Introduction
The use of different types of sensors in industrial areas is a significant aspect of efficient process control. These devices are a fundamental part of the automation and digitalization of industries. These operate by detecting physical variables and converting them into digital signals, which are transmitted to a control system for monitoring, process regulation, and early detection of operational failures, reducing downtime.
In this context, understanding the types of sensors and their characteristics is a key aspect to ensure proper and safe operation of automated systems in various industrial sectors.
What are sensors, and what are they used for?
A sensor is a technological device designed to capture physical variables from the environment, such as physical, chemical, sound or light changes, and transform them into electrical impulses. These impulses, usually in digital format, are interpreted by electronic systems such as computers or machines, allowing the automation and control of industrial processes.
In industrial automation systems, they are responsible for detecting process variables such as temperature, pressure, level, flow, pH and turbidity; electrical variables including voltage, current and frequency; mechanical variables such as rotation, cycle count, position, direction of movement, static and dynamic pressures, and proximity; and environmental variables such as humidity, vibration, wind speed and direction.
Sensors function as information translators, allowing machines to “understand” properties of the environment and react to them. This information is used to monitor variations in conditions in a specific area, triggering automatic responses, such as triggering alarms or activating production systems.
In industrial automation these instruments and are fundamental in different applications, they are used to collect data and provide basic data support in real time improving the efficiency and safety of production processes, for the development of Industry 4.0.
Main types of sensors used in current technology
Velocity sensors
Velocity sensors, also known as speedometers, are devices designed to measure the velocity of a moving object compared to a specific reference point. They work by detecting the time elapsed between changes in the object’s position and transforming this information into electrical signals. These sensors are applied in various fields, such as in traffic radars, which monitor the speed of vehicles to detect violations.
They are also used in industrial systems to measure the speed of moving components, such as rubber belts or production equipment. Generally speaking, velocity sensors can measure both linear and angular velocity, depending on the type of device and its application. The main function of these sensors is to provide accurate data on the displacement of an object, enabling proper management and control in a variety of industrial, transportation and safety processes.
Optical sensors
They detect the presence of objects or people by interrupting a beam of light directed towards the sensor. They use photoelectric or photoresistive principles, such as photoresistors (LDRs), which are common in applications such as robotics. They transform changes in the intensity or interruption of light into electrical signals, making it possible to determine the location or presence of an object in their detection field.
A common use of optical sensors in robotics is to regulate the movement of robots, stopping them before they come into contact with obstacles. Their application is also essential in industry for machinery safety, by detecting intruders or any object or person in their range of action, and stopping the system to prevent accidents. By not relying on conventional vision, they provide accurate data on the environment through variations in luminous flux.
Temperature sensors
They are used to measure temperature variation in an environment and convert this information into electrical signals. They generally operate on the principle of a resistor, using materials whose value changes as a function of temperature. Depending on the direction of change, they can be classified into PTC (Positive Temperature Coefficient) thermistors, which increase in resistance with temperature, and NTC (Negative Temperature Coefficient) thermistors, whose resistance decreases with increasing temperature.
There are different types of temperature sensors; they can be contact sensors, when they come into direct contact with the object to be measured, or non-contact sensors, which detect the thermal radiation emitted by the object. They are widely used in industrial applications to control the temperature of machinery, equipment and processes, as well as to detect anomalies in electrical systems or cooling cycles.
In general, these sensors are essential for thermal monitoring in automated and control systems, providing accurate data for efficient temperature management in various applications.
Proximity sensors
They are devices used to detect the presence and proximity of an object regarding the sensor, without the need for physical contact. They work through a system composed of an emitter and a receiver. The emitter emits periodic signals, which may be ultrasonic, electromagnetic, capacitive or inductive, and the receiver measures the bounce of these signals when an object is encountered, indicating its proximity.
They provide information on the presence of obstacles, people or other objects within their field of operation, and some models also allow the exact distance between the sensor and the object to be measured.
They are widely used in applications such as collaborative robots (cobots), unmanned vehicles and autonomous security systems, and can detect objects without physical contact, making them ideal for environments where precision and safety are required, such as in industrial automation and surveillance technologies.
Pressure sensors
This type of sensor measures the pressure exerted by a fluid in a specific space. Their implementation is necessary in various industrial sectors, as they allow key processes to be controlled, ensure the safe operation of machinery and prevent catastrophic incidents. They are regularly installed in places where fluids circulate through closed compartments, such as in evaporation boilers or hydraulic systems, to measure the force exerted by the fluid on the vessel walls.
In addition to pressure measurement, they can provide additional information on related variables, such as liquid flow, flow rate or the contents of certain containers, if additional data on product characteristics is available. Their accurate, real-time measurements make them critical components in maintaining safety and operational efficiency in the industry.
Humidity sensors
They are used to measure relative humidity and temperature, as well as to translate this data into electrical signals through integrated circuits. The measurement of humidity and temperature in real time is achieved by controlling a variety of industrial processes and automated systems. These sensors are significant in environments where humidity control is required, such as in industrial machinery, where chemical components are handled, liquid tanks, boilers and storage systems.
Additionally, they are used in agriculture to monitor the moisture level in soils and activate irrigation systems, or in greenhouses to maintain optimal conditions. Advanced moisture sensors can also measure moisture on specific surfaces or in materials such as synthetic fibers. The high accuracy and low margin of error allow efficient and safe management of processes where humidity and temperature are critical factors.
Distance sensors
They determine the linear separation between two points, indicating how far apart they are. These devices are important in space measurement and object detection systems, and are even used in security applications such as perimeter surveillance and motion monitoring. Depending on the technology used, distance sensors can operate through infrared, ultrasound or high frequency wave receivers.
Among the types of distance sensors there are infrared sensors, which measure distance by emitting and receiving radiation, and ultrasonic sensors, which send sound pulses that bounce off surfaces, calculating the distance based on the signal’s return time. In addition to measuring distances, they can also detect the presence or movement of objects within their field of action, making them versatile tools for various automated and control systems.
Conclusions
The correct selection and integration of sensors, based on their characteristics and functions, is essential to optimize the efficiency, safety and control of industrial processes. Through these instruments, it is possible to perform accurate real-time monitoring through data that allows strategic decision making. This information facilitates the early detection of failures, the implementation of predictive maintenance and the adaptation of processes to changing conditions, reducing operating costs and improving productivity.
Investment in advanced sensor technologies drives innovation and competitiveness in increasingly demanding industrial environments. The correct application of these technological solutions is important to ensure safer, more efficient and sustainable processes.
References
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