JP7692736B2 - CONTROL DEVICE, UNDERWATER VEHICLE AND CONTROL METHOD - Google Patents

Description

This disclosure relates to a control device, an underwater vehicle, and a control method.

When operating an underwater vehicle, it is necessary to suppress the rocking of the hull due to disturbances such as waves. Non-Patent Document 1 discloses a disturbance estimator that estimates disturbances. Non-Patent Document 2 discloses a method of estimating disturbances by estimating the state of the underwater vehicle. Furthermore, Patent Documents 3 and 4 disclose a control device that estimates the direction, magnitude, frequency, etc. of disturbances acting on the underwater vehicle and generates control commands such as a rudder angle to cancel out the estimated disturbance.

In addition, when controlling the control axes related to depth, roll angle, pitch angle, azimuth angle, etc. while the underwater vehicle is operating, mutual interference may occur between certain axes. For example, even if control is performed to suppress oscillation of each axis, it may take time for the oscillation to converge due to the influence of mutual interference. In response to this, Patent Document 1 discloses a control method that calculates a rudder angle command that compensates for the interference between the axes according to the state of the hull, and de-interferes with the interfering forces between the axes.

In addition, there is a limit to the range in which the rudder of an underwater vehicle can follow changes in rudder angle commands, and if a rudder angle command that exceeds this limit is input, the actual rudder angle cannot follow and speed saturation occurs. In response to this, Patent Document 2 discloses a speed saturation compensator that compensates for rudder angle commands that cause speed saturation to a command value within the range that can be followed. By using a speed saturation compensator, it is possible to suppress sudden rudder movements and avoid the occurrence of speed saturation.

JP 2019-25928 A Patent No. 5984608 JP 2014-12491 A JP 2014-21649 A

Kohei Ohnishi, "Robust Motion Control Using Disturbance Observers", Journal of the Robotics Society of Japan, Vol. 11, No. 4, 1993, pp. 486-493 Masahiko Nakamura et al., "Study on Improving the Navigation Performance of the Small AUV "MR-X1" on Survey Lines," Journal of the Japan Society of Naval Architects and Ocean Engineers, No. 12, 2010, pp. 165-173

The hull's pitching can be suppressed by compensating for disturbances based on a disturbance estimator. However, for example, if the pitching contains high-frequency components, the rudder must be operated frequently to deal with the pitching, which reduces energy-saving performance. There is a demand for control that can adjust the balance between the pitching suppression performance and energy-saving performance.

This disclosure provides a control device, an underwater vehicle, and a control method that can solve the above problems.

The control device disclosed herein has a feedback controller that calculates a control command value based on the difference between the hull position and a target position, a decoupling controller that calculates a decoupling compensation value for canceling out mutual interference between control axes of the hull, a disturbance estimator that estimates the force of a disturbance acting on the hull and calculates a disturbance compensation value for canceling out the disturbance, a speed saturation compensator that calculates a speed saturation compensation value such that speed saturation does not occur when the actuators of the hull are controlled based on the control command value, and a control system adjuster that adjusts at least one parameter of the decoupling controller, the disturbance estimator and the speed saturation compensator based on the rocking caused on the hull and/or the operation of the actuator , and selects the top two principal components based on the results of a frequency component analysis of the rocking of the hull, and sets the frequency between the two principal components to the filter band of a low-pass filter provided in the disturbance estimator and a low-pass filter provided in the decoupling controller.

The underwater vehicle disclosed herein is equipped with the above-mentioned control device.

The control method disclosed herein is a control method executed by a control device having a decoupling controller, a disturbance estimator, and a speed saturation compensator, and includes the steps of: calculating a control command value based on a difference between a hull position and a target position; the decoupling controller calculating a decoupling compensation value for canceling out mutual interference between control axes of the hull; the disturbance estimator estimating the force of a disturbance acting on the hull and calculating a disturbance compensation value for canceling out the disturbance; the speed saturation compensator calculating a speed saturation compensation value such that speed saturation does not occur when actuators of the hull are controlled based on the control command value; and adjusting parameters of at least one of the decoupling controller, the disturbance estimator, and the speed saturation compensator based on the rolling generated in the hull and/or the operation of the actuator , wherein the parameter adjusting step selects top two principal components based on the result of a frequency component analysis of the rolling of the hull, and sets the frequency between the two principal components to the filter band of a low-pass filter provided in the disturbance estimator and a low-pass filter provided in the decoupling controller.

The above-described control device, underwater vehicle, and control method can adjust the balance between rocking suppression performance and energy saving performance. For example, it is possible to achieve both rocking suppression and energy saving performance.

FIG. 1 is a diagram illustrating an example of a control system according to an embodiment. FIG. 11 is a diagram illustrating an example of an evaluation index value according to the embodiment. FIG. 4 is a diagram illustrating control system switching according to the embodiment. 4 is a flowchart showing an example of an operation of the control system according to the embodiment.

The control system of the present disclosure will be described below with reference to Figures 1 to 4. In the following description, components having the same or similar functions will be given the same reference numerals. Furthermore, duplicate descriptions of those components may be omitted.

(System Configuration)
Figure 1 shows a block diagram of a control system for the underwater vehicle 1. As shown in Figure 1, the underwater vehicle 1 includes a control device 10 and an airframe 20. The control device 10 includes an FB (feedback) controller 11, an actuator control system 12, a speed saturation compensator 13, a disturbance estimator 14, a decoupling controller 15, a control system adjuster 16, and a parameter calculation unit 17. The airframe 20 includes the actuators and sensors included in the underwater vehicle 1.

