An experimental platform for UUV navigation test and algorithm verification

Abstract

A kind of test platform of UUV navigation test and algorithm verification, including propulsion device, upper electronic cabin, the propulsion device can be relatively moved and be installed on platform parallel mechanism in linkage, the upper electronic cabin is fixed on platform parallel mechanism, rotation device is provided on the platform parallel mechanism and is rotated in linkage with propulsion device, the rotation device is rotatably connected on support base, the platform parallel structure includes dynamic platform, several middle displacement devices as moving pair, the dynamic platform is connected on the upper part of middle displacement device by ball hinge device and forms ball pair, the lower part of middle displacement device is connected on fixed platform by rotating device and forms rotating pair, and lower electronic cabin is provided on the fixed platform.The platform parallel mechanism of the present application is composed of 3PRS structure by ball pair, moving pair and rotating pair, provides rotation around X, Y axis direction and Z direction displacement for propulsion device, so as to provide three degrees of freedom movement conditions for propulsion device.

Description

Technical Field

[0001] This invention belongs to the field of experimental technology, specifically relating to an experimental platform for UUV navigation testing and algorithm verification. Background Technology

[0002] As human exploration and development continue to push towards the depths of the ocean, UUVs have become one of the most important tools for exploring marine resources. The underwater environment is complex and harsh, with various unforeseen circumstances; therefore, the performance of a UUV is crucial to its ability to complete its intended mission. The UUV control algorithm system, as a vital component of the overall UUV system, determines whether the UUV can accurately perform six degrees of freedom navigation maneuvers underwater—pitch, roll, rotation, surfacing, descent, forward, and backward—by controlling the thrusters according to input commands.

[0003] When conducting navigation tests and algorithm verification for a UUV (Unmanned Underwater Vehicle), the process typically begins with building a complete UUV prototype and porting the developed algorithm into it. Then, tank and lake trials are used to verify the UUV's control algorithm and various functions. After the UUV's control algorithm and functions are verified through tank and lake trials, sea trials are conducted to validate them in real-world application scenarios. In the early stages of UUV development, the control algorithm and functions are not yet perfect, so repeated optimization of the algorithm and adjustment of control parameters are usually necessary during tank or lake trials. However, tank and lake trials are time-consuming, labor-intensive, and expensive. Therefore, there is an urgent need for a method to conduct preliminary simulation tests before tank and lake trials, allowing for UUV algorithm debugging and verification in the laboratory, thereby significantly reducing the debugging workload during the tank and lake trial phases.

[0004] Furthermore, UUVs employing different thruster layouts may require different control algorithms and parameters. The conventional approach is to build a UUV with the corresponding thruster layout and first debug the control algorithm in a water tank. There is an urgent need for a universal platform that can be used to debug UUV control algorithms for different thruster layouts.

[0005] Invention patent 201710588232.7 discloses an experimental platform and method for flight testing and algorithm verification of rotorcraft, providing an experimental platform capable of simulating six degrees of freedom motion for rotorcraft. In this patent, a three-degree-of-freedom turntable uses a universal joint to provide three degrees of freedom rotation, and a telescopic rod provides vertical displacement for the turntable, while also supporting the test body. This structure results in high trim difficulty, low structural strength, and poor stability. Rotorcraft have a single rotor distribution, with only one quadcopter configuration, making it inflexible for testing other aircraft layouts. The platform uses rigid support with a telescopic rod, failing to simulate the state of an aircraft when suspended in the air.

[0006] Patent 202210768322.5 discloses an underwater dual-rotor multi-input multi-output control experimental platform. However, using vertical and horizontal bearings, it can only achieve two-degree-of-freedom motion simulation, failing to simulate six-degree-of-freedom motion of the test object. The rotor distribution is limited to a single dual-rotor configuration, hindering flexible testing of other rotor layouts. Furthermore, the platform uses a single support rod, resulting in high balancing difficulty, low structural strength, and poor stability.

[0007] The existing technology has the following shortcomings:

[0008] 1) Typically, a complete UUV is first built before being placed in water for various tests. In the early stages of UUV development, the control algorithms and functions are not yet perfect, so it is generally necessary to repeatedly optimize the algorithms and adjust the control parameters during pool or lake trials. Such repeated pool and lake trials are time-consuming, labor-intensive, and expensive.

[0009] 2) Some researchers use software simulations in the early stages of development to predict the performance of UUVs and test algorithms. However, there is bound to be a significant discrepancy between simulation results and actual test results.

[0010] 3) There is currently no experimental platform that can perform motion simulation and algorithm verification for UUV six degrees of freedom.

[0011] 4) Existing testing platforms can only be used for testing in a single environment, either on land or in water. Furthermore, they do not consider issues such as sealing, site limitations, and the stability of UUV control algorithms under the influence of ocean currents, resulting in low testing efficiency and limited testing methods.

[0012] 5) Existing test platforms mostly use single structures such as universal joints as support and fixing devices, without considering the stability and load-bearing capacity of the structure, or the issues of balancing and the difficulty of balancing.

[0013] 6) Existing UUV simulation test platforms can only test one type of thruster layout, lacking scalability and unable to be flexibly configured for different thruster layouts.

[0014] 7) The platform and the supporting structure are rigidly connected, making it impossible to simulate suspension conditions. Summary of the Invention

[0015] To address the problems described in the background section, the present invention aims to provide a test platform for UUV navigation testing and algorithm verification. This platform can simulate the six degrees of freedom motion of a UUV, enabling navigation testing and algorithm verification on land as well as underwater testing, significantly reducing the debugging workload during pool and lake trials. Furthermore, it allows for flexible switching between different thruster configurations, enabling testing of UUVs with varying thruster layouts.

