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Waterways: the Many Routes of Water Detection

 

Water is everywhere, in most things living and not, and the amount of this precious resource is always important. The simplest form of monitoring water is if it is there or not. In your body, you feel the effects of dehydration, in your car the motor overheats, and on your lawn, you see the dryness of the grass. What about your specialty machine or your assembly process? Water and other liquids are inherently clear so how do you see them, especially small amounts of it possibly stored in a tank or moving fast? Well, there are several correct answers to that question. Let’s dive into this slippery topic together, pun intended.

While mechanical float and flow switches have been around the longest, capacitive, photoelectric, and ultrasonic sensors are the most modern forms of electronic water detection. These three sensing technologies all have their strong points. Let’s cover a few comparisons that might help you find your path to the best solution for your application.

Capacitive sensors

Capacitive sensors are designed to detect nonferrous materials, but really anything that can break the capacitive field the sensor creates, including water, can do this. This technology allows for adjustment to the threshold of what it takes to break this field. These sensors are a great solution for through tank level detection and direct-contact sensing.

Ultrasonic sensors

Want to view your level from above? Ultrasonic sensors give you that view. They use sound to bounce off the media and return to the sensor, calculating the time it takes to measure distance. Their strong point is that they can overcome foam and can bounce off the water where light struggles when there is a large distance from the target to the receiver. Using the liquid from above, ultrasonics can monitor large tanks without contact.

Photoelectric sensors

Use photoelectric sensors when you’re looking at a solution for small scale. Now, this might require a site tube if you are monitoring the level on a large tank, however, if you want to detect small amounts of water or even bubbles within that water, photoelectric sensors are ideal. Using optical head remote photoelectric sensors tied to an amplifier, the detail and speed are unmatched. Photoelectric sensors are also great at detecting liquid levels on transparent bottles. In these applications with short distances, you need speed. Photoelectric sensors are as fast as light.

So, have you made up your mind yet? No matter which technology you choose, you will have a sensor that gives you accurate detail and digital outputs and is easy on the budget. Capacitive, ultrasonic, and photoelectric sensors provide all this and they grow with your application with adjustability.

Liquids are everywhere and not going away in manufacturing. They will continue to be an important resource for manufacturing.  Cherish them and ensure you account for every drop.

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Magnetic Field Positioning Systems for Reliable, Accurate and Repeatable Absolute Position Feedback

Magnetic field positioning systems are increasingly popular due to their ability to provide reliable, accurate, and repeatable absolute position feedback.

These systems use magnetic field sensors to get a larger range of feedback across a pneumatic cylinder – a great alternative to traditional cylinder prox switches that may not work well in certain applications. They also allow for continuous monitoring of piston position in tight spaces, providing feedback in the form of analog voltage, current output, and IO-Link interface. And in many cases, these systems can replace the need for a linear transducer, making them a cost-effective solution for many industries.

One of the key benefits of magnetic field positioning systems is their versatility. They can be used in a wide range of industrial applications, such as:

    • Ultrasonic welding to validate set height with position feedback
    • Nut welding to verify set height with position feedback
    • Dispensing
    • Gripping for position feedback for different parts
    • Liner position indicators

While using these sensors greatly improves productivity in areas where prox sensors cannot provide the reliability needed, when selecting the magnetic field position system, it is important to consider the application requirements. The accuracy and feedback speed, for example, may vary depending on the application.

Magnetic field position systems are also available in different lengths. If the standard length does not meet requirements, you can choose a non-contact type that can be mounted on a slide with a magnetic trigger.

Overall, magnetic field positioning systems are an excellent choice for any industry that requires reliable, accurate, and repeatable absolution position feedback. With their versatility and flexibility, they are sure to improve productivity and efficiency in a wide range of applications.

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Focusing on Machine Safety

Machine safety refers to the measures taken to ensure the safety of operators, workers, and other individuals who may come into contact with or work in the vicinity of machinery. Safety categories and performance levels are two important concepts to evaluate and design safety systems for machines. A risk assessment is a process to identify, evaluate, and prioritize potential hazards and risks associated with a particular activity, process, or system. The goal of a risk assessment is to identify potential hazards and risks and to take steps to prevent or mitigate those risks. The hierarchy of controls can determine the best way to mitigate or eliminate risk. We can use this hierarchy, including elimination, substitution, engineering, and administrative controls, and personal protective equipment (PPE), to properly mitigate risk. Our focus here is on engineering controls and how they relate to categories and performance levels.

