Chinese7 major sensing methods of sensors
1. Proximity sensing
Proximity sensing generally means detecting:
a. Whether an object is present.
b. The size or simple shape of an object.
Proximity sensors can be further divided into contact or non-contact, and analog or digital in operation. The choice of sensor depends on physical, environmental and control conditions. These include:
Mechanical:
Any suitable mechanical/electrical switch can be adopted, but since a certain force is required to operate a mechanical switch, micro switches are usually used.
Pneumatic:
These proximity sensors work by breaking or disturbing the airflow. Pneumatic proximity sensors are examples of contact sensors. But these products cannot be used for light parts that may be blown away.
Optical:
In the simplest form, optical proximity sensors fall by breaking a beam of light that falls on a light-sensitive device such as a photocell. These are examples of non-contact sensors.
It is worth noting that the lighting environment of these sensors must be handled with great care, for example, optical sensors may be obscured by flashes during arc welding, dust and smoke clouds in the air may hinder the transmission of light, etc.
Electrical:
Electrical proximity sensors can be contact or non-contact. Simple contact sensors operate by having the sensor and component complete an electrical circuit. Non-contact electrical proximity sensors rely on the principle of induction to detect metals or capacitance to detect non-metals.
Range Sensing:
Distance sensing involves detecting how close or far a component is from the sensing location, although they can also be used as proximity sensors. Distance or range sensors use non-contact analog technology. Short-range sensing between a few millimeters and hundreds of millimeters is performed using capacitive, inductive, and magnetic technologies. Longer-range sensing is performed using various types of emitted energy waves, such as radio waves, sound waves, and lasers.
2. Force Sensing
There are six types of forces that may need to be sensed. In each case, the application of force can be either static (at rest) or dynamic. Force is a vector because it must be specified in both magnitude and direction. Therefore, force sensors are analog operations and are sensitive to the direction in which they act. The six forces are:
①, tension
②, compression
③, shear
④, torsion
⑤, bending
⑥, friction
There are a variety of techniques for sensing force, some direct and some indirect.
Tensile force:
Can be determined by strain gauges, which show a change in their resistance when the length increases. The change in resistance measured by these gauges can be converted into force, so it is an indirect device.
Pressure:
Can be determined by devices called load cells, which can "operate by detecting changes in the size of the cell under compressive load, or by detecting an increase in pressure within the cell under load, or by changes in resistance under compressive load."
Torsion:
Can be seen as a combination of tensile and compressive forces, so a combination of the above techniques can be used.
Friction:
These involve situations where motion is to be restricted, so "friction is detected indirectly by using a combination of force and motion sensors.
3. Tactile Sensing
Tactile sensing refers to sensing by touch. The simplest type of tactile sensor uses a simple array of touch sensors arranged in rows and columns, these are often called matrix sensors.
Each individual sensor is activated when it comes into contact with an object. By detecting which sensors are active (digital) or the size of the output signal (analog), the imprint of the component can be determined. The imprint is then compared to previously stored imprint information to determine the size or shape of the component.
Currently implemented machines Mechanical, optical, and electronic tactile sensors.
4. Thermal Sensing
Heat sensing may be required as part of process control or as a safety control. There are a variety of methods to choose from, and the choice of these methods depends primarily on the temperature to be detected.
Some common methods are: bimetallic strips, thermocouples, resistance thermometers, or thermistors. For more complex systems involving low-level heat sources, infrared thermal imaging cameras can be used.
5. Sound Sensing (Hearing)
Acoustic sensors can detect and sometimes distinguish between different sounds. They can be used for voice recognition to give verbal commands or to identify unusual sounds, such as explosions. The most common acoustic sensors are microphones. Wind.
In industrial settings, the obvious problem with acoustic sensors is the large amount of background noise.
Of course, we can also simply tune acoustic sensors to respond only to certain frequencies, allowing them to distinguish between different noises.
6. Gas Sensing (Smell)
Gas or smoke sensors that are sensitive to specific gases rely on chemical changes in the materials contained in the sensor, which will produce physical expansion or generate enough heat to trigger a switch device.
7. Robot Vision (Sight)
Vision is probably the most active area of current research in sensory feedback for robots.
Robot vision refers to the real-time capture of an image by some kind of camera and the conversion of that image into a form that can be analyzed by a computer system. This conversion usually means converting the image into a digital field that the computer can understand. The entire process of image capture, digitization, and data analysis should be fast enough for the robot system to respond to the analyzed image and take appropriate actions during the execution of the task set.
The perfection of robot vision will enable the full potential of artificial intelligence on industrial robots to be realized. Its uses include detecting presence, location and movement, identifying and recognizing different components, styles and features.
However, even the simplest vision technology requires a lot of computer memory and can take considerable processing time.