Multi-working-condition-adapted unsupported in-situ 3D printing cross member device and method

Abstract

The application discloses a kind of in-situ 3D printing cross member devices and methods without support for multiple working conditions, belong to the field of building construction technology.The device includes symmetrically arranged in the middle of component two sides cross support module, for generating multimodal support skeleton multimodal support generation module, for implementing concrete deposition forming concrete additive deposition forming module, first visual module and second visual module;Integrate the above module and control unit, based on the first visual module identification support skeleton cross middle droop, closed-loop control the tension of cross support module, based on the second visual module identification concrete printing path width, closed-loop control the end execution speed of concrete additive deposition forming module.The application can realize the rapid manufacturing of flat piece, arch bridge piece and tunnel arch bottom temporary backfill foundation without formwork, provide an automated and intelligent solution for efficient and high-quality in-situ construction of cross member, reduce the work intensity and safety risk.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, and in particular relates to a supportless in-situ 3D printing device and method for span-bearing components that can adapt to multiple working conditions. Background Technology

[0002] In projects such as high-speed railways, cross-river and cross-sea passages, urban rail transit, and underground integrated pipe corridors, it is often necessary to rapidly form various load-bearing components at specific locations to meet the requirements of load-bearing, passage, or process connection. A load-bearing component refers to a component or temporary functional body that forms a certain span between two supports, capable of traversing space and transmitting its own weight and service loads. Its geometry can be planar, curved, or even irregular. For example, flat-plate load-bearing components commonly found in bridge decks and trestle bridges, arched / arch-shaped load-bearing components commonly found in mountain tunnels and transportation corridors, and temporary backfill bases used to support vehicles and equipment and facilitate work face transitions during tunnel construction and equipment operations are all typical examples of load-bearing components.

[0003] Based on the above requirements, the existing technical routes for manufacturing load-bearing components can be roughly summarized into the following four categories: (1) Off-site casting - transportation to the site - hoisting and assembly: the concrete pouring and curing of the component is completed in the prefabrication yard or factory using template molds. After the finished product is transported to the construction site, it is installed by hoisting, positioning, connection and assembly; (2) On-site template construction - on-site casting: the support and template system are erected at the target location, the steel cage is tied on-site and concrete is poured. After reaching the specified strength, the template is removed to form the load-bearing component; (3) Off-site / on-site additive manufacturing - segmented hoisting - assembly: 3D printed concrete is used to print several segmented / segmented components in an off-site or on-site location. Then, the components are hoisted into place, the joints are treated and the connection structure is connected to achieve overall assembly; (4) Setting up printing support templates - in-situ printing: printing support templates or temporary support components are arranged in advance at the location where the load-bearing component needs to be manufactured, so as to serve as the support base for the 3D printed concrete deposition and forming. Then, in-situ printing is carried out at that location to form the target load-bearing component.

[0004] However, the four existing technical routes for manufacturing load-bearing components generally have relatively systematic shortcomings in engineering applications, mainly reflected in construction organization, safety risks, reliance on manual labor and automation and intelligence levels: (1) Off-site casting-transportation-hoisting assembly is highly dependent on logistics and lifting resources. The larger the component, the stronger the constraints on transportation routes, transfer conditions, hoisting sites and hoisting capabilities. On-site assembly involves multiple hoisting point conversions, aerial alignment and temporary support. The work surfaces are intersecting and there are many risk sources. It is obviously dependent on hoisting command and worker experience. The overall safety management pressure is high. Moreover, there are many assembly links and strong interdependence. The organization and coordination are difficult and the construction rhythm and quality consistency are easily affected. (2) On-site formwork casting usually requires a large number of supports and formwork systems. The material turnover and dismantling work are large, and there are safety risks such as working at height, falling, support instability, and formwork bulging. In addition, the process of rebar binding, formwork correction, pouring, vibration and curing is highly dependent on manual labor. The quality is significantly affected by the workers' proficiency and on-site management, making it difficult to achieve continuous and standardized production. Moreover, the construction site occupies a large space and strongly interferes with the surrounding operations. (3) Although off-site / on-site 3D printing and segmented hoisting and assembly can reduce some formwork processes, it is often necessary to manufacture in segments / sections due to the limitations of the equipment's forming size and buildable boundaries. This leads to more assembly nodes and positioning processes, and on-site hoisting and manual assembly are still required. The accumulation of geometric errors in segments, the difficulty of joint treatment and node connection quality control increase, and the reliance on measurement and layout, alignment adjustment and construction experience is strong. The degree of automation and intelligence has not been fundamentally improved. (4) Setting up a printing support template for in-situ printing can reduce the need for handling and assembly, but the support template itself still needs to be designed, processed, installed, calibrated and dismantled, and the coordination requirements between the template and the printing process are high: once the support stiffness is insufficient or the positioning deviation accumulates, it is easy to cause risks such as deflection, collision and collapse of the span section; at the same time, the manufacturing process of the span component involves the coupling of multiple parameters such as reinforcement laying, pumping, deposition and bridging. If there is a lack of online perception and closed-loop control, the stability of the forming quality is easily affected by material fluctuations, environmental changes and equipment disturbances. In general, the above routes generally have problems such as long process chains, high on-site work intensity, high dependence on manual labor and experience, high proportion of dangerous operations and complex cross-process coordination; at the same time, in terms of automation and intelligence, they mostly rely on offline process settings and manual inspection, lacking real-time monitoring and adaptive control mechanisms, so there is still a lot of room for improvement in quality consistency, construction efficiency and inherent safety level. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a supportless in-situ 3D printing device and method for span-bearing components that can adapt to various working conditions. This solves the problems of cumbersome processes, reliance on manual templates, and low automation in traditional span-bearing component manufacturing methods, and achieves efficient and high-quality in-situ rapid prototyping without the need for additional support templates.

[0006] The technical solution adopted in this invention is as follows:

[0007] A supportless in-situ 3D printed span-bearing component device adaptable to multiple working conditions, comprising:

[0008] The span support modules are symmetrically arranged at the support boundaries on both sides of the span member to be formed, and are used to provide basic support for anchoring and tension adjustment;

[0009] A multimodal support generation module is set on one side of the spanning support module and is used to generate a multimodal support skeleton between the spanning support modules. The orientation, spacing and local densification area of ​​the multimodal support skeleton are matched with the principal stress trace distribution characteristics of the spanning member under external load.

[0010] A concrete additive deposition molding module is located on the other side of the spanning support module and is used to deposit 3D printed concrete layer by layer above the multimodal support skeleton via an end effector.

[0011] The first vision module, installed on the concrete additive deposition molding module, is used to identify the mid-span sag of the multimodal support skeleton.

[0012] The second vision module, installed on the end effector of the concrete additive deposition molding module, is used to identify the width of the newly deposited concrete strips.

[0013] The control unit communicates with each module and, based on the mid-span sag identified by the first vision module, performs closed-loop control of the tension force of the span support module; based on the track width identified by the second vision module, it performs closed-loop control of the end-effector speed of the concrete additive deposition molding module.

[0014] Furthermore, the multimodal support generation module has multiple switchable support modes, including:

[0015] The tensioned steel cable support mode involves directly sleeved and anchored steel cables between the crossing support modules to form a multi-mode support skeleton.

[0016] Metal additive printing of fine steel bar support modalities: The first steel bar is printed in situ between the span support modules by laser melt deposition, forming a multimodal support skeleton;

[0017] In the conventional steel reinforcement laying support mode, the second steel reinforcement is directly laid and anchored between the crossing support modules to form a multimodal support skeleton;

[0018] The first reinforcing bar is an in-situ printed reinforcing bar, and the second reinforcing bar is a prefabricated conventional reinforcing bar with a larger diameter than the first reinforcing bar.

[0019] Furthermore, the arrangement of the multimodal support skeleton includes unidirectional net-type parallel support, multidirectional cross support, and multi-layer cross-stacked support. The arrangement of the multidirectional cross support and multi-layer cross-stacked support corresponds only to the metal additive printing fine steel bar support mode and the conventional steel bar laying support mode.

[0020] Furthermore, the span support module includes a support block, a tension slide rail, a tension slide block, and a multimodal support generation base; the support block is a stackable structural block used to adjust and fix the support height; the tension slide rail is arranged along the span direction and fixed on the uppermost support block; the tension slide block slides in conjunction with the tension slide rail to achieve linear reciprocating motion along the span direction to adjust the tension; the multimodal support generation base is set on the tension slide block and is composed of multiple steel rod components arranged in an array, and the surface of each steel rod component is provided with a structural interface for steel cable sleeve and anchoring, as well as rebar positioning and welding.

[0021] Furthermore, the multimodal support generation module includes a multimodal support generation robotic arm, a laser processing head, and a wire feeding mechanism. The multimodal support generation robotic arm is mounted on a first robotic arm slide, which cooperates with a first robotic arm slide rail fixed to the ground substrate, enabling the multimodal support generation robotic arm to perform linear reciprocating motion along the span direction. The laser processing head is mounted at the end of the multimodal support generation robotic arm and is used to generate laser light and form a molten pool. The wire outlet of the wire feeding mechanism is located adjacent to the laser processing head and is used to continuously transport metal wire to the molten pool generated by the laser processing head for deposition.

