Control system of six-degree-of-freedom hydraulic mechanical arm for dismounting and mounting cylinder

Abstract

The application discloses a control system of a six-degree-of-freedom hydraulic mechanical arm for dismounting and mounting a cylinder, relates to the technical field of cylinder dismounting and mounting, and is characterized in that a multi-angle polarized light source is configured at a light jump area on the surface of the cylinder, a brightness gradient sequence is established, a multi-exposure time chain is constructed, the light intensity is controlled in time, the reflection area is formed into a continuous light level, spot energy diffusion is performed to form a continuous texture transition zone, a pose feature track is extracted, a motion edge is generated by combining light intensity variation to identify an optical flow clue, a visual guide channel is constructed according to the clue, a hydraulic actuator is driven to perform pose fine adjustment, and synchronous compensation and pressure regulation of the alignment process are realized. The application realizes the continuous transition of the light on the surface of the cylinder through the multi-angle polarized light and the multi-exposure time chain, improves the imaging accuracy and the texture recognition stability, and realizes the pose fine adjustment and the pressure balance control by combining the optical flow guide, so that the hydraulic mechanical arm can complete adaptive assembly in a reflection interference environment, and the dismounting and mounting accuracy and safety are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of hydraulic cylinder assembly and disassembly technology, and more specifically to a control system for a six-degree-of-freedom hydraulic robotic arm used for hydraulic cylinder assembly and disassembly. Background Technology

[0002] A six-degree-of-freedom (DOF) hydraulic robotic arm is a hydraulically driven actuator with six independent degrees of freedom of motion (including pitch, yaw, roll, extension, translation, and rotation). Each joint achieves precise position, attitude, and force control adjustment through proportional servo valves and hydraulic cylinders, simulating the multi-dimensional operational capabilities of a human arm. In the disassembly and assembly of hydraulic support balance cylinders, the six-DOF hydraulic robotic arm completes the entire process of grasping, rotating, inserting, aligning, pushing, and locking the cylinder through multi-axis collaborative control. Its end effector is equipped with force sensors and a vision positioning module, which can perceive the spatial attitude and force state of the cylinder in real time, and achieve high-precision control of the movement of each joint through a hydraulic servo system. When the robotic arm performs disassembly operations, the system automatically generates motion trajectories based on the cylinder positioning data and hydraulic pressure feedback signals obtained from visual recognition, and dynamically adjusts the pressure and displacement of each joint to ensure that the cylinder smoothly detaches from the bracket under controlled posture. During the installation phase, the system uses reverse trajectory control to smoothly push the cylinder into the mounting seat, achieving adaptive completion of alignment error compensation and locking actions, thereby achieving a high-precision, safe, and efficient intelligent disassembly and assembly control effect.

[0003] The existing technology has the following shortcomings:

[0004] During the assembly and disassembly of the hydraulic support balance cylinder, when the cylinder surface has a highly reflective metallic coating or is partially covered by a hydraulic oil film, the visual recognition system is prone to brightness jumps and reflection saturation during the imaging acquisition phase, resulting in pseudo-static pixel bands in the time frame. This phenomenon causes the visual algorithm to misjudge the target on the cylinder surface as stationary during dynamic recognition, failing to accurately reflect the minute pose deviations between the end effector and the cylinder interface. As a result, the control system continuously outputs holding force commands in the closed-loop feedback, and the robotic arm end effector continues to apply pressure without detecting any displacement changes, causing irreversible plastic deformation of the cylinder interface threaded pair, slot positioning shoulder, or sealing ring press-fit area. In severe cases, this can not only lead to misalignment of the installation reference surface and loosening of the threaded engagement, but also cause seal failure, ultimately compromising the assembly accuracy and overall stress stability of the cylinder.

[0005] It should be noted that:

[0006] Pseudo-static pixel bands refer to areas in an image that appear unchanged across a series of frames due to excessive light reflection, surface oil film interference, or sudden brightness changes during machine vision recognition. In reality, the target object is still undergoing minute movements. This illusion misleads the vision system into believing the area is stationary, leading to incorrect judgments of the object's position or orientation, and impacting subsequent automatic control and precise operation.

[0007] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a control system for a six-degree-of-freedom hydraulic robotic arm for cylinder assembly and disassembly, in order to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a control system for a six-degree-of-freedom hydraulic robotic arm for cylinder assembly and disassembly, including a multi-angle polarized light layering module, a multi-exposure time chain control module, a spot energy diffusion balance module, a pose feature recognition and tracking module, and a visually guided posture control module.

[0010] The multi-angle polarized illumination layering module configures multi-angle polarized light sources for areas with abrupt illumination jumps on the surface of the cylinder during the imaging acquisition stage. This causes the reflected light to form differences in light intensity distribution at different illumination angles, and establishes a brightness gradient sequence based on these differences in light intensity distribution to provide a layered reference basis for subsequent illumination control.

[0011] The multi-exposure time chain control module constructs a multi-exposure time chain based on the brightness gradient sequence. By adjusting the illumination intensity of multi-angle polarized light sources in a time-division manner, the high-reflectivity area on the surface of the cylinder presents an orderly brightness change in continuous acquisition frames, so as to form a continuous illumination layer and provide an illumination transition basis for subsequent texture feature restoration.

[0012] The spot energy diffusion balancing module performs spot energy diffusion operation on the basis of continuous illumination layers, diffuses the light energy of the reflection points in the concentrated area of ​​reflected energy into a sparsely distributed spot group, thereby forming a continuous texture transition zone in the image, keeping the surface texture features of the cylinder intact, so as to facilitate the extraction of subsequent pose feature trajectories.

[0013] The pose feature recognition and tracking module extracts the pose feature trajectory of the cylinder surface based on the continuous texture transition zone, and combines the curve of light intensity changing with time to identify the tiny moving edges of the cylinder surface, so as to generate stable optical flow cues and provide dynamic feedback basis for the visual guidance and control of the hydraulic robotic arm.

[0014] The visual guidance attitude control module constructs a visual guidance channel based on optical flow cues, and drives the attitude fine-tuning unit of the hydraulic actuator through the visual guidance channel to achieve synchronous attitude compensation and pressure distribution adjustment during the cylinder alignment process. This eliminates the continuous pressure phenomenon caused by reflection distortion and ensures the accuracy and safety of cylinder assembly and disassembly operations.

[0015] Preferably, the step of establishing a brightness gradient sequence based on differences in light intensity distribution includes the following steps:

[0016] In the preparation stage of image acquisition of the hydraulic cylinder, the spatial structure and reflection characteristics of the surface to be observed of the hydraulic cylinder are designed for lighting. The central axis of the hydraulic cylinder is used as a reference. No less than six polarized light sources are evenly arranged around the circumference of the hydraulic cylinder. The incident angle of each polarized light source relative to the central axis of the hydraulic cylinder is set between 30 degrees and 70 degrees, and the polarization angle of adjacent polarized light sources differs by about 15 degrees to form a circumferential multi-angle polarization illumination structure.

[0017] After completing the acquisition of multi-angle illumination images, the light intensity distribution on the surface of the cylinder under each illumination angle is analyzed hierarchically. The area of ​​light abrupt change is identified and multiple hierarchical areas are divided from the highest light intensity point to both sides in descending order of brightness, with the highest light intensity point as the center. The average light intensity value under each illumination angle is recorded and the light intensity layering result is formed.

