CN111999524B - Plant protection unmanned aerial vehicle - Google Patents
Plant protection unmanned aerial vehicle Download PDFInfo
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- CN111999524B CN111999524B CN202010504914.7A CN202010504914A CN111999524B CN 111999524 B CN111999524 B CN 111999524B CN 202010504914 A CN202010504914 A CN 202010504914A CN 111999524 B CN111999524 B CN 111999524B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/10—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring thermal variables
- G01P5/12—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring thermal variables using variation of resistance of a heated conductor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2201/00—Specific applications of microelectromechanical systems
- B81B2201/02—Sensors
- B81B2201/0278—Temperature sensors
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Abstract
The invention relates to a plant protection unmanned aerial vehicle, which comprises a vehicle body, a microprocessor, a spraying device and a flexible wind speed sensor, wherein the flexible wind speed sensor is attached to the bottom of the vehicle body of the plant protection unmanned aerial vehicle; the flexible wind speed sensor comprises a flexible film substrate, and a temperature measuring resistor, a heating resistor and a compensating resistor which are arranged on the front surface of the flexible film substrate, wherein the temperature measuring resistor and the compensating resistor are respectively and symmetrically arranged on two sides of the heating resistor, and the temperature measuring resistor is positioned between the heating resistor and the compensating resistor; the back of the flexible film substrate is provided with a cavity structure, and the temperature measuring resistor and the compensating resistor are arranged on the flexible film substrate at the position of the cavity structure; the temperature measuring resistor, the heating resistor and the compensating resistor are respectively connected with a bridge circuit. Compared with the prior art, the invention has the advantages of small sensor volume, light weight, high sensitivity, strong fitting property, rich application scenes of the plant protection unmanned aerial vehicle and the like.
Description
Technical Field
The invention relates to the technical field of precision agricultural plant protection unmanned aerial vehicles, in particular to a plant protection unmanned aerial vehicle.
Background
Along with the proposal of accurate agricultural thought in the 90 s and the rapid development of modern science and technology, the application range of the plant protection unmanned aerial vehicle is continuously expanded in recent years, and the application of the plant protection unmanned aerial vehicle in spraying operation becomes a necessary trend. However, when the plant protection unmanned aerial vehicle performs aerial spraying operation, the plant protection unmanned aerial vehicle is very easily influenced by the wind speed in the natural environment. Pesticide drift caused by the influence of wind speed in the pesticide spraying process influences the well-growing crops outside the spraying area and the environment of the adjacent area. The long-term contact of the pesticide drift in the air can further affect the human body, thereby causing various diseases, such as respiratory system complications and nervous system diseases. Therefore, the wind speed and the wind direction can be accurately obtained, and the method has important guiding significance on how to benefit and avoid the damage in agricultural production.
Mature reliable plant protection unmanned aerial vehicle is less on the market at present, mostly is the unified configuration of fixed parameter. It is difficult to adjust the spraying path and the spraying agent in real time according to the climate environment condition. As a novel spraying technology, the spraying device is really used for agricultural protection, local meteorological conditions need to be fully considered, and the spraying track and the spraying agent of the unmanned aerial vehicle can be adjusted in real time according to the meteorological conditions.
The traditional wind speed sensor has the defects of large volume, easy influence of environmental temperature and pressure, small flexibility, poor stability and the like, and the application of the traditional wind speed sensor is limited to a great extent; on using plant protection unmanned aerial vehicle with traditional air velocity transducer, cause the influence to unmanned aerial vehicle's operation easily to the sensitivity of traditional sensor is not high, leads to plant protection unmanned aerial vehicle to accomplish accurately and sprays.
Disclosure of Invention
The invention aims to provide the plant protection unmanned aerial vehicle for overcoming the defects that the spraying technology of the existing plant protection unmanned aerial vehicle in the prior art is easily influenced by the ambient wind speed, the volume of the carried traditional sensor is large, the sensitivity is low, the spraying track and the dosage cannot be adjusted in real time and the like.