[0016] The technical solution adopted in this invention is:

[0017] A test platform for UUV navigation testing and algorithm verification includes a propulsion device, an upper electronic compartment, a lower electronic compartment, a platform parallel mechanism, a rotating device, and a support base. The propulsion device is relatively movable and linked to the platform parallel mechanism. The upper electronic compartment is fixed to the platform parallel mechanism. The platform parallel mechanism is equipped with a rotating device that is linked to the rotation of the propulsion device. The rotating device is rotatably connected to the support base. The platform parallel structure includes a moving platform and several central displacement devices as sliding pairs. The moving platform is connected to the upper part of the central displacement devices via ball joints to form a ball joint. The lower part of the central displacement devices is connected to a fixed platform via rotating devices to form a rotary pair. The lower electronic compartment is mounted on the fixed platform. The platform parallel mechanism of this invention moves with the propulsion device. The platform parallel mechanism, through ball joints, sliding pairs, and rotary pairs, forms a 3PRS structure (three-degree-of-freedom spatial mechanism), providing the propulsion device with rotation around the X and Y axes and displacement in the Z direction, thereby providing the propulsion device with three degrees of freedom of motion.

[0018] Furthermore, the moving platform is provided with a slide rail groove, and the slide rail of the propulsion device is clearance-fitted to the slide rail groove and press-fitted onto the moving platform by the upper electronic compartment. The moving platform provides support for the propulsion device and the upper electronic compartment, and is fixed to the upper electronic compartment by screws, thereby fixing the positions of the moving platform, the propulsion device, and the upper electronic compartment. The relative positions of the moving platform, the propulsion device, and the electronic compartment are adjusted to achieve balancing.

[0019] Furthermore, the central displacement device includes an outer wall, an end cap, and a push rod. The end cap, push rod, and outer wall are positioned by screws and threaded holes, forming a lockable sliding pair. The relative position change of the push rod and the outer wall forms the sliding pair. A differential transformer-type displacement sensor is installed on the push rod to collect its displacement. An interference module simulating ocean current interference during hovering is installed below the push rod. The differential transformer-type displacement sensor consists of a coil, an armature, and a displacement acquisition circuit. The armature is located at the bottom of the push rod and is linked to it. The coil is located around the push rod and the armature and is connected to the lower electronic compartment through the displacement acquisition circuit. The end cap, push rod, and outer wall of the central displacement device of this invention can change their relative positions by screwing in screws, facilitating flexible replacement of the components in the central displacement device. When the relative positions of the three are fixed, the sliding pair is locked. The differential transformer-type displacement sensor of this invention has the characteristics of high accuracy and non-contact operation, and can collect the displacement changes of the push rod of the central displacement device in real time for a long period of time.

[0020] Furthermore, the interference module includes a bottom motor disposed within the outer wall, with a pad propelled by the bottom motor. A spring is disposed between the pad and the push rod, causing the push rod to move up and down continuously and passively. The bottom motor of this invention pushes the pad to move up and down at a set frequency, and the energy stored in the spring causes the push rod to move up and down continuously and passively, thereby simulating ocean current interference during hovering. Springs with different elastic coefficients can be used to simulate ocean currents of varying interference intensities.

[0021] Furthermore, the rotating device includes a horizontal rotating shaft, which is interference-fitted with a deep groove ball bearing and a bottom circular hole on the outer wall to form a rotating pair. The horizontal rotating shaft is connected to a single-axis angle sensor that collects its angle changes via a coupling. The deep groove ball bearing is interference-fitted with a rotating base. The single-axis angle sensor is fixed to a sensor base. The rotating base and the sensor base are fixed on a fixed platform. A locking screw is provided on the horizontal rotating shaft to lock it in place. When the locking screw in the rotating device of this invention is tightened, it will lock the horizontal rotating shaft, preventing the rotating shaft from rotating, thereby achieving the function of locking the rotating pair.

[0022] Furthermore, the lower electronic compartment includes a second sealed outer shell, on which a second watertight base and a second antenna are mounted. A second power supply for powering the platform parallel mechanism and rotating device is installed inside the second sealed outer shell. The second watertight base, the second antenna, and the second power supply are all electrically connected to a second control system. The second control system includes a second main control module, on which a second data acquisition module, a second motion control module, and a second communication module are electrically connected. The second power supply of this invention powers the bottom motor, differential transformer-type displacement sensor, single-axis angle sensor, strain gauge pressure sensor in the rotating device, and the modules within the compartment in the platform parallel mechanism. The second motion control module controls the bottom motor. The second watertight base serves as the communication channel between the external sensors and the internal control system. The second antenna enables wireless data communication between the platform parallel mechanism, the rotating device, and the computer.

[0023] Furthermore, the propulsion device includes a slide rail connected to the moving platform. A flow guide is provided on the front side of the slide rail, and an adjustable rudder is provided at the rear of the slide rail. An adjustable sliding base and an adjustable intermediate fixing frame can be mounted on the slide rail, and a tail fixing frame can be mounted at the rear end of the slide rail. Propulsion modules can be installed on both sides of the sliding base, the intermediate fixing frame, and the tail fixing frame to achieve six degrees of freedom of movement. Each propulsion module includes a power-providing thruster, and a collision shield is provided outside the thruster. The collision shield is fixed to the fixing frame, which can be fixedly connected to the sliding base, both sides of the intermediate fixing frame, or the tail fixing frame. The thruster of this invention provides power to the propulsion module, and thus to the entire propulsion device. The propulsion module can be moved on the slide rail via the sliding base to adjust its position and achieve balance. The propulsion module can be arranged in three ways: tail-end, horizontal, and side-end. A propulsion module combined with the slide rail can achieve a horizontal or side-end arrangement; a propulsion module combined with the intermediate fixing frame can achieve a horizontal arrangement; and a propulsion module combined with the tail fixing frame can achieve a tail-end arrangement. The rudder and mid-mounted bracket can be flexibly adjusted in position on the slide rails, and the rudder, mid-mounted bracket, and tail-mounted bracket are detachable. Various UUVs with different propulsion configurations can be simulated by flexibly arranging the propulsion modules and assembling the propulsion module components with the mid-mounted and tail-mounted brackets. The forces generated by the three propulsion modules arranged in different positions act on the propulsion device, providing power for the propulsion device's translation along the X, Y, and Z axes and rotation around these axes, enabling the propulsion device to perform forward, backward, surfacing, diving, lateral, rolling, and hovering movements, thus achieving six degrees of freedom of motion.