[0018] After completing the division of illumination layers, the average light intensity value of each illumination layer is used as the gradient node, and they are arranged in order of increasing illumination angle to form a directional brightness change chain. The light intensity difference between adjacent gradient nodes is used as the transition interval to construct a continuous brightness gradient sequence.

[0019] Preferably, the step of making the highly reflective area on the surface of the cylinder exhibit an orderly brightness gradient in consecutive acquisition frames to form a continuous illumination hierarchy includes the following steps:

[0020] After establishing the brightness gradient sequence, based on the distribution characteristics of brightness values ​​of each layer in the brightness gradient sequence, the exposure time distribution scheme of the multi-exposure time chain is determined, each brightness level is divided into multiple continuous brightness intervals, and a corresponding exposure time interval is set for each brightness interval, so that the exposure time corresponds one-to-one with the brightness level to form a time chain.

[0021] The brightness of the multi-angle polarized light source is controlled in a time-division manner according to the time sequence of the multi-exposure time chain, so that each polarized light source enters an independent illumination period in sequence. The light intensity is adjusted according to the light intensity level of the corresponding illumination angle in the brightness gradient sequence, so that the surface of the oil cylinder presents an orderly brightness gradient light trajectory in the continuous acquisition frame.

[0022] After completing the phased illumination control, the brightness changes on the cylinder surface in consecutive frames are smoothly transitioned and the levels are verified. The camera aperture and photosensitivity are kept constant to ensure that the continuous illumination levels remain stable in space and time and form a smooth brightness gradient curve.

[0023] Preferably, during the time-division brightness control process, the brightness adjustment range of each polarization light source in adjacent exposure time periods is kept within the range of light intensity difference between adjacent levels in the brightness gradient sequence, and the switching interval between adjacent time periods is controlled within 10% of the current exposure time, so as to ensure that the brightness change of the cylinder surface in continuous acquisition frames is smooth and without abrupt changes.

[0024] Preferably, the step of diffusing the light energy of the reflected points in the concentrated area of ​​reflected energy into a sparsely distributed light spot group includes the following steps:

[0025] After completing the construction of the continuous illumination layer, the spatial location and energy distribution characteristics of the concentrated area of ​​reflected energy on the surface of the cylinder are identified. Based on the brightness distribution of the continuous illumination layer, the surface of the cylinder is divided into sections along the axial and radial directions of the cylinder. The center coordinates, illumination angle and brightness range of the concentrated area of ​​reflected energy are marked to determine the range of light energy diffusion.

[0026] After determining the spatial distribution of the concentrated area of ​​reflected energy, a light energy diffusion operation is performed on the concentrated area of ​​reflected energy to make the reflected energy diffuse in an orderly manner along the surface of the cylinder to the surrounding sparsely distributed area of ​​reflected energy. The radius and energy release of the diffusion layer are controlled according to the light energy difference between the reflection point in the concentrated area of ​​reflected energy and the sparsely distributed area of ​​reflected energy, so that the brightness distribution after diffusion forms a continuous transition and avoids new concentration of reflected energy.

[0027] After the light energy diffusion is completed, the overall light distribution on the surface of the cylinder is coordinated and verified. The sparsely distributed light spot groups formed after diffusion are superimposed in space to form a continuous texture transition zone extending along the circumferential and axial directions of the cylinder. This controls the brightness difference between adjacent pixels within a predetermined threshold range, thereby ensuring the continuity of image texture and the integrity of details.

[0028] Preferably, in the light energy diffusion operation, the energy release of each diffusion layer is set to decrease linearly based on the light energy difference between the reflection point in the concentrated reflection energy area and the surrounding sparsely distributed reflection energy area, and the outer boundary of the diffusion range overlaps and coordinates with the energy attenuation boundary of the adjacent concentrated reflection energy area to ensure continuous brightness transition between different high-brightness areas and prevent the formation of new concentrated reflection areas.

[0029] Preferably, the step of generating optical flow cues includes the following steps:

[0030] On the continuous texture transition zone formed by light energy diffusion, pose recognition preparation and feature point confirmation are carried out for the region with significant geometric features and texture differences on the cylinder surface. Based on the illumination distribution and geometric edge direction of the cylinder surface, the texture boundary line used to reflect the spatial pose change is determined, and a spatial texture coordinate system consistent with the cylinder structure is established.

[0031] After completing the spatial localization of feature points, the light intensity changes over time in the feature area is monitored. While keeping the lighting conditions and camera parameters constant, imaging frames are continuously acquired to capture the brightness change pattern of the cylinder surface under minute motion, and the minute motion edges of the cylinder surface are identified based on the light intensity change curve.

[0032] After obtaining the light intensity variation curve over time, optical flow cues are generated based on the directionality and continuity of brightness changes in the light intensity variation curve. The light intensity changes of feature points in consecutive frames are arranged in sequence along the time axis to form a brightness flow path. The light intensity changes of adjacent feature points are spatially matched to construct an optical flow band with directionality and continuity.

[0033] Preferably, in the step of generating optical flow cues, during the monitoring of the light intensity change curve over time, the sampling interval is set within the millisecond range, and the background reflective surface is masked and extinct during the light source arrangement stage to ensure that the light intensity change curve only reflects the brightness change caused by the minute movement of the cylinder surface, thereby improving the temporal continuity and recognition accuracy of the optical flow cues.

[0034] Preferably, the steps of using a vision-guided channel to drive the attitude fine-tuning unit of the hydraulic actuator to achieve synchronous attitude compensation and pressure distribution adjustment during cylinder alignment include the following steps:

[0035] After obtaining the optical flow cues, the directional information and brightness change trend of the optical flow cues are spatially distributed and mapped, and the spatial coordinates of the feature points on the cylinder surface are correlated with the optical flow direction to determine the relative attitude relationship between the end effector of the hydraulic robot and the cylinder surface.

[0036] After determining the spatial distribution relationship of the optical flow cues, a visual guidance channel is established based on the distribution characteristics. The optical flow direction is matched one-to-one with the movement direction of the hydraulic actuator, so that the optical information drives the attitude response of the end effector of the hydraulic robotic arm in a time sequence and the attitude is adjusted in real time through the direction information of the optical path chain.

[0037] After the visual guidance channel is established, the posture fine-tuning and force coordination operation is performed. The angle and extension of each joint are gradually adjusted according to the optical flow direction, so that the end effector of the hydraulic robotic arm moves smoothly along the optical flow direction, and the force is adjusted by pressure micro-distribution.

[0038] After the posture is fine-tuned and stabilized, the operation status of the visual guidance channel is continuously monitored. When the brightness distribution remains stable and symmetrical, the current posture is maintained. When brightness fluctuations or illumination breaks occur, micro-adjustments or pressure corrections are performed based on feedback information to maintain dynamic balance and safety control.

[0039] Preferably, during the posture fine-tuning and force coordination operation, the end effector of the hydraulic robotic arm adjusts the joint angles and extension amounts according to the optical flow direction, while monitoring the brightness distribution of the contact area between the end effector of the hydraulic robotic arm and the cylinder surface in real time. When the local brightness change exceeds the preset threshold, a reverse fine-tuning action is immediately performed to reduce the local contact pressure, thereby further ensuring force balance and preventing plastic deformation of the threaded pair and sealing ring area.

