The reference to 37 sensors and actuators has been widely circulated on the Internet. In fact, there must be more than 37 sensor modules compatible with Arduino. In view of the fact that I have accumulated some sensor and actuator modules on hand, according to the concept of practice to get true knowledge (must be done), for the purpose of learning and communication, I am going to try a series of experiments one by one, regardless of success (the program goes through) or not, They will be recorded - small progress or unsolvable problems, hoping to inspire others.
[Arduino] 168 kinds of sensor module series experiments (data code + simulation programming + graphics programming)
Experiment 139: E18-D80NK infrared obstacle avoidance sensor module proximity switch smart car 3-80cm
Knowledge points: Infrared, infrared tube and infrared obstacle avoidance sensor module
1. Infrared (IR for short)
1. In the spectrum, a section with a wavelength greater than 0.76 microns is called infrared, and infrared is invisible light. All substances above absolute zero (-273.15°C) can produce infrared rays. Modern physics call them heat rays. Medical infrared can be divided into two categories: near infrared and far infrared.
Infrared was discovered in 1800 by the astronomer William Herschel, who, by placing a thermometer outside the red region of the solar spectrum and finding that the temperature rose, pointed out that there is a radiation with a frequency lower than red light: invisible to the naked eye, but still It can increase the temperature of the surface of the irradiated object. More than half of the energy that the earth receives from the sun is in the form of infrared absorption. The balance of Earth's absorption and emission of infrared radiation has a critical impact on its climate. Infrared light is absorbed or emitted when molecules change their rotational or vibratory motion. From the energy of infrared rays, the vibrational modes of molecules and the changes of their dipole moments can be found. Therefore, infrared rays are the ideal frequency range when studying molecular symmetry and energy states. Infrared spectroscopy studies the absorption and emission of photons in the infrared range.
2. Infrared is the abbreviation of infrared, which is a kind of electromagnetic wave. It can realize the wireless transmission of data. Since it was discovered in 1800, it has been widely used, such as infrared mouse, infrared printer, infrared keyboard and so on. Infrared characteristics: Infrared transmission is a point-to-point transmission method, wireless, can not be too far away, must be aligned in the direction, and there must be no obstacles in the middle, that is, it cannot pass through the wall, and it is almost impossible to control the progress of information transmission; IrDA It is already a set of standards, and the components for IR receiving/sending are also standardized products.
3. Infrared communication technology is suitable for low-cost, cross-platform, point-to-point high-speed data connection, especially for embedded systems. The main application of infrared technology: equipment interconnection, information gateway. After the devices are interconnected, the exchange of files and information in different devices can be completed. The information gateway is responsible for connecting the information terminal and the Internet. Infrared communication technology has been supported and adopted by many software and hardware manufacturers around the world. At present, mainstream software and hardware platforms provide support for it. Infrared technology has been widely used in mobile computing and mobile communication equipment. Infrared transmission is A point-to-point transmission method, wireless, can not be too far away, must be aligned in the direction, and there must be no obstacles in the middle, that is, it cannot pass through walls, and it is almost impossible to control the progress of information transmission; IrDA is already a set of standards, IR The receiving/sending components are also standardized products.
Advantages
It enables wireless data transmission between mobile phones and computers;
Information exchange can be performed between devices that also have infrared interfaces; At
the same time, infrared interfaces can save the cost of downloading or other information exchanges;
Due to the need for docking to transmit Information, strong security.
Disadvantages
·The communication distance is short, the communication process cannot be moved, and the communication is interrupted when encountering obstacles;
·The main purpose of infrared communication technology is to replace the cable connection for wireless data transmission, with single function and poor scalability.
2. Infrared pair tube (Infrared pair tube)
1. Infrared pair tube is the general term for when an infrared emitting tube and a photosensitive receiving tube, or an infrared receiving tube, or an infrared receiving head are used together. The infrared tube is the infrared emission and reception. There are two ways of transmitting and receiving it, one is the direct type, and the other is the reflective type. The direct type means that the luminous tube and the receiving tube are relatively placed at the two ends of the transmitter and the controlled object, with a certain distance between them; the reflective type means that the luminous tube and the receiving tube are juxtaposed together, and the receiving tube is always without light at ordinary times, only in the infrared light emitted by the luminous tube. When the light meets the reflector, the receiving tube will only work when it receives the reflected infrared rays.
2. Infrared emitting tubes mainly have three commonly used bands in the LED packaging industry, as follows: 850NM, 875NM, and 940NM. There are also great differences in the products used according to the characteristics of the wavelength. The 850NM wavelength is mainly used for infrared monitoring equipment, the 875NM is mainly used for medical equipment, and the 940NM band is mainly used for infrared control equipment, such as infrared remote control, photoelectric switch, photoelectric counting equipment etc.
