Description:FORM – 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
(SEE SECTION 10, RULE 13)

SYSTEM AND METHOD FOR ACOUSTIC POSITIONING AND TRACKING FOR 3D LOCALIZATION

PLANYS TECHNOLOGIES PRIVATE LIMITED A MICRO, SMALL, AND MEDIUM ENTERPRISES REGISTERED UNDER THE LAWS OF INDIA, WHOSE ADDRESS IS NO. 5 JAYA NAGAR EXTENSION, BALAJI NAGAR MAIN ROAD, G.K. AVENUE, PUZHUTHIVAKKAM, CHENNAI, TAMIL NADU - 600091, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates generally to underwater acoustic positioning and tracking for 3D localization. More specifically, to acoustic positioning and tracking for 3D localization in a reflective environment.

BACKGROUND OF THE INVENTION

[0002] The field of positioning systems for underwater applications has evolved significantly over recent years as industries increasingly require accurate spatial data in challenging environments. In many sectors including industrial inspection and subsea operations, there is a growing need to determine precise positions of objects in acoustically complex or GPS-restricted areas. Various techniques have been utilized to provide location information; however, environments where access is limited, and signal paths are altered by reflective surfaces that are difficult to predict present challenges that are not encountered in more conventional settings. These challenges highlight the importance of developing robust approaches that can operate effectively without the need for extensive modifications to the existing infrastructure.

[0003] In applications where accurate localization is incredibly important, especially in confined, reflective underwater spaces, the primary goal is to achieve reliable and real-time positioning. This becomes particularly significant when deploying systems that are designed to operate without physical alterations inside the area of interest. Industries that rely on timely and accurate data for monitoring or navigating underwater entities benefit from solutions with enhanced adaptability. The overall objective is to ensure that positioning tasks are executed with both safety and efficiency, even in circumstances where traditional methods struggle to offer consistent results.

[0004] Conventional positioning techniques have faced recurring challenges when deployed in environments characterized by significant signal reflections and interference. As system architectures become more complex, these challenges contribute to ambiguous signal interpretations and diminished accuracy. Limitations can arise from inconsistent signal propagation, interference caused by reflections, multipath effects, and the inability to deploy sensors inside restrictive spaces. Such issues often lead to compromised system performance, which is unacceptable in applications demanding elevated levels of precision and reliability.

[0005] In some enclosed or heavily reflective underwater environments, specific obstacles further complicate the localization process. In these confined spaces, the inability to modify or prepare the interior for sensor deployment amplifies the difficulties faced by existing solutions. Signal distortions induced by reflective surfaces and complex acoustic pathways often result in inconsistent and unreliable measurements. This situation highlights the importance of advancing positioning technologies that can adapt to these demanding conditions, enabling accurate and dependable localization even in challenging operational scenarios.

[0006] The following are typical positioning systems available in the market today.
- GNSS: Communication with satellites to get position updates.
- Acoustic systems: Uses time-of-arrival and direction-of-arrival information of acoustic signals to determine location of target.
- Inertial positioning: Uses sensors measuring pose and acceleration to estimate movement and calculate position.
- RADAR/LIDAR – Uses time-of-flight of electromagnetic signals to determine distance.
- Direct field measurement: Using earth’s gravitational and magnetic fields to determine orientation.
- Visual positioning: Using markers on the target to determine position and orientation.

[0007] However, in enclosed spaces, the above methods will face difficulties.
- GNSS: Satellite communication will be disrupted indoors.
- Inertial: While the environment does not matter, the accuracy of this technique depends heavily on the quality of the sensors used and the post processing algorithms.
- RADAR/LIDAR: These systems can be used for localization but are more suited for obstacle detection. Scanning systems can also be extremely expensive.
- Direct field: The Earth’s magnetic field can be distorted inside enclosed spaces and is not useful. The gravitational field on its own is not useful here.
- Visual positioning: Obtaining a position estimate through vision based systems would typically require the use of fiducial markers, however, it is not feasible in some environments to place those markers ahead of time. Visibility is also poor due to lack of sufficient lighting.
- Acoustic: Ultra-short baseline and short baseline systems, and other systems that rely on signal time of flight have lower accuracy inside tanks due to interference from reflected signals. These signals that may be distorted in certain environments.

[0008] Further, in a wide range of industrial and environmental applications, there is a strong desire for positioning solutions that enable precise and real-time location determination. Accurate spatial data plays an important role in achieving operational efficiency and safety in activities such as industrial inspections and autonomous navigation. These applications frequently occur in settings where direct access for sensor placement is restricted.

