CN108614572A - A kind of target identification method for tracing, equipment and storage device based on aircraft - Google Patents
A kind of target identification method for tracing, equipment and storage device based on aircraft Download PDFInfo
- Publication number
- CN108614572A CN108614572A CN201810403029.2A CN201810403029A CN108614572A CN 108614572 A CN108614572 A CN 108614572A CN 201810403029 A CN201810403029 A CN 201810403029A CN 108614572 A CN108614572 A CN 108614572A
- Authority
- CN
- China
- Prior art keywords
- aircraft
- target
- expectation
- tracing
- relative
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000001914 filtration Methods 0.000 claims abstract description 4
- 230000001133 acceleration Effects 0.000 claims description 12
- 238000003384 imaging method Methods 0.000 claims description 8
- 238000012545 processing Methods 0.000 claims description 7
- 230000005484 gravity Effects 0.000 claims description 3
- 230000000007 visual effect Effects 0.000 abstract description 5
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 238000005516 engineering process Methods 0.000 description 4
- 230000036544 posture Effects 0.000 description 4
- 238000001514 detection method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 2
- RZVHIXYEVGDQDX-UHFFFAOYSA-N 9,10-anthraquinone Chemical group C1=CC=C2C(=O)C3=CC=CC=C3C(=O)C2=C1 RZVHIXYEVGDQDX-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
- G05D1/08—Control of attitude, i.e. control of roll, pitch, or yaw
- G05D1/0808—Control of attitude, i.e. control of roll, pitch, or yaw specially adapted for aircraft
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
- G05D1/10—Simultaneous control of position or course in three dimensions
- G05D1/101—Simultaneous control of position or course in three dimensions specially adapted for aircraft
Landscapes
- Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Navigation (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
The present invention provides a kind of target identification method for tracing, equipment and storage device based on aircraft, a kind of target identification method for tracing based on aircraft, image and height are obtained by sensor, and image is handled, the three-dimensional position that aircraft is obtained relative to tracking target obtains the expectation flight attitude of aircraft using the method and PID controller of Kalman filtering, the posture of aircraft is controlled by the Attitude Controller in aircraft, to achieve the purpose that track target；A kind of target identification tracing equipment and storage device based on aircraft, for realizing the target identification method for tracing based on aircraft.The beneficial effects of the invention are as follows：Aircraft can identify specified target, detect and track the movement of target object, and target is followed independently to be tracked, and ensure that objective body is constantly in the visual range of aircraft, and precise and stable flight is above target.
Description
Technical field
The present invention relates to image procossing and embedded-type control fields more particularly to a kind of target identification based on aircraft to chase after
Track method, equipment and storage device.
Background technology
Quadrotor drone has many advantages, such as small, VTOL, hovering, omnidirection flight, can be simple in the air
More comprehensive terrestrial information is effectively singly obtained, and the switching and fixation of its position are simple and practicable, and can carried certain
The article of amount.And since it has the characteristics that of low cost, easy to operate and operational safety, it is widely used in the military, people
The multiple fields such as thing and scientific research.
The present invention is using image processing techniques and control technology as foundation stone, in conjunction with precision machinery, signal processing, servo control
The autonomous navigation system of the technologies such as system, inertial navigation is chased after in the military fields such as automatic strike, information investigation and suspect
The public security civil field such as track, public security fire-fighting, aerial search and rescue, high-altitude tracing monitoring has a wide range of applications, meanwhile, realize tool
It is even more a revolutionary science and technology challenge to have the unmanned plane of independence.
Invention content
To solve the above-mentioned problems, the target identification method for tracing that the present invention provides a kind of based on aircraft, equipment and
A kind of storage device, target identification method for tracing based on aircraft, mainly includes the following steps that：
S101：The flying height that aircraft is obtained using height sensor obtains tracking target using imaging sensor
Image, and the image for tracking target is handled；
S102：According to the image of the obtained flying height and processed tracking target, the aircraft phase is obtained
For tracking the three-dimensional position of target；
S103：The three-dimensional position is input in first order PID controller, with the preset aircraft relative to chasing after
The three-dimensional position of track target is compared, and obtains expectation flying speed of the aircraft relative to tracking target；
S104：Compare the front and back three-dimensional position twice, front and back positional distance difference divided by interval time twice obtains
Practical flight speed to the aircraft relative to tracking target；
S105：Using the method for Kalman filtering, by the aircraft relative to tracking target practical flight speed into
Row is filtered；
S106：The practical flight speed relative to tracking target and the aircraft by the aircraft being filtered
Expectation flying speed relative to tracking target is input in the PID controller of the second level, obtains the aircraft relative to tracking
The expectation acceleration of target；
S107：Expectation acceleration according to the aircraft relative to tracking target, calculates the expectation of the aircraft
Flight attitude angle obtains the expectation flight attitude；
S108：Described fly is controlled by the Attitude Controller in the aircraft according to the expectation flight attitude
The flight attitude of row device makes the aircraft track target.
