A Mecanum wheel with vibration damping function

Abstract

This invention relates to a Mecanum wheel with vibration damping function, comprising a rim for mounting a double-layer roller assembly, the rim being mounted on a hub. The rim includes parallel inner roller mounting frames, middle roller mounting frames, and outer roller mounting frames. Multiple rollers are evenly distributed circumferentially between the inner and middle roller mounting frames to form an inner roller assembly, and multiple rollers are evenly distributed circumferentially between the middle and outer roller mounting frames to form an outer roller assembly. Each roller has an elastomer layer on its outer periphery. This invention can eliminate vibrations caused by structural problems inherent in the Mecanum wheel itself.

Description

Technical Field

[0001] This invention relates to the field of Mecanum wheel vibration reduction technology, and specifically to a Mecanum wheel with vibration damping function. Background Technology

[0002] A Mecanum wheel is an omnidirectional, wheel-like structure based on the principle of a central roller. It consists of a driving wheel hub and driven rollers, with the rollers evenly distributed around the hub at a certain angle. The hub is driven by a motor system, while the rollers themselves do not have a driving function. By carefully designing the roller surface, the outline of the Mecanum wheel can approximate a complete circle, ensuring continuous contact between the rollers and the ground. However, during the periods when the rollers alternately touch the ground, the contact points are not actually continuous. This discontinuous contact leads to vertical vibration of the Mecanum wheel system. The different positions of each Mecanum wheel cause random vibrations in the moving platform. When the moving platform is used for heavy-duty transport, the impact of this vibration is amplified, severely affecting the equipment's usability. Currently, there is little research addressing this problem, with most studies focusing on designing shock absorbers to avoid this situation. However, shock absorbers have strict requirements regarding load-bearing capacity, which significantly limits the application scenarios of Mecanum wheels. When Mecanum wheels are used for heavy-duty transport, vibration not only affects the vehicle's positioning accuracy but also poses safety hazards to other parts of the vehicle's structure. Summary of the Invention

[0003] The purpose of this invention is to provide a Mecanum wheel with vibration damping function to eliminate vibrations caused by structural problems of the Mecanum wheel itself.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a Mecanum wheel with vibration damping function, comprising a rim for mounting a double-layer roller assembly, the rim being mounted on a hub, the rim comprising an inner roller mounting frame, a middle roller mounting frame, and an outer roller mounting frame arranged in parallel, wherein multiple rollers are evenly distributed circumferentially between the inner roller mounting frame and the middle roller mounting frame to form an inner roller assembly, and multiple rollers are evenly distributed circumferentially between the middle roller mounting frame and the outer roller mounting frame to form an outer roller assembly, wherein each roller has an elastomer layer on its outer periphery.

[0005] Furthermore, the inner roller mounting frame has n roller shaft mounting holes evenly arranged around its periphery; the outer roller mounting frame has n roller shaft mounting holes evenly arranged around its periphery; the middle roller mounting frame has 2n roller shaft mounting holes evenly arranged around its periphery, wherein n roller shaft mounting holes face inward and correspond to the roller shaft mounting holes on the inner roller mounting frame, for mounting the inner rollers, and the other n roller shaft mounting holes face outward and correspond to the roller shaft mounting holes on the outer roller mounting frame, for mounting the outer rollers; the two ends of the roller shaft of each roller are respectively fixedly connected to the corresponding roller shaft mounting holes of two adjacent roller mounting frames.

[0006] Furthermore, the axis of each installed roller is at a 45° angle to the axis of the hub; the central angle between two adjacent inner roller axes is 360 / n degrees, the central angle between two adjacent outer roller axes is 360 / n degrees, and the central angle between adjacent inner roller axes and outer roller axes is 180 / n degrees.

[0007] Furthermore, the inner roller mounting frame has 8 roller shaft mounting holes evenly arranged around its periphery, the outer roller mounting frame has 8 roller shaft mounting holes evenly arranged around its periphery, and the middle roller mounting frame has 16 roller shaft mounting holes evenly arranged around its periphery; the central angle between the roller shaft axes of two adjacent inner rollers is 45°, the central angle between the roller shaft axes of two adjacent outer rollers is 45°, and the central angle between the roller shaft axes of adjacent inner rollers and the roller shaft axes of outer rollers is 22.5°.