[0022] Furthermore, the concrete additive deposition molding module includes a concrete additive deposition molding robotic arm and an end effector; in the end effector, a hopper is installed at the end of the concrete additive deposition molding robotic arm, and the spiral extrusion rod inside is driven by a stepper motor, with a nozzle connected to the discharge end of the hopper;

[0023] The concrete additive deposition forming robot arm is mounted on the second robot arm slide, which cooperates with the second robot arm slide rail fixed to the ground base on site, so that the concrete additive deposition forming robot arm can make linear reciprocating motion along the span direction; the end effector is mounted on the end of the concrete additive deposition forming robot arm, and the field of view of the second vision module covers the area of ​​the newly deposited concrete strip by the end effector.

[0024] Secondly, this invention proposes a method for printing a supportless in-situ 3D printed span-bearing component device adaptable to multiple working conditions, comprising the following steps:

[0025] S1: Install and level the span support module at the support boundary on both sides of the span member, and adjust its working elevation;

[0026] S2: Select the support mode and use the multimodal support generation module to generate a multimodal support skeleton between the span support modules. The orientation, spacing and local densification area of ​​the multimodal support skeleton are set according to the principal stress trace of the span member under external load.

[0027] S3: The first vision module identifies the mid-span sag of the multimodal support frame and adjusts the tension of the cross support module in a closed loop to enable the multimodal support frame to achieve and maintain a stable target geometry.

[0028] S4: 3D printed concrete is deposited and formed above the multimodal support skeleton using a concrete additive deposition molding module; during the deposition process, the width of the newly deposited concrete strip is identified online through a second vision module, and the end-effector speed of the concrete additive deposition molding module is adjusted in a closed loop to maintain the stability of the strip width.

[0029] S5: After printing is completed, the multimodal support skeleton and the 3D printed concrete above it together form a load-bearing component, and the multimodal support skeleton works together with the 3D printed concrete as a load-bearing unit during the service stage of the load-bearing component.

[0030] Furthermore, the orientation, spacing, and locally reinforced areas of the multimodal support frame are set according to the principal stress trajectories of the span-bearing components under external loads, specifically including:

[0031] Based on the type of load-bearing member, identify the distribution of principal stress traces in high-stress areas;

[0032] When the span-bearing member is a flat plate, the multimodal support frame is densely arranged in the mid-span region of the flat plate and the transition region between the flat plate and the support, and the number of stress-bearing units in the dense section is higher than that in the low-stress region.

[0033] When the span-supporting component is an arch bridge component, the multimodal support skeleton is arranged along the arch axis of the arch bridge component, and local reinforcement is carried out in the lower edge area of ​​the mid-span and the arch foot area by increasing the number of parallel supports, reducing the spacing, or increasing the number of stacked layers.

[0034] When the span-bearing component is the temporary backfill base of the tunnel arch, the multimodal support skeleton is arranged as the main force-bearing unit along the main span direction of the tunnel, and is densely set in the mid-span area. At the same time, obliquely diffused secondary reinforcement or cross stiffening layer is configured in the transition area near the support.

[0035] Furthermore, the closed-loop adjustment process of the tension force across the support module includes:

[0036] Calculate the current tension component based on the mid-span sagging amount identified by the first vision module;

[0037] Calculate the tension component error between the current tension component and the target tension component;

[0038] Based on the range of the absolute value of the tension component error, different control strategies are switched to calculate the displacement command: when the absolute value of the error is greater than the first threshold, the fast convergence control mode is entered, and the proportional-derivative control algorithm is used to output the displacement command; when the absolute value of the error is less than or equal to the first threshold but greater than the second threshold, the fine-stability control mode is entered, and the proportional-integral control algorithm is used to output the displacement command; when the absolute value of the error is less than or equal to the second threshold, the hold and disturbance compensation control mode is entered, and the fine-tuning command is triggered only when the parameters continuously exceed the limits.

[0039] Furthermore, the process of closed-loop regulation of the end-effector speed of the concrete additive deposition molding module includes:

[0040] Calculate the track width error between the track width recognized by the second vision module and the target track width;

[0041] Based on the range of the absolute value of the track width error, different control strategies are switched to calculate the speed correction: when the absolute value of the track width error is greater than the first threshold, the proportional-derivative control algorithm is used to calculate the speed correction; when the absolute value of the track width error is less than or equal to the first threshold but greater than the second threshold, the proportional-integral control algorithm is used to calculate the speed correction; when the absolute value of the track width error is less than or equal to the second threshold, the system enters the hold and disturbance compensation control mode, and fine-tuning is triggered only when the track width continuously exceeds the limit.

[0042] The speed correction amount is added to the preset speed to obtain the actual speed command.

[0043] The beneficial effects of this invention are:

[0044] This invention, through a highly integrated in-situ operation system design, combines a multimodal support generation module, a concrete additive deposition forming module, and a vision-based perception closed-loop control system. This enables template-free, intelligent, and rapid manufacturing of span-supporting components, supporting multiple switchable support modes such as tensioned steel cables, metal additive printing of fine reinforcing bars, and conventional rebar laying. It flexibly adapts to different working conditions, including flat plate components, arch bridge components, and temporary backfill bases for tunnel arches. Particularly noteworthy is the vision-based perception closed-loop control system. The first vision module monitors the mid-span sag of the support frame in real time and automatically adjusts the tension force, ensuring the frame reaches a precise and stable geometric state before concrete deposition. The second vision module identifies the width of the concrete printing runway online and maintains a constant runway width by adjusting the printing speed, effectively suppressing printing defects and ensuring consistent forming quality.

[0045] The multimodal support frame of this invention does not need to be dismantled as scrap during its service life. It can work in conjunction with concrete as the main load-bearing reinforcement, bearing tensile forces and inhibiting crack development, significantly improving the bending resistance, crack resistance, and overall mechanical properties of the component. Simultaneously, the arrangement of the support frame is optimized based on the principal stress trajectory of the component under external loads, ensuring a high degree of matching between material distribution and stress path. This greatly improves structural stress efficiency and material utilization efficiency while ensuring the feasibility of in-situ manufacturing without formwork, reducing labor intensity and safety risks, and providing reliable technical support for efficient, safe, and high-quality in-situ construction of load-bearing components. Attached Figure Description

[0046] Figure 1 This is an overall schematic diagram of a supportless in-situ 3D printed span-bearing component device adapted to multiple working conditions;

[0047] Figure 2 This is an overall schematic diagram from another perspective of an unsupported in-situ 3D printed span-bearing component device adapted to multiple working conditions.

[0048] Figure 3 This is a structural diagram of the cross-support module;

[0049] Figure 4 This is a structural diagram of the multimodal support generation module;

[0050] Figure 5 This is a structural diagram of a concrete additive deposition molding module;

[0051] Figure 6 This is a structural diagram of the end effector of the concrete additive deposition molding module;

[0052] Figure 7 This is a cross-sectional view of the end effector of the concrete additive deposition molding module;

[0053] Figure 8 This is a schematic diagram of the in-situ fabrication of a flat plate support frame (unidirectional "net" parallel type) using a tensioned steel cable support mode;

[0054] Figure 9 This is a cross-sectional view of the flat plate support skeleton (unidirectional "net" parallel type) prepared in situ using the tensioned steel cable support mode;

[0055] Figure 10 This is a schematic diagram of the in-situ fabrication of a flat plate support skeleton (unidirectional "net" parallel type) using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0056] Figure 11 This is a cross-sectional view of a flat plate support skeleton (unidirectional "net" parallel type) prepared in situ using a metal additive printing fine steel bar support mode or a conventional steel bar laying support mode;

[0057] Figure 12 This is a schematic diagram of in-situ fabrication of a flat plate support skeleton (multi-directional cross type) using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0058] Figure 13 This is a cross-sectional view of a flat plate support skeleton (multi-directional cross type) prepared in situ using a metal additive printing fine steel bar support mode or a conventional steel bar laying support mode;

[0059] Figure 14 This is a schematic diagram of in-situ fabrication of a flat plate support skeleton (multi-layer stacked type) using a metal additive printing fine steel bar support mode or a conventional steel bar laying support mode;

[0060] Figure 15 This is a cross-sectional view of a flat plate support skeleton (multi-layer stacked) prepared in situ using a metal additive printing fine steel bar support mode or a conventional steel bar laying support mode;

[0061] Figure 16 This is a schematic diagram of the in-situ preparation of the arch bridge support skeleton (unidirectional "net" parallel type) using the tensioned steel cable support mode;

[0062] Figure 17 This is a cross-sectional view of the arch bridge support skeleton (unidirectional "net" parallel type) prepared in situ using the tensioned steel cable support mode;

[0063] Figure 18 This is a schematic diagram of the in-situ fabrication of the arch bridge support skeleton (unidirectional "net" parallel type) using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0064] Figure 19 This is a cross-sectional view of the arch bridge support skeleton (unidirectional "net" parallel type) prepared in situ using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0065] Figure 20 This is a schematic diagram of the in-situ fabrication of the arch bridge support skeleton (multi-directional cross type) using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0066] Figure 21 This is a cross-sectional view of the arch bridge support skeleton (multi-directional cross type) prepared in situ using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0067] Figure 22 This is a schematic diagram of the in-situ fabrication of the arch bridge support skeleton (multi-layer stacked type) using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0068] Figure 23This is a cross-sectional view of the arch bridge support skeleton (multi-layer stacked type) prepared in situ using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0069] Figure 24 This is a schematic diagram of the in-situ preparation of the temporary backfill base support skeleton for the tunnel arch bottom using the tensioned steel cable support mode (unidirectional "net" parallel type);

[0070] Figure 25 This is a cross-sectional view of the temporary backfill base support skeleton (unidirectional "net" parallel type) for the tunnel arch bottom prepared in situ using the tensioned steel cable support mode.

