Mobile parallel collaborative robot with constant force mechanism

Abstract

This invention discloses a mobile parallel collaborative robot with a constant force mechanism, comprising a mobile trolley, a plane adjustment module mounted on the trolley's carrier body, a central connecting plate connected to the top of the plane adjustment module, a constant force mechanism assembly mounted on the central connecting plate, a load connecting plate mounted on the side of the constant force mechanism assembly, and a collaborative platform mounted on the load connecting plate. The constant force mechanism assembly includes a spring and a subsequent pulley group constant force compensation mechanism, which maintains the elastic potential energy output by the spring constant throughout the entire stroke of the collaborative platform moving vertically. This invention, through its reasonable structural layout and mechanism design, combines the advantages of high overall rigidity, good motion flexibility, low center of gravity, and wide-range constant force output, effectively solving problems such as difficult precise positioning and poor flexible contact during the docking of heavy-duty components. It has promising application prospects in aerospace, heavy equipment manufacturing, and other fields.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology, specifically relating to a mobile parallel collaborative robot with a constant force mechanism. Background Technology

[0002] In the human-machine collaborative assembly of large components in aerospace, heavy equipment manufacturing and other fields, large components are generally characterized by large size, heavy weight and strict requirements for docking accuracy. Existing collaborative docking equipment and technology systems are difficult to adapt to actual operation needs.

[0003] The current human-machine collaborative docking operations for large components rely heavily on manual labor combined with simple brackets and lifting tools. This not only requires operators to apply significant force to adjust the posture and position of the components, resulting in extremely high labor intensity, but also easily leads to deviations in docking references and imbalances in component postures due to the subjectivity of manual operation. This results in problems such as low assembly accuracy and poor consistency, and may even damage precision parts due to hard contact collisions.

[0004] Currently, single mobile base devices can only achieve large-stroke position movement, lacking precise planar pose fine-tuning capabilities and unable to compensate for minor positional deviations during docking. Traditional planar adjustment mechanisms are mostly fixed in arrangement, lacking mobility and making it difficult to coordinate with the transfer of large components and on-site docking operations. Conventional constant force output devices either have a narrow constant force range and non-adjustable output force values, or cannot coordinate with the movement and pose adjustment mechanisms, easily leading to problems such as hard contact stress concentration and insufficient force control accuracy in human-machine collaboration.

[0005] In summary, the industry currently lacks collaborative equipment that integrates mobile walking, precise planar posture adjustment, and wide-range constant force output. The independent operation mode of each functional module cannot meet the human-machine collaboration and docking requirements of heavy-duty, high-precision, and flexible large components, which has become a key bottleneck restricting the improvement of assembly efficiency and quality in high-end equipment manufacturing. Therefore, it is urgent to develop a mobile parallel collaborative robot that is multi-module collaborative and adaptable to large component operation scenarios.

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a collaborative robot with a large constant force output that is continuously adjustable within a certain range. Summary of the Invention

[0007] This invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a mobile parallel collaborative robot with a constant force mechanism.

[0008] The technical solution of this invention is:

[0009] A mobile parallel collaborative robot with a constant force mechanism is characterized by: a mobile trolley, a plane adjustment module mounted on the trolley's carrier body, a middle connecting plate connected to the top of the plane adjustment module, a constant force mechanism assembly mounted on the middle connecting plate, a load connecting plate mounted on the side of the constant force mechanism assembly, and a collaborative platform mounted on the load connecting plate; the constant force mechanism assembly includes a spring and a rear pulley group constant force compensation mechanism, the rear pulley group constant force compensation mechanism being used to keep the elastic potential energy output by the spring constant throughout the entire stroke of the collaborative platform moving vertically;

[0010] The constant force compensation mechanism of the subsequent pulley block is composed of a pull-line positioning pin, a movable pulley, a fixed pulley, a swing arm, and a rubber wheel.

[0011] The pull wire positioning pin and fixed pulley are installed on the side of the moving platform, and the rubber wheel is installed on the moving end of the swing arm. One end of the rigid wire is fastened to the pull wire positioning pin, and it goes down through the movable pulley fixed to the bottom end of the spring, then up through the fixed pulley and is fixed to the rubber wheel, forming a closed force transmission path. This ensures that when the swing arm is in different angular positions, the resultant force of the swing arm and the rigid wire in the vertical direction remains constant. When the constant force compensation mechanism of the subsequent pulley group moves along the Z direction, it pulls the rigid wire to cause the spring to compress or extend. The movable pulley shaft moves synchronously with the deformation of the spring, realizing constant force compensation and position self-adaptation.

[0012] Furthermore, the planar adjustment module includes a planar branch group installed in the longitudinal space between the intermediate connecting plate and the carrier vehicle body. The planar branch group includes a first branch, a second branch, and a third branch, and the first branch, the second branch, and the third branch have the same structure from the fixed side to the output side.

