Control method of underwater spectral imaging system and its system and storage medium

Abstract

The present invention discloses a control method for an underwater spectral imaging system, a system thereof, and a storage medium thereof, belonging to the field of spectral imaging technology. The underwater spectral imaging system includes a first drive motor, a filter wheel, and an angle detection sensor, the angle detection sensor being used to measure the rotation angle of the filter wheel. The control method includes: obtaining the actual rotation angle of the filter wheel and the rotational angular velocity of the first drive motor at the previous N moments of the filter wheel, where N ≥ 1; determining the predicted rotation angle of the filter wheel at the current moment based on the actual rotation angle and the rotational angular velocity; obtaining the measured rotation angle detected by the angle detection sensor at the current moment; and fusing the measured rotation angle and the predicted rotation angle to obtain the actual rotation angle at the current moment. By fusing the measured rotation angle with the predicted rotation angle of the filter wheel to obtain the actual rotation angle at the current moment, the present application can compensate for the shortcomings of the angle detection sensor in measuring angle accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of spectral imaging, and in particular to a control method of an underwater spectral imaging system, a system thereof, and a storage medium. Background Art

[0002] Ocean remote sensing is a crucial tool for understanding the ocean. Spectral imaging, which can simultaneously capture both spatial and spectral information, is widely used in marine topography mapping, marine resource exploration, marine ecological and environmental monitoring, and marine emergency rescue. To detect and identify submarine targets, underwater spectral imaging has become a new ocean exploration technology that countries around the world are competing to develop.

[0003] The filter wheel in a staring underwater spectral imaging system requires precise alignment of the corresponding filters with the optical path and detector during imaging, thus requiring precise control of the filter wheel's position. Consequently, most companies currently use high-precision photoelectric encoders as angle measurement elements, but these are costly. Smaller, lower-cost angle measurement elements suffer from low accuracy and poor linearity.

[0004] Therefore, the technical problem of how to improve the detection accuracy of underwater spectral imaging systems needs to be solved urgently. Summary of the Invention

[0005] In order to solve the technical problem of how to improve the detection accuracy of an underwater spectral imaging system described in the above background technology, the present invention provides a control method for an underwater spectral imaging system, a system thereof, and a storage medium.

[0006] One object of the present invention is to provide a control method for an underwater spectral imaging system. By selecting a smaller but less precise angle measurement element, the predicted filter wheel rotation angle at the current moment is predicted using the actual rotation angles of the filter wheel at the previous N moments and the rotational angular velocity of a first drive motor. The predicted rotation angle is then combined with the measured rotation angle detected by the angle detection sensor at the current moment to obtain the actual rotation angle of the filter wheel at the current moment. This method can compensate for the angle measurement accuracy limitations of the angle detection sensor and improve the accuracy and linearity of angle measurement.

[0007] Another object of the present invention is to provide an underwater spectral imaging system.

[0008] Another object of the present invention is to provide a storage medium.

[0009] According to a first aspect, an embodiment of the present application provides a control method for an underwater spectral imaging system, wherein the underwater spectral imaging system includes a first drive motor, a filter wheel, and an angle detection sensor, wherein the angle detection sensor is used to measure the rotation angle of the filter wheel. The control method includes: obtaining the actual rotation angle of the filter wheel at the previous N moments of the filter wheel and the rotation angular velocity of the first drive motor, where N ≥ 1; determining the predicted rotation angle of the filter wheel at the current moment based on the actual rotation angle and the rotation angular velocity; obtaining the measured rotation angle detected by the angle detection sensor at the current moment; and fusing the measured rotation angle and the predicted rotation angle to obtain the actual rotation angle at the current moment.

[0010] The present application selects an angle measurement element with a smaller volume but slightly lower accuracy, and uses the actual rotation angle of the filter wheel at the previous N moments and the rotation angular velocity of the first drive motor to first calculate the predicted rotation angle of the filter wheel at the current moment, and then fuses the measured rotation angle detected by the angle detection sensor at the current moment with the predicted rotation angle to obtain the actual rotation angle of the filter wheel at the current moment. This can make up for the defects of the angle detection sensor in the accuracy of measuring angles and improve the accuracy and linearity of angle measurement.