The purpose of the invention can be realized by the following technical scheme:
the plant protection unmanned aerial vehicle comprises a machine body, a microprocessor, a spraying device and a flexible wind speed sensor, wherein the flexible wind speed sensor is attached to the bottom of the machine body of the plant protection unmanned aerial vehicle; the flexible wind speed sensor comprises a flexible film substrate, and a temperature measuring resistor, a heating resistor and a compensating resistor which are arranged on the front surface of the flexible film substrate, wherein the temperature measuring resistor is symmetrically arranged on two sides of the heating resistor, the compensating resistor is symmetrically arranged on two sides of the heating resistor, and the temperature measuring resistor is positioned between the heating resistor and the compensating resistor; the back of the flexible film substrate is provided with a cavity structure, and the temperature measuring resistor and the compensating resistor are arranged on the flexible film substrate at the position of the cavity structure; the resistance ratio of the temperature measuring resistor, the heating resistor and the compensating resistor is 315-440 omega: 240 Ω to 400 Ω: 900 omega-1160 omega; the distance between the temperature measuring resistor and the heating resistor is 135 um-485 um; the temperature measuring resistor, the heating resistor and the compensating resistor are respectively connected with a bridge circuit.
According to the invention, the flexible wind speed sensor is applied to the plant protection unmanned aerial vehicle, the flexible thermal wind speed sensor is prepared by adopting the flexible film substrate and taking the flexible material as the substrate, the sensor has good speed measurement performance, and meanwhile, the sensor can adapt to various curved surfaces due to good flexibility and ductility and can be better attached to the unmanned aerial vehicle. Although the size of the sensor is greatly reduced, the influence on the unmanned aerial vehicle is greatly reduced, the thickness of the flexible film substrate is too small, so that the thermal resistance between the temperature measuring resistor, the heating resistor and the like and the unmanned aerial vehicle is small, and the heat loss is large.
The invention relates to a hot film wind speed measuring method based on heat loss principle constant temperature difference, which designs a flexible film substrate with a temperature measuring resistor, a heating resistor and a compensation resistor, wherein the temperature measuring resistor is used for precisely measuring low wind speed, the heating resistor is used for measuring high wind speed, and the compensation resistor is used for measuring ambient temperature and compensating the ambient temperature in the measuring process, because an unmanned aerial vehicle is easily influenced by natural ambient temperature in the working process, the temperature difference between the ambient temperature and the heating resistor needs to be kept constant, thereby improving the accuracy of a sensor.
For the plant protection unmanned aerial vehicle, various complex measurement conditions need to be dealt with, and in order to improve the measurement accuracy, the resistance values of the resistors and the distance between the temperature measuring resistor and the heating resistor are optimized, so that the sensitivity of the sensor is ensured.
The invention optimizes the application scene of the plant protection unmanned aerial vehicle in the sensor circuit part, so that the circuit is simpler and more efficient. The specific optimization is as follows: the voltage-stabilized power supply module is added to solve the problem that the power supply voltage is unstable in the working process of the sensor; meanwhile, considering that the sensor takes an unmanned aerial vehicle as an application scene, the sensor and a series of accessories of the sensor are minimized and simplified, the circuit is simplified, and the heating resistor, the temperature measuring resistor and the compensating resistor are arranged on the same circuit, so that the sensor can detect the wind speed more efficiently and conveniently.
Most plant protection unmanned aerial vehicle on the present market is the uniform parameter, fixed configuration, and adaptability of this kind of plant protection unmanned aerial vehicle under different topography, weather, environmental condition is relatively poor. According to the method for combining the plant protection unmanned aerial vehicle and the flexible MEMS sensor, the sensor can be attached to the surface of various unmanned aerial vehicles, and meanwhile, an MCU system loaded in the plant protection unmanned aerial vehicle does not need to be damaged. The weight of the sensor is negligible, and the working performance of the unmanned aerial vehicle is almost not influenced. The method has strong applicability, small sensor volume and high sensitivity, and is suitable for various plant protection unmanned aerial vehicles on the market.
The temperature measuring resistor, the heating resistor and the compensating resistor are resistance wires with snake-shaped circuitous structures.
The resistance value can be increased within a certain range by adopting a snake-shaped circuitous structure, and the number of turns and the total length of the resistance wire are further designed according to the resistance value of the thermistor.