[0040] The technical effects and advantages provided by the present invention in the above technical solution are as follows:

[0041] This invention utilizes multi-angle polarized illumination combined with multi-exposure time-chain layered imaging control to create a continuous brightness transition in time and space for the highly reflective areas of the cylinder surface, avoiding abrupt brightness jumps and pseudo-static pixel bands caused by reflection saturation. Through precise control of the illumination layers, the texture details of the cylinder surface are fully presented, and the image brightness distribution is balanced and stable. This fundamentally improves the recognition accuracy and visual perception reliability during the imaging stage, providing a high-fidelity image foundation for subsequent attitude recognition and trajectory extraction.

[0042] This invention achieves real-time attitude compensation and force balance control of a hydraulic robotic arm during cylinder alignment by performing attitude fine-tuning and pressure distribution adjustment under the guidance of optical flow cues. Through the coordinated adjustment of illumination and force control, the end effector of the robotic arm can achieve adaptive pressure release and attitude correction in environments with reflective interference, avoiding structural damage caused by continuous pressure application, ensuring the smoothness, accuracy, and safety of the cylinder assembly process, thereby significantly improving the automation accuracy and execution stability of disassembly and assembly operations. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0044] Figure 1 This is a schematic diagram of the control system for the six-degree-of-freedom hydraulic robotic arm of the present invention for cylinder assembly and disassembly;

[0045] Figure 2 This is a flowchart illustrating how the invention creates continuous light layers in the highly reflective area of ​​the cylinder surface.

[0046] Figure 3 This is a flowchart illustrating how the light energy of a reflection point within a concentrated area of ​​reflected energy is diffused into a sparsely distributed group of light spots according to the present invention. Detailed Implementation

[0047] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the description of this disclosure will be more complete and fully convey the concept of the exemplary embodiments to those skilled in the art.

[0048] like Figures 1 to 3 As shown, the present invention provides a control system for a six-degree-of-freedom hydraulic robotic arm for cylinder assembly and disassembly, including a multi-angle polarized light layering module, a multi-exposure time chain control module, a spot energy diffusion balancing module, a pose feature recognition and tracking module, and a visually guided posture control module.

[0049] The multi-angle polarized illumination layering module configures multi-angle polarized light sources for areas with abrupt illumination jumps on the surface of the cylinder during the imaging acquisition stage. This causes the reflected light to form differences in light intensity distribution at different illumination angles, and establishes a brightness gradient sequence based on these differences in light intensity distribution to provide a layered reference basis for subsequent illumination control.

[0050] The specific steps for establishing a brightness gradient sequence based on differences in light intensity distribution are as follows:

[0051] In the preparation stage of hydraulic cylinder image acquisition, the spatial structure and reflection characteristics of the surface to be observed on the hydraulic cylinder are analyzed for lighting design to achieve comprehensive coverage of high-reflectivity areas and dispersion of reflected energy. Specifically, the central axis of the hydraulic cylinder is used as a reference, and at least six polarized light sources are evenly arranged around the cylinder's circumference. The incident angle of each polarized light source relative to the central axis of the cylinder is set between 30 and 70 degrees, and the polarization angles of adjacent polarized light sources differ by 15 degrees, ensuring that the polarization direction of each light source is different, forming a circumferential multi-angle polarized illumination structure. Each polarized light source is mounted on a positioning base with an adjustable bracket, allowing its illumination direction to be finely adjusted according to the reflection characteristics of the curved surface of the hydraulic cylinder. To ensure the controllability of the illumination intensity, the output brightness of each polarized light source is precisely set using an individual current adjustment device, and the output power is kept within a uniform range to prevent errors caused by uneven brightness between light sources. After lighting is completed, each polarized light source is illuminated sequentially, and the surface of the hydraulic cylinder is imaged angle by angle using single-light source illumination, and the reflected images of the cylinder surface at each angle are recorded. In this way, raw reflection information, including specular reflection, diffuse reflection, and oil film coverage areas, can be collected from the cylinder surface at different incident angles. Images obtained through multi-angle illumination not only demonstrate the differences in reflection direction on the cylinder surface but also reveal the dynamic changes in light intensity distribution under different illumination angles, providing data support for subsequent light intensity difference analysis.

[0052] After acquiring images from multiple irradiation angles, a hierarchical analysis of the light intensity distribution on the cylinder surface at each irradiation angle was performed to establish the spatial distribution pattern of reflected light energy. Specifically, based on the images acquired in the previous stage, the cylinder surface was first divided into several reflective feature regions, including the threaded area, cylinder wall area, mounting shoulder area, and sealing ring contact area. The light intensity data for each region came from the pixel brightness values ​​at the corresponding irradiation angle. The region with the most dramatic brightness changes, i.e., the illumination jump zone, was identified through manual observation and zone recording. Centered on the illumination jump zone, multiple hierarchical regions were divided outwards from the highest light intensity point in descending order of brightness. Each hierarchical region represents a light intensity range. Subsequently, the average light intensity value corresponding to each irradiation angle was recorded within each hierarchical region, and these values ​​were arranged in order of irradiation angle to form a sequence of light intensity data. By comparing the light intensity distribution of each layer of regions at different irradiation angles, the differences in reflection of the cylinder surface at different orientations can be observed.

[0053] For example, at angles near the oil film coverage area, the light intensity is concentrated and the brightness changes sharply, while at angles further away from specular reflection, the light intensity distribution is more gradual. Based on this pattern, the range of light intensity values ​​is divided into several levels, decreasing progressively from the highest brightness layer to the lowest brightness layer, forming a stratified result of illumination intensity. To ensure the stability and repeatability of the stratification, the angle and brightness output of the polarized light source are kept consistent with the previous stage throughout the entire stratification analysis process, and samples are repeated three times at each angle, with the average value used as the basis for the final light intensity level division. Through this continuous stratification method, the high-energy reflection originally concentrated in a local area on the cylinder surface is decomposed into multiple light intensity balance layers, each with a clear spatial orientation and brightness distribution range, providing a stratified basis for constructing brightness gradients.

[0054] In the specific implementation process, the areas of most dramatic changes in brightness abruptly can be identified through manual observation and zoned recording, which can be achieved using the following method:

[0055] After completing the multi-angle polarized light source illumination imaging, the images of the cylinder surface acquired at different illumination angles are arranged sequentially in a circumferential manner to form an unfolded reflection map of the cylinder surface. Based on the structural characteristics of the cylinder, the operator divides the entire imaging area into typical regions according to physical function, such as the threaded connection area, the smooth cylinder wall area, the positioning shoulder area, the sealing ring contact area, and the port transition area. Then, the brightness differences of each region under the same exposure conditions are compared one by one. During operation, a comparison display device is used to overlay and play multiple frames of images. By observing the brightness change trend of each region under different illumination angles, the maximum and minimum brightness values ​​and brightness fluctuation ranges of each region are manually recorded. The region with the most prominent brightness change is selected as a candidate region, and careful comparison is performed under local magnification, focusing on observing the brightness change gradient at the region boundary and the diffusion range of the bright spot edge. For example, when the chromium plating layer on the surface of the threaded connection area reflects strongly and exhibits obvious brightness flickering with changes in the light source angle, while the brightness change in the cylinder wall area is gradual, the threaded connection area can be identified as a region of sudden illumination change. For example, if an oil film covers the contact area of ​​the sealing ring, causing the brightness to gradually darken from the center towards the edges, and a bright band flickers when the light source angle is finely adjusted, this area can also be identified as a region of sudden illumination change. Through this method of manual observation and zonal comparison, it is possible to intuitively determine which local areas exhibit the most significant brightness fluctuations under different illumination angles, thereby accurately identifying the areas where the surface reflection intensity of the cylinder changes most drastically. This provides a clear spatial reference area for subsequent establishment of illumination stratification and brightness gradient sequences.