Further, in step S101, the height sensor and imaging sensor are mounted on the aircraft.
Further, in step s 107, the expectation flight attitude angle of the aircraft can be by formula Meter
It obtains, wherein θ is the expectation flight attitude angle of the aircraft, and a is that the aircraft accelerates relative to the expectation of target
Degree, g is acceleration of gravity.
A kind of storage device, the storage device store instruction and data are known for realizing a kind of target based on aircraft
Other method for tracing.
A kind of target identification tracing equipment based on aircraft, including：Processor and the storage device；The processor
It loads and executes the instruction in the storage device and data for realizing a kind of target identification method for tracing based on aircraft.
The advantageous effect that technical solution provided by the invention is brought is：Aircraft can identify specified target, and detection is simultaneously
The movement of target object is tracked, and target is followed independently to be tracked, ensures that objective body is constantly in the visual range of aircraft
Interior and precise and stable flight is above target.
Description of the drawings
Present invention will be further explained below with reference to the attached drawings and examples, in attached drawing：
Fig. 1 is a kind of flow chart of the target identification method for tracing based on aircraft in the embodiment of the present invention；
Fig. 2 is a kind of block schematic illustration of the target identification method for tracing based on aircraft in the embodiment of the present invention；
Fig. 3 is a kind of flow diagram of the target identification tracing system based on aircraft in the embodiment of the present invention；
Fig. 4 is the schematic diagram that hardware device works in the embodiment of the present invention.
Specific implementation mode
For a clearer understanding of the technical characteristics, objects and effects of the present invention, now control attached drawing is described in detail
The specific implementation mode of the present invention.
The embodiment provides a kind of target identification method for tracing, equipment and storage device based on aircraft.
The embodiment of the present invention uses quadrotor, using F330 quadrotors rack as hardware platform, using the electricity of 20A
Sub- governor drives the brushless motor of 4 880KV, coordinates 8045 type propellers；Autonomous tracking based on quadrotor is visited
The hardware configuration for surveying platform courses software is obtained as posture using STM32F407ZGT6 microprocessors and flight control core, with
The RX23T microprocessors that Renesas is provided are image procossing core, including nine axis attitude transducers, elevation information sensor, regarding
Feel sensor, function button, OLED show, wireless module etc..Sensor includes mainly the distance being equipped on immediately below quadrotor
Sensor and visual sensor.Range sensor uses US-100 ultrasonic distance measuring modules, carries temperature-compensation circuit, ranging essence
Exactness is sent to processor up to 1mm, range data by serial ports；Visual sensor is taken the photograph using the OV7725 of 320*240 pixels
As head module, which can be converted to binaryzation data by image data and be read by microcontroller, save the processing pressure of CPU
Improve the transmission speed of image data.
Referring to FIG. 1, Fig. 1 is a kind of flow of the target identification method for tracing based on aircraft in the embodiment of the present invention
Figure, specifically comprises the following steps：
S101：The flying height that aircraft is obtained using height sensor obtains tracking target using imaging sensor
Image, and the image for tracking target is handled；The height sensor and imaging sensor are mounted on the aircraft；
S102：According to the image of the obtained flying height and processed tracking target, the aircraft phase is obtained
For tracking the three-dimensional position of target；
S103：The three-dimensional position is input in first order PID controller, with the preset aircraft relative to chasing after
The three-dimensional position of track target is compared, and obtains expectation flying speed of the aircraft relative to tracking target；
S104：Compare the front and back three-dimensional position twice, front and back positional distance difference divided by interval time twice obtains
Practical flight speed to the aircraft relative to tracking target；
S105：Using the method for Kalman filtering, by the aircraft relative to tracking target practical flight speed into
Row is filtered；
S106：The practical flight speed relative to tracking target and the aircraft by the aircraft being filtered
Expectation flying speed relative to tracking target is input in the PID controller of the second level, obtains the aircraft relative to tracking
The expectation acceleration of target；
S107：Expectation acceleration according to the aircraft relative to tracking target, calculates the expectation of the aircraft
Flight attitude angle obtains the expectation flight attitude；The expectation flight attitude angle of the aircraft can be by formula
It is calculated, wherein θ is the expectation flight attitude angle of the aircraft, and a is that the aircraft accelerates relative to the expectation of target
Degree, g is acceleration of gravity；
S108：Described fly is controlled by the Attitude Controller in the aircraft according to the expectation flight attitude
The flight attitude of row device makes the aircraft track target.