[0009] Accordingly, there exists a significant need for a system and method for acoustic positioning and tracking for 3D localization in a reflective environment that facilitate developing robust approaches that can operate effectively without the need for extensive modifications to the existing infrastructure while ensuring that position estimates are both timely and precise, thereby addressing important operational requirements in challenging settings.

SUMMARY OF THE INVENTION

[0010] This summary is provided to introduce concepts of the present invention. This summary is neither intended to identify essential features of the present invention nor is it intended for use in determining or limiting the scope of the present invention.

[0011] In one aspect, the present invention provides a system for acoustic positioning and tracking for 3D localization in a reflective environment. The system facilitates developing robust approaches that can operate effectively without the need for extensive modifications to the existing infrastructure while ensuring that position estimates are both timely and precise.

[0012] The system for acoustic positioning and tracking for 3D localization comprises a multi frequency pinger placed in a storage tank to be localized, the multi frequency pinger configured to emit bursts of an ultrasound signal at a predetermined power and frequency at a preset constant rate, one or more ultrasound receivers engaged with the storage tank at a predetermined location, the one or more ultrasound receivers configured to receive the ultrasound signal from the multi frequency pinger and convert the ultrasound signal into an electrical signal; a signal conditioning module connected to the one or more ultrasound receivers, the signal conditioning module configured to receive the electrical signal from the one or more ultrasound receivers and further configured to amplify, filter and rectify the received electrical signal to generate a conditioned signal; a data acquisition module connected to the signal conditioning module, the data acquisition module configured to digitize the conditioned signal received from the signal conditioning module with time and amplitude resolution; and a signal post processing module connected to the data acquisition module, the signal post processing module configured to receive the digitized signal from the data acquisition module and further configured to perform onset detection and 3D position estimation of the multi frequency pinger and visualize the estimated 3D position to an operator.

[0013] Preferably, the multi frequency pinger is mounted on a remotely operated vehicle suspended inside the storage tank to be localized.

[0014] Further, the power and frequency of the multi frequency pinger is selected based on a reflective environment’s material properties inside the storage tank.

[0015] Furthermore, the one or more ultrasound receivers are acoustic and/or contact transducers mounted on the surface of the circumference of the storage tank with magnets or an adhesive and coupled to the storage tank with couplant for maximum signal transmission or the one or more ultrasound receivers are a hydrophone suspended externally on the structure.

[0016] Additionally, for onset detection and 3D position estimation of the multi frequency pinger, the signal post processing module calculates a time of arrival of the multi frequency pinger at the one or more ultrasound receivers based upon the received digitized signals, estimate the position of the multi frequency pinger based on a time difference of arrival of the signal at multiple receivers and return the estimated position and in the form of visualization as a map to the operator.

[0017] In another aspect, the present invention provides a method for an acoustic positioning and tracking for 3D localization in a reflective environment. The method for acoustic positioning and tracking for 3D localization in a reflective environment facilitates developing robust approaches that can operate effectively without the need for extensive modifications to the existing infrastructure while ensuring that position estimates are both timely and precise.

[0018] The method comprises the following steps: placing a multi frequency pinger in a storage tank to be localized to emit bursts of an ultrasound signal at a predetermined power and frequency at a preset constant rate; receiving, by one or more ultrasound receivers engaged with the storage tank, the ultrasound signal from the multi frequency pinger; converting, by the one or more ultrasound receivers, the ultrasound signal received from the multi frequency pinger into an electrical signal; generating, by a signal conditioning module, a conditioned signal by amplifying, filtrating and rectifying on the electrical signal; digitizing, by a data acquisition module, the conditioned signal received from the signal conditioning module with time and amplitude resolution; performing, by a signal post processing module, onset detection and 3D position estimation of the multi frequency pinger and visualizing the estimated 3D position to an operator.

[0019] Further, the step of performing onset detection and 3D position estimation of the multi frequency pinger further comprises the steps of: estimating, by the data acquisition module, a signal frequency and power of the multi frequency pinger, estimating, by a data acquisition module, pre-amplification parameters of one or more ultrasound receivers; calibrating and validating, by the data acquisition module, by placing an acoustic source at a known location; initiating the signal post processing module for processing and visualization of the digitized signal; estimating, by the signal post processing module, time of arrival of the multi frequency pinger at the one or more ultrasound receivers based upon the received signals and simultaneously saving data corresponding to the time of arrival of the multi frequency pinger to log; estimating, by the signal post processing module, the position of the multi frequency pinger based on the time difference of arrival of the signal at plurality of receivers; visualizing the estimated position as a map to the operator.