The FB controller 11 calculates a control command value based on the difference between the position of the underwater vehicle 1 and a predetermined target position. For example, the FB controller 11 calculates a control command value for a control axis (any of the X, Y and Z axis directions and directions around each axis related to the six degrees of freedom of the hull motion) related to depth, pitch angle, azimuth angle, etc., so as to match the position of the underwater vehicle 1 to the target position, using PID control or the like.

The actuator control system 12 converts the control command value calculated by the FB controller 11 into an actual command value (called an actual command value) to be output to the actuator, and controls the actuator (aircraft 20). The actuators are, for example, multiple rudders equipped on the underwater vehicle 1. The actual command value is, for example, a rudder angle command to each rudders. As shown in the figure, when the speed saturation compensator 13, the disturbance estimator 14, and the decoupling controller 15 output compensation values, the control command value calculated by the FB controller 11 is compensated by those compensation values.

The velocity saturation compensator 13 acquires the control command value input to the actuator control system 12 and the actual command value output from the actuator control system 12, calculates a velocity saturation compensation value so that the control command value input to the actuator control system 12 does not reach velocity saturation, and outputs this value. The control command value input to the actuator control system 12 is compensated by the velocity saturation compensation value so that it is within a range that the actuator operation can follow. For the velocity saturation compensator 13 of this embodiment, for example, a velocity saturation compensation unit disclosed in Patent Document 2 can be used. The configuration of the velocity saturation compensator 13 is disclosed in Patent Document 2, so its description is omitted in this specification. The velocity saturation compensator 13 has an internal parameter called a band adjustment gain (an internal parameter of the ideal model 41 in Patent Document 2). Increasing the value of this band adjustment gain acts to more strongly suppress abrupt changes in the actuator. The velocity saturation compensator 13 has the function of suppressing abrupt operations of the actuator, and therefore contributes to energy saving in control. Increasing the value of the band adjustment gain improves the effect of energy saving. The value of the band adjustment gain can be adjusted by the control system adjuster 16.

The disturbance estimator 14 acquires the actual command value output from the actuator control system 12 and information indicating the state of the underwater vehicle 1 (such as the actual steering angle, the measurement value of the gyro sensor and the depth gauge), estimates the force of the disturbance acting on the hull, and calculates a disturbance compensation value for canceling the estimated disturbance. For example, the disturbance estimator 14 estimates disturbance due to waves in each direction of the depth, pitch angle, and azimuth angle, and calculates a disturbance compensation value for each direction to cancel the disturbance. There is no particular limitation on the disturbance estimation method in the disturbance estimator 14 of this embodiment, and a known disturbance observer or the like can be used (for example, Non-Patent Document 1). In addition, a known controller generally used in underwater vehicles can be used for the configuration for calculating the rudder control amount (disturbance compensation value) required to cancel the estimated disturbance (for example, Patent Documents 3 and 4). In addition, the disturbance estimator 14 of this embodiment is internally provided with a low-pass filter 141 (not shown) and an output gain 142 (not shown), which is a configurable parameter. Generally, the disturbance estimated by the disturbance estimator 14 contains a plurality of frequency components. For example, a low-pass filter 141 is provided for each control axis, and reduces a band of a predetermined frequency or higher among the frequency components of the estimated disturbance in each control axis direction. The disturbance estimator 14 calculates a disturbance compensation value (for example, a compensation rudder angle for the rudder corresponding to the direction of the oscillation) that cancels the disturbance in the low frequency band of each control axis direction that has passed through the low-pass filter 141. If the band of frequencies that pass through the low-pass filter 141 is increased, oscillations in a wider frequency band can be suppressed, but high-frequency components of the oscillation must also be dealt with, and the rudder will operate more frequently. This is disadvantageous from the viewpoint of energy saving (energy consumption increases). The output gain 142 is a parameter for adjusting the magnitude of the calculated disturbance compensation value by multiplying it. The disturbance estimator 14 calculates a compensation rudder angle for each rudder that deals with the estimated disturbances in various directions (e.g., a rudder for controlling disturbances in the depth direction, a rudder for controlling disturbances in the left-right direction, etc.). An output gain 142 is prepared for each of these rudder, and adjusts the magnitude of the disturbance compensation value for each rudder. The value of the output gain 142 is set in the range of 0 to 1. For example, if no action is taken against the disturbance, the output gain 142 is set to 0, and if the disturbance is to be offset as much as possible, the output gain 142 is set to 1. The band setting of the low-pass filter 141 and the value of the output gain 142 can be adjusted by the control system adjuster 16.

The decoupling controller 15 compensates for the sway caused by the inter-axis interference between the six axes. For example, when the depth, pitch angle, and azimuth angle of the underwater vehicle 1 are to be controlled to the desired positions, the decoupling controller 15 acquires information indicating the state of the underwater vehicle 1 (such as the actual steering angle, the measurement value of the gyro sensor and the depth gauge, etc.) and calculates a decoupling compensation value (compensation rudder angle for each rudder related to decoupling) that reduces the interference between each control axis. For the decoupling controller 15, for example, a decoupling control unit disclosed in Patent Document 1 can be used. The configuration of the decoupling controller 15 is disclosed in Patent Document 1, so a description thereof will be omitted in this specification. In addition to the configuration disclosed in Patent Document 1, the decoupling controller 15 of this embodiment is internally provided with a low-pass filter 151 (not shown) and an output gain 152 (not shown). In general, the information indicating the state of the underwater vehicle 1 acquired by the decoupling controller 15 contains multiple frequency components. For example, a low-pass filter 151 is provided for each control axis, and reduces a band of a predetermined frequency or higher among the multiple frequency components in each estimated control axis direction. The decoupling controller 15 calculates a decoupling compensation value that cancels the low-frequency band oscillation (oscillation caused by axis interference) in each control axis direction that has passed through the low-pass filter 151. If the band of frequencies that pass through the low-pass filter 151 is raised, the high-frequency components of the oscillation must also be dealt with, and the rudder will operate more frequently, leading to increased energy consumption. The output gain 152 is a parameter that is multiplied by the decoupling compensation value to adjust its magnitude. The output gain 152 can be set for each of multiple rudders. The value of the output gain 152 is set in the range of 0 to 1. The band setting of the low-pass filter 151 and the value of the output gain 152 can be adjusted by the control system adjuster 16.

