 times, the second sensor is turned on, while switching sensors is possible using the same transmission lines, including due to their location on the same sensor board 9, which synchronizes them.

The high resolution realized by the video camera unit 4 without a stabilization mechanism has large losses in image quality.

The stabilization mechanism of the video camera assembly 4 allows the pilot to take photographs or video without the quality of the frames being affected by vibration or jitter of the payload module. External influences on the video camera assembly 4 arise during UAV maneuvers in the air, due to the operation of engines and propellers, as well as from the influence of wind or other external factors. Therefore, the payload module of the video surveillance device 1 is equipped with a stabilization mechanism, which is controlled by the gimbal control module 7 to stabilize the video camera assembly 4 in 3 axes, and operates as follows.

The gimbal control module 7 is equipped with an electronic stabilization circuit 14, the inertial system 19 of which transmits data about the axial position of the video camera assembly 4 to the control controller 18, which in turn, solving the problem of stabilizing the video camera assembly 4, issues control signals to motors 15-17 using drivers engines 20-22.

To determine the position of the rotor relative to the stator in brushless motors 15-17, sensors 23-25 are used, based on the Hall effect, having feedback to the control controller 18. In this case, the number of brushless motors is 15-17, motor drivers 20-22 and sensors 23-25 corresponds to the number of stabilization axes.

The claimed group of inventions fully satisfies the specified requirements, which is confirmed by the results of the Applicant’s development of such a device and the following factors:

1. Availability of available sensors on the market that have high resolution (12 megapixels), large pixel size, and small dimensions. In addition, they require a minimum set of additional electrical and radio products, which allows them to be placed on a printed circuit board of minimal size;

2. Refusal of the optical zoom for optical zoom, in exchange for which two sensors with lenses with different focal lengths are installed on one printed circuit assembly. Magnification is implemented in a hybrid way (digital zoom -> change sensor -> digital zoom);

3. Availability on the market of a thermal imaging radiometric camera with minimal weight and dimensions;

4. Microcoaxial cables are used to transmit the signal from the sensor to the processing processor, allowing high-speed signals to be transmitted via the MIPI CSI interface;

5. For mechanical stabilization, very compact and efficient brushless motors are used, controlled by a special gyro-suspension control module;

6. Video image processing was transferred from the video camera to the UAV, on which a computer with a powerful processor (video image processing processor module) was installed, which made it possible to connect sensors via the MIPI CSI interface, and a thermal imaging camera via USB.

Field tests of a prototype video surveillance device have proven its performance and suitability for obtaining high-resolution data without loss of image quality.

Claims (4)

1. A video surveillance device for an unmanned aircraft, including an on-board control device and a payload module, characterized in that the on-board control device contains a processor module for processing video images, the payload module is made in the form of a video camera unit containing a visible spectrum module with two sensors and two lenses, thermal imaging module, gimbal control module equipped with a stabilization mechanism, interaction between the video processing processor module and the video camera unit is carried out through a set of microcoaxial cables and a flexible connecting cable. 2. A video camera unit having a visible spectrum module with two sensors and two lenses, containing a visible spectrum sensor board on which lenses with different focal lengths are installed, a thermal imaging module made in the form of a thermal imaging radiometric camera connected to a gimbal control module, and a stabilization mechanism , including an electronic stabilization circuit, which is equipped with a gimbal control module, and brushless motors according to the number of stabilization axes. 3. The video surveillance device for an unmanned aircraft according to claim 1, characterized in that the stabilization mechanism of the video camera assembly is implemented as follows: the electronic stabilization circuit of the gimbal control module includes a control controller, an inertial system and motor drivers that have feedback from brushless motors through position sensors , based on the Hall effect. 4. The video surveillance device for an unmanned aircraft according to claim 1, characterized in that the set of microcoaxial cables and a flexible connecting cable for interaction between the video processing processor module and the video camera unit includes a USB interface for transmitting a signal from the thermal imaging module, a MIPI CSI interface for transmitting a signal from sensors visible spectrum module, I2C interface for controlling sensors and a CAN interface for controlling the video camera node.