Performance level

The performance level (PL) of machine safety components is a measure of the reliability and effectiveness of safety systems. Defined as EN ISO 13849-1 standard by the International Organization for Standardization (ISO), it is based on the probability of a safety system failing to perform its intended function. Performance levels are designated by the letters “a” through “e” with PLa being the lowest level of safety and PLe being the highest. Assessing the safety function of the machinery and evaluating the likelihood of a dangerous failure occurring determines the performance level.

Four levels of protection

The categories of machine safety components refer to the four levels of protection required to ensure the safe operation of machinery, as defined by the ISO. Figure 1 below shows how the measured risk determines the performance level and category of circuit performance.

    • Category 1: The occurrence of a fault can lead to loss of the safety function. Single channel safety circuit.
    • Category 2: The occurrence of a fault can lead to loss of the safety function between checks. Single channel safety circuit with monitoring.
    • Category 3: When a single fault occurs, the safety function is always performed. Some faults, but not all, can be detected, but the accumulation of those undetected faults can lead to the loss of the safety function. This category can be implemented using control reliable devices in a dual channel redundant safety circuit that includes monitoring.
    • Category 4: When a fault occurs, the safety function is always performed. Faults will be detected in time to prevent a loss of the safety function and is implemented using control reliable devices in a dual channel redundant safety circuit that includes monitoring.

Using control reliable devices is crucial in Category 3 and 4 safety circuits. One example of a control reliable device is a safety relay that mechanically interlocks the control contacts to the auxiliary contacts. Being mechanically interlocked means when the relay changes states the auxiliary contact will also changes states. Another example of a control reliable device is a safety PLC. A standard PLC is not rated to control safety functions because it is not control reliable and a malfunction could lead to the loss of a safety function.

 

The selection of the appropriate category and performance level for devices used to mitigate a risk in a machine is crucial for ensuring the safety of operators and other individuals. While it is important to note that the purpose of this blog is to provide information, it is not enough to qualify individuals to design or test safety systems. In summary, the category of machine safety defines the level of protection required for safe operation, while the performance level measures the reliability and effectiveness of safety systems.

Now let us go automate with a focus on safety!

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Sensing Ferrous and Non-Ferrous Metals: Enhancing Material Differentiation

Detecting metallic (ferrous) objects is a common application in many industries, including manufacturing, automotive, and aerospace. Inductive sensors are a popular choice for detecting metallic objects because they are reliable, durable, and cost-effective. Detecting a metallic object, however, is not always as simple as it seems, especially if you need to differentiate between two metallic objects. In such cases, it is crucial to understand the properties of the metals you are trying to detect, including whether they are ferrous or non-ferrous.

Ferrous vs. non-ferrous

Ferrous metals, such as mild steel, carbon steel, stainless steel, cast iron, and wrought iron, contain iron. They are typically magnetic, heavier, and more likely to corrode than non-ferrous metals, which do not contain iron. Aluminum, copper, lead, zinc, nickel, titanium, and cobalt are examples of non-ferrous metals. They are typically nonmagnetic, lightweight, and less likely to corrode.

Sensing ferrous and non-ferrous metal:

When it comes to detecting ferrous and non-ferrous metals using inductive sensors, the reduction factor plays a crucial role. The reduction factor is the ratio of the sensor’s effective sensing distance for a given metal to the sensor’s effective sensing distance for steel. In other words, it is the degree to which a metal affects the sensing range of an inductive sensor. Ferrous metals typically have less of an effect on sensing range than non-ferrous metals because inductive sensors function based on the law of induction, and magnetic metals are more likely to interact with the magnetic field created by the sensor.

The reduction factor for each type of metal varies depending on the metal’s properties. Ferrous metals typically have a higher reduction factor than non-ferrous metals, which means they can be detected from a greater distance. For example, both steel and stainless steel have a reduction factor of 0.6 to 1, which means they can be detected from the full switching distance of the sensor of 4 mm. In contrast, non-ferrous metals, such as aluminum, copper, and brass, have a lower reduction factor of 0.25 to 0.5, which means they can only be detected from a fraction of the operating switching distance, typically 1 to 2 mm.

Understanding the reduction factor for each metal allows you to answer the question of what happens when you need to differentiate between two metallic parts. If one metal is ferrous and the other is non-ferrous, then you can place the sensor at a distance that will detect the ferrous metal but not the non-ferrous metal. However, this may not be an efficient solution if the metals have similar reduction factors, or if you need to detect the non-ferrous metal over the ferrous metal.