[0008] Furthermore, the roller includes a roller shaft, bearings, a roller steel core, and an elastomer layer. The roller steel core is sleeved on the outside of the roller shaft, and its two ends are rotatably connected to the roller shaft through bearings. The elastomer layer covers the outer periphery of the roller steel core.

[0009] Furthermore, the roller also includes a bushing, a bearing retaining ring, and an elastic retaining ring. The bearings include a thrust bearing and a needle roller bearing. The roller shaft is a stepped shaft with a stepped protrusion in the middle section. The bushing is installed on the outside of the stepped protrusion. Needle roller bearings are installed on the left and right ends of the stepped protrusion and the bushing to bear radial loads and perform radial positioning. A thrust bearing is installed beside the needle roller bearing to bear axial loads. The left and right ends of the roller core are both installed on the needle roller bearing and the thrust bearing, and there is a gap between the roller core and the bushing to reduce wear. A bearing retaining ring is installed beside the thrust bearing to limit the axial position of the bearing on the roller shaft. An elastic retaining ring is installed beside the bearing retaining ring to fix the various components.

[0010] Furthermore, the thickness of the elastomeric layer of the roller varies on the cross-section at different positions of the roller, so that the contact area between the Mecanum wheel and the ground is the same during rolling and the rolling radius of the Mecanum wheel is a constant value.

[0011] Furthermore, the outer surface of the roller has a roller generatrix that meets the tangency requirement, and the radius of curvature of the outer surface of the roller is the same as that of the contact point with the ground.

[0012] Furthermore, to ensure that the radius of curvature of the roller's outer surface at the contact point with the ground is the same, a method of vector projection is used to project the roller's axis onto the cylindrical surface of the design circle, making the roller's outer surface tangent to the cylindrical surface containing the design circle everywhere; the generatrix equation of the roller is constructed as follows:

[0013]

[0014] In this system, a rectangular coordinate system is established with the cross-section of the hub where the convergence point A at one end of the roller generatrix is ​​located as the xoy plane. The intersection of the xoy plane and the hub axis is the center point O. The line connecting OA is the x-axis, and the direction of the hub axis towards the other convergence point B of the roller generatrix is ​​the z-axis. x, y, and z represent the x, y, and z coordinates of any point F on the roller generatrix, respectively, and θ represents the angle between any point F on the roller generatrix and the x-axis, with the value of θ ranging from [value missing]. D is the minimum distance between the roller axis and the hub axis; R is the hub radius.

[0015] Furthermore, the elastomer layer is made of a hyperelastic material.

[0016] Compared with existing technologies, the present invention has the following advantages: The present invention provides a Mecanum wheel with vibration damping function. This Mecanum wheel, through an innovative double-layer roller assembly structure design, ensures that the grounding area at the grounding point of the grounding roller is the same and sufficiently large during rolling. Simultaneously, the compression of the elastomer layer ensures a consistent rolling radius, thus eliminating vibrations caused by changes in grounding area and rolling radius during the Mecanum wheel's rolling process. This solves the vibration problem caused by structural defects in the Mecanum wheel itself. Therefore, the present invention has strong practicality and broad application prospects. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural diagram of the Mecanum wheel according to an embodiment of the present invention;

[0018] Figure 2 for Figure 1 The front view of the Mecanum wheel is shown below;

[0019] Figure 3 for Figure 1 The side view of the Mecanum wheel shown;

[0020] Figure 4 This is a schematic diagram of the connection structure between the roller shaft and the wheel rim in an embodiment of the present invention;

[0021] Figure 5This is a schematic diagram of the internal structure of the roller in an embodiment of the present invention;

[0022] Figure 6 This is a schematic diagram of the Mecanum wheel assembly in an embodiment of the present invention;

[0023] Figure 7 This is a schematic diagram of the mobile platform structure in an embodiment of the present invention;