[0013] Furthermore, the first branch, the second branch, and the third branch each include a first servo motor. A first connecting rod is mounted on the rotation output part of the first servo motor, and a first rotating joint is mounted on the other end of the first connecting rod. A second connecting rod is mounted on the side wall of the rotation output part of the first rotating joint, and a second rotating joint is mounted on the other end of the second connecting rod. The top of the second rotating joint is connected to the intermediate connecting plate.

[0014] Furthermore, the constant force mechanism group includes a first constant force mechanism, a second constant force mechanism, and a third constant force mechanism, and the upper part of the three is connected to the collaborative platform through a load connecting plate, and the lower part is connected to the plane adjustment module through an intermediate connecting plate.

[0015] Furthermore, the first constant force mechanism, the second constant force mechanism, and the third constant force mechanism all include a lead screw and a nut that cooperates with it. The nut is fixed on the moving platform, and one end of the spring is fixed to the moving platform, while the other end is connected to the movable pulley.

[0016] Furthermore, the first constant force mechanism, the second constant force mechanism, and the third constant force mechanism all include a constant force mechanism side plate connected by the intermediate connecting plate. A second servo motor is installed on the upper part of the constant force mechanism side plate. The output shaft of the second servo motor drives the first synchronous pulley. The first synchronous pulley and the second synchronous pulley form a rotational transmission chain via a closed-loop synchronous belt. The second synchronous pulley is coaxially fixed with the lead screw, and the lead screw helical pair cooperates with the nut.

[0017] Furthermore, the distance between the hinge point of the swing arm and the fixed pulley and the compression of the spring satisfy the geometric constraint relationship of the pulley system.

[0018] Furthermore, the rubber wheel at the moving end of the swing arm rolls against the sliding pair to convert the arc motion of the swing arm into the vertical motion of the sliding pair. The linear output part of the sliding pair is equipped with a load connecting plate, which moves along the slide rail to drive the cooperative platform.

[0019] Furthermore, the three wheels of the mobile trolley are arranged in an equilateral triangle.

[0020] The second objective of this invention is to provide a constant force output control method for a mobile parallel collaborative robot with a constant force mechanism, comprising the following steps:

[0021] Step 1: Convert the rotational motion of the lead screw into the axial displacement of the nut, which drives the pre-compression spring of the moving platform to adjust the pre-compression of the spring.

[0022] Step 2: When the swing arm rotates around its hinge point, the elastic force of the spring is transmitted to the swing arm through the rigid wire, which passes through the movable pulley and the fixed pulley in sequence.

[0023] Step 3: Utilize the geometric constraints determined by the pulley system's geometry, combined with the force balance equations, to keep the output force of the constant force mechanism constant;

[0024] Step 4: Achieve gravity adaptive compensation throughout the entire vertical movement of the collaborative platform.

[0025] The beneficial effects of this invention are as follows:

[0026] This invention discloses a mobile parallel collaborative robot with a constant force mechanism. The planar adjustment and constant force output are arranged in a longitudinally layered manner, with a mobile trolley as the overall base. The planar adjustment module equipped with it can achieve precise adjustment of three degrees of freedom: X-axis translation, Y-axis translation, and Z-axis rotation.

[0027] The constant force mechanism adjusts the spring pressure by controlling the servo screw with a motor. Combined with the mechanical compensation of the subsequent pulley group, it can maintain a large constant force output in the Z direction at any position throughout the stroke, and can achieve multiple levels of continuous constant force adjustment within a certain range.

[0028] The overall structural design balances practicality and precision. Furthermore, the invention's vertically layered layout effectively lowers the machine's center of gravity. Combined with a multi-branch planar adjustment module and a three-mechanism centrally symmetrical constant force mechanism, the equipment possesses both high overall rigidity and excellent motion flexibility. Furthermore, the wide-range and continuously adjustable constant force output effectively solves the problems of difficult precise positioning, poor flexible contact, and high manual operation intensity during heavy-duty component docking. It can stably achieve precise docking of heavy-duty components in human-machine collaborative operations, demonstrating excellent operational adaptability in fields such as aerospace and heavy equipment manufacturing that require the assembly and docking of large components. This significantly improves the accuracy and efficiency of heavy-duty component docking and reduces the operational difficulty and safety risks during human-machine collaboration. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0030] Figure 2 This is a schematic diagram of a mobile trolley including a planar adjustment module according to the present invention;

[0031] Figure 3 This is a schematic diagram of the branch of the planar adjustment module of the present invention;

[0032] Figure 4 This is a schematic diagram of the structure of the entire machine without a collaborative platform according to the present invention;

[0033] Figure 5 This is a schematic diagram of the constant force mechanism of the present invention in a static state;