Using ferrous-only or non-ferrous-only sensors

The better solution is to use a ferrous-only or non-ferrous-only sensor. These sensors are specifically designed to detect only one type of metal and ignore the other type, resulting in a reduction factor of zero. Ferrous-only sensors detect only ferrous metals, and their reduction factors range from 0.1 to 1 for steel and stainless steel, while the reduction factors for non-ferrous metals such as aluminum, copper, and brass are zero. Non-ferrous-only sensors detect only non-ferrous metals, and their reduction factors range from 0.9 to 1.1 for aluminum, copper, and brass, while the reduction factors for ferrous metals are zero. Using ferrous-only or non-ferrous-only sensors eliminates the need to adjust the mounting distance of a standard inductive sensor to detect a ferrous metal over a non-ferrous metal.

Overall, selecting the right sensor for your application depends on the type of metals you need to differentiate and detect. If you are dealing with ferrous and non-ferrous metals, you can use a standard inductive sensor, but you need to be aware of the reduction factor for each metal type and adjust the mounting distance accordingly. If you need to detect only one type of metal, however, a ferrous-only or a non-ferrous-only sensor is the better option. These sensors are specially designed to ignore the other metal type, eliminating the need to adjust the mounting distance.

By understanding the differences between ferrous and non-ferrous metals and the capabilities of different sensors, you can optimize the metal detection system for maximum efficiency and accuracy.

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Tackling the Most Demanding Applications With Precision Sensors

Standard industrial sensors can solve a lot of automation challenges. Photoelectric, capacitive, and inductive technologies detect presence, distances, shapes, colors, thicknesses, and more. To satisfy these general applications, there are a few reputable manufacturers in the market that design and produce such products. In many instances, it is possible to interchange them from manufacturer to manufacturer, due to similar mounting patterns, technical specifications, connectors, and even common pin assignments.

But some applications require more precision – where standard sensors will not do.  Some examples include:

    • The target may be too small or difficult material to detect
    • The target may move very slowly, or very quickly
    • The target may have a minimal displacement, as in valve feedback
    • The sensor must have low mass, for high-acceleration applications
    • The sensor location has severe space constraints or material constraints

Applications that must detect particles that can’t be seen with the naked eye, or something as small as sensing the thin edge of a silicon wafer or the edge of a clear glass microscope slide, require sensors with exceptional precision.

Many precision sensing applications require a custom-designed sensor to meet the customer’s expectations. These expectations typically involve a quality sensor with robust attributes, likely coupled with difficult design parameters, such as high switch-point repeatability, exceptional temperature stability, or exotic materials.

What constitutes a precision sensing application? Let’s take a look.

Approximately 70% of all medical decisions are based on lab results. Our doctors are making decisions about our health based on these test outcomes. Therefore, accurate, trustworthy results, performed quickly, are priorities. Many tests rely on pipetting, the aspirating and dispensing of fluids – sometimes at a microscale level – from one place to another. Using a manual pipette is a time-consuming, labor-intensive process. Automating this procedure reduces contamination and eliminates human errors.

To satisfy the requirements of an application such as this requires a custom-manufactured LED light source, with a wavelength chosen to best interact with the fluids, and an extremely small, concentrated light emission that approaches laser-like properties (yet without the expense and power requirements of the laser). This light source verifies pipette presence and dispensing levels, with a quality check of the fluids dispensed down to the nanoliter scale.

So, the next time you face an application challenge that cannot be tackled with a standard sensor, consider a higher precision sensor and rest assured you will get the reliability you demand.

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Simplified Sensing Over a Complex Headache

The constant need for more data and higher accuracy has pushed sensing technologies to the extreme. Advancements in factory automation have created a perfect storm of innovation and new capabilities. This is probably an unpopular opinion but, do we always need all of this?

I started my career in factory automation in the late 90s. This was a time of technology transitions. PLCs had been around for ages but had never been so affordable. Technologies, such as time-of-flight laser measurement, industrial cameras, and inductive coupling, were new and exciting, and they were becoming more affordable, too.

As a controls engineer, I remember using these advanced technologies and systems as a way of keeping my projects future-proof – or so I thought. In reality, sometimes they just made things more complicated.

Let me explain this using an example where tried, true and affordable sensors could have made the project more reliable and future-proof from the start.

Photoelectric sensors have earned their place in the automation hall of fame. I don’t see a time when their use will not be necessary as a reliable way to conduct presence detection.