[0024] In the diagram: 1-Roller; 2-Roller shaft; 3-Inner roller mounting bracket; 4-Middle roller mounting bracket; 5-Outer roller mounting bracket; 6-Hub; 21-Shaft bolt; 22-Shaft washer; 11-Elastomer layer; 12-Roller steel core; 13-Elastic retaining ring; 14-Bearing retaining ring; 15-Thrust bearing; 16-Needle roller bearing; 17-Shaft sleeve; 100-Mecanum wheel; 101-Motor; 102-Coupling; 103-Reducer; 104-Suspension; 200-Mecanum wheel set; 300-Platform; 400-Battery box. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0028] This invention provides a Mecanum wheel with vibration damping function. The Mecanum wheel features a double-layer roller design, with a variable-thickness elastomer layer covering the rollers. The double-layer roller design arranges two rows of rollers along the Mecanum wheel's axial direction, with the two rows differing by a certain angle. This ensures that when one layer of rollers is at its junction, the other layer is precisely in the middle, thus solving the Mecanum wheel vibration caused by roller transitions during rolling. The outer surface of the rollers with the variable-thickness elastomer layer forms an envelope surface centered on the hub axis. Simultaneously, the elastomer layer is thicker at the smaller circumferential radii on both sides of the roller and thinner at the larger circumferential radii in the middle of the roller, achieving equal ground contact area and rolling radius at different positions during rolling. Therefore, this invention can eliminate vibrations caused by structural problems inherent in the Mecanum wheel itself.

[0029] like Figure 1-5 As shown, the Mecanum wheel with vibration damping function provided in this embodiment includes a rim for mounting a double-layer roller assembly. The rim is bolted to a hub 6. The rim includes an inner roller mounting frame 3, a middle roller mounting frame 4, and an outer roller mounting frame 5 arranged in parallel. Multiple rollers 1 are evenly distributed circumferentially between the inner roller mounting frame 3 and the middle roller mounting frame 4 to form an inner roller assembly. Multiple rollers 1 are evenly distributed circumferentially between the middle roller mounting frame 4 and the outer roller mounting frame 5 to form an outer roller assembly. Each roller 1 has a variable-thickness elastomer layer 11 on its outer periphery.

[0030] The inner roller mounting frame 3 has n roller shaft mounting holes evenly arranged around its periphery; the outer roller mounting frame 5 has n roller shaft mounting holes evenly arranged around its periphery; the middle roller mounting frame 4 has 2n roller shaft mounting holes evenly arranged around its periphery, wherein n roller shaft mounting holes face inward and correspond to the roller shaft mounting holes on the inner roller mounting frame, for mounting the inner rollers, and the other n roller shaft mounting holes face outward and correspond to the roller shaft mounting holes on the outer roller mounting frame, for mounting the outer rollers; the two ends of the roller shaft 2 of each roller are respectively fixedly connected to the corresponding roller shaft mounting holes of two adjacent roller mounting frames by threaded fasteners. Figure 4 As shown, the roller shaft 2 has threads at both ends, which pass through the outer roller mounting hole and the middle roller mounting hole, and the inner roller mounting hole and the middle roller mounting hole, respectively. The roller shaft 2 is connected to the roller mounting frame by bolts 21, and a washer 22 is used between the bolts 21 and the roller mounting frame to prevent loosening.

[0031] Each installed roller axis is at a 45° angle to the hub axis; the central angle between two adjacent inner roller axes is 360 / n degrees, the central angle between two adjacent outer roller axes is 360 / n degrees, and the central angle between adjacent inner roller axes and outer roller axes is 180 / n degrees.

[0032] In this embodiment, the inner roller mounting frame has 8 roller shaft mounting holes evenly distributed around its periphery, the outer roller mounting frame has 8 roller shaft mounting holes evenly distributed around its periphery, and the middle roller mounting frame has 16 roller shaft mounting holes evenly distributed around its periphery. The central angle between the roller shaft axes of two adjacent inner rollers is 45°, the central angle between the roller shaft axes of two adjacent outer rollers is 45°, and the central angle between the roller shaft axes of adjacent inner rollers and outer rollers is 22.5°. This angle design ensures that when one layer of rollers is in the transition position, the other layer of rollers is exactly in the middle, thus solving the problem of Mecanum wheel vibration caused by roller transition during the rolling process.

[0033] It should be noted that the number of rollers in a single-layer roller assembly is not limited to eight and should be selected appropriately based on the actual situation. However, the angle between the inner and outer rollers should be ensured so that when one layer of rollers is at the junction, the other layer of rollers is exactly in the middle, thereby solving the vibration of the Mecanum wheel caused by roller transition during the rolling process.