[0034] Figure 6 This is a simplified diagram of the constant force mechanism of the present invention;

[0035] Figure 7 This is a schematic diagram of the human-machine collaborative handling of large steel frames according to the present invention;

[0036] in:

[0037] 1-Collaboration Platform 2-Constant Force Mechanism Group

[0038] 3-Plane Adjustment Module 4-Mobile Cart

[0039] 5-Load connection plate; 6-First constant force mechanism

[0040] 7-Second constant force mechanism 8-Third constant force mechanism

[0041] 9-Constant force mechanism side plate 10-Slide rail

[0042] 11-Outer shell 12-Intermediate connecting plate

[0043] 13-Wheel 14-First Chain

[0044] 15-Second branch 16-Third branch

[0045] 17-Carrier body 19-First servo motor

[0046] 20-First connecting rod 21-First revolute joint

[0047] 22-Second connecting rod 23-Second revolute joint

[0048] 24- Rigid wire 25- Second servo motor

[0049] 26-First synchronous pulley 27-Synchronous belt

[0050] 28-Second Synchronizing Pulley 29-Lead Screw

[0051] 30-Nut 31-Spring

[0052] 32-Pin locating pin for pull wire; 33-Moving pulley

[0053] 34-Fixed pulley 35-Swing arm

[0054] 36-Mobile Sub-37-Mobile Platform

[0055] 38 - Rubber wheel. Detailed Implementation

[0056] The present invention will now be described in detail with reference to the accompanying drawings and embodiments: Example

[0057] like Figures 1 to 7 As shown, a mobile parallel collaborative robot with a constant force mechanism includes a mobile trolley 4. A plane adjustment module 3 is installed on the carrier body 17 of the mobile trolley 4. The top of the plane adjustment module 3 is connected to an intermediate connecting plate 12. A constant force mechanism group 2 is installed on the intermediate connecting plate 12. A load connecting plate 5 is installed on the side of the constant force mechanism group 2. A collaborative platform 1 is installed on the load connecting plate 5. The constant force mechanism group 2 includes a spring 31 and a rear pulley group constant force compensation mechanism. The rear pulley group constant force compensation mechanism is used to keep the elastic potential energy output by the spring 31 constant throughout the entire stroke of the collaborative platform 1 moving in the vertical direction.

[0058] In this embodiment, as Figure 1As shown, the overall structure includes a collaborative platform 1 that works in conjunction with a person, and a constant force mechanism assembly 2 that provides continuously adjustable constant force output to the collaborative platform 1. A plane adjustment module 3 is installed on the carrier body 17, and an intermediate connecting plate 12 is installed on the top of the plane adjustment module 3. The intermediate connecting plate 12 is used to realize plane position adjustment output. The constant force mechanism assembly 2 is installed on the intermediate connecting plate 12, and a load connecting plate 5 is installed on the side of the constant force mechanism assembly 2. The load connecting plate 5 is connected to the collaborative platform 1, and the constant force mechanism assembly 2 maintains constant force output in the Z direction.

[0059] like Figure 4 The structural diagram of the entire machine without a collaborative platform is shown below. Figure 1 Based on the absence of a shell 11, the mobile trolley 4 performs large-stroke movement, and a plane adjustment module 3 and a constant force mechanism group 2 are installed on its supporting vehicle body 17.

[0060] Specifically, the constant force mechanism group 2 is installed on the plane adjustment module 3 as the base. The constant force mechanism group 2 is installed on the plane position adjustment output end of the plane adjustment module 3. After the plane adjustment module 3 performs plane position adjustment, the constant force mechanism group 2 provides longitudinal constant force output to the collaborative platform 1.

[0061] Furthermore, in the embodiments, the planar adjustment module 3 may include a planar branch group installed in the longitudinal space between the intermediate connecting plate 12 and the carrier body 17. The planar branch group includes a first branch 14, a second branch 15 and a third branch 16, and the first branch 14, the second branch 15 and the third branch 16 have the same structure from the fixed side to the output side.

[0062] In this embodiment, as Figure 2 As shown, the planar adjustment module 3 is installed on the carrier body 17 of the mobile trolley 4 as the base for installation, and is installed longitudinally on the carrier body 17. After the mobile trolley 4 performs a large range of position adjustments, the planar adjustment module 3 performs fine planar position adjustments.

[0063] The planar branch assembly is installed on the carrier body 17 and is located in the longitudinal space between the intermediate connecting plate 12 and the carrier body 17. The planar branch assembly includes a first branch 14, a second branch 15, and a third branch 16. The three branches have the same structure and are distributed in a centrally symmetrical manner. The first branch 14, the second branch 15, and the third branch 16 have three degrees of freedom: translation in the X direction, translation in the Y direction, and rotation around the Z direction.