I was working on a project that required tracking several washing machine cabinet bases to be counted and orientated correctly on a conveyor. I wanted to use an industrial camera because the technology was getting better and better. I paid $7,000  for the camera and accessories. After several days and iterations, the camera system was working perfectly.  It continued working for about a week before it was knocked out of alignment by a production worker who was using it as a leaning post. It took another day or so to dial back in.

Tried, true and affordable win out

The solution I ultimately chose was the easiest. I strategically placed seven basic photoeyes underneath the conveyor to identify what base it was looking at and if certain characteristics were present for quality tracking. My investment was around $400, and it was extremely protected from failure. And, if a sensor went out, rather than calling an engineer in the middle of the night, a maintenance electrician could simply replace it with a new one.

Another huge benefit of using photoeyes was the avoidance of buyer’s remorse. Camera technology is always evolving. From one day to the next they get better and more capable, but also might have proprietary comms or software. Basic photoelectric sensors with a PNP or NPN output can easily be swapped out by almost any brand for decade to come.

Keep it simple

At the end of the day, sometimes it is best to keep the solution simple, clean, and backed by the tried-and-true technologies in factory automation. Next time you dig into a project, take a moment to think about my example. Melt the solution down to the lowest common denominator and build up the complexity from there. You might just save more than just money; you might save a headache or two.

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Detecting Fill Levels With Direct Contact and Non-contact Capacitive Sensors

Capacitive sensors are commonly used in level detection applications. Specific capacitive sensors can supply better solutions than others depending on the type of media you may be detecting and if the sensor will be in direct contact with that media. Keep reading to decide which type works best for different application solutions.

Non-contact capacitive sensors

Capacitive sensors are great for monitoring the fill level of non-conductive materials. In many cases, the capacitive sensor doesn’t need to physically touch the media it is detecting; rather, it can sit outside a thin, non-metal container or pipe. As the level rises or falls, the capacitive sensor can signal if the medium is there. Since non-contact capacitive sensors sit outside the medium, there shouldn’t be any interference or false readings from direct contact with the material.

Selecting the correct capacitive sensor for these applications is important. While you don’t have to risk contaminating the sensor face (and getting a false read) in non-contact applications, you need to keep in mind other factors that can cause a sensor to false trip. One thing that is important to keep in mind with externally mounted capacitive sensors is that viscous materials can still leave a layer of residue on the inside walls of tanks or basins. While the sensor face is not covered, if you select the wrong type of sensor this build up on the wall can cause a false reading (such as reading as reading the tank as full when it is actually half-empty).

Another thing to keep in mind when selecting the correct capacitive sensor for a non-contact application is foam. In applications such as bottling beer in glass bottles, most standard capacitive sensors will detect presence once that layer of foam reaches the sensor face. While the foam may be at the sensor face, the bottle could still be only half way full of actual liquid. Making sure you select a sensor that can account for things like foam is something to keep in mind as well.

There are many benefits when using non-contact capacitive sensors in fill level applications. Not every application requires direct contact with the medium, and not every application even allows for the medium to be touched directly. There are many capacitive sensors in many form factors that are used every day for fill level applications, but making sure the right sensor is selected is important.

Contact with media capacitive sensors

In certain applications, the capacitive sensor will only be able to detect the fill level of a container, pipe, or tank if it is in direct contact with the media it’s trying to sense.

For various reasons, a sensor must be in direct contact with a media like oil, paint, powder, or paste. You may need to place a sensor directly in a tank because the tank is made of metal, or possibly because the walls of the tank are too thick for a capacitive sensor to sense through. Direct contact applications can be difficult to find solutions for if you are not aware of what capacitive sensors are capable of.

There is a way to fix issues such as false tripping in sticky substances.

Advanced technologies allow for capacitive sensors that mask residual build-up or foam when sensing in direct media contact. These level-sensing capacitive sensors are great for applications in the food and beverage industry and for detecting practically all the same materials as non-contact capacitive sensors. In areas of detection where adhesive substances may stick to the sensor face is a perfect application for direct contact capacitive sensors. Some typical direct-contact applications include areas such as vegetable oil or ketchup container fill levels, hydraulic oil levels in a hydraulic cylinder, or even the amount of flour in a container.

For instance, if you stick a capacitive sensor inside a tank of oil to monitor the fill level, the sensor face will get covered in the oil. As the level in the tank drops below the sensor face, that oil will remain on the face. So, even if the tank is empty, the sensor will always detect something. With specialized capacitive sensors that ignore build-up, adhesive or viscous media that typically influence detection is no longer a concern.