And three temperature measuring resistors and one compensating resistor are respectively arranged on two sides of the heating resistor.
The temperature measuring resistor, the heating resistor and the compensating resistor are made of metal platinum.
The metal Pt has the advantages of low melting point, good ductility, small errors of performance temperature and temperature coefficient, and the like, so the metal Pt is selected as the thermistor material.
The diameter of the resistance wires is 5-8 mu m, and the distance between the parallel resistance wires is 9-11 mu m.
The thickness of the flexible film substrate is 25-35 mu m; and along the thickness direction of the flexible film substrate, the thickness of the cavity is 5-6 mu m.
The thickness of flexible film base is the micron level, consequently has high flexibility and ductility to can laminate on various curved surfaces, better with unmanned aerial vehicle laminating.
The flexible film substrate is made of polyimide.
The preparation method of the flexible wind speed sensor comprises the following steps:
(S-1) manufacturing a Cr/Cu metal film with the thickness of 20 nm-30 nm/200 nm-250 nm on a glass substrate as a sacrificial layer by a sputtering process; spinning and coating a polyimide protective layer with the thickness of 5-10 um on the sacrificial layer, and curing the polyimide protective layer;
(S-2) depositing a Cr/Pt metal film with the thickness of 20 nm-30 nm/200 nm-250 nm on the polyimide protective layer through a sputtering process; utilizing photoetching development technology to manufacture patterns of a temperature measuring resistor, a heating resistor and a compensating resistor to obtain a thermistor layer;
(S-3) sputtering a Cr/Cu seed layer with the thickness of 100 nm-200 nm on the thermistor layer through a sputtering process, and photoetching by using photoresist as a mask plate to obtain a pattern of a lead; sequentially electroplating Cu with the thickness of 10 um-20 um as a lead and Ni with the thickness of 15 um-25 um as a pin on the pattern of the lead, and removing the photoresist; removing the redundant Cr/Cu seed layer by using an Ar ion beam bombardment method;
(S-4) spin-coating a polyimide support film with the thickness of 5-10 um on the surface of the thermistor layer; sputtering a Cr/Cu metal barrier layer with the thickness of 100 nm-200 nm by a sputtering process, and taking the photoresist as a mask plate to obtain an etching barrier layer with the same structure size as the bottom of the cavity.
(S-5) spin-coating thick polyimide with the thickness of 20-25 um on the surface of the etching barrier layer to serve as a substrate layer, sputtering a Cu/Cr metal layer with the thickness of 100-200 nm on the substrate layer through a sputtering process, photoetching and patterning the Cu/Cr metal layer through an ion beam bombardment method, forming an etching window on the Cu/Cr metal layer, etching to the Cr/Cu barrier layer through a reactive ion etching method, and forming the cavity on the substrate layer;
and (S-6) protecting the photoresist on the Cu/Cr metal layer, etching the Cu sacrificial layer by using a copper corrosive liquid by adopting a metal sacrificial layer release method, and releasing and stripping to obtain the flexible wind speed sensor.
Compared with the prior art, the invention has the following advantages:
(1) the sensor adopting the flexible film substrate material has small volume, light weight, large flexibility and good ductility, can be well attached to various curved surfaces, is simple to mount, is better attached to the unmanned aerial vehicle, and does not influence the flight of the unmanned aerial vehicle;
(2) the sensitivity and the frequency response of the sensor are improved and the power consumption is reduced by reasonably arranging the cavity structure and the resistor structure;
(3) the method combines the sensor with the plant protection unmanned aerial vehicle to realize the real-time adjustment of the track and the spray of the unmanned aerial vehicle in the aerial spraying operation process of the plant protection unmanned aerial vehicle, thereby realizing the accurate spraying.