[0056] After completing the illumination layer division, these layer data are further integrated in an orderly manner to establish a brightness gradient sequence, accurately reflecting the continuous change in illumination intensity on the cylinder surface. Specifically, the average light intensity value of each illumination layer determined in the previous stage is used as a gradient node, and these nodes are arranged sequentially according to the increasing illumination angle of the light source, forming a directional brightness change chain. Then, the light intensity difference between adjacent gradient nodes is used as a transition interval. The cylinder surface areas corresponding to these transition intervals are arranged according to the direction of brightness change, forming a continuous illumination band from a high-brightness reflection area to a low-brightness diffuse area in space. This illumination band is distributed in a ring shape on the cylinder surface, with smooth brightness changes and obvious directionality, clearly describing the distribution trend of reflected energy on the cylinder surface. To ensure the spatial continuity of the brightness gradient sequence, a superposition method is used to process the previous stage of illumination intensity layers during construction. This involves arranging the average light intensity values ​​of adjacent layers in a linear progression, ensuring that the gradient sequence not only decreases continuously in value but also maintains a physical correspondence in the direction of the illumination angle. Through this integration method, the resulting brightness gradient sequence can characterize the reflection properties of different areas on the cylinder surface and reflect the trend of illumination changes under multi-angle illumination. This brightness gradient sequence serves as a hierarchical reference for subsequent illumination control, providing the correspondence between each exposure time and brightness level during the next stage of multi-exposure timechain construction. This allows the illumination control process to automatically achieve brightness balance based on gradient changes. Through this continuous processing, the entire brightness distribution process transforms from point-like strong reflections to a band-like gradual distribution, fundamentally eliminating the problem of concentrated local reflection energy.

[0057] Through the coordinated steps above, from light source arrangement to brightness stratification and gradient sequence establishment, a complete spatial illumination control process is formed. The multi-angle polarized illumination setup ensures the energy dispersion of reflected light in different directions, the process of dividing light intensity levels quantifies the reflection characteristics of the cylinder surface, and the construction of the brightness gradient sequence provides an executable reference for subsequent multi-exposure control and dynamic illumination adjustment. Through this process, the illumination environment of the cylinder surface during the imaging acquisition stage is effectively balanced. Areas prone to abrupt illumination jumps are transformed into a uniform, gradual illumination distribution, ensuring that the camera can acquire images with distinct layers, clear textures, and sufficient reflection suppression during acquisition.

[0058] The multi-exposure time chain control module constructs a multi-exposure time chain based on the brightness gradient sequence. By adjusting the illumination intensity of multi-angle polarized light sources in a time-division manner, the high-reflectivity area on the surface of the cylinder presents an orderly brightness change in continuous acquisition frames, so as to form a continuous illumination layer and provide an illumination transition basis for subsequent texture feature restoration.

[0059] The specific steps to create continuous lighting layers in the highly reflective areas of the hydraulic cylinder surface are as follows:

[0060] After establishing the brightness gradient sequence, the exposure time distribution scheme for the multi-exposure time chain is determined based on the distribution characteristics of the brightness values ​​of each layer in the sequence. In practice, the brightness gradient sequence, reflecting the brightness changes on the cylinder surface, is divided into several continuous brightness intervals, each corresponding to an exposure time period. The principle for setting the exposure time is: shorter exposure times are allocated to areas with higher brightness gradients to prevent overexposure; longer exposure times are allocated to areas with lower brightness gradients to enhance details in dark areas. This hierarchical correspondence ensures a one-to-one correspondence between exposure time and brightness level, forming a time chain from short to long. The specific duration of each exposure time period is determined based on the light intensity distribution of the previous stage of the brightness gradient sequence. For example, in areas with large brightness jumps, the decrease in exposure time is set smaller to ensure a smooth brightness transition; while in areas with gradual brightness changes, the increase in exposure time is appropriately increased to create a clear difference in level. This operation provides an independent exposure window for each illumination level in the time dimension, laying the foundation for subsequent illumination variation control.

[0061] After determining the multi-exposure time chain, the brightness of the multi-angle polarized light source is adjusted in a time-division manner according to the sequence of the multi-exposure time chain, so that the surface of the cylinder exhibits an orderly change in brightness in continuous acquisition frames. In specific implementation, the multi-angle polarized light source arranged in the previous stage is used as the illumination execution unit of the multi-exposure time chain. Each polarized light source enters an independent illumination period sequentially, and its illumination intensity is adjusted according to the light intensity level corresponding to that angle in the brightness gradient sequence within the corresponding period. For example, when the light source is at a position with a small illumination angle, the output brightness is initially illuminated according to the high brightness level in the brightness gradient sequence; as time progresses, entering the next exposure period, the brightness of the polarized light source gradually decreases by a predetermined margin, causing the reflected brightness of the illuminated area to show a decreasing trend. At the same time, polarized light sources located at adjacent angles synchronously enter the brightness enhancement stage of the next period, so that the same surface area continuously receives light from different angles in time, thus forming an illumination trajectory transitioning from high brightness to low brightness and then to medium brightness in continuous acquisition frames. Through this alternating change method, the brightness of the cylinder surface is continuously distributed along the time axis, rather than abrupt changes in brightness within a single frame. To ensure the stability of this brightness variation process, the magnitude of each illumination intensity adjustment is kept within the range of the intensity difference between adjacent layers of the previous brightness gradient sequence, ensuring that the illumination change is consistent with the spatial brightness distribution. Through this process, the surface of the cylinder exhibits a hierarchical change in illumination intensity across consecutive frames, forming a temporal brightness transition in an optical sense, providing a continuous illumination hierarchy for subsequent texture restoration.

[0062] After completing the multi-exposure time-sharing illumination control, the brightness changes on the cylinder surface in consecutive frames are smoothly transitioned and their levels verified to ensure that the continuous illumination levels remain stable in space and time. Specifically, during continuous acquisition, the camera's aperture and photosensitivity are kept constant, ensuring that brightness changes originate solely from the time-sharing illumination of the polarized light source, thus eliminating brightness interference caused by camera adaptive adjustments. Immediately after each exposure time period ends, the next exposure time period begins, keeping the time interval between adjacent frames within 10% of the same exposure time to prevent abrupt brightness transitions. This high-frequency time-sharing acquisition method creates a brightness gradient curve for the same area on the cylinder surface in consecutive frames. The trend of this curve is consistent with the direction of the brightness gradient sequence in the previous stage, i.e., a gradual transition from a high-reflectivity area to a low-reflectivity area. To further verify the continuity of the brightness gradient, the brightness values ​​of each pixel in the consecutive frames are compared sequentially over time, confirming that the brightness change amplitude between adjacent frames is within a set threshold range, thus ensuring a smooth, abrupt brightness level change visually. Through this brightness coordination process in both time and space, the surface of the cylinder forms a continuous lighting layer from high brightness to low brightness during the imaging acquisition stage. This not only effectively suppresses the oversaturation problem in areas of strong reflection, but also enhances the recognizability of texture details in dark areas.