[0020] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

[0021] The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference like features and modules.

[0022] Figure 1 illustrates a schematic diagram of system for acoustic positioning and tracking for 3D localization in a reflective environment, showing the primary components of the system, according to an exemplary embodiment of the present invention.

[0023] Figure 2 illustrates a schematic flow chart diagram of the process flow for estimating the position of a pinger in a reflective underwater environment, according to an exemplary embodiment of the present invention.

[0024] Figure 3 illustrates a schematic diagram of the system setup for 3D localization of a pinger in a reflective underwater environment, according to an exemplary embodiment of the present invention.

[0025] Figure 4 illustrates a schematic diagram of an ultrasound receiver with a magnetic mount for external deployment, according to an exemplary embodiment of the present invention.

[0026] Figure 5A and Figure 5B illustrate sample acquired signal data and processed data showing the estimated position of the pinger respectively, according to an exemplary embodiment of the present invention.

[0027] Figure 6 illustrates a schematic representation of sample results showing the pinger's position at two separate locations relative to a fixed receiver setup, according to an exemplary embodiment of the present invention.

[0028] Figure 7 illustrates a flowchart of overall method of acoustic positioning and tracking for 3D localization in a reflective environment, according to an exemplary embodiment of the present invention.

[0029] Figure 8 illustrates a flowchart of onset detection and 3D position estimation of the multi frequency pinger, according to an exemplary embodiment of the present invention.

[0030] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative methods embodying the principles of the present invention. Similarly, it will be appreciated that any flow charts, flow diagrams, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The various embodiments of the present invention describe a system and method for acoustic positioning and tracking for 3D localization in a reflective environment.

[0032] In the following description, for the purpose of explanation, specific details are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these details. One skilled in art will recognize that embodiments of the present invention, some of which are described below, may be incorporated into a number of systems.

[0033] However, the systems and methods are not limited to the specific embodiments described herein. Further, the structures and devices shown in the figures are illustrative of exemplary embodiments of the presently invention and are meant to avoid obscuring of the presently invention.

[0034] It should be noted that the description merely illustrates the principles of the present invention. It will thus be appreciated that those skilled in art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present invention. Furthermore, all examples recited herein are principally intended expressly to be only for explanatory purposes to help the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering art and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0035] In one aspect, the present invention provides a system for an acoustic positioning and tracking for 3D localization in a reflective environment. The system facilitates developing robust approaches that can operate effectively without the need for extensive modifications to the existing infrastructure while ensuring that position estimates are both timely and precise.

[0036] The system accurately localizes objects in GPS-denied, heavily reflective underwater environments, such as storage tanks, where conventional positioning systems fail due to signal interference and environmental constraints. Unlike typical acoustic systems that rely on encoded signals prone to distortion, the present system utilizes a multi-frequency ultrasonic pinger with carefully selected acoustic power and frequency to minimize reflection effects. The system employs hyperbolic positioning based on time difference of arrival (TDOA) calculations from multiple ultrasound receiver, ensuring precise 3D localization without requiring prior preparation of the interior environment. Additionally, the modular design of the system, including adaptable signal conditioning processes and customizable software, allows for deployment in diverse reflective environments, making it a versatile and robust solution for underwater positioning challenges.

[0037] This systems resolves limitations associated with existing positioning systems (e.g., GNSS, inertial, RADAR/LIDAR, visual, and conventional acoustic systems) in such environments by utilizing multi-frequency pinger, ultrasonic receivers, signal conditioning electronics, a DAQ, and a signal post processing module. The pinger emits ultrasonic signals, which are captured by receivers and processed to estimate the pinger's position. The system avoids transmitting encoded information, reducing interference issues, and optimizes pinger power and frequency for the environment. The ultrasound receivers are mounted externally on the structure, connected to amplifiers, and linked to the DAQ and signal post processing module. The signal post processing module processes signals to estimate the pinger's position using TDOA and visualizes the location on a map. Th system is designed for environments where conventional systems fail, such as reflective underwater spaces.

[0038] Now referring to Figure 1, a schematic diagram of system for an acoustic positioning and tracking for 3D localization in a reflective environment, showing the primary components of the system, according to an exemplary of the present invention is illustrated.

[0039] The system (100) comprises a tank (1), a multi frequency pinger (2), one or more ultrasound receivers (3), a series of In-line Amplifier (4), a Pull Up Box (5), a Data acquisition module commonly abbreviated as (DAQ module) (6), and a signal post processing module (7). The components interact to capture, process, and analyze acoustic signals emitted by the multi frequency pinger (2) to determine the three-dimensional location of the multi frequency pinger (2) within the tank (1).