[0024] Furthermore, the upper electronic compartment includes a first sealed outer shell, on which a first watertight base and a first antenna are disposed. A first power supply and sensors are installed inside the first sealed outer shell. The first watertight base, first antenna, first power supply, and sensors are all electrically connected to a first control system. The first control system includes a first main control module, which is electrically connected to a first data acquisition module, a first motion control module, and a first communication module. The sensors of this invention include an attitude sensor, a pressure sensor, a water level sensor, and a GPS locator. The first power supply provides power to the thruster and other modules within the compartment. The attitude sensor detects the attitude of the propulsion device in real time, the pressure sensor detects the height of the propulsion device in real time, the water level sensor detects the depth of the propulsion device underwater in real time, and the GPS locator detects the ground position of the propulsion device in real time. The first main control module is the data processing and logic control center. The first data acquisition module processes information data collected from the sensors, the first motion control module centrally controls the thruster to complete various actions, and the communication module uses Bluetooth wireless communication to transmit and receive data. The first sealed outer shell serves to prevent dust and provide waterproofing during underwater testing. The first watertight seat serves as the communication channel between the external thrusters and the internal control system. The first communication module enables data exchange between the propulsion system and the computer via the first antenna.

[0025] Furthermore, the rotating device includes a tapered roller bearing, which is mounted between the fixed platform and the support base via a clamping ring. A bearing cover is provided on the fixed platform, and the bearing cover has threaded holes for fixing a watertight seat. A strain gauge pressure sensor is provided between the bearing cover and the clamping ring to measure the change in clamping force of the clamping ring in real time. A limiting ring is provided on the fixed platform to prevent excessive lift from separating the inner and outer rings of the tapered roller bearing. The strain gauge pressure sensor of this invention has an interference fit with the bearing cover and the clamping ring. When the thruster generates upward lift, a relative movement tendency occurs between the inner and outer rings of the tapered roller bearing. The strain gauge pressure sensor measures the change in clamping force of the clamping ring in real time, thereby recording the change in the vertical force of the entire device. Data collected by strain gauge pressure sensors, differential transformer displacement sensors, and single-axis angle sensors can be analyzed to determine the forces generated during the propulsion device's roll, buoyancy, descent, forward, backward, lateral, and hovering movements. This allows for the determination of the thrust generated by the propeller at different speeds, which is then plotted as a thrust curve, providing a foundation for subsequent analysis. The clamping ring and the stationary platform have a clearance fit, providing clamping force to the outer ring of the tapered roller bearing. The boss on the rotating shaft provides support force to the inner ring of the bearing. The outer ring of the tapered roller bearing has a clearance fit with the stationary platform, while the inner ring has an interference fit with the rotating shaft. The limiting ring prevents excessive lift by separating the inner and outer rings of the tapered roller bearing. The threaded hole at the top of the bearing cap is used to fix the watertight seat, which, along with the boss on the rotating shaft, achieves sealing of the rotating device and cable routing. The tapered roller bearing allows the rotating device to rotate in the Z direction, providing the propulsion device with one degree of freedom of movement. When no rotational force is received, the tapered rollers will self-lock due to the frictional force of the sealing structure on the clamping ring.

[0026] Furthermore, the support base includes a base bracket, on which a rotating shaft is mounted. The rotating shaft has a boss supporting a tapered roller bearing, and a caster wheel is located at the bottom of the base bracket. The rotating shaft of this invention is interference-fitted with the bearing in the rotating device. The support base, as the overall support, provides support force for the entire platform. It can translate in the X and Y directions, providing conditions for two degrees of freedom of movement for the propulsion device. The caster wheel has two control modes: locked and unlocked. When the space is limited, the caster wheel is locked, the base is fixed, and it cannot translate in the X and Y directions. At this time, the entire propulsion device only has the conditions for rotation in the X, Y, and Z directions and translation in the Z-axis direction, i.e., four degrees of freedom of movement. When unlocked, the support base can translate in the X and Y directions, providing two degrees of freedom of movement for the propulsion device. At this time, the propulsion device has the conditions for translation in the X, Y, and Z directions and rotation in the Z-axis direction, i.e., six degrees of freedom of movement.

[0027] Compared with the prior art, the significant advantages of this invention include:

[0028] (1) This invention simulates the underwater environment of UUVs and tests whether the navigation and algorithm performance meet the requirements for use.

[0029] (2) It can flexibly switch between different propulsion layouts, thereby enabling navigation tests and algorithm verification of UUVs with different propulsion layouts, improving R&D efficiency and saving R&D funds.

[0030] (3) It can be used as a UUV algorithm development platform. After repeated testing of the UUV algorithm, operators can continuously develop, improve and optimize the UUV algorithm based on the data generated from the test.

[0031] (4) The test platform can simulate the six degrees of freedom motion of UUVs, and can be used for navigation tests and algorithm verification on land, as well as underwater tests, which greatly reduces the amount of debugging work of UUVs in pool tests and lake tests. (5) With the sliding rail and modular design, the test platform can be built with simple assembly, and the components can be flexibly replaced, which has better interchangeability.

[0032] (6) The use of a platform parallel mechanism improves the stability and load-bearing capacity of the structure and reduces the balancing requirements. It also provides higher accuracy in test data.

[0033] (7) By adding motors and springs, a structure was designed to simulate ocean currents or wave interference, thereby testing the anti-interference ability of the algorithm and making the test content more diverse.

[0034] (8) In order to enable underwater testing, a sealing structure has been added, including a watertight seat plug and a sealing ring. Because the platform has the freedom of rotation, the cable arrangement has been considered to prevent cable entanglement, so that the platform is not limited to a single land or underwater environment. After completing the land test, it can be further tested underwater, which is closer to the actual situation.

[0035] (9) After removing the propulsion device and the upper electronic cabin, an actual UUV prototype can be mounted on the test platform for flight testing, algorithm verification and development, which improves the R&D efficiency of the prototype.

[0036] (10) It can be used as a training platform for machine learning-based control algorithms. The platform in this invention can be used as a training platform for control algorithms and has the function of learning and training.