[0011] Optionally, fusing the measured rotation angle and the predicted rotation angle to obtain the actual rotation angle at the current moment includes: fusing the measured rotation angle and the predicted rotation angle to obtain the actual rotation angle at the current moment using a data fusion algorithm based on Kalman filtering.

[0012] Optionally, the data fusion algorithm based on Kalman filtering fuses the measured rotation angle and the predicted rotation angle to obtain the actual rotation angle at the current moment, including: obtaining the first mean square error and the system noise sequence variance matrix of the underwater spectral imaging system at the previous N moments; and determining the filter gain parameter of the data fusion algorithm of the Kalman filtering based on the first mean square error and the system noise sequence variance matrix.

[0013] Optionally, determining the filter gain parameters of the data fusion algorithm of the Kalman filter based on the first mean square error and the variance matrix of the system noise sequence includes: determining the mean square error at the current moment based on the first mean square error and the variance matrix of the system noise sequence; and determining the filter gain parameters based on the mean square error at the current moment.

[0014] Optionally, determining the filter gain parameter based on the mean square error at the current moment includes: obtaining the state observation matrix, measurement noise variance matrix and mean square error at the current moment of the underwater spectral imaging system; and obtaining the filter gain parameter based on the state observation matrix, the measurement noise variance matrix and the mean square error at the current moment.

[0015] Optionally, the underwater spectral imaging system further includes a position detection sensor, a focusing mechanism and a second drive motor connected to the focusing mechanism, wherein the second drive motor can drive the focusing mechanism to move in different directions for focusing the underwater spectral imaging system. The control method further includes: when a trigger signal from the position detection sensor is obtained, confirming that the focusing mechanism is in zero position; when the trigger signal is not detected, controlling the second drive motor to move in the first direction until it stops when the trigger signal is detected.

[0016] Optionally, when the trigger signal of the position detection sensor is obtained, after confirming that the focusing mechanism is at the zero position, the method includes: judging the movement direction of the second drive motor; when the movement direction of the second drive motor is the first direction, calculating the current position of the focusing mechanism, and obtaining the trigger signal of the position detection sensor; when the trigger signal of the position detection sensor is obtained, determining that the focusing mechanism has reached the zero limit position; when the movement direction of the second drive motor is the second direction, judging whether the second drive motor has reached the maximum output stroke; when the second drive motor reaches the maximum output stroke, determining that the focusing mechanism has reached the maximum limit position.

[0017] According to a second aspect, an embodiment of the present application provides an underwater spectral imaging system, a focusing system for focusing the underwater spectral imaging system; a filter wheel mechanically fixedly connected to the focusing mechanism for switching and selecting imaging spectral bands; and a controller electrically connected to the focusing mechanism and the filter wheel, respectively, for executing the control method steps of the underwater spectral imaging system described in any one of the above claims.

[0018] According to an embodiment of the present invention, the energy recovery system for new energy vehicles uses a smaller but less accurate angle measurement element, utilizes the actual rotation angles of the filter wheel at the previous N moments and the rotational angular velocity of the first drive motor to predict the current rotation angle of the filter wheel, and fuses the measured rotation angle detected by the angle detection sensor at the current moment with the predicted rotation angle to obtain the actual rotation angle of the filter wheel at the current moment, thereby improving the accuracy and linearity of the angle measurement.

[0019] Optionally, the focusing system includes: a second drive motor connected to the controller for providing driving force for the underwater spectral imaging system; a driven shaft fixedly connected to the drive motor; a focusing mechanism rotatably connected to the driven shaft and electrically connected to the controller for focusing the underwater spectral imaging system; a position detection sensor electrically connected to the controller for detecting position information of the focusing mechanism and sending the position information to the controller.