Drawings
Fig. 1 is a schematic structural view of a plant protection unmanned aerial vehicle according to the present invention;
fig. 2 is a schematic structural diagram of an embedded device of the plant protection unmanned aerial vehicle according to the present invention;
FIG. 3 is a schematic structural view of the front side of the flexible wind speed sensor according to the present invention;
FIG. 4 is a schematic structural diagram of the back side of the flexible wind speed sensor according to the present invention;
FIG. 5 is a power supply circuit of the heating resistor, the temperature measuring resistor and the compensating resistor according to the present invention;
in the figure, 1 is heating resistor, 2 is temperature measuring resistor, 3 is the cavity structure, 4 is compensation resistor, 5 is the treater, 6 is the storage card, 7 is external port, 8 is embedded equipment, 9 is the flexible film base, 10 is flexible air velocity transducer, 11 is plant protection unmanned aerial vehicle, 12 is heating resistor or temperature measuring resistor position, 13 is the compensation resistor position.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the concept of the invention. All falling within the scope of the present invention.
Example 1
The utility model provides a plant protection unmanned aerial vehicle 11, as shown in figure 1, including fuselage, microprocessor and sprinkler and laminate in plant protection unmanned aerial vehicle's fuselage bottom flexible air velocity transducer 10, wherein, microprocessor is a commercially available embedded equipment.
As shown in fig. 1, the flexible wind speed sensor 10 is attached to the bottom of the plant protection unmanned aerial vehicle 11 and is in signal connection with the embedded device 8 of the plant protection unmanned aerial vehicle 11; the plant protection unmanned aerial vehicle 11 adjusts the medicament spraying angle and the medicament amount according to the wind speed measured by the flexible wind speed sensor 10. The influence on the aerial work of the unmanned aerial vehicle is greatly reduced while the good performance of the sensor is ensured, the sensor receives the wind speed information from the natural environment and uploads the wind speed information to the computer platform, and the embedded equipment is used as Raspberry in the embodiment
For example, as an embedded computer platform of the unmanned aerial vehicle, as shown in fig. 2, the embedded device 8 is a commercially available Raspberry 4Model B, the embedded device 8 includes a processor 5, a memory card 6, a built-in I/O, an external port 7, and other structures, the processor 5 is BCM2835ARMv6700MHz, the memory card 6 is 512MB SDRAM, and the external port 7 is a UBS interface. After the flexible wind speed sensor 10 receives the wind speed information and transmits the wind speed information to the embedded device 8, the embedded device 8 runs a corresponding algorithm through the processor 5 according to the size of the wind speed, the wind direction and the spraying condition of ground plants to obtain an optimized track change parameter, and the optimized track change parameter is fed back to the unmanned aerial vehicle, so that the track and the spray of the unmanned aerial vehicle can be adjusted in real time. Use plant protection unmanned aerial vehicle 11 to use the carrier as wind speed sensor, spray angle and medicament volume to the medicament and carry out dynamic adjustment after detecting the environment wind speed through wind speed sensor, optimize the medicament and spray effect and medicament use amount under the prerequisite that satisfies crops and spray the demand.
The structure of the flexible wind speed sensor adopted in the embodiment is shown in fig. 3 and 4, and includes a flexible film substrate 9 made of polyimide PI material, and a temperature measuring resistor 2, a heating resistor 1 and a compensating resistor 4 which are arranged on the front surface of the flexible film substrate 9, the compensating resistor 4 is arranged on two sides of the heating resistor 1 and the temperature measuring resistor 2, the temperature measuring resistor 2 is arranged on two sides of the heating resistor 1, and the compensating resistor 4, the temperature measuring resistor 2, the heating resistor 1, the temperature measuring resistor 2 and the compensating resistor 4 are arranged in sequence from left to right; as shown in fig. 4, the cavity structure 3 is disposed on the back surface of the flexible film substrate 9, and the heating resistor 1 and the temperature measuring resistor 2 are disposed on the flexible film substrate 9 at the position of the cavity structure 3. The temperature measuring resistor 2, the heating resistor 1 and the compensating resistor 4 are resistance wires with snake-shaped circuitous structures; the temperature measuring resistor 2, the heating resistor 1 and the compensating resistor 4 are made of metal platinum; the diameter of the resistance wires is 6 μm, and the distance between the parallel resistance wires is 10 μm. The thickness of the flexible film substrate 9 is 30 μm, the length is 9mm, and the width is 7 mm; the thickness of the cavity is 5 μm in the thickness direction of the flexible film substrate 9. The interval between temperature measurement resistance 2 and heating resistor 1 is 485 um.