Referring to FIG. 2, Fig. 2 is that a kind of frame of the target identification method for tracing based on aircraft shows in the embodiment of the present invention
It is intended to, height sensor is used to obtain the elevation information of the aircraft, obtain tracking target using imaging sensor first
Image, and to track target image handle, processed image combination flying height obtain the aircraft relative to
Track the three-dimensional position of target；Then, three dimensional local information is inputted in first order PID controller, with the preset flight
Device is compared relative to the three-dimensional position of tracking target, obtains expectation flight speed of the aircraft relative to tracking target
Degree；Compare the front and back three-dimensional position twice, by front and back positional distance difference divided by interval time twice, obtains the flight
Practical flight speed of the device relative to tracking target；Then, using kalman filter method, by the aircraft relative to tracking
The practical flight speed of target is filtered, and obtains practical flight speed of the stable aircraft relative to tracking target
Degree；By the aircraft being filtered relative to the practical flight speed of tracking target and the aircraft relative to tracking
The expectation flying speed of target is input in the PID controller of the second level, obtains expectation of the aircraft relative to tracking target
Acceleration；Expectation acceleration according to the aircraft relative to tracking target, calculates the expectation flight appearance of the aircraft
State angle obtains the expectation flight attitude；Finally, according to the expectation flight attitude, pass through the flight appearance in the aircraft
State controller controls the flight attitude of the aircraft, to achieve the purpose that track target.
Referring to FIG. 3, Fig. 3 is that a kind of flow of the target identification tracing system based on aircraft is shown in the embodiment of the present invention
It is intended to, the autonomous tracking test platform control software based on quadrotor includes mainly three zones module：Nine axis postures
Detection module, image processing module and flight attitude position control module, the nine axis attitude detection module is for detecting institute
The posture of aircraft is stated, described image processing module is used to handle the image of the tracking target of imaging sensor acquisition, described to fly
Row posture position control module is used to control the aircraft and tracks target according to the expectation flight attitude.Based on quadrotor
The autonomous tracking test platform control software of aircraft completes attitude of flight vehicle, position in real time by coordinating modules operation
And acquisition, processing and the fusion of movable information, and four brushless motors of the aircraft are carried out in real time by cascade PID
Adjustment of rotational speed enables quadrotor to reach splendid tracking effect in autonomous flight.
Fig. 4 is referred to, Fig. 4 is the hardware device operating diagram of the embodiment of the present invention, and the hardware device specifically includes：
A kind of target identification tracing equipment 401, processor 402 and storage device 403 based on aircraft.
A kind of target identification tracing equipment 401 based on aircraft：A kind of target identification tracking based on aircraft
Equipment 401 realizes a kind of target identification method for tracing based on aircraft.
Processor 402：The processor 402 loads and executes the instruction in the storage device 403 and data for real
A kind of existing target identification method for tracing based on aircraft.
Storage device 403：403 store instruction of the storage device and data；The storage device 403 is for realizing described
A kind of target identification method for tracing based on aircraft.
The beneficial effects of the invention are as follows：Aircraft can identify specified target, detect and track the movement of target object,
And target is followed independently to be tracked, ensure that objective body is constantly in the visual range of aircraft, and precise and stable flight
Above target.
The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all the present invention spirit and
Within principle, any modification, equivalent replacement, improvement and so on should all be included in the protection scope of the present invention.