[0071] Figure 26 This is a schematic diagram of the in-situ preparation of the temporary backfill base support skeleton (unidirectional "net" parallel type) for the tunnel arch bottom using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0072] Figure 27 This is a cross-sectional view of the temporary backfill base support skeleton (one-way "net" parallel type) for tunnel arch bottom, prepared in situ using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0073] Figure 28 This is a schematic diagram of the in-situ preparation of the temporary backfill base support skeleton (multi-directional cross type) of the tunnel arch bottom using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0074] Figure 29 This is a cross-sectional view of the temporary backfill base support skeleton (multi-directional cross type) for tunnel arch bottom, prepared in situ using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0075] Figure 30 This is a schematic diagram of the in-situ preparation of a temporary backfill base support skeleton (multi-layer overlapping type) for the tunnel arch bottom using a metal additive printing fine steel bar support mode or a conventional steel bar laying support mode;

[0076] Figure 31 This is a cross-sectional view of the temporary backfill base support skeleton (multi-layer overlapping type) for tunnel arch bottom, prepared in situ using metal additive printing of fine steel bar support mode or conventional steel bar laying support mode;

[0077] Figure 32 It is a principal stress cloud diagram of a flat plate under external load;

[0078] Figure 33 It is a principal stress cloud diagram of the arch bridge components under external load;

[0079] Figure 34 It is a principal stress cloud diagram of the temporary backfill foundation at the tunnel arch under external load;

[0080] In the diagram, 1-Crossing support module, 2-Multimodal support generation module, 3-Concrete additive deposition forming module, 4-First vision module, 5-Multimodal support skeleton, 6-3D printed concrete, 101-Support block, 102-Tension slide rail, 103-Tension slide block, 104-Multimodal support generation substrate, 201-Multimodal support generation robotic arm, 202-First robotic arm slide block, 203-First robotic arm slide rail, 204-Laser processing head, 205-Wire 206-Fiber material export, 207-Connecting device, 208-Heat dissipation device, 301-Concrete additive deposition forming robotic arm, 302-Second robotic arm slide, 303-Second robotic arm slide rail, 304-Stepper motor, 305-Motor support seat, 306-Rigid coupling, 307-Hopper, 308-Nozzle, 309-Spiral extrusion rod, 310-Cylinder wall scraper, 311-Feed inlet, 312-Fixed mounting plate, 313-Second vision module. Detailed Implementation

[0081] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0082] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 also refer to the internal connection of two components. "A plurality of" or "several" means two or more. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0083] This invention addresses the in-situ switchable modal manufacturing of various types of load-bearing components, including flat panels, arch bridge components, and temporary backfill bases for tunnel arches. It achieves continuous forming and rapid fabrication without a template by directly generating a temporary support skeleton at the component's forming location and then performing additive concrete deposition on top of the skeleton. The overall diagram of the supportless in-situ 3D printing device for load-bearing components adapted to multiple working conditions proposed in this invention is shown below. Figure 1 As shown, another overall viewpoint is as follows: Figure 2As shown, the system mainly includes a span support module 1, a multimodal support generation module 2, a concrete additive deposition forming module 3, a first vision module 4, a multimodal support skeleton 5, and 3D printed concrete 6. The span support module is positioned at the support boundaries on both sides of the span-bearing component to be formed, providing basic support conditions for anchoring and tension adjustment. The multimodal support generation module includes three modes: tensioned steel cable support, metal additive printed fine steel bar (first steel bar) support, and conventional steel bar (second steel bar) laying support. It is mainly responsible for rapidly generating multimodal support skeletons of unidirectional "net-like" parallel support, multi-directional cross support, or multi-layer cross-stacked support between the span support modules. It can also optimize the configuration of the number, density, and locally reinforced areas of the support skeleton based on the principal stress trajectory under external loads on the span-bearing component, providing temporary support for concrete additive deposition. The concrete additive deposition forming module is mainly responsible for the continuous deposition and forming of 3D printed concrete above the support skeleton, forming solid span-bearing components such as flat plates, arches, or load-bearing bases.

[0084] The following sections will explain each structure.

[0085] The cross-support module 1 is arranged at the support boundary on both sides of the span-bearing component to be formed, and is fixed to the ground base by bolt connection, welding or deep embedment. The multimodal support generation module 2 and the concrete additive deposition forming module 3 are installed on both sides of the cross-support module 1, and are installed on the ground base by anchor expansion bolts. The multimodal support generation module 2 is used to generate a multimodal support skeleton 5 between the cross-support modules 1, which can be a unidirectional net-type parallel support, a multi-directional cross support or a multi-layer cross-stacked support. The concrete additive deposition forming module 3 is used to perform 3D printing of concrete 6 above the multimodal support skeleton 5. The first vision module 4 is fixedly installed on the concrete additive deposition forming module 3. Its field of view covers the mid-span area of ​​the multimodal support skeleton. It is used to identify the sag of the key mid-span points of the multimodal support skeleton 5 and feed the sag back to the external tensioning actuator to adjust the tension output of the cross-support module 1 in a closed loop, so as to realize the automatic control of the pre-tension force and the stable maintenance of the support state. The multimodal support frame 5 serves as a temporary support and geometric constraint unit during the concrete deposition and forming stage, and as a load-bearing unit during the component's service stage, working in conjunction with the 3D-printed concrete 6 to bear the load. The orientation, spacing, and locally reinforced areas of the steel cables / fine steel bars / conventional steel bars can be comprehensively planned and optimized based on the principal stress trajectories under the external loads on the spanning component. The 3D-printed concrete 6 is deposited on top of the multimodal support frame 5 by the concrete additive deposition forming module 3 and spread out layer by layer to form a surface, ultimately forming the spanning component body manufactured in situ without a support template.

[0086] The structural diagram of the cross-support module 1 is as follows: Figure 3As shown, it mainly includes a support block 101, a tension slide rail 102, a tension slide seat 103, and a multimodal support generation base 104. The support block 101 is fixed to the on-site ground base on both sides of the span-bearing component to be formed by bolts, welding, or deep embedment connection. The support block 101 is usually a modular block component that can be stacked. Several support blocks 101 are stacked vertically to form the span support module foundation. The number of stacked blocks and the total height can be configured according to the design elevation of the span-bearing component to be manufactured and the construction space conditions to achieve rapid adjustment of the installation height of the span support module. The material of the support block 101 can be rock blocks, reinforced concrete blocks, or metal blocks, etc., to meet different load-bearing and durability requirements. The tension slide rail 102 is arranged along the span direction and is fixed to the uppermost support block 101 by a threaded connection, which is used to provide linear guidance for the tension slide 103. The tension slide 103 and the tension slide rail 102 cooperate in the form of a sliding pair to realize linear reciprocating motion along the direction of the tension slide rail 102. The tension slide 103 can be driven by an external tensioning actuator to adjust the effective position of the span support module and output pretension force. The multimodal support generation base 104 is set on the tension slide 103 and fixed to the tension slide 103 by threaded connection. The multimodal support generation base 104 is usually made of stainless steel bars and has a structural interface for cable sleeve and anchoring, and for positioning and welding of thin steel bars or conventional steel bars. This enables the cross support module 1 to generate a multimodal support skeleton 5 with unidirectional "net-like" parallel support, multidirectional cross support or multi-layer cross-stack support under different modes, thereby realizing the rapid generation and stable positioning of the support skeleton under different modes.

[0087] The structure diagram of the multimodal support generation module 2 is as follows: Figure 4As shown, the system mainly includes a multimodal support generation robotic arm 201, a first robotic arm slide 202, a first robotic arm slide rail 203, a laser processing head 204, a wire outlet 205, a wire inlet 206, a connecting device 207, and a heat dissipation device 208. The multimodal support generation module has multiple switchable support modes, including tensioned steel cables that are quickly installed and anchored manually on the multimodal support generation base 104 of the span support module 1; a thin steel reinforcement skeleton printed in situ between the span support modules 1 according to the target skeleton model; and conventional steel reinforcement that is manually laid and anchored to the span support modules 1. The multimodal support generation robotic arm 201 is installed on the first robotic arm slide 202 by bolts. The first robotic arm slide 202 and the first robotic arm slide rail 203 cooperate in the form of a sliding pair to realize the linear reciprocating movement of the multimodal support generation robotic arm 201 along the span direction; the first robotic arm slide rail is fixed to the on-site ground base by anchor expansion bolts. The laser processing head 204 is fixedly mounted at the end of the multimodal support generating robotic arm 201 via a connecting device 207. The laser processing head 204 is used to locally melt the metal substrate to form a molten pool. The wire inlet 206 is connected to an external wire feeding mechanism via a wire guide tube. The metal wire enters through the wire inlet 206 and is continuously extruded into the molten pool from the wire outlet 205. After being melted by the laser processing head 204, it is deposited and formed into a fine steel bar. The heat dissipation device 208 is mounted on the connecting device 207 via a pin. The heat dissipation device 208 can be air-cooled or liquid-cooled to dissipate heat and cool the laser processing head 204 and its adjacent components, ensuring stable long-term operation of the laser processing head 204 and improving the consistency of the fine steel bar forming process. Through the above structural arrangement, the multimodal support generation module 2 can generate unidirectional "net-like" parallel fine steel bars, multidirectional intersecting fine steel bar mesh, or multi-layer intersecting fine steel bar grid in situ between the spanning support modules according to the target support skeleton model. Alternatively, it can anchor the steel cables / conventional steel bars that are manually fitted or laid on the spanning support module 1. The anchoring method is to use the above-mentioned laser printing principle to perform laser welding at the contact position between the steel cables / conventional steel bars and the steel rod components to reinforce them, providing a multimodal support skeleton that can be temporarily supported for in-situ concrete additive deposition without support template.