[0064] In one implementation, the output sections of the first branch 14, the second branch 15, and the third branch 16 are triangular in shape and connected to the bottom of the intermediate connecting plate 12.

[0065] Furthermore, in the embodiments, the first branch 14, the second branch 15, and the third branch 16 may each include a first servo motor 19. A first connecting rod 20 is mounted on the rotation output part of the first servo motor 19. A first rotating joint 21 is mounted on the other end of the first connecting rod 20. A second connecting rod 22 is mounted on the side wall of the rotation output part of the first rotating joint 21. A second rotating joint 23 is mounted on the other end of the second connecting rod 22. The top of the second rotating joint 23 is connected to the intermediate connecting plate 12.

[0066] In this embodiment, as Figure 3 As shown, each of the first branch 14, the second branch 15, and the third branch 16 includes a first servo motor 19. The first servo motor 19 is rotatably connected to a first connecting rod 20 at its rotation output part. The other end of the first connecting rod 20 is rotatably connected to a first rotating joint 21. The side wall of the rotation output part of the first rotating joint 21 is rotatably connected to a second connecting rod 22. The other end of the second connecting rod 22 is rotatably connected to a second rotating joint 23. The intermediate connecting plate 12 is connected to the top of the second rotating joint 23.

[0067] Furthermore, in the embodiments, the constant force mechanism group 2 may include a first constant force mechanism 6, a second constant force mechanism 7 and a third constant force mechanism 8, with the upper part of the three connected to the collaborative platform 1 through a load connecting plate 5 and the lower part connected to the plane adjustment module 3 through an intermediate connecting plate 12.

[0068] Specifically, the constant force mechanism group 2 includes a first constant force mechanism 6, a second constant force mechanism 7, and a third constant force mechanism 8. The first constant force mechanism 6, the second constant force mechanism 7, and the third constant force mechanism 8 have the same structure and are centrally symmetrically distributed. The first constant force mechanism 6, the second constant force mechanism 7, and the third constant force mechanism 8 drive the load connection plate 5 in parallel.

[0069] Furthermore, in the embodiments, the first constant force mechanism 6, the second constant force mechanism 7, and the third constant force mechanism 8 may each include a lead screw 29 and a nut 30 that cooperates with it. The nut 30 is fixed on the moving platform 37, and one end of the spring 31 is fixed to the moving platform 37, while the other end is connected to the constant force compensation mechanism of the subsequent pulley group.

[0070] In this embodiment, the rotational motion of the lead screw 29 is converted into the axial displacement of the nut 30, which drives the moving platform 37 to pre-compress the spring 31 to achieve controllable compression. The compression of the spring 31 changes with the position of the moving platform 37, and its elastic potential energy changes accordingly, providing a continuously adjustable force source for the constant force compensation mechanism of the subsequent pulley group, so as to realize the continuous constant force output of the constant force mechanism throughout the entire stroke.

[0071] Furthermore, in the embodiments, the first constant force mechanism 6, the second constant force mechanism 7, and the third constant force mechanism 8 all include a constant force mechanism side plate 9 connected by the intermediate connecting plate 12. A second servo motor 25 is installed on the upper part of the constant force mechanism side plate 9. The output shaft of the second servo motor 25 drives the first synchronous pulley 26. The first synchronous pulley 26 and the second synchronous pulley 28 form a rotational transmission chain via a closed-loop synchronous belt 27. The second synchronous pulley 28 is coaxially fixed with the lead screw 29. The lead screw 29 is screwed together with the nut 30.

[0072] In this embodiment, as Figure 5 As shown in the schematic diagram of the constant force mechanism, the first constant force mechanism 6, the second constant force mechanism 7, and the third constant force mechanism 8 all include a constant force mechanism side plate 9 connected by an intermediate connecting plate 12.

[0073] Specifically, a second servo motor 25 is installed on the upper part of the side plate 9 of the constant force mechanism. The output shaft of the second servo motor 25 drives the first synchronous pulley 26. The first synchronous pulley 26 and the second synchronous pulley 28 form a rotary transmission chain via the closed-loop synchronous belt 27. The second synchronous pulley 28 is fixed coaxially with the lead screw 29. The lead screw 29 is paired with the nut 30 to convert the rotational motion of the lead screw 29 into the axial displacement of the nut 30. The nut 30 drives the moving platform 37 to move, and the elastic potential energy of the preload spring 31 changes accordingly, providing an adjustable force source for the constant force compensation mechanism of the subsequent pulley group, so as to realize the continuous constant force output of the constant force mechanism throughout the entire stroke.

[0074] Furthermore, in the embodiments, the constant force compensation mechanism of the subsequent pulley block may include a pull-line positioning pin 32, a movable pulley 33, a fixed pulley 34, a swing arm 35, and a rubber wheel 38.

