Four-degree-of-freedom travelling crane trolley with adjustable motion axis

Abstract

The utility model discloses a four degree of freedom travelling crane trolley of motion axis adjustable relates to travelling crane trolley technical field, including travelling crane trolley body, pitch drive system, yaw drive system and linear guide rail assembly, travelling crane trolley body is arranged on the external steel rail through the driving wheel of bearing wheel, realizes the first freedom of movement along the steel rail, pitch drive system is connected between travelling crane trolley body and yaw drive system, realizes second freedom, yaw drive system is connected between pitch drive system and linear guide rail assembly, realizes third freedom, linear guide rail assembly drives external load to do linear motion, realizes fourth freedom, the utility model solves following problem: realize " wide range movement " with " local high accuracy " cooperation, optimize load installation space, make load can sink into the inside mechanism, reduce overall gravity and height, improve system stability, improve load distribution, improve mechanism rigidity, avoid the rigidity loss caused by structure stacking.

Description

Technical Field

[0001] This utility model relates to the field of gantry crane technology, specifically to a four-degree-of-freedom gantry crane with an adjustable motion axis. Background Technology

[0002] Existing gantry crane trolleys mostly use a cross-stacked linear guide module for motion adjustment. The Y-axis linear guide is connected to the load via a slider load platform, and the load moves linearly along the Y-axis using a Y-axis lead screw. The Y-axis linear guide is connected to the X-axis guide slider via a Y-axis base. The X-axis guide is mounted on the X-axis base, and the Y-axis as a whole, along with the load, moves linearly along the X-axis using an X-axis lead screw, thus adjusting the motion axis of the Y-axis guide. This existing technology has the following significant drawbacks: Inconsistent precision and range: Achieving a large range of motion often requires sacrificing motion precision, failing to meet the requirements of both "large-range movement" and "local high precision"; Low space utilization: The load can only be connected to the guide rail via the slider load platform and cannot be recessed into the mechanism, resulting in an excessively high overall height of the equipment and load, a raised center of gravity, and poor system stability; Uneven rigidity and stress distribution: The stress of the cross-stacked structure is concentrated at the connection between the X and Y axes, resulting in uneven load distribution, poor mechanism rigidity, and susceptibility to motion deviation due to vibration or heavy loads. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a four-degree-of-freedom gantry crane with adjustable motion axis, which solves the following problems: achieving the coordination of "large-range movement" and "local high precision" to meet the precision requirements of docking and attitude adjustment scenarios; optimizing the load installation space so that the load can be sunk into the interior of the mechanism, reducing the overall center of gravity and height, and improving system stability; improving load distribution, increasing the rigidity of the mechanism, and avoiding rigidity loss caused by structural stacking.

[0004] To solve the above problems, the technical solution provided by this utility model is as follows:

[0005] A four-degree-of-freedom gantry crane with an adjustable motion axis includes a gantry crane body, a pitch drive system, a yaw drive system, and a linear guide rail assembly. The gantry crane body is mounted on an external steel rail via a load-bearing wheel and a drive wheel, achieving a first degree of freedom of movement along the steel rail. The pitch drive system is connected between the gantry crane body and the yaw drive system, and is used to drive the yaw drive system and the linear guide rail assembly to perform pitch motion around a preset axis, achieving a second degree of freedom. The yaw drive system is connected between the pitch drive system and the linear guide rail assembly, and is used to drive the linear guide rail assembly to perform yaw motion around the center of a circular arc, achieving a third degree of freedom. The linear guide rail assembly drives an external load to perform linear motion, achieving a fourth degree of freedom.

[0006] The structure of this four-degree-of-freedom gantry crane achieves decoupling and coordinated control of multi-directional motion through a layered collaborative design. The gantry crane body, relying on drive wheels and load-bearing wheels, achieves a wide range of coarse adjustments on external steel rails (first degree of freedom), providing the system with basic mobility. The pitch drive system, connecting the gantry crane body and the yaw drive system, drives subsequent components to pitch around a preset axis (second degree of freedom), adapting to the longitudinal adjustment requirements of the load's attitude. The yaw drive system further connects the pitch system and the linear guide assembly, achieving yaw motion in the horizontal plane (third degree of freedom), expanding the horizontal orientation adjustment range of the load. The linear guide assembly ultimately drives the load in precise linear motion (fourth degree of freedom), achieving high-precision local positioning. This structure resolves the contradiction between accuracy and range by separating the wide-range movement and precise adjustment functions; optimizes space utilization and lowers the center of gravity by allowing the load to sink into the mechanism's interior; and improves load distribution and system rigidity through a non-stacked force transmission path.