[0037] (11) The three methods of land-based testing, overall underwater testing, and partial underwater testing can be tested sequentially to form a complete testing system. As the test environment gradually approaches the real underwater environment, the algorithm will eventually meet the needs of real underwater navigation after continuous improvement and optimization by technical personnel. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the present invention.

[0039] Figure 2 This is a schematic diagram of the propulsion device of the present invention.

[0040] Figure 3 This is a structural schematic diagram of the propulsion module of the present invention.

[0041] Figure 4 This is a schematic diagram of the upper electronic compartment of the present invention.

[0042] Figure 5 This is a schematic diagram of the platform parallel mechanism of the present invention.

[0043] Figure 6 This is a schematic diagram of the structure of the middle displacement device of the present invention.

[0044] Figure 7 This is a schematic diagram of the rotating device of the present invention.

[0045] Figure 8 This is a schematic diagram of the rotating device of the present invention.

[0046] Figure 9 This is a schematic diagram of the support base of the present invention.

[0047] Figure 10 This is a structural schematic diagram of the pitching and tilting posture of the present invention.

[0048] Figure 11 This is a schematic diagram of the structure of the invention in the pitching and head-down posture.

[0049] Figure 12 This is a structural schematic diagram of the roll posture of the present invention.

[0050] Figure 13 This is a structural schematic diagram of the forward and backward postures of the present invention.

[0051] Figure 14 This is a structural schematic diagram of the vertical lifting and lowering postures of the present invention.

[0052] Figure 15 This is a schematic diagram of the underwater testing mechanism of this invention. Detailed Implementation

[0053] The present invention will be further described below with reference to specific embodiments, but the invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternatives, improvements, and equivalents that may be included within the scope of the claims.

[0054] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, unless otherwise expressly defined.

[0055] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0056] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0057] See Figure 1This embodiment provides a test platform for UUV navigation testing and algorithm verification, including a propulsion device 1, an upper electronic compartment 2, a lower electronic compartment 4, a platform parallel mechanism 3, a rotating device 6, and a support base 6. The propulsion device 1 is relatively movable and linked to the platform parallel mechanism 3. The upper electronic compartment 2 is fixed to the platform parallel mechanism 3. The platform parallel mechanism 3 is equipped with a rotating device 5 that is linked to the rotation of the propulsion device 1. The rotating device 5 is rotatably connected to the support base 6. Specifically, the slide rail in the propulsion device 1 can move back and forth in the slide rail groove in the platform parallel mechanism 3, thereby achieving flexible balancing. The electronic compartment and the moving platform of the platform parallel mechanism 3 are fixed by screws. After the screws are tightened, the relative positions of the propulsion device 1, the electronic compartment, and the moving platform of the platform parallel mechanism 3 are fixed. Therefore, when the thrust of the propulsion device 1 changes, the attitude of the propulsion device 1 and the moving platform of the platform parallel mechanism 3 will change simultaneously. The platform parallel mechanism 3 and the rotating device 5 are fixed by screws. When the propulsion device 1 rotates, it will drive the rotating device 5 to rotate simultaneously. The bearing in the rotating device 5 is interference-fitted with the shaft in the support base 6, and the support base 6 provides support for the other components.

[0058] See Figure 2 The propulsion device 1 described in this embodiment consists of a fairing 11, a propulsion module 12, a slide rail 13, an intermediate fixed frame 14, a rudder 15, and a tail fixed frame 16. Specifically, the propulsion device 1 includes a slide rail 13 connected to the moving platform 31 of the platform parallel mechanism 3. A fairing 11 is provided on the front side of the slide rail 13, and an adjustable rudder 15 is provided on the rear of the slide rail 13. An adjustable sliding base 17 and an adjustable intermediate fixed frame 14 can be installed on the slide rail 13, and a tail fixed frame 16 can be installed on the rear end of the slide rail 13. Propulsion modules 12 can be provided on both sides of the sliding base 17, the intermediate fixed frame 14, and the tail fixed frame 16 to achieve six degrees of freedom of movement. See also Figure 3The propulsion module 12 includes a propeller 121 that provides power. A crash shield 122 is provided outside the propeller 121. Both the propeller 121 and the crash shield 122 are fixed to a mounting frame 123. The mounting frame 123 can be fixedly connected to a sliding base 17, the sides of a middle mounting frame 24, or a tail mounting frame 26. The propeller 121 is fixed to the mounting frame 123 with screws 124. The crash shield 122 is welded to the mounting frame 123. The mounting frame 123 is fixed to the sliding base 17 with screws 124. The sliding base 17 is tightened or loosened to the slide rail 13 in the propulsion device 1 with screws 124. The propeller 121 of this invention provides power to the propulsion module, and thus to the entire propulsion device. The propulsion module 12 can be adjusted and balanced by moving the sliding base 17 on the slide rail 13. The propulsion module 12 can be arranged in three ways: tail, horizontal, and side. The propulsion module 12, when combined with the slide rail 13, can achieve a horizontal or side arrangement; when combined with the intermediate mounting bracket 14, it can achieve a horizontal arrangement; and when combined with the tail mounting bracket 16, it can achieve a tail arrangement. The rudder 15 and the intermediate mounting bracket 14 can be flexibly adjusted in position on the slide rail 13, and they are detachable. Various UUVs with different propulsion layouts can be simulated by flexibly arranging the propulsion module 12 and assembling its components with the intermediate and tail mounting brackets 14 and 16. The forces generated by the three different propulsion modules 12, acting on the propulsion device 12, provide power for its translation along the X, Y, and Z axes and its rotation around these axes, enabling the propulsion device 12 to perform forward, backward, buoyancy, descent, lateral movement, roll, and hovering actions, thus achieving six degrees of freedom of motion.