[0088] The structural diagram of the concrete additive deposition molding module 3 is as follows: Figure 5 As shown in the figure, the end effector structure of the concrete additive deposition molding module is as follows: Figure 6 As shown, the end effector cross-sectional view is as follows: Figure 7As shown. The concrete additive deposition molding module 3 mainly includes a concrete additive deposition molding robotic arm 301, a second robotic arm slide 302, a second robotic arm slide rail 303, a stepper motor 304, a motor support 305, a rigid coupling 306, a hopper 307, a nozzle 308, a spiral extrusion rod 309, a cylinder wall scraper 310, a feed inlet 311, a fixed mounting plate 312, and a second vision module 313. The concrete additive deposition molding robotic arm 301 is bolted to the second robotic arm slide 302. The second robotic arm slide 302 and the second robotic arm slide rail 303 cooperate in the form of a sliding pair to realize the linear reciprocating motion of the concrete additive deposition molding robotic arm 301 along the span direction. The second robotic arm slide rail 303 is fixed to the ground substrate by anchor expansion bolts. The fixed mounting plate 312 is fixed to the end of the concrete additive deposition molding robot arm 301 by bolts. The motor support 305 is installed on the fixed mounting plate 312 by bolts. The stepper motor 304 is threaded to the motor support 305. The output shaft of the stepper motor 304 passes vertically through the motor support 305 and is connected to the spiral extrusion rod 309 through the rigid coupling 306, thereby driving the spiral extrusion rod 309 to rotate in the hopper 307 to realize material conveying and extrusion. The hopper 307 is threadedly connected to the fixed mounting plate 312. An opening on the upper side of the hopper 307 serves as the feed inlet 311 for automatically pumping material into the hopper. The nozzle 308 is installed at the lower discharge end of the hopper 307 via internal and external threads, used for directional deposition of concrete material. The spiral extrusion rod 309 is located inside the cylinder formed by the nozzle 308 and the hopper 307. A cylinder wall scraper 310 is welded to the spiral extrusion rod 309, used to scrape and rectify the material adhering to the cylinder wall of the hopper 307 during 3D printing, thereby improving extrusion stability and reducing the risk of clogging. The second vision module 313 is bolted to the fixed mounting plate 312. Its field of view covers the newly deposited strip area, used for online identification of the concrete printing run width, and feeding the identification results back to the robotic arm control cabinet to adjust the end effector speed of the concrete additive deposition forming robotic arm 301 in a closed loop, thereby improving the geometric consistency of deposition and the stability of forming quality.

[0089] The device proposed in this invention can be arranged in a unidirectional parallel form similar to a net, or in a multidirectional cross arrangement, or in a multi-layer cross-stack form and support the switching of directions between layers. This expands the design freedom of span, curvature and local stiffening without the need to build a large-scale support template system, and further enhances the engineering advantages of in-situ forming and ready-to-use. Firstly, in the tensioned steel cable support mode, the steel cable is quickly and manually fitted onto the span support module. The pre-tension force is automatically adjusted by the external tensioning actuator through closed-loop control, based on the first vision module's identification of the cable's sag at key points in the mid-span. This ensures rapid convergence and stable maintenance of the support state, providing stable support for template-free in-situ printing. Secondly, in the metal additive printing fine steel bar support mode, after the fine steel bars are printed in-situ according to the target model, the first vision module identifies the sag in the mid-span and adjusts the external tensioning actuator through closed-loop control. This ensures the fine steel bar support skeleton meets the preset geometric state, improving the stability of template-free in-situ forming of the span section. Thirdly, in the conventional steel bar laying support mode, after the conventional steel bars are laid manually, the external tensioning actuator directly applies the preset pre-tension force. Utilizing its high stiffness and small deformation characteristics, it eliminates the need for sag closed-loop control, making it suitable for situations requiring higher efficiency in template-free in-situ construction. Meanwhile, this invention sets up a second vision module to identify the width of the concrete printing runway online, and achieves geometric consistency control of the deposition by controlling the end effector speed of the concrete additive deposition forming robotic arm through closed-loop regulation. This effectively reduces reliance on manual inspection and experience-based parameter adjustment, maintains the target runway width and suppresses runway width fluctuations during the deposition process, and ensures that the concrete printing filaments and the supporting skeleton maintain a matching relationship in spatial position and geometric scale. This reduces the risks of local accumulation, sagging, skeleton instability or relative displacement with the supporting skeleton caused by excessively wide / narrow deposition, thereby improving the geometric controllability and dimensional consistency of the cross-section deposition forming, and enhancing the stability and quality consistency of the templateless in-situ manufacturing process.

[0090] Furthermore, the steel cables, fine reinforcing bars, and conventional reinforcing bars in this invention not only serve as temporary supports and geometric constraints during concrete additive deposition, but also participate in load-bearing as load-bearing units during the service life of the span components. When the span components are subjected to external loads, the aforementioned steel cables / fine reinforcing bars / conventional reinforcing bars work together with the concrete as the main load-bearing components, bearing the external force and inhibiting crack development, thereby significantly enhancing the bending resistance, crack resistance, and overall mechanical properties of the span components. Simultaneously, the arrangement of the aforementioned steel cables / fine reinforcing bars / conventional reinforcing bars can be comprehensively planned and optimized based on the principal stress trajectories of the span components under external loads, matching the stress path with the material distribution. This ensures the feasibility of formworkless in-situ manufacturing while further improving structural stress efficiency and material utilization efficiency. In summary, this invention, through a synergistic mechanism of "support generation—in-situ deposition—visual closed-loop control," significantly enhances the formworkless in-situ manufacturing capability of span components in complex construction environments, providing reliable support for efficient, safe, and repeatable engineering applications.

[0091] The process of unsupported in-situ 3D printing of load-bearing components using the aforementioned multi-condition adaptable unsupported in-situ 3D printing device is as follows:

[0092] S1. First, based on the type and geometric boundary of the spanning component to be manufactured (flat plate component, arch bridge component, or temporary backfill base of tunnel arch bottom, etc.), the support reference height is determined at the spanning support module 1 on both sides, and the working elevation of the spanning support module 1 is adjusted by the number of stacked support blocks 101, so that the formation position of the subsequent support skeleton matches the elevation of the target component.

[0093] S2, then select the support mode and enter the generation stage of the multimodal support skeleton 5. The orientation, spacing and local densification area of ​​the multimodal support skeleton 5 are set according to the principal stress trace of the span member under external load.

[0094] When the tensioned steel cable support mode is adopted, the operator quickly puts the steel cable on the multi-mode support generation base 104 of the cross support module 1 and uses the multi-mode support generation module for laser anchoring to form an initial steel cable skeleton with unidirectional "net-like" parallel support.

[0095] When using metal additive printing to create a fine steel bar support mode, the multimodal support generation robotic arm 201 moves linearly back and forth along the first robotic arm slide rail 203. The laser processing head 204 locally melts the metal substrate to form a molten pool. An external wire feeding mechanism feeds the metal wire through the wire inlet 206 and continuously feeds it to the molten pool through the wire outlet 205. The molten metal is deposited and solidified along the trajectory of the robotic arm, thereby printing a fine steel bar skeleton layer by layer according to the target skeleton model (which can be a unidirectional "net-like" parallel fine steel bar, a multidirectional intersecting fine steel bar mesh, or a multi-layer intersecting stacked fine steel bar grid).

[0096] When using conventional steel reinforcement to lay the support mode, the operator lays the conventional steel reinforcement according to the design direction and uses the multimodal support generation module to perform laser anchoring to form the support skeleton.

[0097] In the three modes described above, the orientation, spacing, and local reinforcement areas of the support frame can be comprehensively planned and optimized based on the principal stress trajectories of the span members under external loads, so that the stress path matches the material distribution. In this embodiment, the distribution of principal stress trajectories in high-stress areas is identified according to the type of span member. When the span member is a flat plate, the multimodal support frame is densely arranged in the mid-span area of ​​the flat plate and the transition area between the flat plate and the support, and the number of stress units in the dense section is higher than that in the low-stress area. When the span member is an arch bridge member, the multimodal support frame is arranged along the arch axis direction of the arch bridge member, and local reinforcement is carried out in the lower edge area of ​​the mid-span and the arch foot area by increasing the number of parallel roots, reducing the spacing, or increasing the number of stacked layers. When the span member is a temporary backfill base for the tunnel arch bottom, the multimodal support frame is arranged with principal stress units along the main span direction of the tunnel, and is densely arranged in the mid-span area, while obliquely diffused secondary reinforcements or cross stiffening layers are configured in the transition area near the support.