[0020] According to a third aspect, an embodiment of the present application provides a storage medium, in which a computer program is stored, wherein the computer program is configured to execute any of the above-mentioned control method steps for the underwater spectral imaging system when running. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0022] Figure 1 This is a control flow chart of an underwater spectral imaging system according to an embodiment of the present invention;

[0023] Figure 2 A schematic diagram of a partial structure of an underwater spectral imaging system according to an embodiment of the present invention;

[0024] Figure 3 This is a focus control flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described with reference to the accompanying drawings. The same reference numerals in the drawings represent components with the same structure or similar structures but the same functions.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0027] The filter wheel in a staring underwater spectral imaging system requires precise alignment of the corresponding filters with the optical path and detector during imaging, thus requiring precise control of the filter wheel's position. Consequently, most companies currently use high-precision photoelectric encoders as angle measurement elements, but these are costly. Smaller, lower-cost angle measurement elements suffer from low accuracy and poor linearity.

[0028] The present application proposes a control method for an underwater spectral imaging system, wherein the underwater spectral imaging system comprises a first drive motor, a filter wheel and an angle detection sensor, wherein the angle detection sensor is used to measure the rotation angle of the filter wheel. Figure 1 As shown, the control method includes:

[0029] S10. Obtaining the actual rotation angle of the filter wheel and the rotation angular velocity of the first drive motor at the previous N moments of the filter wheel, where N≥1.

[0030] S20. Determine a predicted rotation angle of the filter wheel at a current moment based on the actual rotation angle and the rotation angular velocity.

[0031] S30. Obtain the measured rotation angle detected by the angle detection sensor at the current moment.

[0032] S40. Fusing the measured rotation angle and the predicted rotation angle to obtain the actual rotation angle at the current moment.

[0033] In this embodiment, the filter wheel is fixedly connected to the first drive motor. Therefore, the rotational angular velocity of the first drive motor is the rotational angular velocity of the filter wheel. At the same time, the actual rotational angles of the filter wheel at the previous N moments are obtained. Taking N equal to 1 as an example, after the rotational angular velocity, the actual rotational angle at the previous moment, and the interval between the previous moment and the current moment are known, the rotational angle of the filter wheel at the current moment can be calculated in advance.

[0034] See formula (1):

[0035]

[0036] Among them, θ k+1 is the predicted rotation angle at the current moment, θ k is the actual rotation angle at the previous moment, t s is the interval between the current moment and the previous moment, is the angular velocity of the filter wheel, W k is the system excitation noise sequence.

[0037] It should be noted that the predicted rotation in this application is the rotation angle of the first drive motor, which is also the angle at which the control module of the underwater spectral imaging system controls the rotation of the first drive motor, that is, the angle at which the filter wheel is controlled. However, the error in measuring the rotation angle of the filter wheel using an angle detection sensor with lower precision is large. Therefore, the measured rotation angle and the predicted rotation angle are fused, and the error is closed-loop managed to limit the error within a certain range, thereby improving the accuracy of the actual rotation angle finally obtained. The control module controls the movement of the first drive motor according to the actual rotation angle, thereby realizing the rotation of the filter wheel at the actual rotation angle, thereby improving the detection accuracy of the underwater spectral imaging system. The fusion process is described below.

[0038] After calculating the predicted rotation angle at the current moment, the measured rotation angle of the filter wheel detected at the current moment is obtained through the angle detection sensor, and the predicted rotation angle at the current moment and the measured rotation angle are fused to obtain the actual rotation angle at the current moment.

[0039] Exemplarily, fusing the measured rotation angle with the predicted rotation angle to obtain the actual rotation angle at the current moment includes fusing the measured rotation angle with the predicted rotation angle using a Kalman filter-based data fusion algorithm to obtain the actual rotation angle at the current moment. In this embodiment, fusing the predicted rotation angle and the measured rotation angle at the current moment can be performed using a Kalman filter-based data fusion algorithm. During the calculation process, system measurement noise generated by the angle detection sensor when detecting the angle also needs to be considered to further improve the detection accuracy of the underwater spectral imaging system.