[0059] To prevent cable tangling and facilitate cable routing, the electronics compartment is divided into an upper electronics compartment 2 and a lower electronics compartment 4, as follows: Figure 4As shown, the upper electronic compartment 2 includes a first sealed outer shell 21, on which a first watertight base 22 and a first antenna 23 are disposed. A first power supply 24 and a sensor 25 are installed inside the first sealed outer shell 21. The first watertight base 22, the first antenna 23, the first power supply 24, and the sensor 25 are all electrically connected to a first control system 26. The first control system 26 includes a first main control module, which is electrically connected to a first data acquisition module, a first motion control module, and a first communication module. The sensor 25 of this invention includes an attitude sensor, a pressure sensor, a water level sensor, and a GPS locator. The first power supply 24 provides power to the thruster 121 and other modules within the compartment. The attitude sensor detects the attitude of the thruster 1 in real time, the pressure sensor detects the height of the thruster 1 in real time, the water level sensor detects the depth of the thruster 1 underwater in real time, and the GPS locator detects the ground position of the thruster 1 in real time. The first main control module serves as the data processing and logic control center. The first data acquisition module processes information data collected from sensors. The first motion control module centrally controls the thrusters to complete various actions. The communication module uses Bluetooth wireless communication to transmit and receive data. The first sealed outer shell 21 serves to prevent dust and provide waterproofing during water testing. The first watertight base 22 is the communication channel between the external thrusters and the internal control system. The first communication module enables data exchange between the propulsion device 1 and the computer via the first antenna 23.

[0060] See Figure 5 The platform parallel structure 3 described in this embodiment includes a moving platform 31 and several central displacement devices 33 serving as prismatic joints. The moving platform 31 is connected to the upper part of the central displacement devices 33 via ball joints 32 to form a ball joint. The lower part of the central displacement devices 33 is connected to a fixed platform 34 via a rotating device 35 to form a revolute joint. A lower electronic compartment 36 is provided on the fixed platform 34. The platform parallel mechanism 3 of this invention moves with the propulsion device 1. The platform parallel mechanism 3 forms a 3PRS structure (three-degree-of-freedom spatial mechanism) through ball joints, prismatic joints, and revolute joints, providing the propulsion device 1 with rotation around the X and Y axes and displacement in the Z direction, thereby providing the propulsion device 1 with three degrees of freedom of motion. Specifically, the moving platform 31 is provided with a slide rail groove 311, which is clearance-fitted with the slide rail 13 of the propulsion device 1, providing support for the propulsion device 1 and the upper electronic compartment 2. It is fixed to the upper electronic compartment 2 by screws, thereby fixing the positions of the moving platform 31, the propulsion device 1, and the upper electronic compartment 2. Balancing is achieved by adjusting the relative positions of the moving platform 31, the propulsion device 1, and the electronic compartment. The ball joint device 32 is fixed to the moving platform 31 by screws and is connected to the push rod 333 to form a ball joint. See also... Figure 6The central displacement device 33 has three components located at the left, right, and rear positions. It includes an outer wall 332, an end cap 331, and a push rod 333. The end cap 331, push rod 333, and outer wall 332 are positioned by screws and threaded holes, forming a lockable sliding pair. Each component has threaded holes, and their relative positions are controlled by the depth to which the screws are screwed into these holes. The relative position of the push rod 333 and the outer wall 332 changes, forming the sliding pair. A differential transformer-type displacement sensor is installed on the push rod 333 to collect its displacement. An interference module simulating ocean current interference during hovering is located below the push rod 333. The differential transformer-type displacement sensor consists of a winding coil 334, an armature 337, and a displacement acquisition line 335. The armature 337 is located at the bottom of the push rod 333 and is linked to it. The winding coil 334 is located on the outer ring of the push rod 333 and the armature 337 and is connected to the lower electronic compartment 4 through the displacement acquisition line 335. The relative positions of the end cap 331, push rod 333, and outer wall 332 of the central displacement device 33 can be changed by screwing in screws, facilitating flexible replacement of the components in the central displacement device 33. When the relative positions of the three are fixed, the moving pair is locked. The differential transformer-type displacement sensor of this invention features high accuracy and non-contact operation, enabling long-term real-time acquisition of the displacement changes of the push rod of the central displacement device. The interference module includes a bottom motor 339 disposed within the outer wall 332. The bottom motor 339 has a pad 338 pushed by it. A spring 336 is disposed between the pad 338 and the push rod 333, causing the push rod 333 to move up and down passively continuously. The armature 337 moves up and down with the push rod 333. The displacement change of the push rod 333 is collected by a differential transformer-type displacement sensor. Combined with the spring force calculation formula of the spring 336, the spring force of each central displacement device 33 is obtained. In this invention, the bottom motor 339 pushes the pad 338 up and down at a set frequency. The energy stored in the spring 336 causes the push rod 333 to move up and down passively continuously, thereby simulating the interference of ocean currents in a hovering situation. Springs with different elastic coefficients 336 can be used to simulate ocean currents with different interference intensities. See also... Figure 7The rotating device 35 includes a rotating horizontal shaft 351. The rotating horizontal shaft 351 is interference-fitted with a deep groove ball bearing 352 and a bottom circular hole 3322 of the outer wall 332 to form a rotating pair. The rotating horizontal shaft 351 is connected to a single-axis angle sensor 355, which collects its angle changes, via a coupling 354. The deep groove ball bearing 352 is interference-fitted with a rotating base 353. The single-axis angle sensor 355 is fixed to a sensor base 356. The rotating base 353 and the sensor base 356 are fixed on a fixed platform 34. A locking screw 357 is provided on the rotating horizontal shaft 351 to lock it in place. When the locking screw 357 in the rotating device 35 is tightened, it will lock the rotating horizontal shaft 351, preventing it from rotating, thereby achieving the function of locking the rotating pair. The balancing requirements between the platform parallel mechanism 3, the propulsion device 1, and the electronic cabin are relatively low. During balancing, simply placing the centers of gravity of the propulsion device 1 and the electronic cabin within a certain range of the center of the moving platform 31 is sufficient for rapid balancing. Regarding the sealing and cabling issues of the platform parallel mechanism 3, the end cap 331 has a sealing ring and a sealing groove. The outer wall 332 and the rotating horizontal shaft 351 have cable routing holes drilled to facilitate cable passage. The cable routing holes 3321 on the outer wall 332 are sealed with adhesive, while the cable routing holes 358 on the rotating horizontal shaft 351 do not require adhesive sealing. The lower electronic cabin 4 includes a second sealed outer shell, on which a second watertight seat and a second antenna are installed. A second power supply for powering the platform parallel mechanism and the rotating device is installed inside the second sealed outer shell. The second watertight seat, the second antenna, and the second power supply are all electrically connected to the second control system. The second control system includes a second main control module, which is electrically connected to a second data acquisition module, a second motion control module, and a second communication module. The second power source of this invention powers the bottom motor, differential transformer-type displacement sensor, single-axis angle sensor, strain gauge pressure sensor in the rotating device, and the internal modules in the platform parallel mechanism. The second motion control module controls the bottom motor. The second watertight base serves as the communication channel between the external sensors and the internal control system. The second antenna enables wireless data communication between the platform parallel mechanism, the rotating device, and the computer.