[0075] The pull-line positioning pin 32 and the fixed pulley 34 are installed on the side of the moving platform 37. The rubber wheel 38 is installed on the moving end of the swing arm 35. One end of the rigid wire 24 is fastened to the pull-line positioning pin 32, and then winds downward around the movable pulley 33 fixed to the bottom end of the spring 31, and then winds upward around the fixed pulley 34 and is fixed to the rubber wheel 38, forming a closed force transmission path. This ensures that when the swing arm 35 is in different angular positions, the resultant force of the swing arm 35 and the rigid wire 24 in the vertical direction remains constant, achieving constant force compensation and position self-adaptation.

[0076] In this embodiment, the pull wire positioning pin 32 and the fixed pulley 34 are fixed to the side end face of the moving platform 37, the rubber wheel 38 is fixed to the moving end of the swing arm 35, the lower end of the swing arm 35 is fixed to the side plate 9 of the constant force mechanism, and the rigid wire 24 passes through the constant force compensation mechanism of the rear pulley group.

[0077] The rigid wire 24 is fixed on the pull-line positioning pin 32. The rigid wire 24 then winds downwards through the movable pulley 33 fixed to the bottom of the spring 31, and then winds upwards through the fixed pulley 34 and is fixed to the rubber wheel 38, forming a closed force transmission path. This ensures that when the swing arm 35 is in different angular positions, the resultant force of the swing arm 35 and the rigid wire 24 in the vertical direction remains constant.

[0078] Furthermore, in the embodiments, it can be considered that the distance between the hinge point of the swing arm 35 and the fixed pulley 34 and the compression of the spring 31 satisfy the geometric constraint relationship of the pulley group.

[0079] In this embodiment, the rigid wire 24, the movable pulley 33, the fixed pulley 34 and the rubber wheel 38 constitute a pulley group. As can be seen from the geometric structure of the pulley group, the distance between the hinge point of the swing arm 35 and the fixed pulley 34 and the compression of the spring 31 satisfy the geometric constraint relationship.

[0080] Furthermore, in the embodiments, the rubber wheel 38 at the moving end of the swing arm 35 rolls against the sliding pair 36 to convert the arc motion of the swing arm 35 into the vertical motion of the sliding pair 36. The linear output part of the sliding pair 36 is equipped with a load connecting plate 5, and the load connecting plate 5 moves along the slide rail 10 to drive the cooperative platform 1.

[0081] In this embodiment, during the rotation of the swing arm 35, the circular motion of the swing arm 35 is converted into the vertical linear motion of the sliding pair 36 in real time through the rolling contact between the rubber wheel 38 and the sliding pair 36. The sliding pair 36 drives the load connecting plate 5 to slide along the slide rail 10, thereby driving the cooperative platform 1 to move in the vertical direction, so that the cooperative platform 1 obtains the continuous constant force output throughout the entire stroke provided by the constant force mechanism group.

[0082] Furthermore, in the embodiments, the three wheels 13 of the mobile trolley 4 can be arranged in an equilateral triangle.

[0083] In this embodiment, the mobile trolley 4 is equipped with three wheels 13 at the bottom corners and is connected to the plane adjustment module 3 at the top.

[0084] As one implementation method, wheel 13 can be, but is not limited to, Mecanum wheels, steering wheels, casters, and differential wheels. When wheel 13 is a Mecanum wheel, it is driven by a direct-drive motor. Example

[0085] A constant force output control method for a mobile parallel collaborative robot with a constant force mechanism includes the following steps:

[0086] Step 1: Convert the rotational motion of the lead screw 29 into the axial displacement of the nut 30, which drives the moving platform 37 to pre-compress the spring 31, thereby adjusting the pre-compression of the spring 31.

[0087] Step 2: When the swing arm 35 rotates around its hinge point, the elastic force of the spring 31 is transmitted to the swing arm 35 through the rigid wire 24, which passes through the movable pulley 33 and the fixed pulley 34 in sequence.

[0088] Step 3: Using the geometric constraints determined by the pulley system's geometry, and combining them with the force balance equations, the output force of the constant force mechanism group 2 is kept constant.

[0089] Step 4: Implement gravity adaptive compensation throughout the entire vertical movement of the collaborative platform 1.

[0090] Working principle:

[0091] like Figure 6 As shown, the principle by which the constant force mechanism achieves constant force output is as follows:

[0092] When the swing arm 35 rotates around its hinge point, the elastic force of the spring 31 is dissipated through the pulley system consisting of the rigid wire 24, the movable pulley 33, the fixed pulley 34, and the rubber wheel 38. The signal is transferred to the swing arm at 35 degrees.