[0040] In an embodiment, the tank (1) represents a storage tank to be localized with the reflective environment. The tank (1) functions as the enclosed structure where multi frequency pinger (2) is deployed and where the acoustic signals propagate. In one preferred embodiment, the tank (1) represents a metallic storage tank with fluid or maybe a pool, or similar confined underwater space characterized by reflective surfaces and complex acoustic pathways.

[0041] The multi frequency pinger (2) is positioned within the tank (1) and is configured to emit bursts of an ultrasound signal at a predetermined power and frequency at a preset constant rate. In other words, the multi frequency pinger (2) emits non-encoded ultrasonic signals at a preset rate that does not vary. The multi frequency pinger (2) is designed to adjust acoustic power and frequency to reduce reflection effects caused by the surfaces of the tank (1), thereby supporting dependable signal propagation and reception.

[0042] In one embodiment, the multi frequency pinger (2) can be designed as a compact, battery-powered device with adjustable frequency ranges between 20 kHz and 200 kHz, suitable for deployment in small-scale tanks or pools. In another embodiment, the multi frequency pinger (2) may be integrated into a larger, tethered system with external power supply and higher acoustic power output, enabling its use in industrial storage tanks or large underwater environments. In another embodiment, the multi frequency pinger (2) may be designed to emit ultrasonic signals across a range of frequencies between 20 kHz and 200 kHz, with the ability to dynamically adjust frequency and power output based on the acoustic properties of the environment, such as water salinity, temperature, and tank material. In other words, the power and frequency of the multi frequency pinger (2) is selected based on a reflective environment’s material properties inside the tank (1). In another embodiment, the multi frequency pinger (2) may be equipped with a programmable controller to allow operators to predefine emission patterns, such as bursts or continuous waves, to further mitigate reflection effects. Yet, in another embodiment, the multi frequency pinger (2) may be integrated into a remotely operated vehicle (ROV) or autonomous underwater vehicle (AUV) suspended inside the tank (1) to be localized, enabling dynamic localization of the vehicle as it moves through the reflective environment.

[0043] The one or more ultrasound receivers (3) are engaged with the tank (1) and are configured to receive the ultrasound signal from the multi frequency pinger (2) and convert the ultrasound signal into an electrical signal. Further, the one or more ultrasound receivers (3) are strategically disposed of at predetermined external locations relative to the tank (1). The placement of one or more ultrasound receivers (3) ensures optimal signal reception and enables the system to perform hyperbolic positioning calculations for three-dimensional localization.

[0044] In an embodiment, the one or more ultrasound receivers (3) are acoustic and/or contact transducers mounted on the surface of the circumference of the tank (1) with magnets or an adhesive and coupled to the storage tank with couplant for maximum signal transmission. In another embodiment, the one or more ultrasound receivers (3) are hydrophones suspended directly in the liquid in case of large open tank, pool, or lake etc. Further, in one variation, the one or more ultrasound receivers (3) may be arranged in a triangular configuration to optimize hyperbolic positioning calculations, while in another, additional receivers may be deployed to enhance localization accuracy in larger or more complex environments.

[0045] Each ultrasound receiver (3) is connected to an In-line Amplifier (4), which amplifies and filters the captured ultrasonic signals. The In-line Amplifier (4) reduces ambient noise and mitigates multipath effects, ensuring that the signals are conditioned for accurate processing. The In-line Amplifier (4) is significant in maintaining signal integrity in reflective underwater environments.

[0046] The signals from the In-line Amplifier (4) are transmitted to the Pull Up Box (5), which serves as an intermediary module for signal routing and management. The Pull Up Box (5) ensures that the signals are meticulously organized and prepared for digitization by Data acquisition module (6).

[0047] The combination of In-line Amplifier (4) and the Pull Up Box (5) is referred to as a signal conditioning module (8) (referring Figure 2). The signal conditioning module (8) is configured to receive the electrical signal from the one or more ultrasound receivers and further configured to amplify, filter and rectify the received electrical signal to generate a conditioned signal for digitization by Data acquisition module (6). The signal conditioning module (8) may include analog filters tailored to specific frequency bands to reduce noise, or digital signal processors for advanced filtering and amplification.