[0061] See Figure 8The rotating device 5 described in this embodiment includes a tapered roller bearing 51. The tapered roller bearing 51 is installed between the fixed platform 34 and the rotating shaft 61 of the support base 6 via a clamping ring 52. A bearing cover 54 is provided on the fixed platform 34, and a threaded hole for fixing a watertight seat is provided on the bearing cover 54 and the clamping ring 52. A strain gauge pressure sensor 53 is provided between the bearing cover 54 and the clamping ring 52 to measure the change in clamping force of the clamping ring 52 in real time. A limiting ring 55 is provided on the fixed platform 34 to prevent the inner ring and outer ring of the tapered roller bearing 51 from separating due to excessive lift. The strain gauge pressure sensor 53 of this invention has an interference fit with the bearing cover 54 and the clamping ring 52. When the pusher 121 generates an upward lift, there is a relative movement tendency between the inner ring and the outer ring of the tapered roller bearing 51. The strain gauge pressure sensor 53 measures the change in clamping force of the clamping ring 52 in real time, thereby recording the change in the vertical force of the entire device. Data collected by the strain gauge pressure sensor 53, differential transformer displacement sensor, and single-axis angle sensor can be analyzed to determine the forces generated when the propulsion device 1 performs movements such as rolling, buoyancy, diving, forward movement, backward movement, lateral movement, and hovering. This allows for the determination of the thrust generated by the propeller 121 at different speeds, which is then plotted as a thrust curve, providing a basis for subsequent analysis. The clamping ring 52 and the fixed platform 34 have a clearance fit, providing clamping force to the outer ring of the tapered roller bearing 51. The boss 62 on the rotating shaft 61 provides support force to the inner ring of the bearing. The outer ring of the tapered roller bearing 51 has a clearance fit with the fixed platform, while the inner ring has an interference fit with the rotating shaft 61. The limiting ring 55 prevents excessive lift by separating the inner and outer rings of the tapered roller bearing 51. The threaded hole at the upper end of the bearing cover 54 is used to fix the watertight seat. The watertight seat and the boss on the rotating shaft 61 achieve sealing of the rotating device 5 and cable routing. The rotating device 5 can rotate in the Z direction via the tapered roller bearing 51, thus providing the propulsion device 1 with a degree of freedom of motion. When no rotational force is received, the tapered rollers will self-lock due to the frictional force of the sealing structure on the clamping ring.

[0062] See Figure 9In this embodiment, the support base 6 includes a base bracket 63, on which a rotating shaft 61 is mounted. The rotating shaft 61 has a boss 62 supporting a tapered roller bearing 51. A caster wheel 64 is located at the bottom of the base bracket 63. The rotating shaft 61 is interference-fitted with the bearing in the rotating device 5. The support base 6 serves as the overall support, providing support for the entire platform. It can translate in the X and Y directions, providing conditions for the two-degree-of-freedom movement of the propulsion device 1. The caster wheel 64 has two control modes: locked and unlocked. When space is limited, the caster wheel 64 is locked, and the base is fixed, preventing translation in the X and Y directions. In this case, the entire propulsion device only has the conditions for rotation in the X, Y, and Z directions and translation in the Z-axis direction, i.e., four-degree-of-freedom movement. When released, the support base 6 can translate in the X and Y directions, providing two degrees of freedom for the propulsion device 1. At this time, the propulsion device has translation in the X, Y, and Z directions and rotation in the Z-axis direction, that is, six degrees of freedom for the propulsion device.

[0063] When this invention is used for land-based testing, the platform is placed on a land-based site, and the specific steps are as follows:

[0064] (1) Select the propeller layout of the UUV to be tested, and arrange the propulsion module 12 on the slide rail 13, the middle and tail fixing frame according to the propeller 121 layout. Place the propulsion device 1 on the moving platform 31. The slide rail 13 of the propulsion device 1 can move back and forth in the slide rail groove 311 of the moving platform 31. By adjusting the relative position of the propulsion device 1 and the moving platform 31, the center of gravity of the propulsion device 1 and the upper electronic cabin 2 is located above the support surface of the moving platform 31, thereby achieving rapid balancing. Then tighten the screws connecting the upper electronic cabin 2 and the moving platform 31. At this time, the bottom of the upper electronic cabin 2 presses against the slide rail 13, thereby achieving relative fixation between the upper electronic cabin 2, the propulsion device 1 and the moving platform 31.

[0065] (2) When the site is unrestricted, the universal wheel 64 can be released to test the six degrees of freedom of the propulsion device; when the site is restricted, the universal wheel 64 is locked, and only the four degrees of freedom of the propulsion device 1 can be tested. Forward, backward and lateral movements cannot be tested.

[0066] (3) Power is switched on, and the control algorithm code is burned into the control system inside the electronic compartment. The power supply in the upper electronic compartment 2 begins to supply power to the thrusters, in-cabin sensors, and control system. The power supply in the lower electronic compartment 4 begins to supply power to the strain gauge sensors, differential transformer displacement sensors, single-axis angle sensors, and bottom motors. At this time, the sensors begin to collect data and transmit the data to the computer in real time via wireless communication. The communication module simultaneously receives instructions from the computer. The control system, according to the instructions and the algorithm, controls the corresponding thrusters to start rotating at the set speed to generate thrust. The flight test and algorithm verification begin.