Another use for capacitive sensors that allow for direct media contact is for leak detection. If a tank, pipe, or tub is known to leak, there are capacitive sensors that can be mounted to the ground in the area that puddles form. In some instances you know a machine could potentially leak, and puddles form in an area you can’t regularly see, which is where these sensors are perfect for application. Depending on the situation, some of these sensors can be mounted a couple millimeters to an inch off the ground waiting for a leak. As a puddle forms and reaches the sensor’s switching range, maintenance can be alerted of the issue and work to fix it.

Reduce time and costs associated with manual level-checking

Another application for a capacitive sensor with direct media contact capabilities is within the automotive industry. Inside the painting process of an assembly plant, for example, you must be able to monitor the fill levels of the e-coat, the primer, the base coat, and the clear-coat paint tanks. Without a sensor to determine the fill levels, the time and energy and dollars it can cost the workforce to manually check the fill levels can be high.. Luckily, these contact-capacitive sensors can monitor viscous media like paint, reducing the time and costs associated with manual level-checking.

While non-contact and contact capacitive sensors perform the similar functions, they are used in different applications. Some applications allow a sensor to sit outside a container or tank and detect through the walls, while others require direct contact. Now that you understand the differences and their strong points of application, you can determine which sensor is best for you.

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Choosing the Right Sensor for Measuring Distance

Distance-measuring devices help with positioning, material flow control, and level detection. However, there are several options to consider when it comes to choosing the correct sensor technology to measure distance. Here I’ll cover the three most commonly used types in the industrial automation world today, including photoelectric, ultrasonic, and inductive.

Photoelectric sensors

Photoelectric sensors use a light source, such as a laser or light-emitting diode, to reflect the light off an object’s surface to calculate the distance between the face of the sensor and the object itself. The two basic principles for how the sensor calculates the distances are the time of flight (TOF) and triangulation.

    • Time of flight photoelectric distance measurement sensors derive the distance measurement based on the time it takes the light to travel from the sensor to the object and return. These sensors are used to measure over long distances, generally in the range between 500 millimeters and up to 5 meters, with a resolution between 1 to 5 millimeters, depending on the sensor specifications. Keep in mind that this sensor technology is also used in range-finding equipment with a much greater sensing range than traditional industrial automation sensors.

    • In the triangulation measurement sensor, the sensor housing, light source, and light reflection form a triangle. The distance measurement is based on the light reflection angle within its sensing range with high accuracy and resolution. These sensors have a much smaller distance measurement range that is limited to between 20 and 300 millimeters, depending on the sensor specifications.

The pros of using photoelectric distance measurement sensors are the range, accuracy, repeatability, options, and cost. The main con for using photoelectric sensors for distance measurement is that they are affected by dust and water, so it is not recommended to use them in a dirty environment. The object’s material, surface reflection, and color also affect its performance.

Photoelectric distance measurement sensors are used in part contouring, roll diameter measurement, the position of assemblies, thickness detection, and bin-level detection applications.

Ultrasonic sensors

Ultrasonic distance sensors work on a similar principle as photoelectric distance sensors but instead of emitting light, they emit sound waves that are too high for humans to hear, and they use the time of flight of reflecting sound wave to calculate the distance between the object and the sensor face. They are insensitive to the object’s material, color, and surface finish. They don’t require the object or target to be made of metal like inductive position sensors (see below). They can also detect transparent objects, such as clear bottles or different colored objects, that photoelectric sensors would have trouble with since not enough light would be reflected back to reliably determine the distance of an object. The ultrasonic sensors have a limited sensing range of approximately 8 meters.

A few things to keep in mind that negatively affect the ultrasonic sensor is when the object or target is made of sound-absorbing material, such as foam or fabric, where the object absorbs enough soundwave emitted from the sensor making the output unreliable. Also, the sensing field gets progressively larger the further away it gets from the sensing face, thus making the measurement inaccurate if there are multiple objects in the sensing field of the sensor or if the object has a contoured surface. However, there are sound-focusing attachments that are available to limit the sensing field at longer distances making the measurements more accurate.

Inductive sensors

Inductive distance measurement sensors work on the same principle as inductive proximity sensors, where a metal object penetrating the electromagnetic field will change its characteristics based on the object size, material, and distance away from the sensing face. The change of the electromagnetic field detected by the sensor is converted into a proportional output signal or distance measurement. They have a quick response time, high repeatability, and linearity, and they operate well in harsh environments as they are not affected by dust or water. The downside to using inductive distance sensors is that the object or target must be made of metal. They also have a relatively short measurement range that is limited to approximately 50 millimeters.

