Ultrasonic sensors are used for a wide range of detection tasks in the industrial environment. For example, for detecting objects with diverse aggregate states: solid, liquid, granular, color-changing, transparent, or high-gloss.

Toposens (Munich, Germany) has developed advanced ultrasonic sensors that use sound to support robust, low-cost, and precise short-range 3D vision for emerging technologies, such as autonomous driving, robotics, and smart buildings. Unlike existing sensor technologies that can be negatively impacted by light conditions, reflections, and weather, Toposens sensors use echolocation to generate robust, real-time 3D echo location data to guide autonomous systems across a variety of applications. The performance of ultrasonic sensors is particularly robust in harsh environments, as they are extremely dirt tolerant and their reliability is not affected by dust, smoke, mist or similar.

Currently available ultrasonic sensors have the problem that they can only perform tasks in one-dimensional space. This means, that if the localization task requires sensors that measure, object positions and distances in three-dimensional space, ultrasonic sensors are no longer suitable for the application.

Toposens wants to change this now. The company has developed an ultrasonic sensor that locates multiple objects and measures their distances in three-dimensional space. With the 3D ability of the sensor, the technology is no longer confined to the typical applications for currently available ultrasonic sensor technologies such as filling level or distance measurement — whole areas can be observed.

Figure 2. Vehicles can use 3D ultrasound to recognize their close-range environment. (Image courtesy of Toposens)

These sensors will improve autonomous technologies in the industrial environment like AGVs or forklifts and make machines and everyday work safer and more efficient.

What Makes 3D Ultrasound Technology Different From Conventional Ultrasonic Sensors?

For distance measurement, a typical ultrasonic sensor uses a transducer to periodically send out pulses. These pulses get reflected from objects in the detection area of the sensor and are then returned to it. By measuring the time it takes the pulse to travel to the object and back to the sensor, the distance to the object can be calculated. This principle is called time-of-flight (ToF) measurement.

In addition to measuring the distance to an object, Toposens' technology also calculates the horizontal and vertical position of an object relative to the sensor itself — it provides 3D coordinates for the reflected echoes. The localization of objects in three-dimensional space also allows multiple objects to be detected in a single scan. In that sense, the principle behind the 3D ultrasonic technology is similar to the echolocation used by bats.

In comparison, an ordinary ultrasound sensor will normally only give the distance to the nearest object. Because of this, a limited opening angle is usually applied for this type of sensor. In contrast, the Toposens sensor systems allow for opening angles of up to 140°. Due to the quadratic damping of the ultrasonic pulses as they travel through the air, the sensor is especially suited for object detection at close-range distances.

Capabilities of 3D Ultrasound for Autonomous Vehicles in Industrial Environments

Autonomous technologies in industrial environments for example, forklifts or AGVs, are typically equipped with a wide range of sensors to ensure a smooth, safe, and reliable workflow. However, there are still accidents and work delays every day, as these technologies generally have problems with close-range detection — for example objects that suddenly appear.

Figure 3. Noise cancellation in an observed scene. (Image courtesy of Toposens)

Since 3D ultrasound technology is designed to detect objects and obstacles at distances of up to five meters, by using the positions of the detected echoes, the vehicles can use just ultrasound to recognize their close-range environment.

The 3D ultrasonic technology operates by transmitting at a pre-configured frequency and listening for corresponding echoes reflected from objects in the immediate surroundings. These echoes are received by an array of microphones that convert membrane vibrations into electrical signals, which are subsequently sampled by an analog-to-digital converter (ADC). The technology uses digital signal processing functions that are particularly optimized for its architecture to calculate location of the echo.

Toposens uses a proprietary microphone layout to reliably calculate the 3D location of each echo. In addition, the signal strength of each reflection is also available for post-processing functions. This enables autonomous technologies to create a 3D point cloud of warehouses or other industrial environments.

Path and Trajectory Prediction With 3D Ultrasound Technology

Figure 4. Beacon-based 3D tracking system. (Photo courtesy of Toposens)

Through the filtering and clustering of point cloud data, static objects in the scene can be ignored and new objects that enter the observed scene can be tracked in real time. The trajectory of these tracks allows the technology to infer whether objects or people are likely to enter an area of interest in the observed scene

The system, which consists of a receiver and at least one sender is controlled by the receiver unit. To start the tracking process, the receiver sends a trigger via Bluetooth to the sender, which then sends out an ultrasonic pulse. When the receiver detects the ultrasound pulse, the 3D coordinates of the sender are calculated using a patented algorithm and the data is output via USB or UART. In the current development state, the tracking system offers an accuracy of ±30 mm when the distance between the sender and receiver is 10 m.

This functionality was tested in an elevator application. By training an observed scene and clustering the points that do not belong to this scene, the elevator doors were prevented from closing on people.

The system can of course also be used in the industrial sectors. For example, in freight elevators, but also in all other applications wherever areas need to be observed.

Further Applications

Since the possible applications for 3D ultrasonic technology are so diverse, the next logical step was to further develop the system for other applications. Therefore, Toposens started to develop a 3D beacon-based tracking system based on their ultrasound technology. The 3D tracking system can output 3D coordinates based on ultrasound with a single receiver and at least one beacon. This enables a multitude of new applications in the industrial area.

With the help of the tracking system, machine safety, as well as the safety of the workers can be improved. If, for example, machines or autonomous technologies and workers are equipped with the tracking system, an automatic switch-off can be guaranteed if a person comes dangerously close to running machines or vehicles.

But not only can work safety be increased due to the high accuracy of the tracking system in close-range distances, autonomous technologies can for example, dock with millimeter accuracy at charging stations or other locations.

Cutting-Edge Sensor Technology Is Needed for the Future Of Industrial Advancement

There is no doubt that technologies in the industrial environment as well as in other areas will have to be made safer and more efficient in the future. There will be a great demand for reliable, robust, and cost-efficient sensor solutions.

With the Toposens' sensor technology, further applications in the industrial sector can be opened in the future. All this based on their already established and reliable ultrasonic technology.

This article was written by Andreas Just, Head of Marketing at Toposens GmbH (Munich, Germany). You can contact Mr. Just at This email address is being protected from spambots. You need JavaScript enabled to view it. or visit here .

Sensor Technology Magazine

This article first appeared in the September, 2020 issue of Sensor Technology Magazine.

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