[0007] Optionally, the pitch drive system includes a lift, a single-degree-of-freedom hinge, a lift push rod hinge, and a hinge; the single-degree-of-freedom hinge is rotatably connected to the frame of the gantry crane body, and the lift push rod hinge is hinged to the arc-shaped guide rail mounting frame; the lift is connected to lifting seats with gear and rack structures on both sides via a lifting two-way gear shaft, and the lifting seats are hinged to the arc-shaped guide rail mounting frame; the extension and retraction of the retractable push rod of the lifting seat drives the arc-shaped guide rail mounting frame to rotate around the single-degree-of-freedom hinge.

[0008] The core function of this pitch drive system is to achieve pitch attitude adjustment (second degree of freedom) for the yaw drive system and linear guide rail assembly. The elevator (usually an electric push rod) serves as the core power source, providing linear thrust or pull; the single-degree-of-freedom hinge acts as a fixed rotational fulcrum for the system's motion, constraining the pitch motion within a single plane to ensure motion accuracy; the elevator push rod hinge and the central hinge together form a stable force transmission and motion conversion mechanism, converting the linear extension and retraction motion of the elevator push rod into the rotational motion of the arc-shaped guide rail mounting bracket around the single-degree-of-freedom hinge axis. The system's function is to transform compact linear drive into a wide range of pitch angle changes. Simultaneously, its hinged layout optimizes force flow transmission, avoids structural jamming, and withstands the torque load from the upper components, ensuring the smoothness and reliability of the pitch motion.

[0009] Optionally, the yaw drive system includes an arc guide rail, an arc guide rail mounting bracket, an arc rack, and a yaw drive gear; the arc guide rail is fixed to the upper surface of the arc guide rail mounting bracket, and the arc rack is fixed along the arc contour of the arc guide rail; the yaw drive gear meshes with the arc rack, and the yaw drive gear is driven by a yaw drive motor; through the meshing transmission between the yaw drive gear and the arc rack, the linear guide rail assembly is driven to rotate around the center of the arc guide rail.

[0010] The core function of the yaw drive system is to achieve rotational adjustment (third degree of freedom) of the linear guide assembly and its load in the horizontal plane. The circular arc guide and its mounting bracket together form the rigid support foundation and motion track of the system, providing precise arc-shaped path constraints and load-bearing capacity for yaw motion. The circular arc rack, as a stationary transmission element, converts circular motion into a linear tooth profile. The yaw drive gear, as the driving element, meshes with the circular arc rack, converting the rotational power of the motor into a rolling traction force along the rack. The system's function is to precisely and smoothly convert the rotational motion of the drive motor into the rotational motion of the linear guide assembly around a fixed center, thereby achieving large-angle, high-precision stepless adjustment of the load's horizontal orientation. Its integrated circular arc design allows the rotation axis to intersect with the pitch axis, optimizing force transmission and avoiding the torque load and accuracy loss caused by stacked structures.

[0011] Optionally, the linear guide assembly includes a linear guide mounting frame, a linear guide, and a load connecting slider; the linear guide mounting frame is an internally hollow frame structure, and its lower surface is fixedly connected to the slider of the arc guide; the linear guide is fixed along the length direction of the linear guide mounting frame, the load connecting slider slides with the linear guide, and the load connecting slider is fixedly connected to an external load.

[0012] The core function of the linear guide assembly is to achieve the final precise linear movement of the load (fourth degree of freedom) and to serve as an integrated platform for supporting and connecting other subsystems. The linear guide mounting frame, as the core load-bearing and structural foundation, features an internally hollowed-out frame design that significantly reduces overall weight and creates a space allowing external loads to extend upwards and be fixed in place, greatly optimizing the structural layout and lowering the overall center of gravity. The linear guide, fixed to the frame, provides high-precision, high-rigidity guidance and support for the load's movement. The load-connecting slider, as the actuator directly fixed to the load, transmits the power of the linear drive element (a lead screw or linear motor not shown in the diagram) to the load and slides precisely along the guide. This assembly's role is to ultimately convert the linear direction after yaw motion into the precise linear displacement of the load. Its recessed design solves the load installation space problem, achieving the final execution of "large-range movement" with "local high precision."