[0093] Based on the relationship between force equilibrium and geometric constraints, the following can be derived:

[0094] Force balance equation: When the swing arm 35 is at any angle, the tension of the rigid wire 24 With the output force of the mechanism Satisfying the torque balance condition:

[0095] ;

[0096] in The angle between the swing arm (35°) and the vertical direction is... The angle between the rigid wire 24 and the swing arm 35 is the angle between them.

[0097] Geometric constraints: Based on the geometry of the pulley system, the distance between the hinge point of the swing arm 35 and the fixed pulley 34 is... Compression of spring 31 Satisfy geometric constraints:

[0098] ;

[0099] Derivation of constant force output: Elastic force of spring 31 for ,in Let be the spring constant. By combining the force equilibrium and geometric constraint equations, the angle variable can be eliminated. and The output force of the mechanism is obtained. The expression:

[0100] ;

[0101] From the above formula, we can see that the output force of the constant force mechanism is... Only with the spring constant Distance from fixed components Related. After the pre-compression of the spring 31 by the lead screw 29 is adjusted to a certain fixed value, and All of these are constants, so no matter how the angle between the swing arm 35 and the rigid wire 24 changes, the system output force remains constant, thus achieving constant force output and gravity adaptive compensation throughout the entire stroke.

[0102] Application Example 1:

[0103] This application example further illustrates Embodiment 1 and Embodiment 2, as detailed below:

[0104] like Figure 7 As shown, a human and four mobile parallel collaborative robots with constant force mechanisms work together to transport a large steel frame. This application example is based on the basic design concept of a high-load, high-precision mobile positioning robot, and integrates a constant force mechanism and a multi-machine collaborative control strategy to achieve precise transfer and attitude adjustment of the large steel frame under light manual control, verifying the practicality and flexibility of this type of mobile robot in multi-machine collaborative heavy load transport scenarios.

[0105] The steel frame to be moved is an H-beam steel frame for industrial plants, with overall dimensions of 8m×3m×2m and an overall weight of 5.6t. The center of gravity is located at the geometric center of the steel frame. Four standardized connection and lifting points are arranged at the bottom of the steel frame, located at the four corners of the bottom surface of the steel frame, for connecting and fixing with the moving platform of the mobile parallel collaborative robot.

[0106] The experiment employed four identical mobile parallel collaborative robots with constant force mechanisms. Each robot was optimized based on the aforementioned high-load, high-precision mobile positioning robot architecture. Its planar adjustment module possessed three degrees of freedom: X-axis and Y-axis translation, and rotation around the Z-axis. Each robot had a rated load capacity of 2 tons and an end-effector positioning accuracy of ±0.1 mm. The constant force mechanism, integrated into the planar adjustment module, employed an elastically damped constant force structure, capable of outputting an adjustable constant force of 0-500 N. This enabled flexible force control between the robot and the steel frame, avoiding stress concentration from hard contact. The mobile trolley used Mecanum wheels, with a maximum travel speed of 0.5 m / s. Equipped with a multi-robot collaborative communication module, it supported the synchronization of pose and force control information across the four robots, with a synchronization delay ≤10 ms. The overall center of gravity was 0.3 m above the ground, meeting the stability requirements for low-altitude operation. A small manual force was applied directly to the steel frame; this force was converted into a speed command and sent to the multi-robot collaborative control system, thus achieving a manually guided operation mode.

[0107] The test site is a flat cement floor in an industrial plant. The transfer path is 50m long and includes a straight section, a 90° turn section and a precise docking station at the end point. The docking accuracy requirement is ±1mm.

[0108] Two core test scenarios were set up: straight-line transport and precise docking at a turn. The straight-line transport scenario required a human to apply a horizontal force of ≤50N to the steel frame and guide four robots to work together to move the steel frame in a straight line for 50m. The synchronization of the positions and postures of the multiple robots, the stability of the steel frame's posture, and the magnitude of the human operating force were recorded during the transport process.

[0109] The precise docking condition during the turn requires manual guidance of the steel frame to complete a 90° turn, followed by precise positioning and docking at the final docking station. The collaborative attitude adjustment capability of multiple machines during the turn, the attitude compensation accuracy during the docking process, and the final docking error are recorded.

[0110] Multi-machine collaborative control is based on the pose acquisition information of 4 robots, establishes a multi-machine global coordinate system, and adopts a master-slave collaborative control strategy. One robot is selected as the master and the other 3 are slaves. The slaves track the pose and movement speed of the master in real time. At the same time, combined with the force feedback information of the constant force mechanism, the actions of the parallel mechanism of each robot are dynamically adjusted to ensure that the steel frame is always in a horizontal posture and avoid local stress overload.