The temperature measuring resistor 2, the heating resistor 1 and the compensating resistor 4 form a constant temperature difference power supply circuit of the hot film anemometer, and the resistance ratio of the temperature measuring resistor 2, the heating resistor 1 and the compensating resistor 4 is 440 omega: 400 Ω: 1160 omega, wherein the position 13 of the compensation resistor is not changed, and the position 12 of the heating resistor or the temperature measuring resistor is provided with the heating resistor or the temperature measuring resistor.
The flexible wind speed sensor circuit part that adopts in this embodiment has optimized for the application scene to plant protection unmanned aerial vehicle for the circuit is simpler and high-efficient. As shown in FIG. 5, the flexible wind speed sensor circuit adopts a constant temperature difference measurement and control circuit of a double Wheatstone bridge, wherein a heating resistor and a temperature measuring resistor are arranged on the same circuit, the heating resistor RJIARE and the temperature measuring resistor RCEWEN are arranged at two ends of the left Wheatstone bridge, a compensation resistor RBUCHANG is arranged at one end of the right Wheatstone bridge, output ends of the two bridges output final signals after passing through two stages of amplifiers, wind speed measurement in a high flow speed state and a low flow speed state can be simultaneously completed through one circuit, two circuits are not required to be arranged, accessories are simplified, and the volume is reduced. The power supply end of the circuit is provided with a three-terminal voltage-stabilizing integrated module L7805CP, the output end of the L7805CP is respectively connected with two bridges, and the problem of unstable power supply voltage in the working process of the sensor can be solved.
When wind speed is measured, the temperature of the heating resistor or the temperature measuring resistor in the sensor can rise rapidly after the heating resistor or the temperature measuring resistor is connected into a circuit, and when ambient wind flows through the heating resistor or the temperature measuring resistor, heat on the resistor can be taken away through heat exchange, so that the resistance value of the resistor is changed, and the voltage difference between two ends of a Wheatstone bridge where the heating resistor and the temperature measuring resistor are located is changed. The flow rate is obtained by detecting the heat loss amount of the heating resistor or the temperature measuring resistor. The compensation resistor in the sensor plays a role in environmental compensation on the whole circuit, and belongs to hardware compensation. And finally, performing signal amplification processing on the branch where the heating resistor and the temperature measuring resistor are located and the branch where the temperature measuring resistor is located to obtain an output electric signal and obtain the wind speed.
The flexible wind speed sensor of the embodiment takes polyimide PI as a flexible film substrate material, takes metal platinum Pt as a thermistor material on the sensor, and completes the preparation of the novel wind speed sensor with a cavity 3 by using MEMS preparation processes such as a sputtering process, an electroplating process, a photoetching process, an ion milling process, a reactive ion etching process, a releasing process and the like. The method specifically comprises the following steps:
taking a polyimide material as a flexible substrate and platinum as a material of a thermistor layer, and depositing a Cr/Cu metal film with the thickness of 20nm/200nm onto a 3-inch glass substrate as a sacrificial layer by a sputtering process; polyimide with the thickness of 5um is spin-coated to be used as a protective layer.
And photoetching a Cr/Cu metal film with the thickness of 20nm/200nm and the PI protective layer by using photoresist as a mask plate through a sputtering process to obtain the thermistor layer.
Electroplating a Cr/Cu seed layer with the thickness of 100nm by a sputtering process, photoetching by using photoresist as a mask plate, electroplating Cu with the thickness of 10um, using Ni with the thickness of 15um as a lead and a pin, and removing redundant Cr/CU by using an Ar ion beam bombardment method to obtain a lead and pin layer.
And (3) carrying out spin coating on a PI support film with the thickness of 5um, sputtering a Cr/Cu metal barrier layer with the thickness of 100nm by using a sputtering process, and taking the photoresist as a mask plate to obtain an etching barrier layer for protecting a subsequent etching cavity.