[0067] (4) Simplified motion testing. To test and verify the platform's motion performance in a single or partial degree of freedom, and to more quickly test and resolve any potential problems, operators can manually lock some revolute and prismatic joints. When performing roll or pitch adjustments, the operator manually tightens the screw of the middle displacement device in the rear branch mechanism of the platform's parallel mechanism to its deepest point to lock the prismatic joint, and tightens the screw of the revolute device to lock the revolute joint of the rear branch mechanism. The control system in the upper electronic cabin controls the corresponding thrusters to rotate at a set speed. The forces generated by the thrust modules arranged in different positions act together on the thrust device, and the thrust device and the moving platform begin to move. Figure 10 The image shows the head-up posture during pitching, as shown. Figure 11 The image shows a head-down posture during pitching, as shown. Figure 12 The image shows a roll posture; when executing commands for forward, backward, vertical ascent, vertical descent, rotation, and lateral movement, the operator locks all rotating joints in the three branches of the platform's parallel mechanism. For example... Figure 13 The image shows forward and backward postures, as shown. Figure 14 It refers to the vertical ascent and descent postures.

[0068] (5) Six-DOF Motion Test. Having tested and verified the motion performance of a single degree of freedom in the previous step, this step will test and verify the overall comprehensive performance of the platform with all motion pairs open. All prisms and rotations that can be opened will be set to the open state. Operators can conduct comprehensive tests on various motions to test and verify more navigation and control performance of the UUV. Motions include forward, backward, pitching up, pitching down, rolling, vertical lift, vertical descent, rotation, lateral movement, depth holding, hovering, and any feasible combinations thereof, as well as arbitrary motion control. Data for each command will be transmitted to the computer and recorded.

[0069] (6) Anti-interference test. Upon receiving an interference command, the control system controls the bottom motor in the middle displacement device of the three branches of the platform's parallel mechanism. The bottom motor pushes the spring at a set frequency, causing the push rod to passively begin displacement, thus interfering with the propulsion device. Springs with different elastic coefficients are used to simulate ocean currents or waves of varying interference intensities. The anti-interference performance of the UUV control algorithm is verified through an anti-interference test.

[0070] (7) During command execution, the attitude sensor, barometric pressure sensor, GPS locator, strain gauge sensor, differential transformer displacement sensor, and single-axis angle sensor transmit the collected angle data of the propulsion device to the computer in real time. The computer further analyzes the collected data. Operators can then observe navigation data such as pitch angle, yaw angle, roll angle, turning radius, position coordinates, speed, roll torque, and thrust of each propeller at different speeds through the computer's software interface. By observing the data curves displayed on the computer and combining them with the actual motion attitude of the test platform, operators can determine whether the UUV's navigation performance and control algorithm meet the requirements.

[0071] (8) If the navigation performance and control algorithm meet the requirements, proceed to step nine; if not, the operator needs to readjust the parameters and improve the algorithm. Step three should only be executed after the algorithm has been optimized and improved. If the algorithm still cannot achieve certain or multiple basic motion performances after multiple adjustments and optimizations, it proves that the thruster layout is unreasonable and the thruster layout needs to be changed before proceeding to step one.

[0072] (9) After completing the above steps, turn off the power to complete the UUV navigation test and algorithm verification on land.

[0073] This invention can serve as an algorithm development platform, a training platform for machine learning-based control algorithms, and a foundational platform for UUV prototypes. Specifically:

[0074] This is a UUV algorithm development platform. Various propulsion module arrangements can be used to develop UUV algorithms for different propulsion layouts. For example, a UUV with four propulsion modules fixed to the tail mount and two propulsion modules fixed to the middle mount. The testing process follows the same steps as land-based testing.

[0075] A training platform for control algorithms based on machine learning. The platform described in this invention serves as a training platform for control algorithms, possessing learning and training capabilities. The testing process follows the steps used in land-based testing.

[0076] The basic platform for the UUV prototype. The upper propulsion system and upper electronics compartment were removed from the platform, and then the actual UUV prototype was fixed to the moving platform to verify and test its navigation performance and control algorithms. The testing process followed the procedures used in land-based testing.

[0077] This invention allows for complete underwater testing. The test platform is placed in an underwater environment, and its sealed structure provides the necessary conditions for underwater testing. Underwater expansion testing involves deploying the entire test platform underwater, following the same steps as on-land testing. Compared to on-land testing, underwater testing more closely resembles real-world conditions.

[0078] This invention allows for underwater testing of the navigation component. The propulsion device 1, upper electronics compartment 2, and moving platform 31 are detached from the assembly, their relative positions are fixed, and then the components are placed in water. The system is then balanced based on the buoyancy of the navigation component in the water. Operators can flexibly modify the propulsion layout to quickly test the effects of different layouts. The effectiveness of the propulsion layout can also be tested underwater after land-based testing or overall underwater testing. Compared to overall underwater testing, underwater testing of the navigation component more closely resembles real-world conditions. The test procedures are the same as those for land-based testing. Figure 15 For some underwater testing organizations.