[0111] Before the experiment began, the four mobile parallel collaborative robots were connected and fixed to the four suspension points on the bottom of the steel frame. The multi-machine collaborative control system was started, and the global coordinate system calibration of the multi-machine was completed. Through the fine adjustment of the parallel mechanism of each machine, the initial posture of the steel frame was kept horizontal (the horizontality error ≤ 0.05°). At the same time, the constant force mechanism was adjusted and the output constant force was set to 200N to ensure the flexible connection between the robot and the steel frame.

[0112] Subsequently, a straight-line transport operation was performed. The operator directly applied a horizontal thrust to one side of the steel frame (the measured maximum thrust was 45N, and the average thrust was 28N). This force was converted into a travel speed command of 0.2m / s and sent to the host. The slave robot synchronously tracked the movement of the host. During the transport process, if the steel frame deviated in posture (the deviation was greater than 0.1°), the multi-machine collaborative control system would drive the parallel mechanism of the corresponding robot to perform real-time posture compensation until the steel frame returned to horizontal.

[0113] After completing the straight-line transfer, the robot performs a precise turning docking operation. The operator applies a lateral force (maximum measured 35N) to the steel frame to guide the robot to complete a 90° turn. During the turn, multiple robots dynamically adjust their speed and steering angle according to the turning radius. At the same time, the parallel mechanism adjusts the posture of the steel frame to ensure that the steel frame does not scrape or tilt during the turn.

[0114] After reaching the docking station, the robot completes coarse positioning, acquires the pose error between the steel frame and the docking station through pose acquisition, feeds the error information back to the parallel mechanism of each robot, performs joint pose compensation, locks the robot brake after compensation, and completes precise docking.

[0115] Throughout the experiment, the robot's control system collected data in real time, including multi-machine pose, travel speed, constant force mechanism output force, and steel frame posture. At the same time, it recorded key indicators such as manual operation force, transfer time, and docking error.

[0116] This experiment was repeated three times, and the average of the three tests was taken as the final result. The core experimental data are as follows:

[0117] Under the linear transport condition, the maximum manual operating force is 45N, the average operating force is 28N, the multi-machine position synchronization error is ±0.08mm, the maximum steel frame attitude offset is 0.04°, the average linear transport speed is 0.18m / s, and the total time for a single operation is 280s. Under the turning precision docking condition, the maximum manual operating force is 35N (turning) / 40N (docking guidance), the average operating force is 25N, the multi-machine position synchronization error is ±0.10mm, the maximum steel frame attitude offset is 0.07° (turning process), the turning radius deviation is ±0.05m, the final docking position error is ±0.08mm in the X direction and ±0.09mm in the Y direction, the final docking rotation error (around Z) is ±0.03°, and the total time for a single operation is 350s.

[0118] The test results show that the maximum manual operating force during the test was ≤45N, which is much smaller than the overall inertial force of the steel frame. This indicates that the mobile parallel collaborative robot with constant force mechanism effectively offsets the large load inertia of the steel frame, realizes the operation mode of manual micro-force guidance and robot main load bearing, and greatly reduces the intensity of manual operation.

[0119] The multi-machine pose synchronization error is ≤ ±0.10mm, and the maximum deviation of the steel frame posture is ≤0.07°, indicating that the multi-machine collaborative control system can achieve precise synchronous movement of 4 robots. Combined with the real-time pose compensation capability of the parallel mechanism, it ensures the posture stability of the heavy-load steel frame during the transfer process and avoids local stress overload or steel frame damage caused by posture deviation.

[0120] The positional error of the final docking station is ≤ ±0.09mm, and the rotational error is ≤ ±0.03°, which is far higher than the ±1mm docking accuracy requirement set in the experiment. This verifies the high-precision positioning capability of this type of robot in multi-robot collaborative scenarios and meets the precise docking requirements of large steel frames. The elastic damping constant force mechanism realizes the flexible connection between the robot and the steel frame. No hard contact stress concentration phenomenon occurred during the experiment, which effectively protects the connection structure between the steel frame and the robot and improves the safety of the operation.