[0048] The data acquisition module (6) is electrically connected to the signal conditioning module (8) (specifically the Pull Up Box (5)) and is responsible for digitizing the conditioned signals with time and amplitude resolution. The data acquisition module (6) converts the analog signals into digital format, enabling further processing and analysis. In an embodiment, the data acquisition module (6) may be implemented using commercial off-the-shelf (COTS) hardware with varying sampling rates and resolutions, such as 16-bit or 24-bit analog-to-digital converters, to accommodate various levels of precision required for specific applications. Further, the data acquisition module (6) also estimates signal frequency and power of the multi frequency pinger (2), pre-amplification parameters of one or more ultrasound receivers (3) and calibrate and validate the parameters by placing an acoustic source at a known location.

[0049] The signal post processing module (7) is operatively connected to the data acquisition module (6) and is configured to process the digitized signals and perform onset detection and 3D position estimation of the multi frequency pinger (2) and visualize the estimated 3D position to an operator (9). The signal post processing module (7) detects the presence of received signals, determines the time of arrival at each ultrasound receiver (3), computes time differences of arrival among the ultrasound receivers (3), and performs hyperbolic positioning calculations to determine the three-dimensional location of the multi frequency pinger (2). The signal post processing module (7) may also display the determined location on a visual map interface for real-time monitoring and analysis. In other words, for onset detection and 3D position estimation of the multi frequency pinger (2), the signal post processing module (7) calculates a time of arrival (TOA) of the multi frequency pinger (2) at the one or more ultrasound receivers (3) based upon the received digitized signals, estimate the position of the multi frequency pinger (2) based on a time difference of arrival of the signal at multiple receivers and return the estimated position and in the form of visualization as a map to the operator (9).

[0050] This configuration enables the system (100) to accurately localize the multi frequency pinger (2) within the tank (1), overcoming challenges posed by reflective surfaces and complex acoustic pathways without requiring prior preparation of the interior environment.

[0051] A schematic flow chart diagram of the process flow for estimating the position of the multi frequency pinger (2) in a reflective underwater environment, according to an exemplary embodiment of the present invention is illustrated. The diagram outlines the key components and steps involved in the system's (100) operation, from signal emission to position estimation and visualization. The process begins with the multi frequency pinger (2) emitting ultrasonic signals at a preset rate. The multi frequency pinger (2) is configured to adjust its acoustic power and frequency to minimize reflection effects in the underwater environment. The emitted ultrasonic signals propagate through the reflective underwater environment and are captured by one or more ultrasound receivers (3). The one or more ultrasound receivers (3), strategically positioned at predetermined external locations relative to the structure, capture the ultrasonic signals to generate electrical signal. The electrical signals are then amplified and filtered by the signal conditioning module (8) to produce conditioned signals. This step reduces ambient noise and mitigates multipath effects. The conditioned signals are transmitted to the data acquisition module (6) for further processing. The data acquisition module (6) digitizes the conditioned signals into data buffers of a predetermined length. These digitized signals are then sent to the processing computer for analysis. The digitized signals are analyzed by the signal post processing module (7) to detect the presence of received ultrasonic signals. Thresholding or signal energy analysis is applied to estimate the time of arrival (TOA) at each receiver. The signal post processing module (7) computes the time differences of arrival (TDOA) among the estimated TOAs for ultrasound receiver (3). Hyperbolic positioning calculations are then performed based on the computed TDOA to determine the three-dimensional location of the pinger (1). The determined position of the pinger (1) is visualized on a map interface for real-time monitoring and analysis by the operator (9). The operator (9) can view the estimated position of the pinger (1) and use the information for navigation, inspection, or other applications. This flow chart demonstrates the system's ability to accurately localize the pinger in GPS-denied, reflective underwater environments without requiring prior preparation of the interior environment.

[0052] Figure 3 illustrates a schematic diagram of the system setup for 3D localization of a pinger in a reflective underwater environment, according to an exemplary embodiment of the present invention.

[0053] In Figure 4, a schematic diagram of an ultrasound receiver (3) with a magnetic mount for external deployment, according to an exemplary embodiment of the present invention is illustrated. The figure highlights the components and design features that enable the ultrasound receiver (3) to be securely mounted on the exterior of a structure while ensuring optimal signal transmission. An acoustic transducer (31) is designed to convert acoustic signals into electrical signals. It is configured to operate within the frequency range suitable for capturing ultrasonic signals emitted by the pinger (2). A transducer mount (32) connected to the acoustic transducer (31) provides structural support for the acoustic transducer (31) and ensures its secure attachment to the surface of the structure. A series of magnets (33) is integrated into the mount that enables the transducer to be rigidly attached to the metallic surfaces, such as the exterior of a storage tank. This magnetic mounting mechanism allows for non-intrusive deployment without requiring modifications to the structure. Lastly, the face (34) of the ultrasound receiver (3) is designed to maximize acoustic coupling with the structure. Coupling materials, such as silicone grease or epoxy, may be applied to enhance signal transmission and reduce losses. This figure mainly demonstrates the adaptability of the ultrasound receiver (3) for external deployment in reflective underwater environments, ensuring reliable signal capture while maintaining ease of installation and removal.