As shown in the figure, a second loop including a disturbance estimator 14 is configured outside a first loop consisting of an actuator control system 12 and a velocity saturation compensator 13. This ideally cancels out disturbances within the second loop. If oscillation is still confirmed from information indicating the state of the underwater vehicle 1 obtained from the aircraft 20, the oscillation is considered to be due to inter-axis interference. For this reason, the decoupling controller 15 is configured to be placed in the outermost loop so that a decoupling compensation value can be calculated for only the oscillation caused by inter-axis interference.

The control system adjuster 16 acquires the actual command value output from the actuator control system 12 and information indicating the state of the underwater vehicle 1 (actual steering angle, measurements from the gyro sensor and depth gauge, etc.) from the aircraft 20, calculates an evaluation index value described below, and based on the calculated evaluation index value, changes one or more of the following as necessary: the value of the band adjustment gain of the speed saturation compensator 13, the band setting and value of the output gain 142 of the low-pass filter 141 of the disturbance estimator 14, and the band setting and value of the output gain 152 of the low-pass filter 151 of the decoupling controller 15. This process is called parameter adjustment or control system switching.

(Evaluation index)
FIG. 2 shows an example of the evaluation index calculated by the control system regulator 16.
(1) Evaluation value of the swing state: The control system adjuster 16 acquires the measurement values of the depth gauge and gyro sensor, and calculates the peak-to-peak value (the difference between the maximum and minimum values measured within a given time) or the RMS value (root mean square value) of the measurement values within a given time for the swing in each control axis direction, such as the depth, pitch angle, and azimuth angle. The measured peak-to-peak value or RMS value for each control axis direction is the evaluation value of the swing state.

(2) Actuator operation evaluation value: The control system adjuster 16 acquires the actual actuator operation amount (e.g., the actual steering angle at each moment) from the underwater vehicle 1 from moment to moment, and calculates the total operation amount (absolute value integral) within a specified time and the absolute value integral of the actuator operation speed. These values are the actuator operation evaluation value.

(3) Evaluation value of oscillation frequency component: The control system adjuster 16 acquires the measurement values of the depth gauge and gyro sensor, and performs frequency component analysis using FFT (fast Fourier transform) or the like on the waveform data that indicates the oscillation within a predetermined time for each control axis direction. The result of the frequency component analysis is the evaluation value of the oscillation frequency component.

(4) Evaluation value of the actuator compensation amount...The control system adjuster 16 acquires the compensation steering angle (disturbance compensation value and non-interference compensation value, respectively) output from the disturbance estimator 14 and the non-interference controller 15 at every moment, and calculates the peak-to-peak value of the compensation steering angle. Alternatively (or in addition to the peak-to-peak value), the control system adjuster 16 performs frequency component analysis on the compensation steering angle using FFT or the like. The peak-to-peak value of the compensation steering angle or the result of the frequency component analysis is the evaluation value of the actuator compensation amount.

The above evaluation index values (1) and (3) are evaluation index values indicating the swaying of the underwater vehicle 1, and (2) and (4) related to the actuator operation are evaluation index values for energy saving performance. The control system adjuster 16 uses these evaluation index values to adjust the parameters of the disturbance estimator 14 and the non-interference controller 15 so that the swaying suppression of the underwater vehicle 1 and energy saving can be achieved at the same time. As described below, the control system adjuster 16 has a function to switch between a control mode that emphasizes sway suppression and a control mode that emphasizes energy saving, while assuming that sway suppression and energy saving can be achieved at the same time, and adjusts the parameters (low-pass filter band, output gain, etc.) of each compensator (speed saturation compensator 13, disturbance estimator 14, non-interference controller 15) according to the purpose of control.

(Control system switching timing)
The control system adjuster 16 automatically switches the control system (adjusts parameters) at regular intervals (e.g., 5 minutes, 10 minutes, etc.). Alternatively, the control system adjuster 16 automatically switches the control system when the operation mode of the underwater vehicle 1 is switched (e.g., between navigation and anchoring), the control purpose is switched (emphasis on oscillation suppression or energy saving), or the sea area is changed. Alternatively, the control system adjuster 16 switches the control system by manual operation by the user. Note that, since the period of oscillation due to waves and the like is generally several seconds to several tens of seconds, when the control system is automatically switched, the control system is switched at a period longer than the oscillation period, not at the calculation period of the control device 10.

