A measurement sensor is a device that determines a distance or dimensions of an object based on the readings and signals from an electronic element. Depending on the type of electronic element, a measurement sensor can have several types. These include but are not limited to ultrasonic sensors, contact sensors, laser & optical sensors, and inductive displacement sensors.
One of the more well-known measurement sensors, the ultrasonic sensor uses high-frequency sounds waves to determine the distance to an object. This is accomplished by emitting the sound waves towards the object and starting a timer. The sound waves are then reflected back, the receiver picks it up and stops the timer. The distance is then calculated based on time of travel and speed of sound (constant value in a standard medium). Ultrasonic sensors usually consume minimal power and can be used to measure objects that other sensors could not, such as liquid or transparent surfaces. However, ultrasonic sensors have a low detection range and accuracy compared to other measurement sensors.
As the name suggests, this sensor measures the distance of an object by directly contacting it. Contact sensors are usually used for detecting the height, thickness, or profile of an object since it works in one dimension. These sensors are also very durable due to the constant physical movements they are subjected to. They transmit high-precision data, often with a resolution in the micrometers. Contact sensors are especially useful in environments which are subject to water or oil since the sensor relies on a magnetic sensing method.
Laser and optical sensors contain the bulk of measurement sensors; therefore, we will address three technologies in this section. First is the Laser Profiler. This technology uses a sensor and special lensing to produce a laser line rather than a single laser point. This allows for 2D and 3D measurements like height, width, angle, and profile to be recorded using triangulation. This process can be completed at high speeds which makes it an ideal choice for fast-paced environments like a factory assembly line.
Next is the laser displacement sensor. Unlike the laser profiler, the laser displacement sensor concentrates its triangulation to convene at a single point, which results in an extremely accurate reading. A laser displacement sensor is more accurate than a laser profiler, but if a two-dimensional measurement is required, the displacement sensor won’t be as efficient (since it would need to measure the object point by point).
Finally, there is the optical micrometer. This sensor generates a beam of light that encompasses the entire object. As the object moves through the beam, light is blocked from the receiver and it records the measurement of the ‘shadow’. In other words, this sensor would be able to generate the cross-sectional area of an object as it passes through the beam. From there, specific details about the object would be recorded. This includes detecting defects (like cracks or dents), creating a 2D representation, etc. This technology is extremely accurate and is often seen in many manufacturing settings.
Inductive Displacement Sensors
An inductive displacement sensor is a non-contact proximity sensor used for the detection of metal objects. This sensor uses electromagnetic induction to determine the distance of the magnetic object; therefore, non-ferrous metals (which are less magnetic) will not be as effective in sensing. An inductive displacement sensor is made up of a galvanometer which defects its position when a magnet is moved closer to it. Once the magnet is stationary the galvanometer is returned to its original position. When the magnet is pulled away, it defects in the opposite direction. Hence, the sensor will know when the object is moving closer or further away from it. Once the magnet has been calibrated with real-world measurement units, displacement sensing is accomplished.
This concludes the week’s post about robotic inspection installations. Please stay connected for the third and final post where we will address Optical Comparators and their applications in the robotic industry. If you have any questions regarding the material addressed, feel free to contact us and we will put you in touch with one of our experts.