[0054] In Figure 5A and Figure 5B, sample acquired signal data and processed data showing the estimated position of the pinger respectively, are illustrated. The figure demonstrates the transformation of raw ultrasonic signals captured by the ultrasound receiver (3) into processed data used for localization. Figure 5A displays the raw signal waveforms received by multiple ultrasound receiver (3), while Figure 5B visualizes the computed position of the multi frequency pinger (1) based on hyperbolic positioning calculations.

[0055] Figure 5A shows sample acquired signal data on the left and sample processed data on the right, illustrating the estimated position of the multi frequency pinger (1). Each waveform corresponds to the signal received by a specific ultrasound receiver (3), showing variations in amplitude and timing due to differences in signal propagation paths and environmental reflections. These signals are conditioned and digitized by the signal conditioning module (5) and data acquisition module (6) to prepare them for further processing. The distinct waveforms highlight the challenges posed by reflective underwater environments, such as multipath effects and signal attenuation.

[0056] Figure 5B visualizes the processed data, showing the estimated position of the multi frequency pinger (1) within the reflective underwater environment. The visualization includes hyperbolic curves generated from the computed time differences of arrival (TDOA) between ultrasound receiver (3). The intersection points of these hyperbolic curves represent the calculated location of the multi frequency pinger (1). The figure demonstrates the system's ability to accurately localize the multi frequency pinger (1) by leveraging hyperbolic positioning techniques, even in acoustically complex environments.

[0057] A schematic representation of sample results showing the multi frequency pinger's position at two separate locations relative to a fixed receiver setup, according to an exemplary embodiment of the present invention is illustrated in Figure 6. The figure demonstrates the hyperbolic positioning calculations used to determine the three-dimensional location of the pinger based on the time differences of arrival (TDOA) of ultrasonic signals at multiple receivers. For ultrasound receiver (3), hyperbolic curves are generated based on the computed TDOA of the signals. The hyperbolic curves represent the possible locations of the multi frequency pinger (1) that corresponds to the recorded TDOA values. The intersection of hyperbolic curves from multiple ultrasound receiver (3) identifies the precise location of the pinger. The figure visually depicts the calculated positions of the pinger at two separate locations. This figure highlights the system's ability to accurately localize the pinger in GPS-denied, reflective underwater environments by leveraging hyperbolic positioning techniques. It also demonstrates the adaptability of the system to track the pinger's movement within the structure.

[0058] In another aspect, the present invention provides a method for acoustic positioning and tracking for 3D localization in a reflective environment. The method for acoustic positioning and tracking for 3D localization in a reflective environment facilitates developing robust approaches that can operate effectively without the need for extensive modifications to the existing infrastructure while ensuring that position estimates are both timely and precise.

[0059] A flowchart of overall method of acoustic positioning and tracking for 3D localization in a reflective environment, according to an exemplary embodiment of the present invention, is illustrated in Figure 7. The overall method includes the following steps.

[0060] In the first step (701) a multi frequency pinger (2) is placed in a storage tank (1) to be localized to emit bursts of an ultrasound signal at a predetermined power and frequency at a preset constant rate.

[0061] In the next step (701), one or more ultrasound receivers (3) engaged with the storage tank (1) receives the ultrasound signal from the multi frequency pinger (2) and the ultrasound signal received from the multi frequency pinger (2) are converted (703) into an electrical signal.

[0062] In next step (704), a conditioned signal is generated by a signal conditioning module (8) by amplifying, filtrating and rectifying on the electrical signal.

[0063] The conditioned signal received from the signal conditioning module (8) is then digitized (705) by a data acquisition module (6) with time and amplitude resolution.

[0064] Lastly, a signal post processing module (7) performs (706) onset detection and 3D position estimation of the multi frequency pinger and visualize the estimated 3D position to an operator.