(Control system switching)
FIG. 3 shows an overview of parameters to be adjusted when switching the control system in this embodiment.
(A) The control system adjuster 16 adjusts the filter bands of the low-pass filter 141 of the disturbance estimator 14 and the low-pass filter 151 of the decoupling controller 15, regardless of the control purpose.
(A1) The control system adjuster 16 identifies the first principal component f1 and the second principal component f2, which are the top two components with the largest peak values among the frequency components constituting the oscillation in each control axis direction, based on the evaluation index value "(3) Evaluation value of oscillation frequency component". Here, it is assumed that the frequencies of the first principal component f1 and the second principal component f2 have a relationship of f1<f2. The control system adjuster 16 sets the filter band (and approximate differential band) f of the low-pass filter 141 and the low-pass filter 151 for each control axis so that f1<f<f2 is satisfied based on the high-low frequency relationship, regardless of the magnitude relationship of the peak values of f1 and f2. Here, f1 is the lowest frequency component among the main frequency components constituting the oscillation of the hull. In the operation of the underwater vehicle 1, the influence of the low-frequency component f1 is most dominant, and by setting the filter band f as described above, a compensation value (compensation rudder angle) that deals with this low-frequency component can be calculated. Furthermore, if the oscillation frequency f2, which is higher than f1, is addressed, the oscillation suppression effect will improve (compared to that effect), but the actuator (rudder) will operate more and energy consumption will increase. Therefore, by setting the band of the low-pass filters 141, 151 for each control axis to f, which is a lower frequency than f2, the frequency component of f2 is blocked and the actuator operation is prevented from being excessive. In this way, by adjusting the filter band f of the low-pass filters 141, 151 according to the frequency component of the actual oscillation, it is possible to achieve both oscillation suppression and energy saving.

The method for setting the filter band f is arbitrary. For example, the control system adjuster 16 may set f to the average value of f1 and f2, or may set f to a value shifted a predetermined value toward the f1 or f2 side from the average value. Alternatively, the control system adjuster 16 may store a table or function that defines the relationship between f1 and f2 and f, and set f based on the FFT results f1 and f2 and a predefined table.

(A2) As another method, the control system adjuster 16 may identify the first principal component f1 and the second principal component f2 from the results of the frequency component analysis of the estimated disturbance value estimated by the disturbance estimator 14, and set a filter band f such that f1<f<f2 to the low-pass filters 141, 151 for each control axis.

The control system adjuster 16 adjusts the parameters according to the control purpose in addition to setting the filter bands of the low-pass filters 141 and 151.

(Control objective: When emphasis is placed on suppressing oscillation)
(B) The control system adjuster 16 turns on both the disturbance estimator 14 and the decoupling controller 15. That is, the control system adjuster 16 sets the values of the output gain 142 and the output gain 152 to 1. As a result, both the oscillation due to the disturbance and the oscillation due to the interference between the control axes are suppressed, and the oscillation of the underwater vehicle 1 is suppressed.

(Control objective: When emphasis is placed on energy conservation)
(C) The control system adjuster 16 adjusts the output gain 142 of the disturbance estimator 14 and the output gain 152 of the decoupling controller 15 between 0 and 1 based on the oscillation frequency, the frequency of the compensation steering angle, the magnitude of the compensation steering angle, etc.

(C1) When the oscillation becomes high frequency, the control system adjuster 16 sets the output gain 152 of the decoupling controller 15 for the actuator corresponding to the oscillation to a value smaller than 1. When the oscillation becomes high frequency, the peak value of f2 of the first principal component f1 and the second principal component f2 obtained from the evaluation index value "(3) Evaluation value of oscillation frequency component" becomes equal to or greater than a predetermined threshold value. When the oscillation becomes high frequency, it is known that oscillation often occurs due to compensation for inter-axis interference. Therefore, the output gain 152 of the decoupling controller 15 is lowered to reduce the adverse effects of decoupling control. For example, when the peak value of f2 for the oscillation in the depth direction (vertical direction) exceeds the threshold value, the value of the output gain 152 for the compensation rudder angle for the rudder used for control in the depth direction is set to less than 1. In addition, the specific value of the output gain 152 may be determined, for example, by creating a table in advance that defines the relationship between the frequency and peak value of f2 and the output gain 152, and setting the output gain 152 based on the principal component f2 of the frequency component analysis result of the fluctuation measured during a predetermined period (e.g., 5 minutes or 10 minutes) immediately before adjusting the value of the output gain 152, and the table created in advance.

(C2) The control system adjuster 16 identifies the top two main frequency components f1, f2 (f1<f2) for each of the disturbance compensation value output by the disturbance estimator 14 and the non-interference compensation value output by the non-interference controller 15 based on the evaluation index value "(4) Evaluation value of actuator compensation amount", in the same manner as in the case of oscillation. Then, the control system adjuster 16 sets the output gain of the compensator having the larger peak value between the disturbance compensation value f2 and the non-interference compensation value f2 to a value smaller than 1 (for example, it may be 0). For example, when the principal component f2 of the disturbance compensation value calculated for a certain control axis direction (for example, depth) is _f214 and the principal component f2 of the non-interference compensation value is _f215 , if the peak value of _f214 <the peak value of _f215 is satisfied, the output gain 152 is set to a value smaller than 1. Conversely, if the peak value of _f214 >the peak value of _f215 is satisfied, the output gain 142 is set to a value smaller than 1. Specific values of the output gain 142 and the output gain 152 are determined, for example, based on a table showing the relationship between the frequency and peak value of f2 and the magnitude of the output gain, which are determined in advance individually for each of the disturbance estimator 14 and the decoupling controller 15. This makes it possible to reduce or set to zero the compensation value that causes frequent rudder operation, thereby improving energy saving performance.