Spin-coating polyimide with the thickness of 20um as a substrate layer, sputtering a Cu/Cr metal layer with the thickness of 100nm on the PI supporting film through a sputtering process, photoetching and patterning the PI supporting film through an ion beam bombardment method. And etching the etched Cr/Cu film to a Cr/Cu barrier layer by a reactive ion etching method to form a film cavity.
And finally, spin-coating photoresist for protection, etching the Cu film by using a copper corrosive liquid by adopting a metal sacrificial layer release method, and stripping to obtain the flexible MEMS sensor.
Example 2
The utility model provides a plant protection unmanned aerial vehicle 11, as shown in figure 1, including fuselage, microprocessor and sprinkler and laminate in plant protection unmanned aerial vehicle's fuselage bottom flexible air velocity transducer 10, wherein, microprocessor is a commercially available embedded equipment.
As shown in fig. 1, the flexible wind speed sensor 10 is attached to the bottom of the plant protection unmanned aerial vehicle 11 and is in signal connection with the embedded device 8 of the plant protection unmanned aerial vehicle 11; the plant protection unmanned aerial vehicle 11 adjusts the medicament spraying angle and the medicament amount according to the wind speed measured by the flexible wind speed sensor 10. The influence on the aviation operation of the unmanned aerial vehicle is greatly reduced while the good performance of the sensor is ensured, the sensor receives wind speed information from a natural environment and uploads the wind speed information to a computer platform, in the embodiment, the embedded device is taken as an embedded computer platform of the unmanned aerial vehicle by taking Raspberry 4Model B as an example, as shown in fig. 2, the embedded device 8 is a commercially available product Raspberry 4Model B, the embedded device 8 comprises a processor 5, a memory card 6, a built-in I/O (input/output) and external port 7 and the like, the processor 5 is BCM2835ARMv6700MHz, the memory card 6 is 512MB SDRAM, and the external port 7 is a UBS interface. After the flexible wind speed sensor 10 receives the wind speed information and transmits the wind speed information to the embedded device 8, the embedded device 8 runs a corresponding algorithm through the processor 5 according to the size of the wind speed, the wind direction and the spraying condition of ground plants to obtain an optimized track change parameter, and the optimized track change parameter is fed back to the unmanned aerial vehicle, so that the track and the spray of the unmanned aerial vehicle can be adjusted in real time. Use plant protection unmanned aerial vehicle 11 to use the carrier as wind speed sensor, spray angle and medicament volume to the medicament and carry out dynamic adjustment after detecting the environment wind speed through wind speed sensor, optimize the medicament and spray effect and medicament use amount under the prerequisite that satisfies crops and spray the demand.
The structure of the flexible wind speed sensor adopted in the embodiment is shown in fig. 3 and 4, and includes a flexible film substrate 9 made of polyimide PI material, and a temperature measuring resistor 2, a heating resistor 1 and a compensating resistor 4 which are arranged on the front surface of the flexible film substrate 9, the compensating resistor 4 is arranged on two sides of the heating resistor 1 and the temperature measuring resistor 2, the temperature measuring resistor 2 is arranged on two sides of the heating resistor 1, and the compensating resistor 4, the temperature measuring resistor 2, the heating resistor 1, the temperature measuring resistor 2 and the compensating resistor 4 are arranged in sequence from left to right; as shown in fig. 2, a cavity structure 3 is provided on the back surface of the flexible film substrate 9, and the heating resistor 1 and the temperature measuring resistor 2 are provided on the flexible film substrate 9 at the position of the cavity structure 3. The temperature measuring resistor 2, the heating resistor 1 and the compensating resistor 4 are resistance wires with snake-shaped circuitous structures; the temperature measuring resistor 2, the heating resistor 1 and the compensating resistor 4 are made of metal platinum; the diameter of the resistance wires is 6 μm, and the distance between the parallel resistance wires is 10 μm. The thickness of the flexible film substrate 9 is 30 μm, the length is 9mm, and the width is 7 mm; the thickness of the cavity is 6 μm in the thickness direction of the flexible film substrate 9. The distance between the temperature measuring resistor 2 and the heating resistor 1 is 135 umum.