[0040] As an exemplary embodiment, the data fusion algorithm based on Kalman filtering fuses the measured rotation angle and the predicted rotation angle to obtain the actual rotation angle at the current moment, including: obtaining the first mean square error and the system noise sequence variance matrix of the underwater spectral imaging system at the previous N moments; and determining the filter gain parameter of the Kalman filtering data fusion algorithm based on the first mean square error and the system noise sequence variance matrix.

[0041] During fusion, it is necessary to obtain the filter gain parameter of the Kalman filter data fusion algorithm. For example, the mean square error of the current moment is calculated by the mean square error of the previous moment, as shown in formula (2):

[0042] P (k|k-1) =AP k-1 A T +Q (2)

[0043] Among them, P k-1 is the mean square error of the previous moment, Q is the variance matrix of the system noise sequence, A is the state transfer matrix, P (k|k-1)is the mean square error at the current moment.

[0044] After calculating the mean square error at the current moment, the filter gain parameter is calculated based on the mean square error at the current moment and the measurement noise variance matrix, as shown in formula (3):

[0045] K k =P (k|k-1) H T (HP (k|k-1) H T +R) -1 (3)

[0046] Among them, K k is the filter gain parameter, P (k|k-1) is the mean square error at the current moment, R is the measurement noise variance matrix, H is the state observation matrix, and T represents the transpose.

[0047] The filter gain parameter is obtained by calculation. Based on the filter gain parameter and the state observation matrix, the measured rotation angle and the predicted rotation angle are fused, as shown in formula (4):

[0048]

[0049] in, is the actual rotation angle at the current moment, is the predicted rotation angle at the current moment, K k is the filter gain parameter, θ m,k is the measured rotation angle at the current moment, and H is the state observation matrix.

[0050] If control relies solely on the predicted rotation angle, the error will accumulate over time, and the longer the time, the greater the uncertainty. If control is based solely on the measured rotation angle, it is limited by the low measurement accuracy of the sensor and cannot achieve a good control effect. Therefore, in this application, the Kalman filter algorithm is used to cleverly integrate the predicted rotation angle and the measured rotation angle, performing closed-loop management of the error and limiting the error to a certain range. This results in a more reliable actual rotation angle, and the accuracy and linearity of the actual rotation angle after processing are greatly improved.

[0051] As an exemplary embodiment, the underwater spectral imaging system also includes a position detection sensor, a focusing mechanism and a second drive motor connected to the focusing mechanism, the second drive motor can drive the focusing mechanism to move in different directions, and is used to focus the underwater spectral imaging system. The control method also includes: when a trigger signal from the position detection sensor is obtained, confirming that the focusing mechanism is in zero position; when the trigger signal is not detected, controlling the second drive motor to move in the first direction until it stops when the trigger signal is detected.

[0052] When the underwater spectral imaging system is in operation, the focusing mechanism needs to be positioned to facilitate the control of the focusing of the underwater spectral imaging system. Due to the volume and space requirements of the underwater spectral imaging system and to reduce costs, for example, the position detection sensor can use a switch Hall sensor to achieve the positioning of the focusing mechanism.

[0053] See also Figure 2 As shown, the switch Hall sensor is set at the proximal end of the second drive motor 10. In the initial stage, the trigger signal of the position detection sensor 20 is obtained. When the trigger signal is obtained, the position is calibrated as the zero position, which serves as the reference for the movement of the focusing mechanism 30 to achieve precise control of the focusing. When the trigger signal is not detected, the focusing mechanism 30 is controlled to move in the direction of the second drive motor 10. In this application, the direction in which the focusing mechanism 30 moves toward the second drive motor 10 is set as the first direction, and the direction opposite to the first direction is set as the second direction. During the movement of the focusing mechanism 30, the trigger signal is obtained in real time. Only when the trigger signal is detected, this position is calibrated as the zero position, and the focusing mechanism 30 is controlled to stop moving. It should be noted that there is interference from other signals when detecting the trigger signal. Therefore, the current position is determined to be the zero position only when the trigger signal is detected for multiple consecutive beats. However, in order to prevent the focusing mechanism 30 from colliding with the mechanical limit, the number of consecutive detection beats should not be too many.