[0065] Thus, by the above method, the system has ability to manage data acquisition, process signals, and provide real-time visualization of the pinger's position, ensuring accurate localization in GPS-denied, reflective underwater environments.
[0066] Accordingly, the above method can be summarized as follows:

- placing (701) a multi frequency pinger (2) in a storage tank (1) to be localized to emit bursts of an ultrasound signal at a predetermined power and frequency at a preset constant rate;
- receiving (702), by one or more ultrasound receivers (3) engaged with the storage tank (1), the ultrasound signal from the multi frequency pinger (2);
- converting (703), by the one or more ultrasound receivers (3), the ultrasound signal received from the multi frequency pinger into an electrical signal;
- generating (704), by a signal conditioning module (8), a conditioned signal by amplifying, filtrating and rectifying on the electrical signal;
- digitizing (705), by a data acquisition module (6), the conditioned signal received from the signal conditioning module with time and amplitude resolution;
- performing (706), by a signal post processing module (6), onset detection and 3D position estimation of the multi frequency pinger; and
- visualizing (707) the estimated 3D position to an operator.

[0067] In Figure 8, the specific steps performed for onset detection and 3D position estimation of the multi frequency pinger (2) is illustrated. The step of performing onset detection and 3D position estimation of the multi frequency pinger (2) further comprises the steps as mentioned below.

[0068] Firstly, the data acquisition module (6) estimates (801) a signal frequency and power of the multi frequency pinger (2) and also estimates (802) pre-amplification parameters of one or more ultrasound receivers(3).

[0069] In the next step (803), the data acquisition module (6) calibrates and validates the parameters by placing an acoustic source at a known location.

[0070] Later in (804), the signal post processing module (7) is initiated for processing and visualization of the digitized signal.

[0071] In next step (805), the signal post processing module (7) estimates a time of arrival of the multi frequency pinger (2) at the one or more ultrasound receivers (3) based upon the received signals and simultaneously saving (806) data corresponding to the time of arrival of the multi frequency pinger (2) to log.

[0072] Based on the estimated TOA, the signal post processing module (7) estimates (807) the position of the multi frequency pinger (2) based on the time difference of arrival of the signal at plurality of receivers and visualizes (808) the estimated position as a map to the operator (9).

[0073] Accordingly, the above method can be summarized as follows:

- estimating (801), by the data acquisition module (6), a signal frequency and power of the multi frequency pinger (2),
- estimating (802), by a data acquisition module (6), pre-amplification parameters of one or more ultrasound receivers (3);
- calibrating and validating (803), by the data acquisition module (6), by placing an acoustic source at a known location;
- initiating (804) the signal post processing module (7) for processing and visualization of the digitized signal;
- estimating (805), by the signal post processing module (7), time of arrival of the multi frequency pinger (2) at the one or more ultrasound receivers (3) based upon the received signals and simultaneously saving data (806) corresponding to the time of arrival of the multi frequency pinger (2) to log;
- estimating (807), by the signal post processing module (7), the position of the multi frequency pinger (2) based on the time difference of arrival of the signal at plurality of receivers (3);
- visualizing (808) the estimated position as a map to the operator (9).

[0074] The arrangement of the multi frequency pinger, ultrasound receivers, signal conditioning module, data acquisition module, and the signal post processing module facilitates precise three-dimensional localization of a tank in GPS-denied, reflective underwater environments. By configuring the multi frequency pinger to emit non-encoded ultrasonic signals at a preset constant rate and adapting the acoustic power and frequency to reduce reflection effects, the system mitigates signal distortion caused by multipath propagation and reflective surfaces. This approach promotes reliable signal transmission and reception, even in acoustic complex environments.

[0075] The placement of ultrasound receivers at predetermined external locations relative to the structure eliminates the need for invasive modifications or prior preparation of the interior environment. This external deployment approach is particularly advantageous in confined or hazardous spaces, such as storage tanks, where direct access to the interior is restricted. The receivers capture the emitted ultrasonic signals and transmit them to the signal conditioning module, which amplifies and filters the signals to reduce ambient noise and mitigate multipath effects. This conditioning step enhances signal clarity and ensures accurate digitization by the data acquisition system.

[0076] The data acquisition module digitizes the conditioned signals into data buffers, enabling the signal post processing module to analyze the signals and estimate the time of arrival (TOA) at each receiver. By computing time differences of arrival (TDOA) among the receivers and performing hyperbolic positioning calculations, the processing computer determines the three-dimensional location of the pinger. This computational approach leverages hyperbolic geometry to resolve signal ambiguities and achieve precise localization, even in environments characterized by significant acoustic interference.

[0077] The modular design of the system, which incorporates adaptable signal conditioning processes and customizable software, facilitates deployment across various reflective environments. The capability of the system to function without necessitating prior preparation of the interior environment streamlines installation and minimizes operational intricacies, rendering the system appropriate for applications such as industrial inspections, autonomous navigation, and underwater robotics.