[0079] This invention simulates the underwater environment of UUVs to test whether their navigation and algorithm performance meet usage requirements. It allows for flexible switching between different propeller layouts, enabling navigation tests and algorithm verification for UUVs with different propeller configurations, improving R&D efficiency and saving R&D funds. It can serve as an algorithm development platform for UUVs; operators can repeatedly test the UUV algorithm and continuously develop, improve, and optimize it based on the test data. This experimental platform can simulate the six degrees of freedom of UUV motion, allowing for navigation tests and algorithm verification on land as well as underwater testing, significantly reducing the debugging workload during pool and lake trials. The sliding rail and modular design require only simple assembly to build the experimental platform, and the components are flexibly replaceable, providing better interchangeability. The use of a parallel mechanism improves structural stability and load-bearing capacity, reducing balancing requirements. It also provides higher accuracy in test data. By adding motors and springs, a structure simulating ocean currents or wave interference is designed to test the algorithm's anti-interference ability, making the test content more diverse. To facilitate underwater testing, a sealing structure was added, including watertight connectors and sealing rings. Because the platform has rotational freedom, cable routing was carefully considered to prevent cable entanglement, allowing the platform to operate without being limited to a single land or underwater environment. This enables further underwater testing after land-based testing, more closely approximating real-world conditions. After removing the propulsion system and upper electronics compartment, an actual UUV prototype can be mounted on the test platform for navigation testing, algorithm verification, and development, improving the prototype's development efficiency. The platform can also serve as a training platform for machine learning-based control algorithms, possessing learning and training capabilities. Land-based testing, overall underwater testing, and partial underwater testing can be conducted sequentially to form a complete testing system. As the test environment gradually approaches the real underwater environment, the algorithm, through continuous improvement and optimization by engineers, will ultimately meet the requirements of real underwater navigation.

Claims

1. A test platform for UUV navigation testing and algorithm verification, comprising a propulsion device, an upper electronic compartment, a lower electronic compartment, a platform parallel mechanism, a rotation device, and a support base, characterized in that: The propulsion device is relatively movable and linked to the platform parallel mechanism. The upper electronic compartment is fixed on the platform parallel mechanism. The platform parallel mechanism is provided with a rotating device that is linked to the rotation of the propulsion device. The rotating device is rotatably connected to the support base. The platform parallel mechanism includes a moving platform and several middle displacement devices as moving pairs. The moving platform is connected to the upper part of the middle displacement devices through a ball joint device to form a ball pair. The lower part of the middle displacement devices is connected to a fixed platform through a rotating device to form a rotating pair. The lower electronic compartment is provided on the fixed platform. The propulsion device includes a slide rail connected to a moving platform. A flow guide is provided on the front side of the slide rail, and an adjustable rudder is provided at the rear of the slide rail. An adjustable sliding base and an adjustable intermediate fixing frame can be installed on the slide rail, and a tail fixing frame can be installed at the rear end of the slide rail. Propulsion modules can be provided on both sides of the sliding base, the intermediate fixing frame, and the tail fixing frame to achieve six degrees of freedom of movement. The propulsion module includes a thruster that provides power. A collision protection shell is provided outside the thruster. The collision protection shell is fixed on the fixing frame. The fixing frame can be fixedly connected to the sliding base, the sides of the intermediate fixing frame, or the tail fixing frame.

2. The experimental platform for UUV navigation testing and algorithm verification according to claim 1, characterized in that: The moving platform is provided with a slide rail groove, and the slide rail of the propulsion device is clearance-fitted to the slide rail groove and press-fitted onto the moving platform through the upper electronic compartment.

3. The experimental platform for UUV navigation testing and algorithm verification according to claim 1, characterized in that: The central displacement device includes an outer wall, an end cap, and a push rod. The end cap, push rod, and outer wall are positioned by screws and threaded holes, forming a lockable sliding pair. The relative position change between the push rod and the outer wall forms the sliding pair. A differential transformer displacement sensor is installed on the push rod to collect its displacement. An interference module simulating ocean current interference during hovering is installed below the push rod. The differential transformer displacement sensor consists of a coil, an armature, and a displacement acquisition circuit. The armature is located at the bottom of the push rod and is linked to it. The coil is located on the outer ring of the push rod and the armature and is connected to the lower electronic compartment through the displacement acquisition circuit.

4. The experimental platform for UUV navigation testing and algorithm verification according to claim 3, characterized in that: The interference module includes a bottom motor installed inside the outer wall, a pad that is pushed by the bottom motor, and a spring that causes the push rod to move up and down continuously and passively between the pad and the push rod.

5. The experimental platform for UUV navigation testing and algorithm verification according to claim 1, characterized in that: The rotating device includes a rotating horizontal shaft, which is interference-fitted with a deep groove ball bearing and a bottom circular hole on the outer wall to form a rotating pair. The rotating horizontal shaft is connected to a single-axis angle sensor that collects its angle changes via a coupling. The deep groove ball bearing is interference-fitted with a rotating base. The single-axis angle sensor is fixed to a sensor base. The rotating base and the sensor base are fixed on a fixed platform. The rotating horizontal shaft is provided with a locking screw that can lock it in place.

6. The experimental platform for UUV navigation testing and algorithm verification according to claim 1, characterized in that: The lower electronic compartment includes a second sealed outer shell, on which a second watertight base and a second antenna are provided. A second power supply for powering the platform parallel mechanism and the rotating device is installed inside the second sealed outer shell. The second watertight base, the second antenna, and the second power supply are all electrically connected to the second control system. The second control system includes a second main control module, on which a second data acquisition module, a second motion control module, and a second communication module are electrically connected.

7. The experimental platform for UUV navigation testing and algorithm verification according to claim 1, characterized in that: The upper electronic compartment includes a first sealed outer shell, on which a first watertight base and a first antenna are disposed. A first power supply and a sensor are installed inside the first sealed outer shell. The first watertight base, the first antenna, the first power supply, and the sensor are all electrically connected to a first control system. The first control system includes a first main control module, on which a first data acquisition module, a first motion control module, and a first communication module are electrically connected.

8. The experimental platform for UUV navigation testing and algorithm verification according to claim 1, characterized in that: The rotating device includes a tapered roller bearing, which is mounted between the rotating shaft of the fixed platform and the support base via a clamping ring. The fixed platform is provided with a bearing cover, which has a threaded hole for fixing a watertight seat. A strain gauge pressure sensor is provided between the bearing cover and the clamping ring to measure the change in clamping force of the clamping ring in real time. The fixed platform is provided with a limiting ring to prevent the inner ring and outer ring of the tapered roller bearing from separating due to excessive lift.

9. The experimental platform for UUV navigation testing and algorithm verification according to claim 8, characterized in that: The support base includes a base bracket, on which a rotating shaft is mounted, and a boss for supporting a tapered roller bearing is provided on the rotating shaft. A caster wheel is provided at the bottom of the base bracket.

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