[0013] Optionally, a drive rack is provided on one side of the linear guide rail, and a drive gear that meshes with the drive rack is provided on the load connecting slider. The drive gear is driven by an external motor and is used to drive the load connecting slider and the load to move along the linear guide rail.

[0014] The drive rack is fixed to one side of the linear guide, serving as a long-stroke, high-precision linear power source. The drive gear is integrated with the load-connecting slider, acting as the active component to convert the motor's rotational motion into linear traction force. An external motor provides the initial power to the system. The core function of this mechanism is to overcome the elastic deformation, slippage, or creep problems that easily occur in traditional belt or lead screw drives under long strokes and heavy loads through gear and rack meshing transmission, ensuring extremely high positioning accuracy and repeatability even during large-scale movements. Its rigid contact characteristics significantly improve the system's response speed, load-bearing capacity, and anti-interference ability, directly meeting the drive requirements of "local high precision."

[0015] Alternatively, the linear guide mounting frame may be made of one piece of aluminum alloy.

[0016] Aluminum alloy offers excellent strength-to-weight ratio, while the unibody construction avoids the added weight, stress concentration, and risk of loosening associated with traditional welding or bolted connections. Its internal hollow design is easily achieved, further reducing weight and creating space for load embedding. Ultimately, this design significantly reduces the inertia of moving parts, improving the system's dynamic response speed, motion accuracy, and energy efficiency, while ensuring load-bearing stability.

[0017] Optionally, the telescopic push rod has a telescopic stroke range of 0-100mm, and the pitch angle adjustment range of the yaw drive system is ±5°.

[0018] The 0-100mm telescopic stroke provides sufficient range of motion to generate adequate lever arm, while the ±5° pitch angle range is precisely calculated to meet the necessary attitude adjustment requirements of the load in the vertical plane (such as compensating for height differences or leveling during docking) while avoiding excessive movement that could lead to mechanism interference or decreased stability. As an actuator, the electric linear actuator possesses high-precision position control, self-locking, and good load-bearing capacity, directly ensuring the accuracy and reliability of the second degree of freedom motion.

[0019] Optionally, the load-bearing wheel and the drive wheel are symmetrically mounted on both sides of the frame, and the drive wheel is connected to the external servo motor through a reducer.

[0020] The load-bearing wheels are symmetrically mounted on both sides of the frame. Their main function is to bear and distribute the weight of the trolley body and its entire load to the external rails, while providing stable support to prevent tipping. The drive wheels are also symmetrically mounted and directly connected to the external servo motor via a reducer. Their function is to convert the precise rotational output of the servo motor into frictional force between the drive wheels and the rails, thereby providing precise traction for the trolley. This symmetrical layout ensures even load distribution and a centered point of application of the driving force, preventing jamming or deviation during operation and providing a stable and flat moving platform for the precise motion of the three degrees of freedom above.

[0021] Optionally, the radius of curvature of the arc guide rail is 800-2000mm, the module of the yaw drive gear and the arc rack is 1-3, and the yaw angle adjustment range of the yaw drive system is ±5°.

[0022] The curvature radius range of 800-2000mm is an optimized compromise design. A smaller radius makes the structure more compact, while a larger radius provides a smoother motion trajectory and more internal space. The choice of gear rack pairs with a module of 1-3 balances transmission accuracy and torque load. A smaller module is conducive to high-precision, low-noise transmission, while a larger module can transmit greater torque and is suitable for heavy-duty conditions. The yaw angle range of ±5° ensures that the load has sufficient orientation adjustment capability in the horizontal plane to meet the needs of most docking and attitude adjustment scenarios, while avoiding complex problems such as cable entanglement caused by infinite rotation.

[0023] Optionally, the three-degree-of-freedom guide rail module is integrated with a pitch drive system, a yaw drive system, and a linear guide rail assembly, and the three-degree-of-freedom guide rail module is detachably connected to the gantry crane body.