[0098] S3. After the multimodal support skeleton 5 is formed, the first vision module 4 performs imaging recognition on the mid-span region of the multimodal support skeleton 5, obtains the sagging amount of key mid-span points, and compares it with the target sagging range. The external tensioning actuator drives the tensioning slide rail 102 and tensioning slide block 103 of the span support module to adjust the tensioning output, so that the geometric state of the steel cable or thin steel bar skeleton quickly converges and is stably maintained within the target range, thereby providing stable support and geometric constraints for subsequent unsupported template deposition.

[0099] In this step, since conventional steel bars have high stiffness and small deformation, when using conventional steel bars to lay the support mode, a preset preload can be applied directly to complete the support state setting, omitting the closed-loop adjustment based on the sag.

[0100] S4, then proceeds to the concrete additive deposition forming stage: the concrete additive deposition forming robotic arm 301 reciprocates linearly along the second robotic arm slide rail 303, and the stepper motor 304 drives the spiral extrusion rod 309 to rotate, stably conveying the freshly mixed concrete continuously fed into the hopper 307 through the feed port 311 to the nozzle 308 for directional extrusion deposition; the cylinder wall scraper 310 rotates with the spiral extrusion rod 309 to scrape and rectify the material adhering to the cylinder wall, thereby reducing the risk of clogging and improving extrusion stability. The concrete is deposited layer by layer above the multimodal support frame 5 and bridged and stacked according to the plan to form a continuous slab / arch / base surface.

[0101] During the deposition process, the second vision module 313 identifies the new deposition strips online to obtain the printing width and feeds the width back to the robotic arm control cabinet. The robotic arm control cabinet suppresses the width fluctuation by adjusting the end-effector speed of the concrete additive deposition forming robotic arm 301 through closed-loop adjustment, so that the deposition strips and the supporting skeleton are continuously matched in spatial position and geometric scale, thereby reducing the risks of local accumulation, sagging, skeleton instability and boundary mismatch and improving the consistency of forming.

[0102] S5 After the concrete deposition is completed and reaches the specified initial stable state, the multimodal support frame 5 not only provides temporary support and geometric constraints, but also acts as the main load-bearing unit in service, working together with the 3D printed concrete 6 to bear load and suppress crack development, thereby improving the bending resistance, crack resistance and overall mechanical properties of the span component and realizing in-situ manufacturing without support templates.

[0103] This invention integrates a multimodal support generation module, a concrete additive deposition forming module, and vision-based perception control into a single in-situ operation system. This enables in-situ, formwork-free, switchable modal manufacturing of various types of load-bearing components, including flat panels, arch bridge components, and temporary backfill bases for tunnel arch construction. This significantly shortens the manufacturing process chain for load-bearing components, reduces the intensity of manufacturing, transportation, hoisting, and assembly operations, decreases the proportion of hazardous operations, reduces reliance on manual experience, and simplifies cross-process collaboration. Simultaneously, it provides an automated and intelligent foundation for in-situ, online-controllable manufacturing of load-bearing components. Unlike methods relying on traditional formwork or modular prefabrication, this invention directly constructs a temporary support framework at the component's forming location, providing immediate support and geometric constraints during the concrete deposition process across the span, significantly improving the feasibility and applicability of formwork-free, continuous in-situ forming of load-bearing components.

[0104] In one specific embodiment of the present invention, for load-bearing components under different working conditions such as flat plate components, arch bridge components, and temporary backfill bases at the bottom of tunnel arches, the selection conditions for three support modes and the corresponding in-situ preparation process of the load-bearing components are given as follows:

[0105] Operating Condition A: Flat Part

[0106] like Figure 8 and Figure 9 The figures show a schematic diagram and a cross-sectional view of an in-situ fabrication of a flat plate support frame (a unidirectional "net" parallel type) using a tensioned steel cable support mode, as follows: Figure 10 and Figure 11 The images show schematic diagrams and cross-sectional views of in-situ fabrication of a flat plate support skeleton (unidirectional "net" parallel type) using either a metal additive printing mode for fine steel reinforcement support or a conventional steel reinforcement laying mode. Figure 12 and Figure 13The images show schematic diagrams and sectional views of in-situ fabrication of a flat plate support skeleton (multi-directional cross-type) using either a metal additive printing mode with fine steel reinforcement or a conventional steel reinforcement laying mode. Figure 14 and Figure 15 The images show schematic diagrams and cross-sectional views of in-situ fabrication of a flat plate support skeleton (multi-layered) using either a metal additive printing fine steel bar support mode or a conventional steel bar laying support mode.

[0107] Mode A: Tensioned steel cable support mode, suitable for construction scenarios with small to medium spans, allowable sag control within the range achievable through pre-tensioning, limited construction sites, and the desire for rapid deployment of the support frame in a lightweight manner and controllable adjustment through visual closed loop.

[0108] First, the span support module 1 is installed on both sides of the boundary, and the multimodal support generation base 104 is arranged. Steel cables are then quickly and manually placed onto the multimodal support generation base 104 to form a unidirectional "net-like" parallel support. Laser welding is then performed at the contact points between the steel cables and steel rod components using laser printing principles for reinforcement. Subsequently, the first vision module 4 identifies the sag at the midpoint of the steel cable span, compares it with the target sag range, and drives the external tensioning actuator to adjust the pre-tension force in a closed loop, stabilizing the geometric state of the steel cable support frame within the allowable range. After the support frame is stabilized... Concrete additive deposition is performed, depositing layer by layer along the support direction to form a continuous plate surface. During the deposition process, the second vision module 313 identifies the printing layer width online, and the end-effector speed of the concrete additive deposition forming robot arm 301 is controlled by a closed loop to suppress the layer width fluctuation, so that the 3D printed concrete 6 and the steel cable skeleton are continuously matched in spatial position and geometric scale. Finally, the steel cable not only serves as a temporary support, but also as a stress unit during service, and its direction and density can be comprehensively arranged according to the principal stress traces under load of the plate to enhance crack resistance and bending resistance.

[0109] Modal B: Metal additive printing of fine steel bar support mode, suitable for construction scenarios where there are on-site conditions for metal additive operation, where it is desirable to manufacture the support skeleton more precisely into a lattice / truss form that fits the force path, or where higher geometric controllability is required in locations such as local openings, thickening, and edge reinforcement.

[0110] The cross-support module 1 and the multimodal support generation matrix 104 are first set according to the plate boundary. The multimodal support generation module 2 prints a fine steel reinforcement skeleton in situ between the two cross-support modules 1 according to the target model. It can be a unidirectional "net-like" parallel support skeleton arranged along the main span direction, or a multidirectional cross grid of main reinforcement + transverse distribution reinforcement, or a multi-layer cross-stacked spatial grid, forming a supportable metal support system. After the skeleton is formed, the first vision module 4 identifies the mid-span sag and controls the external tensioning actuator in a closed loop to adjust the pre-tension force provided by the tensioning force slide 103, so that the fine steel reinforcement skeleton reaches the preset geometric state and remains stable. Then, concrete is deposited and formed on the skeleton. The same width vision-speed closed loop is used to keep the strip dimensions consistent and finally form a continuous plate surface. The fine steel reinforcement skeleton not only provides temporary support and geometric constraints, but also works together with the concrete as the main stress unit during the service stage. Its arrangement can also be optimized according to the principal stress trajectory to improve material utilization efficiency and overall mechanical performance.

[0111] Mode C: Conventional rebar laying support mode, suitable for construction scenarios where the project objective is more inclined to "prioritize construction efficiency", the span is large or the support stiffness requirement is high, and the on-site desire is to reduce closed-loop control and debugging links.

[0112] After the cross-support module 1 is in place, conventional steel bars are quickly laid manually and anchored and welded to the multimodal support generation base 104. The laying method can be a unidirectional "net-like" parallel support, a multidirectional cross support, or a multi-layer cross-stacked support. Laser welding is performed at the contact position between the conventional steel bars and the steel bar components using the laser printing principle to reinforce them. The tensioning slide 103 directly applies a preset pre-tightening force or clamping locking force to form a stable support. Since the conventional steel bars have a large diameter, high stiffness, and small shape changes during the arrangement stage, this mode usually does not require drooping closed-loop control, thus achieving a faster deployment cycle. Subsequently, concrete additive deposition is carried out. The second vision module 313 still identifies the lane width and controls the end speed of the concrete additive deposition forming robot arm 301 in a closed loop to ensure that the deposition strip is uniform and maintains a good geometric match with the conventional steel bars. The conventional steel bars are ultimately retained as the load-bearing unit in the load-bearing stage. Their orientation and densification zone can be configured according to the principal stress direction of the flat plate to improve crack resistance and load-bearing capacity.

[0113] Working condition B: Arch bridge component

[0114] like Figure 16 and Figure 17 The figures show a schematic diagram and a cross-sectional view of an arch bridge support frame (unidirectional "net" parallel type) prepared in situ using tensioned steel cable support mode, as follows: Figure 18 and Figure 19 The images show schematic diagrams and cross-sectional views of in-situ fabrication of arch bridge support skeletons (unidirectional "net" parallel type) using either a metal additive printing of fine steel reinforcement support mode or a conventional steel reinforcement laying support mode. Figure 20 and Figure 21 The images show schematic diagrams and sectional views of in-situ fabrication of arch bridge support skeletons (multi-directional cross-type) using either a metal additive printing of fine steel reinforcement support mode or a conventional steel reinforcement laying support mode. Figure 22 and Figure 23 The images show schematic diagrams and cross-sectional views of arch bridge support skeletons (multi-layered) prepared in situ using either a metal additive printing of fine steel reinforcement support mode or a conventional steel reinforcement laying support mode.