The temperature measuring resistor 2, the heating resistor 1 and the compensating resistor 4 form a constant temperature difference power supply circuit of the hot film anemometer, and the resistance ratio of the temperature measuring resistor 2, the heating resistor 1 and the compensating resistor 4 is 315 omega: 240 Ω: 900 omega; the temperature measuring resistor 2 functions at a low flow rate, and the heating resistor 1 functions at a high flow rate.
In the flexible wind speed sensor of the embodiment, polyimide PI is used as a flexible film substrate material, metal platinum Pt is used as a heating resistor material 1, and a sputtering process, an electroplating process, a photoetching process, an ion milling process, a reactive ion etching process, a release process and other MEMS preparation processes are used to complete the preparation of the novel wind speed sensor with the cavity 3. The method specifically comprises the following steps:
taking a polyimide PI material as a flexible substrate, taking metal platinum Pt as a material of a thermistor layer, and depositing a Cr/Cu metal film with the thickness of 30nm/250nm onto a 3-inch glass substrate as a sacrificial layer by a sputtering process; polyimide with a thickness of 10um was spin coated as a protective layer.
And photoetching a Cr/Cu metal film with the thickness of 30nm/250nm and the PI protective layer by using photoresist as a mask plate through a sputtering process to obtain the thermistor layer.
Electroplating a Cr/Cu seed layer with the thickness of 200nm by a sputtering process, photoetching by using photoresist as a mask plate, electroplating Cu with the thickness of 20um, using Ni with the thickness of 25um as a lead and a pin, and removing redundant Cr/CU by using an Ar ion beam bombardment method to obtain a lead and pin layer.
And (3) performing spin coating on a PI support film with the thickness of 10um, sputtering a Cr/Cu metal barrier layer with the thickness of 200nm by using a sputtering process, and taking the photoresist as a mask plate to obtain an etching barrier layer for protecting a subsequent etching cavity.
Spin-coating 25um thick polyimide as a substrate layer, sputtering a Cu/Cr metal layer with the thickness of 200nm on the PI supporting film by a sputtering process, photoetching and patterning by an ion beam bombardment method. And etching the etched Cr/Cu film as a mask plate to the Cr/Cu barrier layer by a reactive ion etching method to form a film cavity.
And finally, spin-coating photoresist for protection, etching the Cu film by using a copper corrosive liquid by adopting a metal sacrificial layer release method, and stripping to obtain the flexible MEMS sensor.
According to the embodiment, the flexible MEMS wind speed sensor is combined with the plant protection unmanned aerial vehicle, wind speed information from the environment is received, information interaction is carried out through an embedded hardware system carried on the plant protection unmanned aerial vehicle, and finally, optimized track change parameters are obtained through a corresponding algorithm, so that real-time track change of the plant protection unmanned aerial vehicle is achieved. Compared with the existing plant protection unmanned aerial vehicle carrying the wind speed sensor, the invention has the advantages of small sensor volume, light weight, high sensitivity, strong fitting property, rich application scene of the plant protection unmanned aerial vehicle and the like.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.
Claims (8)
1. The plant protection unmanned aerial vehicle comprises a machine body, a microprocessor and a spraying device, and is characterized by further comprising a flexible wind speed sensor (10) attached to the bottom of the machine body of the plant protection unmanned aerial vehicle, wherein the plant protection unmanned aerial vehicle adjusts the spraying angle and the dosage of a medicament according to the wind speed measured by the flexible wind speed sensor (10); the flexible wind speed sensor comprises a flexible film substrate (9), and a temperature measuring resistor (2), a heating resistor (1) and a compensating resistor (4) which are arranged on the front surface of the flexible film substrate (9), wherein the heating resistors (1) are symmetrically arranged on two sides of the heating resistor (1), the compensating resistor (4) is respectively symmetrically arranged on two sides of the heating resistor (1), and the temperature measuring resistor (2) is positioned between the heating resistor (1) and the compensating resistor (4); the back of the flexible film substrate (9) is provided with a cavity structure (3), and the temperature measuring resistor (2) and the compensating resistor (4) are arranged on the flexible film substrate (9) at the position of the cavity structure (3); the resistance ratio of the temperature measuring resistor (2), the heating resistor (1) and the compensation resistor (4) is 315-440 omega: 240 Ω -400 Ω: 900-1160 omega; the distance between the temperature measuring resistor (2) and the heating resistor (1) is 135-485 um; the temperature measuring resistor (2), the heating resistor (1) and the compensating resistor (4) are respectively connected with a bridge circuit;
the flexible wind speed sensor circuit adopts a constant temperature difference measurement and control circuit of a double Wheatstone bridge, wherein a heating resistor and a temperature measuring resistor are arranged on the same circuit, the heating resistor and the temperature measuring resistor are positioned at two ends of the left Wheatstone bridge, a compensating resistor is positioned at one end of the right Wheatstone bridge, and output ends of the two bridges output final signals after passing through two stages of amplifiers.