[0024] By highly integrating the three precise degrees of freedom of pitch, yaw, and linear motion (the second, third, and fourth degrees of freedom) into a single module, making it an independent functional unit, the overall structural design, assembly process, and precision debugging work are greatly simplified. The detachable connection between the module and the gantry crane body (the first degree of freedom) endows the system with extremely high flexibility, maintainability, and scalability. This design allows users to quickly replace or upgrade different three-degree-of-freedom modules according to different task requirements (such as load type, working range, and accuracy requirements) without modifying the basic gantry crane structure; it also greatly facilitates transportation, on-site installation, and subsequent maintenance and repair, reducing the total life-cycle cost.

[0025] Compared with the prior art, the technical solution provided by this utility model has the following advantages:

[0026] Four-degree-of-freedom coordinated adjustment: Through the coordination of the gantry crane body (X-axis movement), pitch drive system (pitch around the Y-axis), yaw drive system (yaw around the Z-axis) and linear guide rail assembly (linear movement along the guide rail axis), four-degree-of-freedom motion is achieved to meet the complex motion requirements of docking and attitude adjustment scenarios.

[0027] Balance between accuracy and range: The three-degree-of-freedom guide rail module (pitch, yaw, and linear motion) is integrated into the gantry crane body, enabling the gantry crane to move over a wide range while the three-degree-of-freedom module enables local high-precision adjustment, thus resolving the contradiction of "large range and high precision cannot be achieved at the same time".

[0028] Improved space utilization and stability: The linear guide mounting frame adopts an internal hollow design, allowing the load to sink into the frame, reducing the overall center of gravity height by more than 30%, reducing vibration interference, and improving the system's operational stability.

[0029] Rigidity and stress optimization: The yaw drive system distributes the load evenly through the arc structure of the arc guide rail and the arc guide rail mounting bracket 5, while the pitch drive system disperses the force through the elevator and the double hinge structure, avoiding the rigidity loss of the traditional stacked structure and improving the overall rigidity of the mechanism.

[0030] High attitude adjustment flexibility: The pitch drive system and yaw drive system are independently controlled, and the pitch angle and yaw angle of the linear guide 8 can be adjusted separately to adapt to the axis adjustment requirements of different docking scenarios. Attached Figure Description

[0031] Figure 1 A motion diagram of a four-degree-of-freedom traveling crane trolley with an adjustable motion axis, as proposed in an embodiment of this utility model;

[0032] Figure 2 A schematic diagram of the structure of a four-degree-of-freedom gantry crane with adjustable motion axis proposed in an embodiment of this utility model;

[0033] Figure 3 A partial structural schematic diagram of a four-degree-of-freedom gantry crane with an adjustable motion axis, as proposed in an embodiment of this utility model;

[0034] Figure 4 A top view of a four-degree-of-freedom gantry crane with an adjustable motion axis, as proposed in an embodiment of this utility model;

[0035] Figure 5 A side view of the removal of the gantry crane body of a four-degree-of-freedom gantry crane with adjustable motion axis proposed in an embodiment of this utility model;

[0036] Figure 6 A schematic diagram of the lifting end structure of a four-degree-of-freedom gantry crane with an adjustable motion axis, as proposed in an embodiment of this utility model;

[0037] Figure 7 A top-down view of the lifting end of a four-degree-of-freedom gantry crane with an adjustable motion axis, as proposed in an embodiment of this utility model;

[0038] Figure 8 A bottom view of the transmission end of a lifting platform for a four-degree-of-freedom gantry crane with an adjustable motion axis, as proposed in an embodiment of this utility model.

[0039] 1. Rail; 2. Single-degree-of-freedom hinge; 3. Lifting push rod hinge; 4. Hinge; 5. Arc guide rail mounting bracket; 6. Arc guide rail; 7. Linear guide rail mounting frame; 8. Linear guide rail; 9. Load; 10. Load-bearing wheel; 11. Drive wheel; 12. Lifting machine; 13. Arc rack; 14. Yaw drive gear; 15. Lifting push rod; 16. Lifting seat; 17. Lifting two-way gear shaft; 18. Overhead crane trolley body; 19. Bullseye bearing mounting column; 20. Bullseye bearing mounting body; 21. Yaw drive motor; 22. Yaw crossbeam. Detailed Implementation

[0040] To further understand the content of this utility model, a detailed description of this utility model will be provided in conjunction with the accompanying drawings and embodiments.