[0115] Mode A: Tensioned steel cable support mode, suitable for construction scenarios with small to medium arch spans, allowable controllable deformation of the support frame, and require rapid deployment of adjustable supports in a lightweight manner on site.

[0116] First, span support modules 1 are arranged at the arch foot positions on both sides, and the direction of the steel cable is planned according to the principal stress trajectory under the external load of the arch bridge (usually along the direction of the arch rib). The steel cable is manually sleeved on the multimodal support generation matrix 104. Laser welding is performed at the contact position between the steel cable and the steel rod component using the laser printing principle to reinforce it. Pre-tension is applied by the external tensioning actuator to form a unidirectional "net"-type support skeleton close to the target arch shape. Then, the first vision module 4 identifies the sag of the key control point in the mid-span of the arch bridge, and the output of the external tensioning actuator is adjusted in a closed loop to make the support skeleton converge to the target geometry and maintain stability. Subsequently, concrete is deposited along the arch line direction, expanding layer by layer to form the arch surface. Local stiffening can be achieved in key areas such as the arch foot and mid-span by increasing the number of steel cable layers / crossing density. During the deposition process, the width vision-velocity closed loop suppresses strip fluctuations, reducing the risk of local accumulation on the arch surface, skeleton instability and sag. Finally, the steel cable participates in bearing the load and suppresses crack propagation as a load-bearing unit in the service stage, thereby enhancing the overall mechanical performance of the arch bridge components.

[0117] Modal B: Metal additive printing of fine steel reinforcement support mode, suitable for construction scenarios that require stronger "skeleton forming controllability" and "spatial lattice customized according to the force path", or where it is desirable to form a more defined force transfer structure in the arch rib and arch foot anchorage area of ​​an arch bridge.

[0118] After the span support module 1 is built, the multimodal support generation module 2 prints fine steel bars in situ according to the target arch bridge skeleton model (which can be parallel "net" type fine steel bars along the arch direction, or multi-directional cross-shaped fine steel bar mesh with arch main bars and transverse distribution bars, or multi-layer cross-stacked fine steel bar grid), so that it geometrically fits the arch curved surface and principal stress direction; after the fine steel bar skeleton is printed, the first vision module 4 identifies the mid-span sag and adjusts the external tensioning actuator in a closed loop to keep the skeleton maintaining the preset arch profile and resisting deformation during the concrete deposition process; then the concrete deposition and forming is carried out, and the strip scale is stabilized through the width vision-speed closed loop, and the arch surface is formed as needed; the fine steel bars not only serve as a temporary support skeleton, but also serve as the main stress unit in service and work together with the concrete to bear the load, which is especially suitable for targeted crack resistance, bending resistance and toughness improvement in the arch foot and mid-span areas.

[0119] Mode C: Conventional rebar laying support mode, suitable for construction scenarios that emphasize organizational efficiency, aim to quickly form a supportable arch support and minimize control and commissioning costs, and where the size and stiffness of the arch bridge allow for such construction.

[0120] First, conventional arch-shaped steel bars are manually laid and anchored on the span support modules 1 on both sides. The external tensioning actuator directly applies a preset preload to form a stable support. The laying form can be a parallel support in the arch direction "net-like" or a multi-directional cross support or a multi-layer cross-stack support. Laser welding is performed at the contact position between the conventional steel bars and the steel bar components using the laser printing principle to reinforce them. This mode usually does not require drooping closed-loop control, thereby reducing system complexity and increasing on-site cycle time. Subsequently, concrete strips are deposited along the arch direction to form the arch surface. The second vision module 313 continuously identifies the width of the printed concrete channel and maintains uniform deposition by adjusting the end speed of the concrete additive deposition forming robot arm 301 to avoid drooping and displacement caused by excessive local thickness. The conventional steel bar skeleton is finally retained as the load-bearing unit. Its arrangement can be densified or locally strengthened along the principal stress traces in the arch direction to improve the overall load-bearing capacity and durability of the arch bridge components.

[0121] Condition C: Temporary backfill foundation at the tunnel arch base

[0122] like Figure 24 and Figure 25 The images show a schematic diagram and a cross-sectional view of the in-situ preparation of a temporary backfill foundation support frame for the tunnel arch bottom using a tensioned steel cable support mode (a parallel "net" structure). Figure 26 and Figure 27 The images show schematic diagrams and cross-sectional views of in-situ fabrication of a temporary backfill foundation support skeleton (unidirectional "net" parallel type) for the tunnel arch bottom using either a metal additive printing fine steel bar support mode or a conventional steel bar laying support mode. Figure 28 and Figure 29The images show schematic diagrams and sectional views of the in-situ fabrication of a temporary backfill foundation support skeleton (multi-directional cross-type) for the tunnel arch bottom using either a metal additive printing fine steel bar support mode or a conventional steel bar laying support mode. Figure 30 and Figure 31 The images show schematic diagrams and cross-sectional views of in-situ fabrication of a temporary backfill base support skeleton (multi-layered) for the tunnel arch bottom using either a metal additive printing fine steel bar support mode or a conventional steel bar laying support mode.

[0123] Mode A: Tensioned steel cable support mode, suitable for construction scenarios where the working space at the bottom of the arch is limited, the transportation and laying of steel bars are hindered, the span is small, and a certain degree of controllable deformation is allowed.

[0124] Cross-support modules 1 are set on both sides of the arch bottom and a supporting skeleton (parallel "net" type in the arch direction) is planned. Steel cables are quickly and manually installed, and laser welding is performed at the contact points between the steel cables and steel rod components using the principle of laser printing to reinforce them. The first vision module 4 identifies the mid-span sag of the supporting skeleton and adjusts the output of the external tensioning actuator in a closed loop to make the steel cable supporting skeleton reach the target geometric state. Subsequently, concrete additive deposition is carried out on the supporting skeleton, and it is spread into a continuous base surface by section and lane. During the deposition process, the target lane width is maintained by the lane width vision-velocity closed loop and the fluctuation is suppressed, thereby reducing the adverse effects of local accumulation, flow and undulation on flatness and early load-bearing capacity. The steel cable provides immediate support and geometric constraints during the concrete deposition and forming stage. After the service stage, it serves as a stress unit to improve crack resistance and integrity. Its orientation and densification zone can be optimized by combining the principal stress trace under the external load during the actual service of the temporary backfill base of the tunnel arch bottom to improve load-bearing efficiency and material utilization.

[0125] Modal B: Metal additive printing of fine steel reinforcement support mode, suitable for construction scenarios where metal additive manufacturing is available on site, higher geometric controllability of the support skeleton (such as local thickness changes, stiffening of stress concentration areas, complex contour boundaries) and more refined skeleton manufacturing are required.

[0126] First, between the two span support modules 1, the arch-shaped parallel fine steel bars, multi-directional intersecting fine steel bar mesh, or multi-layer intersecting fine steel bar grid are printed in situ as a metal skeleton according to the target support skeleton model. The direction, spacing, and densification area of ​​the fine steel bars can be comprehensively planned and optimized according to the principal stress trace of the temporary backfill base at the bottom of the tunnel arch under external load, so that the stress path of the skeleton matches the material distribution. Then, the first vision module 4 identifies the sag at the key point in the middle of the span and adjusts the external tensioning actuator in a closed loop to keep the skeleton in the preset support skeleton shape. Subsequently, concrete is laid and deposited on the skeleton to form a continuous base. The width vision-speed closed loop is used to stabilize the scale of the laid strip and improve the flatness consistency. The fine steel bar skeleton provides temporary support during the concrete deposition and forming stage, participates in the stress during the service stage, and inhibits crack development, thereby improving the bending resistance, crack resistance, and overall mechanical performance of the span component.

[0127] Mode C: Conventional rebar laying support mode, suitable for construction scenarios where the engineering goal is to "form a usable load-bearing skeleton as quickly as possible", the on-site organization emphasizes high efficiency and aims to simplify the control chain to the minimum.

[0128] After the span support module 1 is in place, conventional steel bars are quickly laid and anchored manually. The external tensioning actuator directly applies a preset preload to form a support skeleton. The laying method can be an arched "net-like" parallel support, a multi-directional cross support, or a multi-layer cross-stacked support. Laser welding is performed at the contact points between the conventional steel bars and the steel rod components using the laser printing principle to reinforce them. Since conventional steel bars have high stiffness, they usually do not require sag closed-loop control, thus reducing debugging and waiting time. The direction, spacing, and local densification areas of conventional steel bars can be comprehensively planned and optimized according to the principal stress traces of the span components under external loads to match the stress path with the material distribution. Subsequently, concrete additive deposition is used to quickly spread the surface. The uniformity of the deposition strips is maintained by relying on the width-visual-speed closed loop, reducing local undulations and boundary mismatches caused by excessive width / narrowness. Conventional steel bars not only serve as a temporary support skeleton during the concrete deposition and forming stage, but also act as the main load-bearing unit during the service stage, working together with the concrete to bear the load and inhibit crack development, thereby enhancing the bending resistance, crack resistance, and overall mechanical properties of the span components.