Working principle: When emitting infrared rays to control the corresponding controlled device, the controlled distance is proportional to the emission power. In order to increase the control distance of infrared rays, the infrared emission tube works in a pulsed state, because the effective transmission distance of pulsating light (modulated light) is proportional to the peak current of the pulse, and the emission distance of infrared light can be increased by increasing the peak Ip as much as possible . The way to improve Ip is to reduce the pulse duty ratio, that is, to compress the pulse width т, some color TV infrared remote controllers, the working pulse hollow ratio of the infrared light-emitting tube is about 1/4 1/3; some electrical products infrared remote controllers , whose duty cycle is 1/10. Reducing the duty cycle can also greatly increase the emission distance of low-power infrared light-emitting diodes. The power of common infrared light-emitting diodes is divided into three categories: low power (1mW 10mW), medium power (20mW 50mW) and high power ( above 50mW 100mW). To make the infrared light-emitting diode produce modulated light, it is only necessary to add a pulse voltage of a certain frequency to the driving tube.
3. The infrared receiving tube is named in the LED industry, and it is specially used to receive and sense the infrared light emitted by the infrared emitting tube. In general, it is used in a complete set with the infrared emitting tube in the product equipment.
Features and principles: The infrared receiving tube is a semiconductor device that converts infrared optical signals into electrical signals. Its core component is a PN junction of a special material. Compared with ordinary diodes, it has adopted a large change in structure. The infrared receiving tube In order to receive incident light in a larger area, the area of the PN junction should be as large as possible, and the electrode area should be reduced as much as possible, and the junction depth of the PN junction is very shallow, generally less than 1 micron. Infrared receiving diodes work under the action of reverse voltage. When there is no light, the reverse current is very small (generally less than 0.1 microampere), which is called dark current. When there is infrared light, the infrared photons carrying energy enter the PN junction, and transfer the energy to the bound electrons on the covalent bond, so that some electrons break free from the covalent bond, thereby generating electron-hole pairs (abbreviation: photogenerated carriers) ). They participate in the drift movement under the action of the reverse voltage, which makes the reverse current significantly larger, and the greater the intensity of the light, the greater the reverse current. This property is called "photoconductivity". The current generated by the infrared receiving diode under the light of general illumination is called photocurrent. If a load is connected to the external circuit, an electrical signal is obtained on the load, and this electrical signal changes correspondingly with the change of light.
3. E18-D80NK infrared obstacle avoidance sensor module
1. It is a digital photoelectric sensor integrating emission and reception. Mainly used for obstacle detection. The transmitted light is sent out after being modulated, and the receiving head demodulates the reflected light and outputs it. Effectively avoid the interference of visible light. The use of the lens also allows the sensor to detect a distance of up to 80 cm (due to the characteristics of infrared light, objects of different colors have different maximum detection distances; white objects are the farthest and black objects are the closest). The sensing distance to obstacles can be adjusted by the knob at the rear according to requirements. The sensor has the characteristics of long detection distance, less interference by visible light, low price, easy assembly, and convenient use. It can be widely used in many intelligent automation occasions such as robot obstacle avoidance and assembly line piece counting.
Electrical Characteristics
Brown: VCC; Blue: GND; Black: OUT.
Working voltage: 5VDC
Working current: 10-15mA
Driving current: 100mA
Sensing distance: 3-80CM
Mechanical characteristics:
Color: orange
Diameter: 18MM
Length: 45MM
Lead length: 18CM
2. Module technical parameters
(1) Output current DC / SCR / relay control: 100mA/5v power supply
(2) Current consumption >25mA (minimum value) <100mA (maximum value)
(3) Response time <2ms
(4) Pointing angle : Less than 15°, the effective distance is adjustable within the range of 3-80CM
(5) Detection object: transparent or opaque object
(6) Working environment temperature: -25 °C ~ 55 °C
(7) Standard detection object: sunlight 10000LX is the following incandescent lamp 3000LX
(8) Shell material: Plastic
(9) Type: DC 3 Wire NPN-NO (normally open)
(10) Sensing distance regulator and output LED indicator
(11) Control signal level: High2. 3V≤Vin≤5V Low-0.3V≤Vin≤1.5V
3. Working principle of E18-D80NK
When the infrared rays emitted by the transmitter are blocked by the surface of the measured object, the infrared light will be reflected, and the reflected light will be demodulated after being received by the photocell, and the demodulated signal is input to the development board such as Arduino to Object detection is ready. E18-D80NK integrates an adjustable potentiometer, which can adjust the measurement gain by adjusting the potentiometer. E18-D80NK is different from KS-103 and HR04, it is usually not used for distance test, but more for collision detection. Therefore, E18-D810NK can be used in robotics, wearable devices, automobiles and other fields.
4. Internal structure diagram of the module
5. Module application scenarios
(1) Automatic counting equipment for goods in the production line
(2) Multi-function reminder
(3) Maze walking robot
(4) Kitchen automation system
(5) Security and anti-theft system, etc.
6. Module pin definition
The experimental environment of the E18 - D80NK infrared obstacle avoidance sensor module
1. The hardware list required for the experiment of the infrared obstacle avoidance sensor
module Diode (green, blue) X2 High level trigger single 5V relay module X1 E18-D80NK infrared obstacle avoidance sensor module X1 Proto Shield prototype expansion board (with mini breadboard) X1