[0041] Example 1

[0042] Combined with appendix Figure 1-2 A four-degree-of-freedom gantry crane with an adjustable motion axis includes a gantry crane body 18, a pitch drive system, a yaw drive system, and a linear guide rail assembly 8. The gantry crane body 18 is mounted on an external steel rail 1 via a load-bearing wheel 10 and a drive wheel 11, achieving the first degree of freedom of movement along the steel rail 1. The pitch drive system is connected between the gantry crane body 18 and the yaw drive system, and is used to drive the yaw drive system and the linear guide rail assembly 8 to perform pitch motion around a preset axis, achieving the second degree of freedom. The yaw drive system is connected between the pitch drive system and the linear guide rail assembly 8, and is used to drive the linear guide rail assembly 8 to perform yaw motion around the center of a circular arc, achieving the third degree of freedom. The linear guide rail assembly 8 drives an external load 9 to perform linear motion, achieving the fourth degree of freedom.

[0043] During system operation, the gantry crane body 18 first moves along the rail 1 via the drive wheels 11, achieving a wide range of translational movement of the load 9 (first degree of freedom). The pitch drive system (such as an articulated mechanism and a pitch motor) drives the yaw drive system and the linear guide rail 8 assembly to rotate around the transverse axis, changing the pitch angle of the load 9 (second degree of freedom). The yaw drive system (such as a slewing bearing and a yaw motor) drives the linear guide rail 8 assembly to rotate around the vertical axis, adjusting the horizontal direction of the load 9 (third degree of freedom). The linear guide rail 8 assembly (such as a precision lead screw or linear motor) ultimately drives the load 9 to move precisely in a straight line along the guide rail (fourth degree of freedom). Each degree of freedom works collaboratively through independent drive units, first achieving rapid positioning through a wide range of movement, then adjusting the attitude through pitch / yaw, and finally achieving wire-level precision docking through the linear guide rail 8, with an accuracy of up to 0.02mm, thus balancing the range of motion and precision.

[0044] Combined with appendix Figure 5-8 The pitch drive system includes a lift 12, a single-degree-of-freedom hinge 2, a lift push rod hinge 3, and a hinge 4; the single-degree-of-freedom hinge 2 is rotatably connected to the frame of the gantry crane body 18, and the lift push rod hinge 3 is hinged to the arc guide rail mounting frame 5; the seat of the lifting seat 16 connected to the lift 12 via the lifting bidirectional gear shaft 17 is hinged to the arc guide rail mounting frame 5 via the hinge 4; the extension and retraction of the telescopic push rod drives the arc guide rail mounting frame 5 to rotate around the single-degree-of-freedom hinge 2. The end of the arc guide rail mounting bracket 5 is also provided with a bullseye bearing mounting column 19. The top of the bullseye bearing mounting column 19 is provided with a bullseye bearing mounting body 20. The bullseye bearing mounting column 19 is mounted on the arc guide rail mounting bracket 5. The bullseye bearing mounting body 20 rests on the support frame below. The other end of the support frame is connected to the linear guide rail mounting frame. The bottom of the support frame is provided with a friction pad that abuts against the bullseye bearing mounting body 20 to balance the torque generated by the lifting force of the elevator 12 on the arc guide rail 6.

[0045] The pitch drive system operates based on the four-bar linkage principle. When the push rod of the lifting platform 12 begins to extend or retract, the linear thrust or pull force it generates is transmitted to the arc-shaped guide rail mounting frame 5 through the lifting push rod hinge 3. Since the seat of the lifting platform 16, which is connected to the lifting platform 12 via the lifting double-axis gear shaft 17, is connected to the mounting frame via hinge 4, this point becomes a movable force application point. At the same time, the rear part of the entire mounting frame is fixedly connected to the frame of the gantry crane body 18 via a single-degree-of-freedom hinge 2, and this hinge 4 constitutes the center of rotation (axis of rotation). The linear motion (extension or retraction) of the push rod forces the arc-shaped guide rail mounting frame 5 to rotate upward or downward around the axis of the single-degree-of-freedom hinge 2, thereby driving the entire yaw drive system and linear guide rail 8 assembly fixed on it to complete the pitch action. Throughout the process, multiple hinges 4 work together to smoothly convert the driving force into rotational torque and allow the mechanism to adapt to small position changes during movement, ensuring smooth movement without over-constraint.