[0078] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limited. Since modifications of the disclosed embodiments incorporating the substance of the invention may occur to a person skilled in the art, the invention should be construed to include everything within the scope of the invention. , Claims:
1. A system for an acoustic positioning and tracking for 3D localization in a reflective environment, the system (100) comprising:
- a multi frequency pinger (2) placed in a storage tank (1) to be localized, the multi frequency pinger (2) configured to emit bursts of an ultrasound signal at a predetermined power and frequency at a preset constant rate,
- one or more ultrasound receivers (3) engaged with the storage tank (1) at a predetermined location, the one or more ultrasound receivers (3) configured to receive the ultrasound signal from the multi frequency pinger (2) and convert the ultrasound signal into an electrical signal;
- a signal conditioning module (8) connected to the one or more ultrasound receivers (3), the signal conditioning module (8) configured to receive the electrical signal from the one or more ultrasound receivers (3) and further configured to amplify, filter and rectify the received electrical signal to generate a conditioned signal;
- a data acquisition module (6) connected to the signal conditioning module (8), the data acquisition module configured to digitize the conditioned signal received from the signal conditioning module (8) with time and amplitude resolution; and
- a signal post processing module (7) connected to the data acquisition module (6), the signal post processing module (7) configured to receive the digitized signal from the data acquisition module (6) and further configured to perform onset detection and 3D position estimation of the multi frequency pinger (2) and visualize the estimated 3D position to an operator (9).

2. The system (100) as claimed in claim 1, wherein the multi frequency pinger (2) is mounted on a remotely operated vehicle suspended inside the storage tank (1) to be localized.
3. The system (100) as claimed in claims 1 and 2, wherein the power and frequency of the multi frequency pinger (2) is selected based on a reflective environment’s material properties inside the storage tank (1).

4. The system (100) as claimed in claim 1, wherein the one or more ultrasound receivers (3) are acoustic and/or contact transducers mounted on the surface of the circumference of the storage tank (1) with magnets (33) or an adhesive and coupled to the storage tank with couplant for maximum signal transmission, or
wherein the one or more ultrasound receivers (3) are a hydrophone suspended externally on the structure.

5. The system (100) as claimed in claim 1, wherein for onset detection and 3D position estimation of the multi frequency pinger (2); the signal post processing module (7) calculates a time of arrival of the multi frequency pinger (2) at the one or more ultrasound receivers based upon the received digitized signals, estimate the position of the multi frequency pinger (2) based on a time difference of arrival of the signal at multiple receivers (3) and return the estimated position and in the form of visualization as a map to the operator (9).

6. A method for an acoustic positioning and tracking for 3D localization in a reflective environment, the method comprising steps of:
- placing (701) a multi frequency pinger (2) in a storage tank (1) to be localized to emit bursts of an ultrasound signal at a predetermined power and frequency at a preset constant rate;
- receiving (702), by one or more ultrasound receivers (3) engaged with the storage tank (1), the ultrasound signal from the multi frequency pinger (2);
- converting (703), by the one or more ultrasound receivers (3), the ultrasound signal received from the multi frequency pinger (2) into an electrical signal;
- generating (704), by a signal conditioning module (8), a conditioned signal by amplifying, filtrating and rectifying on the electrical signal;
- digitizing (705), by a data acquisition module (6), the conditioned signal received from the signal conditioning module with time and amplitude resolution;
- performing (706), by a signal post processing module (7), onset detection and 3D position estimation of the multi frequency pinger (2); and
- visualizing (707) the estimated 3D position to an operator (9).

7. The method as claimed in claim 6, wherein the step of performing onset detection and 3D position estimation of the multi frequency pinger (2) further comprises the steps of:
- estimating (801), by the data acquisition module (6), a signal frequency and power of the multi frequency pinger (2),
- estimating (802), by a data acquisition module (6), pre-amplification parameters of one or more ultrasound receivers (3);
- calibrating and validating (803), by the data acquisition module (6), by placing an acoustic source at a known location;
- initiating (804) the signal post processing module (7) for processing and visualization of the digitized signal;
- estimating (805), by the signal post processing module (7), time of arrival of the multi frequency pinger (2) at the one or more ultrasound receivers (3) based upon the received signals and simultaneously saving data (806) corresponding to the time of arrival of the multi frequency pinger (2) to log;
- estimating (807), by the signal post processing module (7), the position of the multi frequency pinger (2) based on the time difference of arrival of the signal at plurality of receivers (3);
- visualizing (808) the estimated position as a map to the operator (9).