[0129] This invention proposes a closed-loop control method for "mid-span sag - pretension force". The method uses a first vision module to identify the mid-span sag f(t) of the steel cable / rebar in real time and drives an external tensioning actuator to adjust the tension force output. This allows the geometry of the support frame to automatically converge and remain stable, providing reliable support for in-situ deposition of unsupported formwork.

[0130] The control system uses the mid-span sag f(t) as the controlled variable and sets the target sag f. ref (or allowed interval [f]) min ,f maxUnder the small deflection approximation, the steel cable / thin reinforcing bar can be approximated by a parabola, and its horizontal tension component satisfies:

[0131]

[0132] Where L is the span between the two multimodal support-generated bases, w is the equivalent load per unit length (which can be preset according to "framework self-weight and additional loads to be considered"), f is the mid-span sag, and H is the tension component. Therefore, the current tension component can be obtained after measuring f(t). :

[0133]

[0134] And based on the preset mid-span sag, the target tension component is obtained. :

[0135]

[0136] The first vision module acquires a mid-span image in each sampling period and identifies the positions of the matrix markers generated by the multimodal supports at both ends in the image, connecting them to form a "reference chord". AB (This is equivalent to a reference line stretched straight at both ends). Identify the centerline of the steel cable / reinforcing bar in the mid-span region (which can be obtained through edge extraction and curve fitting). Find the point P(t) on the centerline that is farthest from the reference chord. The shortest distance from this point to the reference chord is the mid-span sag.

[0137]

[0138] If there are multiple parallel steel cables / multiple thin steel bars, the sag of multiple (n) cables can be adjusted. Take the average value as the control input:

[0139]

[0140] The error is defined by "insufficient tension / excessive tension". and The difference between them is used as input and output to the external tensioning actuator. The mid-span sag error is defined as:

[0141]

[0142] Alternatively, the tension component error can be calculated using mechanical methods, i.e., the current tension component. With the target tension component H ref The difference between them:

[0143]

[0144] To facilitate engineering implementation, this invention preferably employs a composite control method combining sag error and mechanical mapping feedforward: first, the target H is calculated from the target sag. ref Then calculate based on actual droop. , with e H The main error quantity is used to output the displacement command of the external tensioning actuator. (Slide displacement increment):

[0145]

[0146] in, For the initial tension displacement, K p For proportional gain, K i For integral gain, K d This is the differential gain.

[0147] Closed-loop control consists of three levels of control logic. The first level is fast convergence control: when drooping exceeds the limit... ( When the threshold is reached, the system enters fast mode, using proportional-derivative control to output a larger tension step size, causing the support skeleton to quickly converge towards the target shape.

[0148]

[0149] in, For the scaling gain of the fast convergence mode, The differential gain for the fast convergence mode.

[0150] Level 2 is for precise and stable control: when Then it switches to the precision-stable mode, using proportional-integral control to eliminate steady-state deviation and reducing the adjustment step size to avoid overshoot:

[0151]

[0152] in, The proportional gain for the precision-stable mode ( Less than ), This is the integral gain for the precision-stable mode.

[0153] Level 3 is for maintaining and compensating for disturbances, when Then, it enters the hold and disturbance compensation control mode, which only triggers a small fine adjustment when several consecutive frames exceed the bandwidth, to offset the drooping drift caused by deposition weight gain, vibration, etc., thereby achieving stable maintenance of the support state.

[0154] In the aforementioned closed-loop control mechanism of mid-span sag-tension force based on the first vision module, in the tensioned steel cable mode and the metal additive printing fine steel bar mode, the first vision module identifies the mid-span sag of the steel cable / fine steel bar in real time and drives the external tensioning actuator to adjust the tension force output of the cross support module, so that the geometric state of the support frame converges quickly and remains stable. In the conventional steel bar laying mode, the cross support module can directly apply the preset preload to form a stable support, further simplifying the control link and making it suitable for occasions with higher requirements for construction cycle and on-site organization efficiency.

[0155] This invention proposes a deposition geometry consistency control method based on "path width recognition and end-effector speed control". The method uses a second vision module 313 to measure the newly deposited strips online and obtain the concrete printing path width w(t) in real time. The path width fluctuation is suppressed by adjusting the end-effector speed v(t) of the concrete additive deposition forming robot arm 301. This ensures that the concrete printing filament and the supporting skeleton are matched geometrically, thereby reducing the risks of local accumulation, sagging, skeleton instability, and relative displacement with the supporting skeleton caused by excessively wide or narrow path widths.

[0156] In each frame of the image, the key region containing the newly deposited strips is extracted. The left and right boundaries of the strips are obtained using edge extraction techniques. Multiple cross-sectional measurements are performed along the centerline of the strips to obtain a set (n) of local trace widths. The average value is taken as the track width output for that control cycle:

[0157]

[0158] Set target lane width w ref And set the allowed range [w min ,w max The lane width error is defined as:

[0159]

[0160] when hour The end speed should be increased to "thin" the strip; when hour The end speed should be reduced to "widen" the strip. The control cabinet should be adjusted based on the strip width error. Input, output end velocity correction amount Receive speed command:

[0161]

[0162] Where v0 is the preset speed for offline planning of this trajectory segment, using PID control:

[0163]

[0164] Among them, K p For proportional gain, K i For integral gain, K d This is the differential gain.

[0165] The closed-loop control adopts a three-stage control logic of "fast adjustment - stable adjustment - hold". The first stage is fast convergence control: when ( When the first threshold is reached, proportional-derivative control is used to quickly correct the speed in order to bring the lane width back to the vicinity of the allowable range as soon as possible.

[0166]

[0167] in, For the scaling gain of the fast convergence mode, The differential return for the fast convergence mode.

[0168] Level 2 is for precise and stable control: when When switching to the precision-stability mode, proportional-integral control is used to eliminate steady-state deviation, while avoiding the "fluctuating width" of the strip caused by speed overshoot.

[0169]

[0170] in, The proportional gain for the precision-stable mode ( Less than ), This is the integral gain for the precision-stable mode.

[0171] Level 3 is for hold and disturbance compensation control: when Then, it enters the hold and disturbance compensation control mode, which only triggers a small fine adjustment when several consecutive frames exceed the bandwidth, to offset the track width fluctuation caused by changes in material rheological properties, thereby achieving stable maintenance of print quality.

[0172] In the above-mentioned track width recognition-end velocity closed-loop control mechanism based on the second vision module, the second vision module identifies the track width of the newly deposited strip online and suppresses track width fluctuations only by controlling the end execution speed of the concrete additive deposition forming robot arm in a closed loop. This ensures that the concrete printing filament and the supporting skeleton are continuously matched in spatial position and geometric scale, reducing the risks of local accumulation, sagging, skeleton instability, and relative displacement with the supporting skeleton caused by excessively wide / narrow track widths. This improves the geometric consistency and quality stability of the cross-section deposition forming.

[0173] like Figures 32-34The image shows the principal stress cloud diagrams of load-bearing members (flat plates, arch bridge components, and temporary backfill bases at the bottom of tunnel arches) under external loads, obtained based on finite element analysis. The high-stress areas of these members under external loads are mainly concentrated in the mid-span region and the transition zones between supports or corners.

[0174] Firstly, the high stress values ​​of the flat plate are concentrated in the upper / lower part of the mid-span and the transition zone between the flat plate and the support. This indicates that stress concentration and damage initiation points are more likely to occur in the upper / lower part of the mid-span and the transition zone between the support and this type of component. By increasing the density of steel cables / fine steel bars / steel bars and increasing the number of local stiffening layers within a certain length of the upper / lower part of the mid-span and the transition zone between the support, the number of stress-bearing units in this section is significantly higher than that in the low-stress area.

[0175] Secondly, the high stress value areas of arch bridge components are distributed along the arch axis and are more prominent in the lower edge area of ​​the mid-span and the arch feet on both sides. Therefore, it is preferable to maintain the continuous arrangement of the main reinforcement along the arch axis and to achieve local reinforcement in the lower edge area of ​​the mid-span and the arch feet by increasing the number of parallel reinforcements, reducing the spacing, or increasing the number of stacked layers, so that the density of stress-bearing units in the key force transmission area is higher than that in the general section.

[0176] Third, the presence of a continuous high principal stress zone in the lower half of the temporary backfill base at the tunnel arch bottom indicates that the lower half of the span bears the main bending effect and is prone to forming a tensile stress control zone. Therefore, steel cables, thin steel bars, or conventional steel bars are preferably arranged along the span direction (main span direction) as the main force unit, and appropriately densified in the mid-span area to enhance bending and crack resistance. At the same time, local stress abrupt changes and oblique diffusion characteristics can be seen near the support, indicating that there is a significant bending effect near the support. It is preferable to configure obliquely diffused secondary reinforcement or cross stiffening layers in the transition zone of the support to suppress the expansion of cracks from the support edge to the mid-span.