2. The plant protection unmanned aerial vehicle of claim 1, wherein the temperature measuring resistor (2), the heating resistor (1) and the compensating resistor (4) are resistance wires with a serpentine winding structure.
3. A plant protection unmanned aerial vehicle according to claim 1, wherein the heating resistor (1) is provided with three temperature measuring resistors (2) and one compensating resistor (4) on both sides.
4. The plant protection unmanned aerial vehicle of claim 2, wherein the temperature measuring resistor (2), the heating resistor (1) and the compensation resistor (4) are made of platinum.
5. The unmanned aerial vehicle for plant protection according to claim 2, wherein the resistance wires have a diameter of 5-8 μm, and the distance between the parallel resistance wires is 9-11 μm.
6. A plant protection drone according to claim 1, characterised in that the thickness of the flexible film base (9) is 25-35 μm; along the thickness direction of the flexible film substrate (9), the thickness of the cavity is 5-6 mu m.
7. A plant protection unmanned aerial vehicle according to claim 1, wherein the flexible film substrate (9) is made of polyimide.
8. The plant protection unmanned aerial vehicle of claim 1, wherein the flexible wind speed sensor is prepared by the following steps:
(S-1) manufacturing a Cr/Cu metal film with the thickness of 20 nm-30 nm/200 nm-250 nm on a glass substrate as a sacrificial layer by a sputtering process; spinning and coating a polyimide protective layer with the thickness of 5-10 um on the sacrificial layer, and curing the polyimide protective layer;
(S-2) depositing a Cr/Pt metal film with the thickness of 20 nm-30 nm/200 nm-250 nm on the polyimide protective layer through a sputtering process; utilizing photoetching development technology to manufacture patterns of a temperature measuring resistor, a heating resistor and a compensating resistor to obtain a thermistor layer;
(S-3) sputtering a Cr/Cu seed layer with the thickness of 100 nm-200 nm on the thermistor layer through a sputtering process, and photoetching by using photoresist as a mask plate to obtain a pattern of a lead; sequentially electroplating Cu with the thickness of 10-20 um as a lead and Ni with the thickness of 15-25 um as a pin on the pattern of the lead, and removing the photoresist; removing the redundant Cr/Cu seed layer by using an Ar ion beam bombardment method;
(S-4) spin-coating a polyimide support film with the thickness of 5-10 um on the surface of the thermistor layer; sputtering a Cr/Cu metal barrier layer with the thickness of 100 nm-200 nm by a sputtering process, and taking photoresist as a mask plate to obtain an etching barrier layer with the same structure size as the bottom of the cavity;
(S-5) spin-coating polyimide with the thickness of 20-25 um on the surface of the etching barrier layer to serve as a substrate layer, sputtering a Cu/Cr metal layer with the thickness of 100-200 nm on the substrate layer through a sputtering process, photoetching and patterning the Cu/Cr metal layer through an ion beam bombardment method, forming an etching window on the Cu/Cr metal layer, etching to the Cr/Cu barrier layer through a reactive ion etching method, and forming the cavity on the substrate layer;
and (S-6) protecting the photoresist on the Cu/Cr metal layer, etching the Cu sacrificial layer by using a copper corrosive liquid by adopting a metal sacrificial layer release method, and releasing and stripping to obtain the flexible wind speed sensor (10).
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