Tag Archives: Ultrasonic Sensors

Ultrasonic Sensors in IoT

For sensing, it has been a standard practice to employ ultrasonic sensors. This is mainly due to their exceptional capabilities, low cost, and flexibility. With IoT or the Internet of Things now virtually entering most industries and markets, one can now find ultrasonic sensors in newer applications in healthcare, industrial, and smart offices and homes.

As their name suggests, ultrasonic sensors function using sound waves, especially those beyond the hearing capability of humans. These sensors typically send out chirps or small bursts of sound in the range of 23 kHz to 40 kHz. As these chirps bounce back from nearby objects, the sensor detects them. It keeps track of the time taken by the chirp for a round trip and thereby calculates the distance to the object based on the speed of sound.

There are several benefits from using ultrasonic sensors, the major one being very accurate detection of the object. The effect of material is also minimal—the sensor uses sound waves and not electromagnetic waves—the transparency or color of the object has minimum effect on the readings. Additionally, this also means that apart from detecting solid objects, ultrasonic sensors are equally good at detecting gases and liquid levels.

As ultrasonic sensors do not depend on or produce light during their operation, they are well-suited for applications that use variable light conditions. With their relatively small footprints, low cost, and high refresh rates, ultrasonic sensors are well-established over other technologies, like inductive, laser, and photoelectric sensors.

According to a recent study, the smart-office market will likely reach US$90 billion by 2030. This is mainly due to a surging demand for sensor-based networks, brought about by the need for safety and advancements in technology. Ultrasonic sensors will be playing an expanded role due to industry and local regulations supporting increased energy efficiency for automating different processes around the office.

A prime example of this is lighting and HVAC control in offices. Ultrasonic sensors are adept at detecting populated rooms in offices all through the day. This data is useful in programming HVAC systems, for keeping rooms hot or cool when populated, and turning the system off at the end of the day, kicking back on at first arrival.

Similarly, as people enter or leave rooms or areas of the office, ultrasonic sensors can control the lights automatically. Although the process looks simple, the energy savings from cutting back on lighting and HVAC can be huge. This is especially so for large office buildings that can have many unoccupied office spaces. For sensing objects across large areas, ultrasonic sensors offer ideal solutions, with detecting ranges of 15+ meters and detecting beam angles of >80°.

Additionally, smart offices can also have other smart applications like hygiene and touchless building entry devices. Touchless devices include automatic door entries and touchless hygiene products include faucets, soap dispensers, paper towel dispensers, and automatically lifting waste bin lids. During the COVID-19 pandemic, people’s awareness of these common applications has increased as public health and safety became critical for local offices and businesses.

Protecting Pedestrians Using Ultrasound Techniques

With vehicular traffic increasing on the roads, pedestrians are shifting to the status of endangered species. Frequent news reports of pedestrians falling victims to collisions with motor vehicles bear testimony to the statement. Now, researchers want to provide a remedy. At the Frankfurt University of Applied Sciences or FRA-UAS, researchers have developed a pedestrian detection sensor that can differentiate a human being from among inanimate matter.

At FRA-UAS, Professors Andreas Pech and Peter Nauth have developed the pedestrian detection system utilizing highly sensitive and efficient ultrasonic sensors. It can discriminate a human being from an object in areas where a collision is likely. Typically, vehicles use such highly cost-effective ultrasonic sensors at their rear to help in parking. The researchers have added an algorithm for recognizing patterns from the signals coming from these sensors. The algorithm, the actual innovation from the researchers, generates a situational analysis within half of a second. This is then used to activate specific protection systems.

In a collision situation, there can be two possibilities. The first could be a vehicle-to-vehicle collision, where the system activates airbags and belt pre-tensioners as it detects an imminent collision with another vehicle. However, if the system determines that the collision situation involves a pedestrian and not a vehicle, it initiates measures that will reduce the impact. These measures could vary, such as, heightening the bonnet to mitigate the impact, providing an exterior airbag to be deployed prior to collision or even reducing the rigidity of the body of the vehicle.

According to the researchers, this pedestrian detection system is relatively more cost-effective in comparison to other systems available in the market. It is possible to retrofit this system even in lower priced vehicles. Moreover, such a pedestrian detection system is also useful in other areas of application. For example, in case of a building fire, where smoke detectors trigger fire alarms, the pedestrian detection system from FRA-UAS can help to locate human beings trapped inside the burning house or apartment.

Application of such a pedestrian detection system can be seen in the crosswalk flasher system installed at the Weaver Lake Elementary School in Maple Grove, Minnesota. The school added the automatic detection system to increase the safety of children who occasionally forget to push the button to activate a flashing beacon before starting to cross the road. The pedestrian detection system uses ultrasonic sensors for detecting the presence of pedestrians waiting at the curb and automatically activates a flashing beacon to alert the approaching vehicles to the presence of the pedestrian.

Ultrasonic detectors emit sound waves of frequency ranging beyond the hearing capabilities of humans. In the presence of moving pedestrians or vehicles, part of the transmitted sound waves reflects back to the receiver. The associated electronics computes the distance and speed of the object from the time and strength of the reflected signal. Ultrasonic detectors detect objects as far away as 30 feet.

The amount of sound energy reflected from the pedestrian depends on the nature of clothes the person is wearing. It also depends on the temperature, pressure, humidity and wind speed at the location.