Claims (5)
1. a kind of target identification method for tracing based on aircraft, it is characterised in that：Include the following steps：
S101：The flying height that aircraft is obtained using height sensor obtains the image of tracking target using imaging sensor,
And the image for tracking target is handled；
S102：According to the image of the obtained flying height and processed tracking target, obtain the aircraft relative to
Track the three-dimensional position of target；
S103：The three-dimensional position is input in first order PID controller, with the preset aircraft relative to tracking mesh
Target three-dimensional position is compared, and obtains expectation flying speed of the aircraft relative to tracking target；
S104：Compare the front and back three-dimensional position twice, by front and back positional distance difference divided by interval time twice, obtains institute
State practical flight speed of the aircraft relative to tracking target；
S105：Using the method for Kalman filtering, the practical flight speed by the aircraft relative to tracking target is filtered
Wave processing；
S106：The aircraft being filtered is opposite relative to the practical flight speed of tracking target and the aircraft
It is input in the PID controller of the second level in the expectation flying speed of tracking target, obtains the aircraft relative to tracking target
Expectation acceleration；
S107：Expectation acceleration according to the aircraft relative to tracking target calculates the expectation flight of the aircraft
Attitude angle obtains the expectation flight attitude；
S108：The aircraft is controlled by the Attitude Controller in the aircraft according to the expectation flight attitude
Flight attitude, so that the aircraft is tracked target.
2. a kind of target identification method for tracing based on aircraft as described in claim 1, it is characterised in that：In step S101
In, the height sensor and imaging sensor are mounted on the aircraft.
3. a kind of target identification method for tracing based on aircraft as described in claim 1, it is characterised in that：In step S107
In, the expectation flight attitude angle of the aircraft can be by formulaIt is calculated, wherein θ is the aircraft
It is expected that flight attitude angle, a is expectation acceleration of the aircraft relative to target, and g is acceleration of gravity.
4. a kind of storage device, it is characterised in that：The storage device store instruction and data are for realizing claims 1 to 3
Target identification method for tracing of any one described based on aircraft.
5. a kind of target identification tracing equipment based on aircraft, it is characterised in that：Including：Processor and the storage device；
The processor loads and executes the instruction in the storage device and data for realizing arbitrary described in claims 1 to 3
A kind of target identification method for tracing based on aircraft.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810403029.2A CN108614572A (en) | 2018-04-28 | 2018-04-28 | A kind of target identification method for tracing, equipment and storage device based on aircraft |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810403029.2A CN108614572A (en) | 2018-04-28 | 2018-04-28 | A kind of target identification method for tracing, equipment and storage device based on aircraft |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN108614572A true CN108614572A (en) | 2018-10-02 |
Family
ID=63661387
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810403029.2A Pending CN108614572A (en) | 2018-04-28 | 2018-04-28 | A kind of target identification method for tracing, equipment and storage device based on aircraft |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108614572A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111420326A (en) * | 2020-03-27 | 2020-07-17 | 国网湖南省电力有限公司 | Control method and system for hovering and spraying fire extinguishing of aviation fire extinguishing device |
| CN111580542A (en) * | 2019-02-15 | 2020-08-25 | 北京京东尚科信息技术有限公司 | Dynamic unmanned aerial vehicle formation control method and device and storage medium |
| CN113176789A (en) * | 2021-04-27 | 2021-07-27 | 北京三快在线科技有限公司 | Aircraft control method, device, equipment and readable storage medium |
| CN117572885A (en) * | 2023-11-20 | 2024-02-20 | 鸣飞伟业技术有限公司 | Night tracking method, system and related device based on thermal infrared camera of unmanned aerial vehicle |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104536453A (en) * | 2014-11-28 | 2015-04-22 | 深圳一电科技有限公司 | Aircraft control method and device |
| CN104597912A (en) * | 2014-12-12 | 2015-05-06 | 南京航空航天大学 | Tracking flying control system and method of six-rotor unmanned helicopter |
| KR101802880B1 (en) * | 2016-04-22 | 2017-11-30 | 가천대학교 산학협력단 | A position recognition and control device for a remote control device |
| CN107807661A (en) * | 2017-11-24 | 2018-03-16 | 天津大学 | Four rotor wing unmanned aerial vehicle formation demonstration and verification platforms and method in TRAJECTORY CONTROL room |