(C3) Based on the evaluation index value "(2) actuator operation evaluation value", the control system adjuster 16 sets the output gain of the larger of the disturbance compensation value (e.g., the integral of the absolute value of the compensation steering angle) output by the disturbance estimator 14 and the non-interference compensation value (the integral of the absolute value of the compensation steering angle) output by the non-interference controller 15 in the same manner as in (C2). For example, if the disturbance compensation value > the non-interference compensation value, the control system adjuster 16 sets the output gain 142 to a value smaller than 1, and if the disturbance compensation value > the non-interference compensation value, the control system adjuster 16 sets the output gain 152 to a value smaller than 1. By suppressing the operation of the compensator that contributes to an increase in actuator operation, it is possible to improve energy saving performance.

(C4) During operation with emphasis on energy saving, the control system adjuster 16 automatically sets the output gain 152 of the decoupling controller 15 to 1 if the azimuth angle or roll angle of the hull sways above a certain threshold based on the evaluation index value "(1) Oscillation evaluation value". If the azimuth angle or roll angle changes significantly, this means that the hull is receiving waves from the side. In this case, the control of the azimuth angle and roll angle sway (disturbance) interferes with the control of the depth and pitch angle, so if the lateral sway exceeds a certain threshold, the decoupling control is automatically turned on.

(C5) During operation with emphasis on energy saving, if the evaluation index value (e.g., the integral of the absolute value of the actuator operation speed) is equal to or greater than a predetermined threshold based on the evaluation index value "(2) actuator operation evaluation value", the control system adjuster 16 changes the parameter (band adjustment gain) of the speed saturation compensator 13 based on a predetermined table that defines the relationship between the evaluation index value and the band adjustment gain. For example, in a situation where the actuator operation is large, the energy saving performance can be improved by increasing the band adjustment gain.

The parameter calculation unit 17 creates a table for determining values of various parameters to be adjusted when the control system is switched by the control system adjuster 16. The parameter calculation unit 17 includes a disturbance information storage unit 171 and a simulation evaluation unit 172.
The disturbance information memory unit 171 acquires and stores disturbance information (disturbance waveform data) indicating the disturbances for each control axis direction estimated by the disturbance estimator 14 with the output gain 142 set to 0 during operation of the underwater vehicle 1.
The simulation evaluation unit 172 has a hull model that simulates the operation and state of the underwater vehicle 1, and can calculate the oscillation when a disturbance is applied to the underwater vehicle 1, and the state of the underwater vehicle 1 when control is performed by setting any value to the parameters of each compensator. The simulation evaluation unit 172 inputs the disturbance information stored in the disturbance information storage unit 171 to the hull model, and simulates the oscillation when a disturbance identical to the disturbance information is applied to the underwater vehicle 1. The simulation evaluation unit 172 also uses the hull model to execute a control simulation when the underwater vehicle 1 is operated with various values set for the band adjustment gain of the speed saturation compensator 13, the filter band and output gain 142 of the low-pass filter 141 of the disturbance estimator 14, and the filter band and output gain 152 of the low-pass filter 151 of the decoupling controller 15, for the simulated oscillation, and evaluates the values set for each parameter. The simulation evaluation unit 172 calculates the above-mentioned evaluation index values (1) to (4) from the information on the oscillation and actuator operation calculated during the control simulation, and for example, calculates the time until the oscillation converges (for example, the time until the peak-to-peak value becomes equal to or less than a threshold value) based on "(1) the evaluation value of the oscillation state", calculates the operation amount of the actuator during control execution based on "(2) the actuator operation evaluation value", and selects the parameter value when each satisfies a predetermined criterion. The simulation evaluation unit 172 selects the value of each parameter for each disturbance information stored in the disturbance information storage unit 171, and registers the result in a table. For example, the simulation evaluation unit 172 creates a table that defines the relationship between the principal components f1, f2 and the filter band f of the low-pass filters 141, 151 for the switching of the control system (A1), a table that defines the value of the principal component f2 and the output gain 152 for (C1), and so on. The simulation evaluation unit 172 may perform a control simulation for each speed of the underwater vehicle 1 and create each table. Then, the parameter calculation unit 17 outputs the table created by the simulation evaluation unit 172 to the control system adjuster 16. The control system adjuster 16 adjusts the parameters for the above control system switching (A1) to (C5) based on the table created by the simulation evaluation unit 172. It is difficult to prepare a parameter table in advance assuming all kinds of disturbances. On the other hand, for example, in the same sea area, there is a high possibility that a disturbance similar to the disturbance observed at a predetermined time (actually estimated by the disturbance estimator 14) will occur steadily. The parameter calculation unit 17 makes it possible to perform control using parameter values appropriate to disturbances corresponding to the waves of the sea area in which the underwater vehicle 1 is actually sailing.

(operation)
Next, the operation of the control device 10 will be described.
FIG. 4 is a flowchart showing an example of the operation of the control system according to the embodiment.
The underwater vehicle 1 is in operation, and the user (pilot) has instructed the control device 10 in advance to select a control mode (emphasis on suppressing oscillation, emphasis on energy saving). The control device 10 judges whether to create a table (step S1). The user judges whether to create a table, and if so, inputs that to the control device 10, and the control device 10 makes the judgment of step S1 based on this input. For example, when the change in ocean area or sea state causes a large change in waves, the user inputs a table creation instruction to the control device 10 to obtain disturbance information due to actual waves. If it is considered that the (standard) table stored in the control system adjuster 16 in advance can be used to deal with the situation, the user does not issue a table creation instruction. When the table creation instruction is input, the control device 10 judges that the table is to be created. If not (step S1; No), the process proceeds to step S5.