[0063] By continuously executing the above steps, the relationship between exposure time and light intensity is precisely controlled in layers using a brightness gradient sequence. This achieves an orderly variation of illumination on the cylinder surface over time, dynamically balancing the brightness jumps caused by reflection during imaging. This process, through continuous illumination layers formed by time-division multi-angle illumination, makes the light energy distribution on the cylinder surface more uniform at any given time, avoiding excessively bright or dark local spots. This ensures that the image obtained during the imaging stage has smooth brightness, clear layers, and controllable reflection.

[0064] The spot energy diffusion balancing module performs spot energy diffusion operation on the basis of continuous illumination layers, diffuses the light energy of the reflection points in the concentrated area of ​​reflected energy into a sparsely distributed spot group, thereby forming a continuous texture transition zone in the image, keeping the surface texture features of the cylinder intact, so as to facilitate the extraction of subsequent pose feature trajectories.

[0065] The light energy of the reflected points in the concentrated area of ​​reflected energy is diffused into a sparsely distributed group of light spots, forming a continuous texture transition band in the image. The specific steps are as follows:

[0066] After constructing the continuous illumination hierarchy, the spatial location and energy distribution characteristics of each concentrated reflective energy region on the cylinder surface are identified to determine the effective range of light diffusion. Specifically, the continuous illumination hierarchy formed in the previous stage is used as a spatial distribution reference, and the cylinder surface is divided into zones along the cylinder's axial and radial directions. Each zone is divided based on brightness distribution data collected from the previous exposure time chain, numbered sequentially from highest to lowest brightness value, and the center coordinates, illumination angle, and brightness range of each concentrated reflective energy region are labeled. This spatial calibration method clarifies the actual distribution location and energy concentration of reflection points within each concentrated reflective energy region on the cylinder surface. For example, in the curved area of ​​the cylinder wall, due to the superposition effect of multi-angle polarized light illumination, some areas will form reflection spots with strong energy concentration. These spots are usually distributed in areas where the angle between the incident light angle and the cylinder surface normal is small. By statistically analyzing the energy range of these reflection points, the average light intensity and boundary range of each reflection region can be obtained. At this point, to ensure the balance of the subsequent light energy diffusion process, the sum of the energy of all reflection points within the concentrated reflection energy area is compared with the average energy of the low-reflection area to determine the target distribution ratio of light energy diffusion. This analytical process allows for the spatial definition of the light energy diffusion region's boundaries, providing a clear operational basis for the next stage of light energy redistribution.

[0067] After determining the spatial distribution of high-energy reflection areas, light energy diffusion is performed on these areas, causing the reflected energy to diffuse in an orderly manner along the cylinder surface to the surrounding sparsely reflected energy areas, forming a gradual transition in light energy distribution. Specifically, starting from the center of the reflection point within the concentrated energy area, the energy diffusion range is expanded layer by layer along the surrounding area with equal brightness. The radius of each diffusion layer is determined based on the continuous illumination layer variation pattern of the previous stage, ensuring that the direction of energy diffusion aligns with the direction of brightness gradient change. To ensure continuous brightness distribution after light energy diffusion, the energy release of each diffusion layer is determined based on the light energy difference between the reflection point within the concentrated energy area and the surrounding sparsely reflected energy areas, resulting in a linear or approximately linear decreasing energy change during diffusion. Through multi-layered diffusion, the reflected energy originally concentrated at one point forms a ring-shaped distribution band in space, with light energy gradually attenuating from the center outwards, creating a visually natural transition in brightness. Meanwhile, to avoid the formation of new concentrated areas of light energy during diffusion, the outer boundary of the diffusion range overlaps and coordinates with the energy attenuation boundary of adjacent concentrated areas of reflected energy. This ensures a smooth spatial transition of light energy diffusion results in different areas, preventing brightness gaps or uneven transitions. Through this continuous light energy diffusion method, the original strong reflection points on the cylinder surface gradually transform into a larger, softer light spot cluster, resulting in a more balanced brightness distribution across the entire surface.

[0068] The light energy difference refers to the energy difference between adjacent areas on the surface of a hydraulic cylinder caused by varying light intensities. Specifically, it is the difference between the light energy received per unit area at a high-reflection point (i.e., the brighter area) and the light energy received by its surrounding lower-brightness areas. This difference reflects the degree of unevenness in local light distribution and serves as a basis for judging the degree of reflection concentration and determining the amount of light energy diffusion. A large light energy difference indicates that the local reflected energy is too concentrated, requiring stronger diffusion; a small light energy difference indicates that the light distribution is becoming more uniform, and the diffusion range can be reduced accordingly. Therefore, the light energy difference essentially quantifies the light energy gradient between areas of concentrated and sparse reflected energy distribution, guiding the direction and intensity of light energy diffusion.

[0069] After light diffusion is complete, the illumination distribution on the cylinder surface is coordinated and verified to ensure that the diffused light forms a stable and continuous texture transition zone, maintaining the continuity and detail integrity of the image texture. Specifically, the sparsely distributed light spots formed after diffusion are spatially superimposed to create a continuous band-like structure in the brightness transition area between adjacent light spots. This structure extends both circumferentially and axially along the cylinder surface, with brightness gradually transitioning from a central high-brightness area to a peripheral low-brightness area, without obvious abrupt changes or reflection breaks. After the illumination distribution adjustment, the cylinder surface is photographed again using an imaging acquisition device to observe the illumination uniformity of the reflective area. When the difference between adjacent pixels in the same area within the continuous illumination layer is controlled within a predetermined threshold range, it indicates that the light diffusion effect has reached a balanced state. In the imaging results at this point, the whitened areas on the cylinder surface caused by strong reflection have been softened into smooth illumination transition zones, and the image texture has been restored from a fragmented state to a continuous state. Tiny surface texture details (such as the edge lines of the threaded opening, the contour lines of the sealing groove, and the boundary lines of the oil film) are clearly visible. Through this continuous interaction of light energy diffusion and brightness coordination, a light distribution with a natural sense of layering is formed on the surface of the cylinder. This not only maintains the integrity of the original texture but also provides a high-contrast, low-reflection-interference image basis for the subsequent extraction of pose feature trajectories.

[0070] This implementation achieves spatial energy dispersion and brightness balancing of reflection points within concentrated reflection energy areas, based on continuous illumination layers. It transforms the originally concentrated and saturated reflection energy into a uniformly distributed cluster of light spots, forming textured regions with layered transition characteristics. This light spot energy diffusion process not only effectively eliminates the texture interruption and feature loss problems caused by strong reflection, but also makes the overall illumination of the cylinder surface softer and more balanced, thereby ensuring the acquisition of detailed and layered images during the imaging stage.

[0071] The pose feature recognition and tracking module extracts the pose feature trajectory of the cylinder surface based on the continuous texture transition zone, and combines the curve of light intensity changing with time to identify the tiny moving edges of the cylinder surface, so as to generate stable optical flow cues and provide dynamic feedback basis for the visual guidance and control of the hydraulic robotic arm.