[0046] Combined with appendix Figure 8 The yaw drive system includes an arc guide rail 6, an arc guide rail mounting bracket 5, an arc rack 13, and a yaw drive gear 14. The arc guide rail 6 is fixed to the upper surface of the arc guide rail mounting bracket 5, and the arc rack 13 is fixed along the arc contour of the arc guide rail 6. The yaw drive gear 14 meshes with the arc rack 13, and the yaw drive gear 14 is driven by the yaw drive motor 21. Through the meshing transmission between the yaw drive gear 14 and the arc rack 13, the linear guide rail 8 assembly is driven to rotate around the center of the arc guide rail 6.

[0047] The yaw drive system operates based on the principle of gear and rack meshing transmission. After the yaw drive motor 21 starts, its output torque drives the yaw drive gear 14 to rotate. Because the gear meshes with the arc rack 13, the rotational motion of the gear, due to its interaction with the fixed rack, generates a reaction force that propels the entire gear mechanism and the yaw beam 22, which is fixed to it, to rotate around its center along the trajectory of the arc guide rail 6 (i.e., the effect of "the gear crawling on the fixed rack"). The arc guide rail 6, through its rollers, constrains the movement path of the yaw beam 22, ensuring that it rotates smoothly along a predetermined arc trajectory, thereby achieving precise yaw angle control. The yaw beam 22 is fixed between the linear guide rail mounting frames 7, the arc guide rail 6 cooperates with the rollers, and the arc rack 13 and the arc guide rail 6 are integrated. The rollers are mounted below the sliding seat, which is fixed to the motor housing of the yaw drive motor 21.

[0048] Combined with appendix Figure 1-2 The linear guide 8 assembly includes a linear guide 8 mounting frame 7, a linear guide 8, and a load 9 connecting slider. The linear guide 8 mounting frame 7 is an internally hollow frame structure, and its lower surface is fixedly connected to the slider of the arc guide 6. The linear guide 8 is fixed along the length of the linear guide 8 mounting frame 7. The load 9 connecting slider is slidably engaged with the linear guide 8, and the load 9 connecting slider is fixedly connected to the external load 9.

[0049] When the linear drive source (such as a lead screw motor or linear motor) integrated within the component operates, it drives the load 9 connected to the slider to perform precise linear motion along the fixed linear guide 8. Since the load 9 is directly fixed to the slider, it also achieves precise linear movement (fourth degree of freedom). The entire linear guide 8 is mounted on the frame 7, which is fixed to the slider of the arc guide 6 via its lower surface. This means that when the yaw drive system operates (third degree of freedom), it will cause the entire frame, along with the linear guide 8, slider, and load 9, to rotate around the center, thereby changing the final direction of the linear motion. The hollow frame structure allows the load 9 to be embedded within it, reducing the overall height of the equipment and lowering the center of gravity, thus improving operational stability.

[0050] A drive rack is provided on one side of the linear guide rail 8, and a drive gear that meshes with the drive rack is provided on the load 9 connecting slider. The drive gear is driven by an external motor and is used to drive the load 9 connecting slider and the load 9 to move along the linear guide rail 8.

[0051] When the external motor starts, its output shaft drives the drive gear to rotate. Because the drive gear meshes with the drive rack fixedly mounted beside the linear guide rail 8, the rotating gear cannot move along the rack on its own; instead, the meshing generates a huge reaction force. This reaction force propels the entire load 9 connected to the slider (along with the drive motor and external load 9 fixed to it) to move precisely in a straight line along the guide direction of the linear guide rail 8. The motor speed controls the gear speed, which in turn controls the slider's movement speed; the number of rotations of the motor precisely corresponds to the number of teeth the gear rolls on the rack, thus achieving precise closed-loop control of the slider's position.

[0052] The linear guide rail 8 and the mounting frame 7 are made of one piece of aluminum alloy.

[0053] During operation, when the yaw drive system drives the entire frame to rotate around the center (third degree of freedom), the low weight means a smaller moment of inertia, resulting in a lower load on the yaw motor, faster start-stop, and more precise control. When the load 9 connected to the slider performs high-speed or high-precision linear motion on the frame (fourth degree of freedom), the high rigidity and integral molding stability ensure that the frame will not twist or vibrate due to the acceleration, deceleration, or off-center loading of the load 9, thus directly transmitting the precision of the drive unit to the end load 9 and avoiding positioning errors caused by deformation of the basic structure.

[0054] The telescopic push rod has a telescopic stroke range of 0-100mm, and the pitch angle adjustment range of the yaw drive system is ±5°.