When it is determined that the table is to be created (step S1; Yes), the control system adjuster 16 first sets the output gain 142 to 0. In the disturbance estimator 14, the disturbance estimation process continues even after the output gain 142 becomes 0. The disturbance estimator 14 acquires measurement values measured by a depth gauge that measures the swing in the depth direction and a gyro sensor that detects the swing of the pitch angle and azimuth angle from time to time, and performs disturbance estimation for each control axis direction (step S2). The disturbance estimator 14 outputs the estimated disturbance information to the parameter calculation unit 17. The disturbance information storage unit 171 acquires and stores the disturbance information from the disturbance estimator 14. The disturbance information storage unit 171 may store the speed of the underwater vehicle 1 in association with the disturbance information. When the collection of the disturbance information is completed, the control system adjuster 16 sets the output gain 142 to 1. Next, the simulation evaluation unit 172 provides the estimated disturbance information to the hull model, performs a control simulation while setting various values for various parameters, and determines appropriate parameters by associating them with the evaluation index values used in the control system switching (A1) to (C5) (step S3). Next, the simulation evaluation unit 172 creates a table in which the determined parameters are registered (step S4). A table is created for each parameter set in the control system switching (A1) to (C5). For example, for the control system switching (A2), a table is created in which the principal components f1 and f2 for each disturbance are associated with the filter band f of the low-pass filter 141, and a table is created in which the principal components f1 and f2 are associated with the filter band f of the low-pass filter 151 within the range of the actually observed (estimated) disturbance. For the control system switching (C3), a table is created in which the values of the output gain 142 and the output gain 152 that can best prevent a decrease in energy-saving performance obtained in the control simulation for the actually observed (estimated) disturbance are registered.

When the table is created, or when the table is not created, the control system adjuster 16 acquires sensor measurement values from the aircraft 20 and calculates the above evaluation index values (1) to (4) (step S5). For example, the control system adjuster 16 calculates each of the evaluation index values (1) to (4) for a certain period (e.g., 10 minutes). Next, the control system adjuster 16 adjusts the filter band f of the low-pass filters 141 and 151 (control system switching (A1) or (A2)) based on the calculated evaluation index values (step S6). Next, the control system adjuster 16 adjusts parameters according to the control objective based on the calculated evaluation index values (step S7). For example, when the control objective is to emphasize oscillation, the control system adjuster 16 performs control system switching (B). When the control objective is to emphasize energy saving, the control system adjuster 16 performs control system switching (C1) to (C5).

The control system adjuster 16 executes the processes of steps S6 and S7 at regular intervals (e.g., 10 minutes). Alternatively, the control system adjuster 16 executes the processes of steps S6 and S7 when the operation mode, control purpose, or sea area changes, or when instructed by the user. The control device 10 repeatedly executes the processes of steps S1 to S7.

The control objective setting may be switched manually by the user, or automatically by the control system adjuster 16 based on the evaluation index values (1) to (4). For example, the control system adjuster 16 may switch the control mode to one that emphasizes oscillation suppression when the total time during which the peak-to-peak value of "(1) oscillation state evaluation value" exceeds the threshold value becomes longer than a predetermined time during control with emphasis on energy saving. Alternatively, the control system adjuster 16 may switch the control mode to one that emphasizes oscillation suppression when the total time during which the "(2) actuator operation evaluation value" exceeds the threshold value becomes longer than a predetermined time during control with emphasis on oscillation suppression.

(effect)
As described above, according to this embodiment, the disturbance estimator 14 performs direct compensation for disturbances, the decoupling controller 15 suppresses the occurrence of rocking within the interference characteristics of the hull, while the speed saturation compensator 13 suppresses sudden actuator operation, and these are operated in an appropriate balance according to the rocking state, making it possible to achieve both the contradictory phenomena of rocking suppression and reduced actuator operation (energy saving). In addition, the balance between rocking suppression performance and energy saving performance can be adjusted as desired.

The above-mentioned control device 10 is implemented in a computer equipped with a processor such as a CPU (Central Processing Unit), a main storage device, an auxiliary storage device, etc., and each of the above-mentioned functions is realized by the processor executing a program stored in the auxiliary storage device. The processor secures a storage area in the main storage device according to the program. The processor secures a storage area in the auxiliary storage device for storing data being processed according to the program. Note that some or all of the processes of the control device 10 may be executed by hardware such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate Array).

As described above, several embodiments of the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and gist of the invention.

<Additional Notes>
The control device, underwater vehicle, control method, and program described in each embodiment can be understood, for example, as follows.

(1) The control device 10 of the first aspect comprises a feedback controller 11 that calculates a control command value based on the difference between the position of the hull and a target position, a decoupling controller 15 that calculates a decoupling compensation value for canceling out mutual interference between control axes of the hull, a disturbance estimator 14 that estimates the force of a disturbance acting on the hull and calculates a disturbance compensation value for canceling out the disturbance, a speed saturation compensator 13 that calculates a speed saturation compensation value such that speed saturation does not occur when the actuators of the hull are controlled based on the control command, and a control system adjuster 16 that updates at least one parameter of the decoupling controller, disturbance estimator and speed saturation compensator based on the swaying generated in the hull and/or the operation of the actuators.
This makes it possible to adjust the balance between sway suppression performance and energy saving performance.

(2) A control device 10 according to a second aspect is a control device according to (1), comprising: a first control loop including the speed saturation compensator that compensates the control command by the speed saturation compensation value; a second control loop including the disturbance estimator that provides the control command compensated by the disturbance compensation value to the first control loop; and a third control loop including the decoupling controller that provides the control command compensated by the decoupling compensation value to the second control loop.
This makes it possible to appropriately eliminate interference between the control axes, and as a result, it is possible to effectively suppress disturbances.

