A sensor is a device that can sense what is being measured and convert it into a usable signal output (usually an electrical signal) according to certain rules. It is an important tool for obtaining information. Sensors can measure various quantities, and any information system and control system cannot do without sensors. In recent years, with the in-depth development of high technology, the application field of sensors has become wider and wider. The following introduces the application of sensors in agriculture.
1. Application of sensors in agricultural mechanization
Mechatronics is an important trend in the development of agricultural machinery and the only way to modernize agriculture. Sensor technology is one of the key technologies of mechatronics. The transformation of traditional agricultural machinery cannot be separated from sensors, and the development of modern agricultural machinery requires a large number of sensors. It can be seen that sensors are widely used in agricultural machinery. In recent years, agricultural machinery such as tractors, harvesters, rice mills, and irrigation machines have been installed and used with various sensors to increase or improve their performance. For example, the United States has developed and launched an automatic control system for harvester cutting height. The system is composed of sensors, electronic circuits, and hydraulics. The crop height signal is detected by the level sensor on the conveyor belt of the header. The electronic controller converts the output signal of the sensor into a signal to increase, decrease, or continue to maintain the height of the header after filtering, and then drives the solenoid valve to make the hydraulic cylinder controlling the header perform corresponding actions to adjust the height of the header. The system also installs a ground proximity sensor at both ends of the header to prevent the header from touching the ground. For example, Japan's Toyo Rice Mill has developed a magnetic sensor that can be installed on a combine harvester to judge and remove metal and other impurities mixed in grains. Its working principle is to form a high-frequency electromagnetic field around the bobbin where the grains roll, use magnetic sensors to measure the changes in the electromagnetic field caused by the rolling of the grains, and use a sorter to remove metal impurities in the grains.
2. Application of sensors in breeding improved varieties
Seeds are the first link in agricultural production and should be given great attention. In recent years, biotechnology and genetic engineering have become important technologies for breeding improved varieties, among which biosensors have played an important role. For example, agricultural scientists in Spain manipulated the genetic genes of seeds through biosensors, found genes that prevent dehydration in corn seeds, and cultivated excellent corn seeds. In addition, temperature sensors, humidity sensors, light sensors, etc. are needed to monitor the breeding environment; moisture sensors, suction sensors, hydrogen ion sensors, temperature sensors, etc. are needed to measure soil conditions; various ion-sensitive sensors are needed to measure nitrogen, phosphorus, potassium and other nutrients.
3. Application of sensors in planting
Planting is a basic operation in agriculture. There are many stages in the planting of crops. During the whole process, various sensors can be used to collect information so that appropriate measures can be taken in time to complete scientific planting. For example, American researchers measure the composition of the soil by ion-sensitive sensors buried in the soil, and use computers to analyze and process the data to scientifically determine the type and amount of fertilizer that should be applied to the soil. In addition, during the growth of plants, shape sensors, color sensors, weight sensors, etc. can be used to monitor the shape, color, size, etc. of objects to determine the maturity of the objects so that they can be picked and harvested in time; carbon dioxide sensors can be used to monitor the artificial environment of plant growth to promote photosynthesis. For example, monitoring of the vegetable planting environment in plastic greenhouses; ultrasonic sensors, volume and audio sensors can be used to eliminate rats and insects; flow sensors and computer systems can be used to automatically control farmland irrigation.
4. Application of sensors in animal husbandry
Animal husbandry is an industry that provides important agricultural and sideline products. High-quality agricultural and sideline products from animal husbandry are extremely important to people's lives. Sensors can play a big role in this regard. A few years ago, agricultural researchers in my country used biosensors and genetic engineering to cultivate a transgenic pig that grows fast, has a high proportion of lean meat, and consumes less feed, meeting the needs of the market. Sensors can also be used to monitor the freshness of livestock, poultry, eggs, etc. For example, Nagasaki University in Japan has developed a sensor for measuring the freshness of livestock and poultry meat. It can accurately measure the concentration of dimethylamine (DMA), a smelly component emitted when chicken, fish, meat and other foods go bad. The minimum concentration can reach 1 ppm. This sensor can accurately grasp the freshness of meat and prevent it from going bad. For another example, chicken farms in the United States use egg detectors to detect the quality of eggs. This instrument consists of two piezoelectric sensors and a monitor. During the inspection, the egg is placed between the two sensors, one of which is the "speaker" and the other is the "receiver", and they are connected to the monitor at the same time. If the eggs are not bad, the monitor will show a resonant peak. If the eggs are contaminated by salmonella and deteriorate, two peaks, one high and one low, will appear on the monitor. It is fast and accurate to use it to check eggs. In addition, in the scientific breeding process, temperature sensors, dissolved oxygen sensors, water composition sensors, etc. are needed to measure water conditions; temperature sensors, humidity sensors, light sensors, etc. are needed to monitor the breeding environment; various ion sensors are needed to measure the composition of the feed; mechanized breeding robots need force sensors, tactile sensors, light sensors, etc.
5. Application of sensors in agricultural product classification and processing
The classification and processing of agricultural products is the post-process of agricultural production. Generally, agricultural products and agricultural and sideline products need to be classified and processed. Various sensors are still needed in this process. For example, Japan uses optical sensors to measure the sugar content of fruits and classify them according to the sugar content to ensure the taste and sweetness of the fruits. In addition, the sensors used in the processing process include humidity sensors, temperature sensors, moisture sensors, etc. For example, the processing of grains, medicinal materials, and tea leaves cannot be separated from the above sensors.
6. Application of sensors in agricultural product storage
Various agricultural products need to be stored, and sensors are also very useful in the storage process. For example, Japan uses fruit mildew sensors to monitor the mildew of peanuts and other fruit beans in the warehouse. This sensor uses near-infrared rays with wavelengths of 700 nanometers and 1100 nanometers. When irradiating fruit beans, it identifies normal fruit beans and mildewed fruit beans by comparing the transmittance. If a conveyor belt is used for sequential detection, the detection speed is 3 meters per second, and one sensor can check 75 kilograms of fruit beans per hour. The sensor can detect aflatoxin with an accuracy of up to one billionth of a gram. In addition, in order to ensure the suitability of the storage environment, various sensors are also needed to monitor the environment in a timely manner. For example, temperature sensors, humidity sensors, moisture sensors, etc. are needed for the storage of grains; sensors for measuring ethylene, oxygen, carbon dioxide, ammonia, freon, temperature, humidity, etc. are needed for the storage of vegetables and fruits.
7. Application of sensors in agricultural meteorology and environment
Agricultural production is inseparable from the climate environment. It is crucial to monitor environmental changes at all times and accurately grasp the farming time to ensure a good harvest. The sensors used in this regard mainly include air pressure sensors, wind speed sensors, temperature sensors, humidity sensors, light sensors, etc. In short, sensors are widely used in agricultural production, and they can penetrate into every link of agricultural production. In recent years, with the increase in domestic investment in agricultural science and technology and the in-depth development of the strategy of revitalizing agriculture through science and technology, sensors have a broad market in agriculture. The urgent task facing the domestic sensor industry is to reduce costs, provide a large number of cheap and applicable sensors to agriculture, occupy the market for agricultural sensors, and at the same time, promote the development of agriculture, benefiting the country and the people.