[0055] The telescopic end of the electric push rod is connected to the arc-shaped guide rail mounting bracket 5 via the lift push rod hinge 3, and the fixed end of the push rod is connected to the mounting bracket via the central hinge 4. The mounting bracket itself forms a rotation fulcrum with the vehicle frame via a single-degree-of-freedom hinge 2. When the telescopic push rod of the electric push rod extends or retracts within the range of 0 to 100 mm, it pushes or pulls the arc-shaped guide rail mounting bracket 5, causing it to rotate around the axis of the single-degree-of-freedom hinge 2. The linear displacement (X) of the push rod and the rotation angle (θ) of the mounting bracket are precisely converted through a set of trigonometric functions (specifically depending on the relative positions of several hinge points). Through mechanical design, the maximum stroke of the push rod is limited to 100 mm, precisely constraining the extreme position of the pitch angle within ±5°. The system can precisely control the pitch angle by controlling the extension and retraction of the push rod.

[0056] The load-bearing wheel 10 and the drive wheel 11 are symmetrically mounted on both sides of the frame, and the drive wheel 11 is connected to the external servo motor through a reducer.

[0057] When the gantry crane trolley needs to be moved, the control system sends commands to the external servo motor, and the motor output shaft generates precise speed and torque. This output is transmitted to the drive wheel 11 through a reducer, and the drive wheel 11 drives the entire trolley to move along the track through static friction with the external steel rail 1. The torque required for direct motor drive is too large, resulting in a doubling of the motor's power. By using a reducer, the output speed is reduced while the output torque is greatly increased, enabling a small motor to drive a large load. The symmetrically arranged load-bearing wheels 10 rotate accordingly, sharing the load 9 and maintaining the balance of the trolley. The closed-loop control characteristics of the servo motor enable precise control of the movement distance, speed, and acceleration, thereby achieving precise positioning during large-scale movements.

[0058] The radius of curvature of the arc guide rail 6 is 800-2000mm, the module of the yaw drive gear 14 and the arc rack 13 is 1-3, and the yaw angle adjustment range of the yaw drive system is ±5°. The radius of curvature of the arc guide rail 6 can be 800, 1500 or 2000mm.

[0059] The radius of curvature (R) directly determines the physical dimensions of the circular arc rack 13 and the relationship between the yaw angle (θ) and the rolling arc length (S) of the gear (S=R*θ). Within a fixed angle range of ±5°, a larger radius R means that the gear needs to roll a longer arc length S, which usually requires a longer rack and more installation space, but the movement is smoother and the resolution is higher; a smaller R makes the system more compact. The gear module (m) is related to the pitch circle diameter (d) and the number of teeth (Z) of the gear (d=m*Z), which determines the size of the gear, the strength of the teeth, and the controllable accuracy of the meshing. The larger the module, the stronger the load-bearing capacity of a single tooth, but it may affect the smoothness and accuracy of the movement. When the system is running, the servo motor drives the yaw drive gear 14 to rotate, and the gear meshes and rolls on the fixed rack. The number of rotations is converted into a precise linear rolling distance through the module and pitch circle diameter, and then converted into a yaw angle (θ=S / R) through the radius of curvature, thereby achieving precise and rigid closed-loop control over the entire ±5° yaw angle range.

[0060] The three-degree-of-freedom guide rail module is composed of a pitch drive system, a yaw drive system, and 8 linear guide rail components. The three-degree-of-freedom guide rail module is detachably connected to the gantry crane body 18.

[0061] During operation, the pitch, yaw, and linear drive systems, coordinated by the control system, can move independently or in combination, jointly guiding the end-effector 9 to any target pose within the workspace. The kinematic chain is as follows: the gantry crane body 18 provides basic large-range movement (first degree of freedom) → the pitch drive system drives the yaw system and linear assembly on it to pitch via the single-degree-of-freedom hinge 2 (second degree of freedom) → the yaw drive system, in the pitched position, drives the linear guide rail 8 assembly to yaw around the center of the arc (third degree of freedom) → the linear guide rail 8 assembly ultimately achieves precise linear telescoping motion (fourth degree of freedom).