(3) A control device according to a third aspect is a control device of (1) to (2), which selects the top two principal components based on the results of a frequency component analysis of the hull's rolling motion, and sets the frequency between the two principal components to the filter band of a low-pass filter provided in the disturbance estimator and a low-pass filter provided in the decoupling controller.
This makes it possible to achieve both the contradictory goals of suppressing oscillation and reducing actuator operation (energy saving).

(4) A control device according to a fourth aspect is a control device of (1) to (3), wherein when a control objective is to suppress fluctuations, the control system adjuster sets the values of the output gain provided by the disturbance estimator and the output gain provided by the decoupling controller to 1.
This makes it possible to suppress the oscillation.

(5) A control device according to a fifth aspect is a control device according to any one of (1) to (4), wherein when a control objective is energy saving, the control system adjuster sets a value smaller than 1 to the output gain of the disturbance estimator or the output gain of the decoupling controller.
This makes it possible to suppress the actuator operation.

(6) A control device according to a sixth aspect is the control device of (5), wherein, when the control objective is energy saving, the control system adjuster selects the top two principal components based on the results of frequency analysis of the hull's rocking, and when the frequency of the higher frequency component is equal to or higher than a threshold, sets the output gain value of the decoupling controller to a value less than 1.
It is possible to suppress excessive actuator operation caused by the influence of the compensation value output by the decoupling controller.

(7) A control device according to a seventh aspect is the control device of (5) to (6), wherein the control system adjuster, when a control objective is energy saving, sets a value of an output gain of the disturbance estimator to a value smaller than 1 when a high frequency component of the disturbance compensation value is larger than a high frequency component of the non-interference compensation value or the disturbance compensation value is larger than the non-interference compensation value, and sets a value of an output gain of the non-interference controller to a value smaller than 1 when the high frequency component of the non-interference compensation value is larger than the high frequency component of the disturbance compensation value or the non-interference compensation value is larger than the disturbance compensation value.
This reduces the effect of the compensation value that causes the actuator operation to become large, and improves energy saving performance.

(8) A control device according to an eighth aspect is a control device according to any one of (5) to (7), wherein when the control objective is energy saving, the control system adjuster sets the output gain of the decoupling controller to 1 when the azimuth angle or roll angle of the hull is fluctuating by more than a predetermined threshold value.
In a situation where inter-axis interference occurs, even under control aimed at energy saving, the de-interference controller is turned ON to suppress inter-axis interference.

(9) A control device according to a ninth aspect is a control device of (1) to (8), wherein the control system adjuster adjusts parameters of the speed saturation compensator so as to enhance the effect of compensating for speed saturation when improving energy saving control.
This makes it possible to suppress sudden movements of the actuator and improve energy saving performance.

(10) A control device according to a tenth aspect is a control device of (1) to (9), further comprising a parameter calculation unit that calculates a swaying motion occurring in the hull based on the disturbance estimated by the disturbance estimator, executes a simulation to control the hull against the calculated swaying motion while setting various values for at least one of the parameters of the decoupling controller, the disturbance estimator and the speed saturation compensator, evaluates the values of the parameters based on the simulation results, and determines a value that satisfies a predetermined criterion from among the variously set values of the parameter.
This makes it possible to set appropriate values for the parameters of the decoupling controller, the disturbance estimator, and the speed saturation compensator.

(11) The underwater vehicle according to the eleventh aspect is equipped with a control device according to any one of (1) to (10).

(12) The control method according to the twelfth aspect is a control method executed by a control device having a decoupling controller, a disturbance estimator, and a speed saturation compensator, and includes the steps of: calculating a control command value based on the difference between the position of the hull and a target position; the decoupling controller calculating a decoupling compensation value for canceling mutual interference between the control axes of the hull; the disturbance estimator estimating the force of a disturbance acting on the hull and calculating a disturbance compensation value for canceling the disturbance; the speed saturation compensator calculating a speed saturation compensation value such that speed saturation does not occur when the actuators of the hull are controlled based on the control command value; and adjusting at least one parameter of the decoupling controller, the disturbance estimator, and the speed saturation compensator based on the swaying generated in the hull and/or the operation of the actuators.

1: Underwater vehicle, 10: Control device, 11: FB controller, 12: Actuator control system, 13: Speed saturation compensator, 14: Disturbance estimator, 15: Non-interference controller, 16: Control system adjuster, 17: Parameter calculation unit, 171: Disturbance information storage unit, 172: Simulation evaluation unit

Claims (12)