Several variables exist to consider when choosing the correct sensor technology for your application solution, such as color, material, finish, size, measurement range, and environment. Any one of these can have a negative effect on the performance or success of your solution, so you must take all of them into account.

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Choosing a Contactless Sensor to Measure Objects at a Distance

Three options come to mind for determining which contactless sensor to use when measuring objects at a distance: photoelectric sensors, ultrasonic sensors, and radar detection. Understanding the key differences among these types of technologies and how they work can help you decide which technology will work best for your application.

Photoelectric sensor

The photoelectric sensor has an emitter that sends out a light source. Then a receiver receives the light source. The common light source LED (Light Emitting Diodes), has three different types:

    • Visible light (usually red light) has the shortest wavelength, but allows for easy installment and alignment as the light can be seen.
    • Lasers are amplified beams that can deliver a large amount of energy over a distance into a small spot, allowing for precise measurement.
    • Infrared light is electromagnetic radiation with wavelengths longer than visible light, generally making them invisible to the humans. This allows for infrared to be used in harsher environments that contain particles in the air.

Along with three types of LEDs, are three models of photoelectric sensors:

    • The retro-reflective sensor model includes both an emitter and receiver in one unit and a reflector across from it. The emitter sends the light source to the reflector which then reflects the light back to the receiver. When an object comes between the reflector and the emitter, the light source cannot be reflected.
    • The through-beam sensor has an emitter and receiver in two separate units installed across from the emitter. When an object breaks the light beam, the receiver cannot receive the light source.
    • The diffuse sensor includes an emitter and receiver built into one unit. Rather than having a reflector installed across from it the light source is reflective off the object back to the receiver.

The most common application for photoelectric sensors is in detecting part presence or absence. Photoelectric sensors do not work well in environments that have dirt, dust, or vibration. They also do not perform well with detecting clear or shiny objects.

Ultrasonic sensor

The ultrasonic sensor has an emitter that sends a sound wave at a frequency higher than what a human can hear to the receiver.  The two modes of an ultrasonic sensor include:

    • Echo mode, also known as a diffused mode, has an emitter and receiver built into the same unit. The object detection works with this mode is that the emitter sends out the sound wave, the wave then bounces off the target and returns to the receiver. The distance of an object can be determined by timing how long it takes for the sound wave to bounce back to the receiver.
    • The second type of mode is the opposed mode. The opposed mode has the emitter and receiver as two separate units. Object detection for this mode works by the emitter will be set up across from the receiver and will be sending sound waves continuously and an object will be detected once it breaks the field, similarly to how photoelectric sensors work.

Common applications for ultrasonic sensors include liquid level detection, uneven surface level detection, and sensing clear or transparent objects. They can also be used as substitutes for applications that are not suitable for photoelectric sensors.

Ultrasonic sensors do not work well, however, in environments that have foam, vapors, and dust. The reason for this is that ultrasonic uses sound waves need a medium, such as air, to travel through. Particles or other obstructions in the air interfere with the sound waves being produced. Also, ultrasonic sensors do not work in vacuums which don’t contain air.

Radar detection

Radar is a system composed of a transmitter, a transmitting antenna, a receiving antenna, a receiver, and a processor. It works like a diffuse mode ultrasonic sensor. The transmitter sends out a wave, the wave echoes off an object, and the receiver receives the wave. Unlike a sound wave, the radar uses pulsed or continuous radio waves. These wavelengths are longer than infrared light and can determine the range, angle, and velocity of objects. radar also has a processor that determines the properties of the object.

Common applications for radar include speed and distance detection, aircraft detection, ship detection, spacecraft detection, and weather formations. Unlike ultrasonic sensors, radar can work in environments that contain foam, vapors, or dust. They can also be used in vacuums. Radio waves are a form of electromagnetic waves that do not require a transmission medium to travel. An application in which radar does not perform well is detecting dry powders and grains. These substances have low dielectric constants, which are usually non-conductive and have low amounts of moisture.

Choosing from an ultrasonic sensor, photoelectric sensor, or radar comes down to the technology being used. LEDs are great at detecting part presences and absence of various sizes. Sound waves are readily able to detect liquid levels, uneven surfaces, and part presence. Electromagnetic waves can be used in environments that include particles and other substances in the air. It also works in environments where air is not present at all. One technology is not better than the other; each has its strengths and its weaknesses. Where one cannot work, the others typically can.