High-Precision OFDM-Based Multiple Ultrasonic Transducer Positioning Using a Robust Optimization Approach

Ultrasonic positioning systems (UPSs) are used for various types of applications across a wide variety of fields, including robot navigation, device location, and pose estimation. In this paper, the focus is on investigating two major problems in the signaling and positioning the phases of existing UPSs and providing corresponding solutions. First, most of the existing UPSs use a single tone or a narrowband chirp signal for positioning, which suffer from multiple access due to signal interference. Second, if all reference points are placed in a single plane, which is logistically simpler for indoor applications and their distance from the target is larger than the distance between them, which is likely to happen, produced large dilution of precision errors when using lateration for position estimation. In this paper, first, to solve the multiple access problem, a narrowband orthogonal division-multiplexing signal, which can efficiently utilize the entire available frequency spectrum, is proposed. Second, a robust optimization approach for not only overcoming the limitation of the lateration algorithm but also ignoring errors in the distance measurements of the receivers corresponding to one complete cycle of the transmitted signal is proposed. The experimental results show that the proposed system has the precision required for high accuracy applications, and its cost and complexity are anticipated to be lower than those of alternative traditional optical systems.