| CN107943102A (en) * | 2017-12-28 | 2018-04-20 | 南京工程学院 | A kind of aircraft of view-based access control model servo and its autonomous tracing system |
-
2018
- 2018-04-28 CN CN201810403029.2A patent/CN108614572A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104536453A (en) * | 2014-11-28 | 2015-04-22 | 深圳一电科技有限公司 | Aircraft control method and device |
| CN104597912A (en) * | 2014-12-12 | 2015-05-06 | 南京航空航天大学 | Tracking flying control system and method of six-rotor unmanned helicopter |
| KR101802880B1 (en) * | 2016-04-22 | 2017-11-30 | 가천대학교 산학협력단 | A position recognition and control device for a remote control device |
| CN107807661A (en) * | 2017-11-24 | 2018-03-16 | 天津大学 | Four rotor wing unmanned aerial vehicle formation demonstration and verification platforms and method in TRAJECTORY CONTROL room |
| CN107943102A (en) * | 2017-12-28 | 2018-04-20 | 南京工程学院 | A kind of aircraft of view-based access control model servo and its autonomous tracing system |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111580542A (en) * | 2019-02-15 | 2020-08-25 | 北京京东尚科信息技术有限公司 | Dynamic unmanned aerial vehicle formation control method and device and storage medium |
| CN111580542B (en) * | 2019-02-15 | 2024-07-19 | 北京京东乾石科技有限公司 | Dynamic unmanned aerial vehicle formation control method, device and storage medium |
| CN111420326A (en) * | 2020-03-27 | 2020-07-17 | 国网湖南省电力有限公司 | Control method and system for hovering and spraying fire extinguishing of aviation fire extinguishing device |
| CN111420326B (en) * | 2020-03-27 | 2021-04-23 | 国网湖南省电力有限公司 | Control method and system for hovering and spraying fire extinguishing of aviation fire extinguishing device |
| CN113176789A (en) * | 2021-04-27 | 2021-07-27 | 北京三快在线科技有限公司 | Aircraft control method, device, equipment and readable storage medium |
| CN113176789B (en) * | 2021-04-27 | 2023-04-04 | 北京三快在线科技有限公司 | Aircraft control method, device, equipment and readable storage medium |
| CN117572885A (en) * | 2023-11-20 | 2024-02-20 | 鸣飞伟业技术有限公司 | Night tracking method, system and related device based on thermal infrared camera of unmanned aerial vehicle |
| CN117572885B (en) * | 2023-11-20 | 2024-05-31 | 鸣飞伟业技术有限公司 | Night tracking method, system and related device based on thermal infrared camera of unmanned aerial vehicle |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Wenzel et al. | Automatic take off, tracking and landing of a miniature UAV on a moving carrier vehicle | |
| CN106774436B (en) | Control system and method for stably tracking target of rotor unmanned aerial vehicle based on vision | |
| CN105492985B (en) | A kind of system and method for the control loose impediment in environment | |
| Wenzel et al. | Low-cost visual tracking of a landing place and hovering flight control with a microcontroller | |
| CN103587708B (en) | The microminiature unmanned rotary wing aircraft field zero autonomous soft landing method in blind area of fixing a point | |
| CN108614572A (en) | A kind of target identification method for tracing, equipment and storage device based on aircraft | |
| CN107463181A (en) | A kind of quadrotor self-adoptive trace system based on AprilTag | |
| WO2015100899A1 (en) | Intelligent cruise robot based on wireless charging odd-shaft aircraft | |
| CN103365297A (en) | Optical flow-based four-rotor unmanned aerial vehicle flight control method | |
| Yang et al. | Precise quadrotor autonomous landing with SRUKF vision perception | |
| CN105182992A (en) | Unmanned aerial vehicle control method and device | |
| WO2019127029A1 (en) | Obstacle avoidance method and device and aircraft | |
| CN108037768A (en) | Unmanned plane obstruction-avoiding control system, avoidance obstacle method and unmanned plane | |
| CN106500699B (en) | A kind of position and orientation estimation method suitable for Autonomous landing in unmanned plane room | |
| CN110498039A (en) | A kind of intelligent monitor system based on bionic flapping-wing flying vehicle | |
| CN102190081A (en) | Vision-based fixed point robust control method for airship | |
| CN110109469A (en) | It is a kind of with color, identification, positioning, following function quadrotor drone control system | |
| CN110456822A (en) | A kind of small and medium size unmanned aerial vehicles double redundancy independently measures flight control system | |
| Wang et al. | Monocular vision and IMU based navigation for a small unmanned helicopter | |
| CN109521785A (en) | It is a kind of to clap Smart Rotor aerocraft system with oneself | |
| CN109709975B (en) | Four-rotor aircraft indoor security system and method based on visual SLAM | |
| CN108227749A (en) | Unmanned plane and its tracing system | |
| Amidi et al. | Research on an autonomous vision-guided helicopter | |
| Razinkova et al. | Tracking a moving ground object using quadcopter UAV in a presence of noise | |
| Gao et al. | Altitude information acquisition of uav based on monocular vision and mems |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20181002 |
|
| RJ01 | Rejection of invention patent application after publication |