[0054] After finding the zero position, the zero position coordinates need to be calculated. For example, when the trigger signal of the position detection sensor 20 is obtained, after confirming that the focusing mechanism 30 is at the zero position, the following steps are included: determining the movement direction of the second drive motor 10; when the movement direction of the second drive motor 10 is the first direction, calculating the current position of the focusing mechanism 30 and obtaining the trigger signal of the position detection sensor 20; when the trigger signal of the position detection sensor 20 is obtained, determining that the focusing mechanism 30 has reached the zero limit position; when the movement direction of the second drive motor 10 is the second direction, determining whether the second drive motor 10 has reached the maximum output stroke; when the second drive motor 10 has reached the maximum output stroke, determining that the focusing mechanism 30 has reached the maximum limit position. The second drive motor 10 is explained by taking a stepper motor as an example.

[0055] See also Figure 3As shown, first determine the movement direction of the focusing mechanism 30, that is, the movement direction of the stepper motor. When the movement direction of the stepper motor is the first direction, the current position of the focusing mechanism 30 is the previous position minus one step length, and determine whether a trigger signal is detected at this time. When no trigger signal is detected, control the stepper motor to continue to move one step length in the first direction, and detect the trigger signal. When the trigger signal is detected, determine that the focusing mechanism 30 reaches the zero limit position, and at this time the stepper motor cannot continue to move in the first direction; when the movement direction of the stepper motor is the second direction, the current position of the focusing mechanism 30 is the previous position plus one step length, and determine whether the stepper motor reaches the maximum number of steps at this time. When the stepper motor reaches the maximum number of steps, determine that the focusing mechanism 30 reaches the maximum limit position, and at this time the stepper motor cannot continue to move in the second direction.

[0056] By finding the zero position, current position, zero limit position and maximum limit position of the focusing mechanism 30 , the coordinates of the focusing mechanism 30 can be accurately calculated, thereby achieving accurate control of the focusing mechanism 30 and precise focusing.

[0057] According to the second aspect of the present application, an underwater spectral imaging system is provided, comprising: a focusing system for focusing the underwater spectral imaging system; a filter wheel mechanically fixedly connected to the focusing mechanism 30 for switching and selecting imaging spectral bands; a controller electrically connected to the focusing mechanism 30 and the filter wheel, respectively, for executing any of the above-mentioned control method steps for the underwater spectral imaging system. The focusing system comprises: a second drive motor 10 connected to the controller for providing driving force for the underwater spectral imaging system; a driven shaft 40 fixedly connected to the drive motor; a focusing mechanism 30 rotatably connected to the driven shaft 40 and electrically connected to the controller for focusing the underwater spectral imaging system; and a position detection sensor 20 electrically connected to the controller for detecting position information of the focusing mechanism 30 and sending the position information to the controller.

[0058] The underwater spectral imaging system in the present application can achieve precise control of the rotation angle of the filter wheel based on Kalman filtering using a smaller angle detection sensor, and can rely on low-cost components such as switch Hall sensors to achieve precise focusing of the focusing mechanism 30, greatly improving the detection accuracy of the underwater spectral imaging system.

[0059] According to a third aspect of the present application, a storage medium is further provided, in which a computer program is stored, wherein the computer program is configured to execute any of the above-mentioned steps of the control method for the underwater spectral imaging system when running.

[0060] In addition, other components and functions of the vehicle according to the embodiment of the present invention are well known to ordinary technicians in this field and will not be described here to reduce redundancy.