Claims

1. A mobile parallel collaborative robot with a constant force mechanism, characterized in that: The system includes a mobile trolley (4), on which a plane adjustment module (3) is installed. The top of the plane adjustment module (3) is connected to an intermediate connecting plate (12). A constant force mechanism group (2) is installed on the intermediate connecting plate (12). A load connecting plate (5) is installed on the side of the constant force mechanism group (2). A cooperative platform (1) is installed on the load connecting plate (5). The constant force mechanism group (2) includes a spring (31) and a rear pulley group constant force compensation mechanism. The rear pulley group constant force compensation mechanism is used to keep the elastic potential energy output by the spring (31) constant throughout the entire stroke of the cooperative platform (1) moving in the vertical direction. The constant force compensation mechanism of the rear pulley block is composed of a pull-line positioning pin (32), a movable pulley (33), a fixed pulley (34), a swing arm (35), and a rubber wheel (38); The pull wire positioning pin (32) and the fixed pulley (34) are installed on the side of the moving platform (37), and the rubber wheel (38) is installed on the moving end of the swing arm (35). One end of the rigid wire (24) is fastened to the pull wire positioning pin (32), and it goes down through the movable pulley (33) fixed to the bottom end of the spring (31), and then goes up through the fixed pulley (34) and is fixed to the rubber wheel (38), forming a closed force transmission path. When the swing arm (35) is in different angle positions, the resultant force of the swing arm (35) and the rigid wire (24) in the vertical direction remains constant. When the constant force compensation mechanism of the rear pulley group moves along the Z direction, it pulls the rigid wire (24) to drive the spring (31) to produce compression or extension deformation. The shaft of the movable pulley (33) moves synchronously with the deformation of the spring (31) to achieve constant force compensation and position self-adaptation.

2. The mobile parallel collaborative robot with a constant force mechanism according to claim 1, characterized in that: The planar adjustment module (3) includes a planar branch group installed in the longitudinal space between the intermediate connecting plate (12) and the carrier vehicle body (17). The planar branch group includes a first branch (14), a second branch (15) and a third branch (16), and the first branch (14), the second branch (15) and the third branch (16) have the same structure from the fixed side to the output side.

3. A mobile parallel collaborative robot with a constant force mechanism according to claim 2, characterized in that: The first branch (14), the second branch (15), and the third branch (16) all include a first servo motor (19). A first connecting rod (20) is installed on the rotation output part of the first servo motor (19). A first rotating joint (21) is installed at the other end of the first connecting rod (20). A second connecting rod (22) is installed on the side wall of the rotation output part of the first rotating joint (21). A second rotating joint (23) is installed at the other end of the second connecting rod (22). The top of the second rotating joint (23) is connected to the intermediate connecting plate (12).

4. A mobile parallel collaborative robot with a constant force mechanism according to claim 1, characterized in that: The constant force mechanism group (2) includes a first constant force mechanism (6), a second constant force mechanism (7) and a third constant force mechanism (8), and the upper part of the three is connected to the collaborative platform (1) through a load connecting plate (5), and the lower part is connected to the plane adjustment module (3) through an intermediate connecting plate (12).

5. A mobile parallel collaborative robot with a constant force mechanism according to claim 4, characterized in that: The first constant force mechanism (6), the second constant force mechanism (7) and the third constant force mechanism (8) all include a lead screw (29) and a nut (30) that cooperates with it. The nut (30) is fixed on the moving platform (37). One end of the spring (31) is fixed to the moving platform (37) and the other end is connected to the movable pulley (33).

6. A mobile parallel collaborative robot with a constant force mechanism according to claim 5, characterized in that: The first constant force mechanism (6), the second constant force mechanism (7), and the third constant force mechanism (8) all include a constant force mechanism side plate (9) connected by the intermediate connecting plate (12). A second servo motor (25) is installed on the upper part of the constant force mechanism side plate (9). The output shaft of the second servo motor (25) drives the first synchronous pulley (26). The first synchronous pulley (26) and the second synchronous pulley (28) form a rotation transmission chain through the closed-loop synchronous belt (27). The second synchronous pulley (28) is coaxially fixed with the lead screw (29). The lead screw (29) is screwed together with the nut (30).

7. A mobile parallel collaborative robot with a constant force mechanism according to claim 1, characterized in that: The distance between the hinge point of the swing arm (35) and the fixed pulley (34) and the compression of the spring (31) satisfy the geometric constraint relationship of the pulley group.

8. A mobile parallel collaborative robot with a constant force mechanism according to claim 1, characterized in that: The rubber wheel (38) at the moving end of the swing arm (35) rolls against the sliding pair (36) to convert the arc motion of the swing arm (35) into the vertical motion of the sliding pair (36). The linear output part of the sliding pair (36) is equipped with a load connecting plate (5), and the load connecting plate (5) moves along the slide rail (10) to drive the cooperative platform (1).

9. A constant force output control method for a mobile parallel collaborative robot with a constant force mechanism as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Convert the rotational motion of the lead screw (29) into the axial displacement of the nut (30), which drives the moving platform (37) to preload the spring (31), thereby adjusting the pre-compression of the spring (31). Step 2: When the swing arm (35) rotates around its hinge point, the elastic force of the spring (31) is transmitted to the swing arm (35) through the rigid wire (24) passing through the movable pulley (33) and the fixed pulley (34) in sequence. Step 3: Using the geometric constraints determined by the pulley system's geometry, combined with the force balance equation, the output force of the constant force mechanism (2) is kept constant; Step 4: Implement gravity adaptive compensation throughout the entire vertical movement of the collaborative platform (1).

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