How to Use the DYA-21-G Ultrasonic Transducer for Indoor Positioning

Indoor positioning is an application that has emerged in recent years. How can ultrasonic transducers be used for indoor positioning? Here we take a recent experiment conducted by a university using the DYA-21-G ultrasonic transducer as an example and give a brief introduction.

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Figure 1: The DYA-21-G horizontal omnidirectional air transducer used as the transmitting source

The test site was an indoor space of approximately 20×30 meters, with a ceiling height of about 3.5 meters. On the ground there was an automatically moving cart, measuring 1 meter × 0.6 meters in length × width. The DYA-21-G horizontal omnidirectional air transducer was placed flat on the cart as the transmitting source. Depending on the experimental requirements and the size of the cart, multiple transducers can be placed. While the cart is moving, the DYA-21-G air transducer continuously emits ultrasonic waves at around 21 kHz, transmitting toward the ceiling in a 180-degree emission pattern.

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Figure 2 Schematic diagram of the indoor positioning experiment cart in operation

To achieve the indoor positioning effect, when the cart moves to any given position, at least 3 receiving transducers must be able to receive the ultrasonic waves emitted by the DYA-21-G ultrasonic transducer. Therefore, density must be considered when arranging the receiving transducers on the ceiling. The site was 30 meters wide and 20 meters long, and the schematic diagram of the transducers arranged on the ceiling is as follows:

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Figure 3 Schematic diagram of the distribution of receiving transducers for ceiling positioning

The distribution of receiving transducers for ceiling positioning can be adjusted according to the emission angle of the transmitting transducer. Generally speaking, the larger the emission angle, the fewer receiving transducers are required.
To improve positioning accuracy, a transmitting antenna can be added to the cart to synchronously transmit signals. When the transmitting transducer emits, the antenna broadcasts the transmission time, allowing the receiving transducers on the ceiling to receive the transmission time, thereby improving positioning accuracy.