[0061] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0062] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A control method for an underwater spectral imaging system, characterized in that: The underwater spectral imaging system includes a first drive motor, a filter wheel, and an angle detection sensor, wherein the angle detection sensor is used to measure the rotation angle of the filter wheel. The control method includes: Obtaining the actual rotation angle of the filter wheel and the rotation angular velocity of the first drive motor at the previous N moments of the filter wheel, where N≥1; determining a predicted rotation angle of the filter wheel at a current moment based on the actual rotation angle and the rotation angular velocity; Obtaining a measured rotation angle detected by the angle detection sensor at the current moment; Fusing the measured rotation angle and the predicted rotation angle to obtain the actual rotation angle at the current moment; The fusing the measured rotation angle and the predicted rotation angle to obtain the actual rotation angle at the current moment includes: A data fusion algorithm based on Kalman filtering fuses the measured rotation angle and the predicted rotation angle to obtain the actual rotation angle at the current moment; The Kalman filter-based data fusion algorithm fuses the measured rotation angle and the predicted rotation angle to obtain the actual rotation angle at the current moment, including: Obtaining the first mean square error and system noise sequence variance matrix of the underwater spectral imaging system at the first N moments; Determine a filter gain parameter of the data fusion algorithm of the Kalman filter based on the first mean square error and the variance matrix of the system noise sequence; The determining of the filter gain parameter of the Kalman filter data fusion algorithm based on the first mean square error and the system noise sequence variance matrix includes: Determine a mean square error at a current moment based on the first mean square error and the variance matrix of the system noise sequence; Determine the filter gain parameter based on the mean square error at the current moment; The determining the filter gain parameter based on the mean square error at the current moment includes: Obtaining a state observation matrix, a measurement noise variance matrix, and a mean square error at the current moment of the underwater spectral imaging system; The filter gain parameter is obtained based on the state observation matrix, the measurement noise variance matrix and the mean square error at the current moment.

2. The control method of the underwater spectral imaging system according to claim 1, characterized in that: The underwater spectral imaging system further includes a position detection sensor, a focusing mechanism, and a second drive motor connected to the focusing mechanism, wherein the second drive motor is capable of driving the focusing mechanism to move in different directions for focusing the underwater spectral imaging system. The control method further includes: When a trigger signal of the position detection sensor is obtained, confirming that the focusing mechanism is at zero position; When the trigger signal is not detected, the second drive motor is controlled to move in the first direction until the trigger signal is detected and the motor stops.

3. The control method of the underwater spectral imaging system according to claim 2, characterized in that: The method of obtaining the trigger signal of the position detection sensor and confirming that the focus mechanism is at the zero position includes: determining a movement direction of the second drive motor; When the movement direction of the second driving motor is the first direction, calculating the current position of the focusing mechanism and obtaining a trigger signal of the position detection sensor; When a trigger signal of the position detection sensor is obtained, determining that the focusing mechanism has reached a zero limit position; When the movement direction of the second drive motor is the second direction, determining whether the second drive motor reaches a maximum output stroke; When the second driving motor reaches a maximum output stroke, it is determined that the focusing mechanism reaches a maximum limit position.

4. An underwater spectral imaging system, characterized in that: include: A focusing system, used for focusing the underwater spectral imaging system; The filter wheel is mechanically fixed to the focusing mechanism and is used to switch and select the imaging spectral band; A controller is electrically connected to the focusing mechanism and the filter wheel, respectively, and is used to execute the control method steps of the underwater spectral imaging system according to any one of claims 1 to 3.

5. The underwater spectral imaging system according to claim 4, characterized in that: The focusing system comprises: a second driving motor, connected to the controller, for providing driving force for the underwater spectral imaging system; A driven shaft, fixedly connected to the drive motor; a focusing mechanism, rotatably connected to the driven shaft and electrically connected to the controller, for adjusting the focus of the underwater spectral imaging system; A position detection sensor is electrically connected to the controller and is used to detect position information of the focusing mechanism and send the position information to the controller.

6. A storage medium, characterized in that The storage medium stores a computer program, wherein the computer program is configured to execute the steps of the control method for the underwater spectral imaging system according to any one of claims 1 to 3 when running.

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