[0177] In summary, the supportless in-situ 3D printing device and method for span-supporting components adapted to multiple working conditions proposed in this invention focuses on the key needs in the construction process of span-supporting components: directly generating a temporary support skeleton at the component forming location, and realizing concrete additive deposition forming on the skeleton, thereby minimizing the time and space distance of span-supporting components from "manufacturing-transportation-hoisting-assembly" to "forming-putting into use", reducing the intermediate steps in the manufacturing and assembly of span-supporting components, and realizing supportless in-situ switchable modal manufacturing of various types of span-supporting components such as flat plate components, arch bridge components, and temporary backfill bases for tunnel arch bottoms. It significantly reduces the problems of high work intensity, long organizational chains, and high proportion of dangerous operations caused by off-site prefabrication, transportation, hoisting, and assembly in traditional solutions, and reduces the reliance on manual experience and on-site inspection. It can also switch modes and configurable density support skeletons, and quickly adjust the support scheme and densification strategy for different component sizes, curvatures and stress requirements. It has great application potential in realizing in-situ manufacturing of support-free templates for span components, online closed-loop adaptive control of the forming process and improvement of deposition quality stability.

[0178] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. Those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A supportless in-situ 3D printed span-bearing component device adaptable to multiple working conditions, characterized in that, include: A cross-support module (1) is symmetrically arranged at the support boundaries on both sides of the span-bearing component to be formed, and is used to provide basic support for anchoring and tension adjustment; the cross-support module (1) includes a support block (101), a tension slide rail (102), a tension slide seat (103), and a multimodal support generation base (104); the support block (101) is a stackable structural block used to adjust and fix the support height; the tension slide rail (102) is arranged along the span direction and fixed on the uppermost support block (101); the tension slide seat (103) slides with the tension slide rail (102) to realize linear reciprocating motion along the span direction to adjust the tension force; the multimodal support generation base (104) is set on the tension slide seat (103), and is composed of multiple steel rod components arranged in an array, and the surface of each steel rod component is provided with a structural interface for steel cable sleeve and anchoring, as well as steel bar positioning and welding; A multimodal support generation module (2) is set on one side of the span support module (1) and is used to generate a multimodal support skeleton (5) between the span support modules (1). The orientation, spacing and local densification area of ​​the multimodal support skeleton (5) are matched with the distribution characteristics of the principal stress traces of the span member under external load. The concrete additive deposition molding module (3) is located on the other side of the span support module (1) and is used to deposit 3D printed concrete (6) layer by layer above the multimodal support skeleton (5) via the end effector. The first vision module (4) is installed on the concrete additive deposition molding module (3) and is used to identify the mid-span sag of the multimodal support skeleton (5). The second vision module (313) is installed on the end effector of the concrete additive deposition forming module (3) and is used to identify the width of the newly deposited concrete strips. The control unit communicates with each module and, based on the mid-span sag identified by the first vision module (4), controls the tension of the span support module (1) in a closed loop; based on the track width identified by the second vision module (313), it controls the end-effector speed of the concrete additive deposition molding module (3) in a closed loop.

2. The unsupported in-situ 3D printing span-bearing component device adaptable to multiple working conditions according to claim 1, characterized in that, The multimodal support generation module (2) has multiple switchable support modes, including: The tensioned steel cable support mode is formed by directly sleeved and anchored steel cables between the crossing support modules (1) to form a multi-mode support skeleton; Metal additive printing of fine steel bar support mode: the first steel bar is printed in situ between the span support module (1) by laser melt deposition to form a multimodal support skeleton; In the conventional steel reinforcement laying support mode, the second steel reinforcement is directly laid and anchored between the crossing support modules (1) to form a multimodal support skeleton; the diameter of the second steel reinforcement is larger than that of the first steel reinforcement.

3. The unsupported in-situ 3D printing span-bearing component device adaptable to multiple working conditions according to claim 2, characterized in that, The arrangement of the multimodal support skeleton includes unidirectional net-type parallel support, multidirectional cross support, and multi-layer cross-stacked support. The arrangement of the multidirectional cross support and multi-layer cross-stacked support corresponds only to the metal additive printing fine steel bar support mode and the conventional steel bar laying support mode.

4. The unsupported in-situ 3D printing span-bearing component device adaptable to multiple working conditions according to claim 1, characterized in that, The multimodal support generation module (2) includes a multimodal support generation robotic arm (201), a laser processing head (204), and a wire feeding mechanism. The multimodal support generation robotic arm (201) is mounted on a first robotic arm slide (202), which cooperates with a first robotic arm slide rail (203) fixed to the ground substrate on site, so that the multimodal support generation robotic arm (201) can make linear reciprocating motion along the span direction. The laser processing head (204) is mounted at the end of the multimodal support generation robotic arm (201) and is used to generate laser and form a molten pool. The wire outlet (205) of the wire feeding mechanism is set adjacent to the laser processing head (204) and is used to continuously transport metal wire to the molten pool generated by the laser processing head (204) for deposition.

5. The unsupported in-situ 3D printed span-bearing component device adaptable to multiple working conditions according to claim 1, characterized in that, The concrete additive deposition molding module (3) includes a concrete additive deposition molding robotic arm (301) and an end effector; the concrete additive deposition molding robotic arm (301) is mounted on a second robotic arm slide (302), and the second robotic arm slide (302) cooperates with a second robotic arm slide rail (303) fixed to the ground substrate on site, so that the concrete additive deposition molding robotic arm (301) can make linear reciprocating motion along the span direction; An end effector is mounted at the end of a concrete additive deposition forming robot arm (301), and the field of view of a second vision module (313) covers the area of ​​the newly deposited concrete strip by the end effector.

6. A printing method for a supportless in-situ 3D printed span-bearing component device adaptable to multiple working conditions, as described in claim 1, characterized in that, Includes the following steps: S1: Install and level the span support module at the support boundary on both sides of the span member, and adjust its working elevation; S2: Select the support mode and use the multimodal support generation module to generate a multimodal support skeleton between the span support modules. The orientation, spacing and local densification area of ​​the multimodal support skeleton (5) are set according to the principal stress trace of the span member under external load. S3: The first vision module identifies the mid-span sag of the multimodal support frame and adjusts the tension of the cross support module in a closed loop to enable the multimodal support frame to achieve and maintain a stable target geometry. S4: 3D printed concrete is deposited and formed above the multimodal support skeleton using a concrete additive deposition molding module; during the deposition process, the width of the newly deposited concrete strip is identified online through a second vision module, and the end-effector speed of the concrete additive deposition molding module is adjusted in a closed loop to maintain the stability of the strip width. S5: After printing is completed, the multimodal support skeleton and the 3D printed concrete above it together form a load-bearing component, and the multimodal support skeleton works together with the 3D printed concrete as a load-bearing unit during the service stage of the load-bearing component.

7. The printing method for a supportless in-situ 3D printed span-bearing component device adaptable to multiple working conditions according to claim 6, characterized in that, The orientation, spacing, and locally reinforced areas of the multimodal support frame (5) are set according to the principal stress traces of the span-bearing components under external loads, specifically including: Based on the type of load-bearing member, identify the distribution of principal stress traces in high-stress areas; When the span-bearing member is a flat plate, the multimodal support frame is densely arranged in the mid-span region of the flat plate and the transition region between the flat plate and the support, and the number of stress-bearing units in the dense section is higher than that in the low-stress region. When the span-supporting component is an arch bridge component, the multimodal support skeleton is arranged along the arch axis of the arch bridge component, and local reinforcement is carried out in the lower edge area of ​​the mid-span and the arch foot area by increasing the number of parallel supports, reducing the spacing, or increasing the number of stacked layers. When the span-bearing component is the temporary backfill base of the tunnel arch, the multimodal support skeleton is arranged as the main force-bearing unit along the main span direction of the tunnel, and is densely set in the mid-span area. At the same time, obliquely diffused secondary reinforcement or cross stiffening layer is configured in the transition area near the support.

8. The printing method for a supportless in-situ 3D printing span-bearing component device adaptable to multiple working conditions according to claim 6, characterized in that, The process of closed-loop adjustment of the tension force across the support module (1) includes: Calculate the current tension component based on the mid-span sagging amount identified by the first vision module; Calculate the tension component error between the current tension component and the target tension component; Based on the range of the absolute value of the tension component error, different control strategies are switched to calculate the displacement command: when the absolute value of the error is greater than the first threshold, the fast convergence control mode is entered, and the proportional-derivative control algorithm is used to output the displacement command; when the absolute value of the error is less than or equal to the first threshold but greater than the second threshold, the fine-stability control mode is entered, and the proportional-integral control algorithm is used to output the displacement command; when the absolute value of the error is less than or equal to the second threshold, the hold and disturbance compensation control mode is entered, and the fine-tuning command is triggered only when the parameters continuously exceed the limits.

9. The printing method for a supportless in-situ 3D printing span-bearing component device adaptable to multiple working conditions according to claim 6, characterized in that, The process of closed-loop regulation of the end-effector speed of the concrete additive deposition molding module includes: Calculate the track width error between the track width recognized by the second vision module and the target track width; Based on the range of the absolute value of the track width error, different control strategies are switched to calculate the speed correction: when the absolute value of the track width error is greater than the first threshold, the proportional-derivative control algorithm is used to calculate the speed correction; when the absolute value of the track width error is less than or equal to the first threshold but greater than the second threshold, the proportional-integral control algorithm is used to calculate the speed correction; when the absolute value of the track width error is less than or equal to the second threshold, the system enters the hold and disturbance compensation control mode, and fine-tuning is triggered only when the track width continuously exceeds the limit. The speed correction amount is added to the preset speed to obtain the actual speed command.

Images