[0072] The specific steps for generating optical flow cues are as follows:

[0073] On the continuous texture transition zone formed by light diffusion, pose recognition preparation and feature point confirmation are performed for areas with significant geometric features and texture differences on the cylinder surface. Specifically, the cylinder surface is divided into several typical recognition areas according to its structural features, including the cylinder wall area, the mounting thread area, the positioning shoulder area, and the sealing ring contact area. Within each area, using the texture image with continuous brightness levels and uniform reflection formed in the previous stage, the illumination distribution and geometric edge direction of each area are compared to determine the texture boundary line that best reflects spatial pose changes. For example, the longitudinal polishing texture on the cylinder wall area, the spiral lines in the mounting thread area, and the annular edge of the sealing groove can all serve as basic reference lines for pose recognition. After confirming these reference lines, the spatial position of surface features is determined point by point according to the brightness distribution direction of the continuous texture transition zone, so that the feature points exhibit clear light-dark contrast under continuous illumination levels. In this way, a spatial texture coordinate system consistent with the cylinder structure can be established in the imaging area, ensuring a stable spatial correspondence for each feature point in subsequent light intensity change analysis. This step ensures the consistency between texture features and spatial location, providing an accurate reference benchmark for the next stage of dynamic recognition based on changes in light intensity.

[0074] After spatially locating the feature points, the light intensity over time is monitored in these feature areas to capture the brightness changes on the cylinder surface under minute movements. Specifically, in a continuous sequence of imaging frames acquired from the cylinder surface, the lighting conditions and camera parameters are kept constant, ensuring that the brightness difference in each frame fully reflects the optical changes caused by the object's movement. When the cylinder or robotic arm's end effector performs minute movements or attitude adjustments, the angle of incidence of light and the direction of the surface normal change slightly, causing the light intensity at the feature points to fluctuate periodically over time. By observing the brightness change trends of these feature points frame by frame, the dynamic response characteristics of the cylinder surface under minute movements can be clearly identified. To ensure temporal continuity, the sampling interval for each exposure time period is set within the millisecond range during acquisition, ensuring that the light intensity change curve accurately reflects the lighting changes caused by each minute displacement of the cylinder surface. Simultaneously, to avoid interference from stray light, the background reflective surface is masked and extinct during the light source setup stage, ensuring that the light intensity change curve is only affected by the movement of the cylinder surface. This continuous time observation method can obtain light intensity change curves with high temporal resolution. Each brightness peak or valley in the light intensity change curve corresponds to the actual moment of the tiny movement on the surface of the cylinder, thereby realizing the time capture of the changes in the movement edge.

[0075] After obtaining the light intensity variation curve over time, optical flow cues are generated based on the directionality and continuity of brightness changes within the curve, thus describing the dynamic trend of the cylinder surface pose change. Specifically, using the feature points identified in the previous stage as references, their light intensity changes in consecutive acquisition frames are arranged sequentially along the time axis, forming an optically significant brightness flow path. This path reflects the direction of light energy transmission in the time dimension, consistent with the actual micro-displacement direction of the cylinder surface. When a local area on the cylinder surface undergoes a slight rotation or axial shift, the corresponding light intensity variation curve shifts in the time series; this shift trend can be used as a basis for determining the surface movement direction. To enhance spatial continuity, the light intensity variation curves of adjacent feature points are spatially matched to ensure consistent brightness changes between adjacent points, thereby forming an optical flow band that runs through the entire observation area. This optical flow band has a clear directionality and continuity, and its brightness gradient change trend can intuitively reflect the trajectory of the cylinder surface pose change. By temporally correlating these optical flow cues, the pose characteristic trajectory of the cylinder surface over a continuous time period can be obtained. This trajectory, composed of multiple optical flow bands, is characterized by temporal continuity, directional stability, and smooth energy distribution. Thus, the minute moving edges of the cylinder surface are accurately identified, and the optical flow cues are stably constructed, providing dynamic feedback for the visual guidance and control of the hydraulic robotic arm during alignment, insertion, and locking operations.

[0076] Through the above steps, a complete transformation from static texture features to dynamic optical flow cues is achieved based on the continuous texture transition zone. Precise confirmation of pose feature points ensures the accuracy of spatial correspondence, continuous monitoring of light intensity over time guarantees the authenticity of dynamic changes, and the generation of optical flow cues allows the motion state of the cylinder surface to be captured and expressed in real time in the form of optical features. This comprehensive recognition method based on brightness continuity and temporal stability accurately reflects the minute motion edges of the cylinder surface, effectively suppressing misjudgments during image recognition.

[0077] The visual guidance attitude control module constructs a visual guidance channel based on optical flow cues and drives the attitude fine-tuning unit of the hydraulic actuator through the visual guidance channel to achieve synchronous attitude compensation and pressure distribution adjustment during the cylinder alignment process, thereby eliminating the continuous pressure phenomenon caused by reflection distortion and ensuring the accuracy and safety of cylinder disassembly and assembly operations.

[0078] The posture fine-tuning unit of the hydraulic actuator is driven by a vision-guided channel to achieve synchronous posture compensation and pressure distribution adjustment during the cylinder alignment process. The specific steps are as follows:

[0079] After obtaining stable optical flow cues, the directional information and brightness variation trends within these cues are spatially mapped to determine the relative attitude relationship between the end effector of the hydraulic manipulator and the cylinder surface. Specifically, the optical flow band formed in the previous stage is considered a combination of the cylinder surface movement direction and the illumination variation direction. The direction of the illumination gradient is used to determine the movement trend of local areas on the cylinder surface. For example, when the optical flow cues show a continuous decrease in brightness along the cylinder axis, it indicates a slight backward movement of the cylinder surface in that direction; when the flow cues show an increase in brightness along the radial direction, it indicates a slight approach movement of the end effector in that area. By observing these optical flow directions frame by frame, the current attitude offset direction and amount of the cylinder can be accurately determined. Simultaneously, to ensure the continuity of the spatial mapping, the spatial coordinates of feature points on the cylinder surface are mapped to the optical flow directions, so that each illumination variation trend corresponds to a specific attitude adjustment direction of the hydraulic actuator. Through this mapping method, the spatial distribution of the optical flow cues is directly transformed into a reference for mechanical attitude adjustment, providing continuous guidance for subsequent attitude compensation.

[0080] After clarifying the spatial distribution of optical flow cues, a visual guidance channel is established based on this distribution. In practice, the optical flow direction is mapped one-to-one with the movement direction of the hydraulic actuator, enabling optical information to drive the actuator's attitude response in a temporal sequence. To achieve continuous transmission of this mapping, during the construction of the visual guidance channel, the directional changes of adjacent feature points in the optical flow band are sequentially arranged to form an optical path chain, which represents the true direction of the cylinder surface movement. When the optical flow cues exhibit a continuous brightness change trend over time, the directionality of the path chain remains consistent, indicating a stable cylinder surface movement trend. At this point, the hydraulic actuator, based on the directional information of the optical path chain, sequentially performs corresponding pose adjustment actions, gradually matching the spatial attitude of the end effector with the attitude change of the cylinder surface. In this process, the visual guidance channel connects optical changes and mechanical responses, ensuring real-time synchronization between the two in the time dimension. When the optical flow trend deviates, the hydraulic actuator can respond promptly and correct the attitude deviation, ensuring the continuity and accuracy of the alignment process.