[0062] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A four-degree-of-freedom travelling crane trolley with adjustable axis of motion, characterized in that, The system includes a gantry crane body, a pitch drive system, a yaw drive system, and a linear guide rail assembly. The gantry crane body is mounted on an external steel rail (1) via a load-bearing wheel (10) and a drive wheel (11), enabling movement along the steel rail (1) in the first degree of freedom. The pitch drive system is connected between the gantry crane body and the yaw drive system, and is used to drive the yaw drive system and the linear guide rail assembly to perform pitch motion around a preset axis, thus achieving the second degree of freedom. The yaw drive system is connected between the pitch drive system and the linear guide rail assembly, and is used to drive the linear guide rail assembly to perform yaw motion around the center of a circular arc, thus achieving the third degree of freedom. The linear guide rail assembly drives an external load (9) to perform linear motion, thus achieving the fourth degree of freedom.

2. The four-degree-of-freedom trolley crane with adjustable axis of motion according to claim 1, characterized in that The pitch drive system includes a lift (12), a single-degree-of-freedom hinge (2), a lift push rod hinge (3), and a hinge (4); the single-degree-of-freedom hinge (2) is rotatably connected to the frame of the gantry crane body, and the lift push rod hinge (3) is hinged to the arc guide rail mounting frame (5); the lift (12) is connected to a lifting seat (16) with a gear and rack structure on both sides through a lifting two-way gear shaft (17), and the lifting seat (16) is hinged to the arc guide rail mounting frame (5) through the hinge (4); the arc guide rail mounting frame (5) is driven to rotate around the single-degree-of-freedom hinge (2) by the extension and retraction of the telescopic push rod (15) of the lifting seat (16).

3. The four-degree-of-freedom trolley crane with adjustable motion axis according to claim 1 or 2, characterized in that The yaw drive system includes an arc guide rail (6), an arc guide rail mounting bracket (5), an arc rack (13), and a yaw drive gear (14). The arc guide rail (6) is fixed to the upper surface of the arc guide rail mounting bracket (5), and the arc rack (13) is fixed along the arc contour of the arc guide rail (6). The yaw drive gear (14) meshes with the arc rack (13), and the yaw drive gear (14) is driven by the yaw drive motor (21). Through the meshing transmission between the yaw drive gear (14) and the arc rack (13), the linear guide rail assembly is driven to rotate around the center of the arc guide rail (6).

4. The four-degree-of-freedom trolley crane with adjustable axis of motion according to claim 3, characterized in that The linear guide assembly includes a linear guide mounting frame (7), a linear guide (8), and a load connecting slider; the linear guide mounting frame (7) is an internally hollow frame structure, and its lower surface is fixedly connected to the slider of the arc guide (6); the linear guide (8) is fixed along the length direction of the linear guide mounting frame (7), the load connecting slider is slidably engaged with the linear guide (8), and the load connecting slider is fixedly connected to the external load (9).

5. The four-degree-of-freedom trolley crane with adjustable axis of motion according to claim 4, characterized in that The linear guide (8) is provided with a drive rack on one side, and the load connecting slider is provided with a drive gear that meshes with the drive rack. The drive gear is driven by an external motor and is used to drive the load connecting slider and the load (9) to move along the linear guide (8).

6. The four-degree-of-freedom trolley crane with adjustable axis of motion according to claim 4, characterized in that The linear guide mounting frame (7) is made of aluminum alloy in one piece.

7. The four-degree-of-freedom trolley crane with adjustable axis of motion according to claim 2, characterized in that The telescopic push rod (15) has a telescopic stroke range of 0-100mm, and drives the pitch angle adjustment range of the yaw drive system to be ±5°.

8. The four-degree-of-freedom trolley crane with adjustable axis of motion according to claim 1, characterized in that, The load-bearing wheel (10) and the drive wheel (11) are symmetrically installed on both sides of the frame, and the drive wheel (11) is connected to the external servo motor through a reducer.

9. The four-degree-of-freedom trolley crane with adjustable axis of motion according to claim 1, characterized in that, The radius of curvature of the arc guide rail (6) is 800-2000mm, the module of the yaw drive gear (14) and the arc rack (13) is 1-3, and the yaw angle adjustment range of the yaw drive system is ±5°.

10. The four-degree-of-freedom trolley crane with adjustable axis of motion according to claim 1, characterized in that, The three-degree-of-freedom guide rail module is composed of a pitch drive system, a yaw drive system and a linear guide rail assembly, and the three-degree-of-freedom guide rail module is detachably connected to the gantry crane body.

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