a feedback controller that calculates a control command value based on a difference between a vessel position and a target position;
a decoupling controller for calculating a decoupling compensation value for canceling mutual interference between the control axes of the hull;
a disturbance estimator that estimates a disturbance force acting on the hull and calculates a disturbance compensation value for canceling the disturbance;
a speed saturation compensator that calculates a speed saturation compensation value that prevents speed saturation from occurring when the actuator of the hull is controlled based on the control command value; and
a control system adjuster that adjusts at least one parameter of the decoupling controller, the disturbance estimator, and the speed saturation compensator based on the rocking motion generated in the hull and/or the operation of the actuator;
having
based on the result of the frequency component analysis of the hull pitching, select top two principal components, and set a frequency between the two principal components as a filter band of a low-pass filter included in the disturbance estimator and a low-pass filter included in the decoupling controller;
Control device. a feedback controller that calculates a control command value based on a difference between a vessel position and a target position;
a decoupling controller for calculating a decoupling compensation value for canceling mutual interference between the control axes of the hull;
a disturbance estimator that estimates a disturbance force acting on the hull and calculates a disturbance compensation value for canceling the disturbance;
a speed saturation compensator that calculates a speed saturation compensation value that prevents speed saturation from occurring when the actuator of the hull is controlled based on the control command value; and
a control system adjuster that adjusts at least one parameter of the decoupling controller, the disturbance estimator, and the speed saturation compensator based on the rocking motion generated in the hull and/or the operation of the actuator;
having
When a control objective is to suppress fluctuations, the control system adjuster sets a value of an output gain of the disturbance estimator and an output gain of the decoupling controller to 1.
Control device. a feedback controller that calculates a control command value based on a difference between a vessel position and a target position;
a decoupling controller for calculating a decoupling compensation value for canceling mutual interference between the control axes of the hull;
a disturbance estimator that estimates a disturbance force acting on the hull and calculates a disturbance compensation value for canceling the disturbance;
a speed saturation compensator that calculates a speed saturation compensation value that does not cause speed saturation when the actuator of the hull is controlled based on the control command value; and
a control system adjuster that adjusts at least one parameter of the decoupling controller, the disturbance estimator, and the speed saturation compensator based on the rocking motion generated in the hull and/or the operation of the actuator; and
having
When a control objective is energy saving, the control system adjuster sets a value smaller than 1 to a value of an output gain of the disturbance estimator or an output gain of the decoupling controller.
Control device. the control system adjuster selects two top principal components based on the result of the frequency analysis of the hull pitch, and when the frequency of the higher frequency component is equal to or higher than a threshold, sets a value smaller than 1 to the output gain of the decoupling controller;
The control device according to claim 3 . the control system adjuster sets a value smaller than 1 to an output gain of the disturbance estimator when a peak value of a high frequency component of the disturbance compensation value is larger than a peak value of a high frequency component of the non-interference compensation value or when the disturbance compensation value is larger than the non-interference compensation value;
When the peak value of the high frequency component of the non-interference compensation value is greater than the peak value of the high frequency component of the disturbance compensation value or when the non-interference compensation value is greater than the disturbance compensation value, a value smaller than 1 is set as the output gain of the non-interference controller.
The control device according to claim 3 or 4 . The control system adjuster sets the output gain of the decoupling controller to 1 when the azimuth angle or roll angle of the ship's hull is fluctuating by a predetermined threshold value or more.
The control device according to any one of claims 3 to 5 . When the control system adjuster is configured to improve the energy saving control, the control system adjuster adjusts the parameters of the speed saturation compensator so as to enhance the action of compensating for the speed saturation.
The control device according to any one of claims 1 to 6 . a parameter calculation unit which calculates a rolling motion generated in the hull based on the disturbance estimated by the disturbance estimator, executes a simulation for controlling the hull in response to the calculated rolling motion while setting various values for at least one parameter of the decoupling controller, the disturbance estimator and the speed saturation compensator, evaluates values of the parameters based on the results of the simulation, and determines a value that satisfies a predetermined criterion from among the variously set values of the parameters;
The control device according to any one of claims 1 to 7 , further comprising: a first control loop including the speed saturation compensator that compensates the control command value by the speed saturation compensation value, a second control loop including the disturbance estimator that provides the control command value compensated by the disturbance compensation value to the first control loop, and a third control loop including the decoupling controller that provides the control command value compensated by the decoupling compensation value to the second control loop;
The control device according to any one of claims 1 to 8, further comprising: An underwater vehicle comprising the control device according to any one of claims 1 to 9 . A control method implemented by a control device having a decoupling controller, a disturbance estimator, and a speed saturation compensator, comprising the steps of:
calculating a control command value based on a difference between a vessel position and a target position;
a step of the decoupling controller calculating a decoupling compensation value for canceling mutual interference between the control axes of the hull;
a disturbance estimator estimating a disturbance force acting on the hull and calculating a disturbance compensation value for canceling the disturbance;
a step of calculating a speed saturation compensation value such that speed saturation does not occur when the speed saturation compensator controls the actuators of the hull based on the control command value;
adjusting a parameter of at least one of the decoupling controller, the disturbance estimator and the speed saturation compensator based on the rocking motion generated in the hull and/or the operation of the actuator;
having
In the step of adjusting the parameters, two principal components are selected based on the result of the frequency component analysis of the rolling motion of the hull, and a frequency between the two principal components is set to a filter band of a low-pass filter provided in the disturbance estimator and a low-pass filter provided in the decoupling controller.
Control methods. A control method implemented by a control device having a decoupling controller, a disturbance estimator, and a speed saturation compensator, comprising the steps of:
calculating a control command value based on a difference between a vessel position and a target position;
a step of the decoupling controller calculating a decoupling compensation value for canceling mutual interference between the control axes of the hull;
a disturbance estimator estimating a disturbance force acting on the hull and calculating a disturbance compensation value for canceling the disturbance;
a step of calculating a speed saturation compensation value such that speed saturation does not occur when the speed saturation compensator controls the actuators of the hull based on the control command value;
adjusting a parameter of at least one of the decoupling controller, the disturbance estimator and the speed saturation compensator based on the rocking motion generated in the hull and/or the operation of the actuator;
having
In the step of adjusting the parameters,
When the control objective is to suppress fluctuations, the output gain of the disturbance estimator and the output gain of the decoupling controller are set to 1;
When the control objective is energy saving, a value smaller than 1 is set to the output gain of the disturbance estimator or the output gain of the decoupling controller.
Control methods.

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