[0081] After the visual guidance channel is established and operational, fine-tuning of posture and coordination of force are performed to achieve synchronous compensation and pressure balance during the cylinder alignment stage. Specifically, the hydraulic actuator, based on the optical flow direction provided by the visual guidance channel, gradually adjusts the angles and extensions of each joint, allowing the end effector to move smoothly in space along the optical flow direction. When the brightness change in a localized area of ​​the cylinder surface, indicated by the optical flow clues, tends to stabilize, it indicates that the relative movement in that area is nearing cessation, and the hydraulic actuator immediately enters a force balance adjustment state. At this time, the output pressure of the hydraulic cylinder is slightly distributed according to the contact state between the end effector and the cylinder surface, ensuring that the contact surface maintains a stable posture without generating excessive pressure. If an area with abnormally enhanced light reflection appears in a certain direction, it indicates a posture deviation or force concentration in that direction. The hydraulic actuator immediately performs slight reverse compensation in the opposite direction based on the directional information fed back by the visual guidance channel, gradually reducing the local pressure. Through this coordinated optical and mechanical adjustment, the cylinder maintains a balanced force state during installation or disassembly, thereby avoiding deformation of the threaded pair or damage to the seals due to localized overpressure.

[0082] After the attitude fine-tuning and force coordination are stabilized, the operation status of the visual guidance channel is continuously monitored to ensure that the entire alignment process remains dynamically balanced and safe. Specifically, by continuously observing optical flow cues, it is determined whether the brightness distribution on the cylinder surface remains within the equilibrium range established in the previous stage. When the brightness distribution is stable and symmetrical across consecutive frames, it indicates that the attitude between the cylinder and the end effector is fully aligned. When local brightness fluctuations or illumination breaks occur, it indicates a slight offset or surface interference during alignment. Based on feedback from the visual guidance channel, the hydraulic actuator immediately performs micro-adjustments or pressure distribution corrections to restore force balance. Throughout the process, the visual guidance channel continuously provides information on optical flow direction, brightness change trends, and temporal continuity, enabling the hydraulic actuator to perform adaptive adjustments without relying on additional position sensors. Through this dynamic coordination of attitude and pressure based on optical feedback, the assembly or disassembly process of the cylinder can remain precise, stable, and safe under complex lighting conditions, avoiding continuous pressure and structural damage caused by reflection distortion.

[0083] This implementation achieves dynamic closed-loop control from optical flow cues to mechanical posture adjustment. Spatial mapping of the optical flow cues ensures the accuracy of the motion direction, the establishment of a visual guidance channel enables synchronous transmission of information and action, posture fine-tuning and force coordination keep the cylinder stably aligned during the alignment phase, and continuous monitoring and feedback correction further guarantee operational safety and reliability. Therefore, the hydraulic robotic arm can not only automatically identify posture deviations during cylinder assembly and disassembly, but also achieve adaptive posture compensation and pressure distribution even in optical distortion environments, significantly improving assembly accuracy, efficiency, and operational safety.

[0084] This invention achieves full-process optimization from light to force in hydraulic cylinder assembly and disassembly operations through a collaborative control mechanism of illumination layering, reflection control, optical flow recognition, and attitude compensation. This solution not only significantly improves visual recognition accuracy, force control stability, operational efficiency, and safety, but also demonstrates excellent robustness and adaptability in scenarios with high reflectivity metal and oil film interference, providing a highly efficient and reliable new approach for the intelligent assembly control of hydraulic robotic arms.

[0085] This invention utilizes multi-angle polarized illumination combined with multi-exposure time-chain layered imaging control to create a continuous brightness transition in time and space for the highly reflective areas of the cylinder surface, avoiding abrupt brightness jumps and pseudo-static pixel bands caused by reflection saturation. Through precise control of the illumination layers, the texture details of the cylinder surface are fully presented, and the image brightness distribution is balanced and stable. This fundamentally improves the recognition accuracy and visual perception reliability during the imaging stage, providing a high-fidelity image foundation for subsequent attitude recognition and trajectory extraction.

[0086] This invention achieves real-time attitude compensation and force balance control of a hydraulic robotic arm during cylinder alignment by performing attitude fine-tuning and pressure distribution adjustment under the guidance of optical flow cues. Through the coordinated adjustment of illumination and force control, the end effector of the robotic arm can achieve adaptive pressure release and attitude correction in environments with reflective interference, avoiding structural damage caused by continuous pressure application, ensuring the smoothness, accuracy, and safety of the cylinder assembly process, thereby significantly improving the automation accuracy and execution stability of disassembly and assembly operations.

[0087] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A control system for a six-degree-of-freedom hydraulic robotic arm used for cylinder assembly and disassembly, characterized in that, It includes a multi-angle polarized light layering module, a multi-exposure time chain control module, a spot energy diffusion balance module, a pose feature recognition and tracking module, and a visually guided posture control module. The multi-angle polarized illumination layering module configures multi-angle polarized light sources for areas with abrupt illumination changes on the surface of the cylinder during the imaging acquisition stage. This causes the reflected light to form differences in light intensity distribution at different illumination angles, and a brightness gradient sequence is established based on these differences in light intensity distribution. The multi-exposure time chain control module constructs a multi-exposure time chain based on the brightness gradient sequence. By adjusting the illumination intensity of multi-angle polarized light sources in a time-division manner, the reflective area on the surface of the cylinder presents an orderly brightness change in continuous acquisition frames, forming a continuous illumination layer. The spot energy diffusion balancing module performs spot energy diffusion operation on the basis of continuous illumination layers, diffuses the light energy of the reflection points in the concentrated area of ​​reflected energy into a sparsely distributed spot group, forming a continuous texture transition zone in the image; The pose feature recognition and tracking module extracts the pose feature trajectory of the cylinder surface based on the continuous texture transition zone, and combines the curve of light intensity changing with time to identify the moving edge of the cylinder surface and generate optical flow cues. The steps for generating optical flow cues include the following: On the continuous texture transition zone formed by light energy diffusion, pose recognition preparation and feature point confirmation are carried out for the region with geometric features and texture differences on the cylinder surface. Based on the light distribution and geometric edge direction of the cylinder surface, the texture boundary line used to reflect the spatial pose change is determined, and a spatial texture coordinate system consistent with the cylinder structure is established. After completing the spatial localization of feature points, the light intensity changes over time in the feature area is monitored. While keeping the lighting conditions and camera parameters constant, imaging frames are continuously acquired to capture the brightness change pattern of the cylinder surface in motion, and the moving edge of the cylinder surface is identified based on the light intensity change curve. After obtaining the light intensity change curve over time, optical flow cues are generated based on the directionality and continuity of brightness change in the light intensity change curve. The light intensity change sequence of feature points in consecutive frames is arranged according to the time axis to form a brightness flow path. The light intensity changes of adjacent feature points are spatially matched to construct an optical flow band with directionality and continuity. The visual guidance attitude control module constructs a visual guidance channel based on optical flow cues, and drives the attitude fine-tuning unit of the hydraulic actuator through the visual guidance channel to achieve synchronous attitude compensation and pressure distribution adjustment during the cylinder alignment process.

2. The control system for the six-degree-of-freedom hydraulic robotic arm used for cylinder assembly and disassembly according to claim 1, characterized in that, The steps for establishing a brightness gradient sequence based on differences in light intensity distribution include the following: In the preparation stage of oil cylinder image acquisition, the spatial structure and reflection characteristics of the surface to be observed of the oil cylinder are designed for lighting. The central axis of the oil cylinder is used as a reference. No less than six polarized light sources are evenly arranged around the oil cylinder. The incident angle of each polarized light source relative to the central axis of the oil cylinder is set between 30 degrees and 70 degrees, and the polarization angle of adjacent polarized light sources differs by 15 degrees, forming a circumferential multi-angle polarization illumination structure. After completing the acquisition of multi-angle illumination images, the light intensity distribution on the surface of the cylinder under each illumination angle is analyzed hierarchically. The area of ​​light abrupt change is identified and multiple hierarchical areas are divided from the highest light intensity point to both sides in descending order of brightness, with the highest light intensity point as the center. The average light intensity value under each illumination angle is recorded and the light intensity layering result is formed. After completing the division of illumination layers, the average light intensity value of each illumination layer is used as the gradient node, and they are arranged in order of increasing illumination angle to form a directional brightness change chain. The light intensity difference between adjacent gradient nodes is used as the transition interval to construct the brightness gradient sequence.

3. The control system for the six-degree-of-freedom hydraulic robotic arm used for cylinder assembly and disassembly according to claim 1, characterized in that, The steps to make the reflective area on the surface of the hydraulic cylinder exhibit an orderly brightness gradient in continuous acquisition frames, forming a continuous lighting hierarchy, include the following steps: After establishing the brightness gradient sequence, based on the distribution characteristics of brightness values ​​of each layer in the brightness gradient sequence, the exposure time distribution scheme of the multi-exposure time chain is determined, each brightness level is divided into multiple continuous brightness intervals, and a corresponding exposure time interval is set for each brightness interval, so that the exposure time corresponds one-to-one with the brightness level to form a time chain. The brightness of the multi-angle polarized light source is controlled in a time-division manner according to the time sequence of the multi-exposure time chain, so that each polarized light source enters an independent illumination period in sequence. The light intensity is adjusted according to the light intensity level of the corresponding illumination angle in the brightness gradient sequence, so that the surface of the oil cylinder presents an orderly brightness gradient light trajectory in the continuous acquisition frame. After completing the light-sharing control, the brightness changes on the surface of the cylinder in consecutive frames are smoothly transitioned and the layers are verified, while keeping the camera aperture and photosensitivity constant, thus forming a brightness gradient curve.

4. The control system for the six-degree-of-freedom hydraulic robotic arm used for cylinder assembly and disassembly according to claim 3, characterized in that, During time-division brightness control, the brightness adjustment range of each polarized light source in adjacent exposure time periods is kept within the range of light intensity difference between adjacent levels in the brightness gradient sequence, and the switching interval between adjacent time periods is controlled within 10% of the current exposure time.

5. The control system for the six-degree-of-freedom hydraulic robotic arm used for cylinder assembly and disassembly according to claim 3, characterized in that, The steps to diffuse the light energy from reflection points within a concentrated area of ​​reflected energy into a sparsely distributed group of light spots include the following: After completing the construction of the continuous illumination layer, the spatial location and energy distribution characteristics of the concentrated area of ​​reflected energy on the surface of the cylinder are identified. Based on the brightness distribution of the continuous illumination layer, the surface of the cylinder is divided into sections along the axial and radial directions of the cylinder. The center coordinates, illumination angle and brightness range of the concentrated area of ​​reflected energy are calibrated to determine the effective range of light energy diffusion. After determining the spatial distribution of the concentrated area of ​​reflected energy, a light energy diffusion operation is performed on the concentrated area of ​​reflected energy to make the reflected energy diffuse in an orderly manner along the surface of the cylinder to the surrounding sparsely distributed area of ​​reflected energy. The radius and energy release of the diffusion layer are controlled according to the light energy difference between the reflection point in the concentrated area of ​​reflected energy and the sparsely distributed area of ​​reflected energy, so that the brightness distribution after diffusion forms a continuous transition. After the light energy diffusion is completed, the overall light distribution on the surface of the cylinder is coordinated and verified. The sparse distribution of light spots formed after diffusion is superimposed in space to form a continuous texture transition zone extending along the circumferential and axial directions of the cylinder, so that the brightness difference between adjacent pixels is controlled within a predetermined threshold range.

6. The control system for the six-degree-of-freedom hydraulic robotic arm used for cylinder assembly and disassembly according to claim 5, characterized in that, In the light energy diffusion operation, the energy release of each diffusion layer is set to decrease linearly based on the light energy difference between the reflection point in the concentrated area of ​​reflected energy and the surrounding sparsely distributed area of ​​reflected energy, and the outer boundary of the diffusion range is overlapped and coordinated with the energy attenuation boundary of the adjacent concentrated area of ​​reflected energy.

7. The control system for the six-degree-of-freedom hydraulic robotic arm used for cylinder assembly and disassembly according to claim 1, characterized in that, In the step of generating optical flow cues, during the monitoring of the light intensity change curve over time, the sampling interval is set within the millisecond range, and the background reflective surface is masked and extinct during the light source arrangement stage.

8. The control system for the six-degree-of-freedom hydraulic robotic arm used for cylinder assembly and disassembly according to claim 1, characterized in that, The steps for achieving synchronous attitude compensation and pressure distribution adjustment during cylinder alignment by driving the attitude fine-tuning unit of the hydraulic actuator through a vision-guided channel include the following: After obtaining the optical flow cues, the directional information and brightness change trend of the optical flow cues are spatially distributed and mapped, and the spatial coordinates of the feature points on the cylinder surface are correlated with the optical flow direction to determine the relative attitude relationship between the end effector of the hydraulic robot and the cylinder surface. After determining the spatial distribution relationship of optical flow cues, a visual guidance channel is established based on the distribution space, and the optical flow direction is matched one-to-one with the movement direction of the hydraulic actuator. This allows the optical information to drive the attitude response of the end effector of the hydraulic robotic arm in a time sequence, and to make real-time attitude adjustment through the direction information of the optical path chain. After the visual guidance channel is established, the posture fine-tuning and force coordination operation is performed. The angle and extension of each joint are gradually adjusted according to the optical flow direction, so that the end effector of the hydraulic robotic arm moves smoothly along the optical flow direction, and the force is adjusted by pressure micro-distribution. After the posture is fine-tuned and stabilized, the operation status of the visual guidance channel is continuously monitored. When the brightness distribution remains stable and symmetrical, the current posture is maintained. When brightness fluctuations or illumination breaks occur, micro-adjustments or pressure corrections are performed based on feedback information.

9. The control system for the six-degree-of-freedom hydraulic manipulator used for cylinder assembly and disassembly according to claim 8, characterized in that, During the posture fine-tuning and force coordination operation, the end effector of the hydraulic robotic arm adjusts the angle and extension of each joint according to the optical flow direction, while monitoring the brightness distribution of the contact area between the end effector and the cylinder surface in real time. When the local brightness change exceeds the preset threshold, the reverse fine-tuning action is performed.

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