[0034] In this embodiment, the roller 1 includes a roller shaft 2, bearings, a roller steel core 12, an elastomer layer 11, a bushing 17, a bearing retaining ring 14, and an elastic retaining ring 13. The bearings specifically include a thrust bearing 15 and a needle roller bearing 16. The roller steel core 12 is sleeved on the outside of the roller shaft 2, and its two ends are rotatably connected to the roller shaft through bearings. The elastomer layer covers the outer periphery of the roller steel core, and the inner surface of the elastomer layer is in close contact with the outer surface of the roller steel core. The roller shaft 2 is a stepped shaft with a stepped protrusion in the middle section. The bushing 17 is installed on the outside of the stepped protrusion. The left and right ends of the stepped protrusion and the bushing are respectively equipped with needle roller bearings 16 to bear radial load and perform radial positioning. The thrust bearing 15 is installed on the side of the needle roller bearing 16 to bear axial load. The left and right ends of the roller steel core 12 are both installed on the needle roller bearing 16 and the thrust bearing 15, and there is a gap between the roller steel core 12 and the bushing 17 to reduce wear. The bearing retainer ring 14 is installed on the side of the thrust bearing 15 to limit the axial position of the bearing on the roller shaft. The elastic retainer ring 13 is installed on the side of the bearing retainer ring 14 to fix the various components.

[0035] The thickness of the elastomer layer 11 of the roller 1 varies on different cross-sectional positions of the roller. The thickness of the elastomer layer is determined by the roller radius and the number of rollers at the ground contact position. The elastomer layer is thicker at the smaller cross-sectional radius positions on both sides of the roller and thinner at the larger cross-sectional radius position in the middle of the roller. This ensures that the contact area between the Mecanum wheel and the ground is the same during the rolling process and that the rolling radius of the Mecanum wheel is a constant value. This solves the problem of vibration of the Mecanum wheel caused by the different ground contact area and compression of the roller elastomer layer at different circumferential cross-sectional positions.

[0036] The outer surface of the roller 1 has a roller generatrix that meets the tangency requirement, and the radius of curvature of the outer surface of the roller is the same as that of the contact point with the ground.

[0037] The envelope formed by the outer surface of the roller is a cylindrical surface centered on the hub axis. To ensure that the radius of curvature at the contact point between the roller's outer surface and the ground is the same, a vector projection method is used to project the roller axis onto the cylindrical surface of the design circle, making the roller's outer surface tangent to the cylindrical surface containing the design circle at every point. To simplify the design process, based on the roller's formation principle, the generatrix equation of the roller is constructed as follows:

[0038]

[0039] In this system, a rectangular coordinate system is established with the cross-section of the hub where the convergence point A at one end of the roller generatrix is ​​located as the xoy plane. The intersection of the xoy plane and the hub axis is the center point O. The line connecting OA is the x-axis, and the direction of the hub axis towards the other convergence point B of the roller generatrix is ​​the z-axis. x, y, and z represent the x, y, and z coordinates of any point F on the roller generatrix, respectively, and θ represents the angle between any point F on the roller generatrix and the x-axis, with the value of θ ranging from [value missing]. D is the minimum distance between the roller axis and the hub axis; R is the hub radius.

[0040] The length of the rollers can be determined according to actual needs, and the rollers have different circumferential radii, resulting in variations in the ground contact area. Shorter roller radii provide a larger ground contact area; therefore, the ground contact area of ​​the rollers should be designed rationally to ensure the stability of the ground contact area during rolling.

[0041] The elastomer layer 11 is made of a hyperelastic material. This hyperelastic material exhibits the properties of undergoing very large deformations under external forces, returning to its initial state after the force is removed, and being incompressible. Different materials should be selected to provide greater cushioning and shock absorption as needed, and to provide additional stiffness and support during large deformations or to maintain high stiffness and rigidity within a small deformation range, while simultaneously maintaining a relatively gentle hardening effect during large deformations.

[0042] Figure 6 This illustration shows a complete Mecanum wheel assembly based on the Mecanum wheel provided in this embodiment. The Mecanum wheel assembly consists of a motor 101, a coupling 102, a reducer 103, a Mecanum wheel 100, and a suspension 104. The motor 101 provides power, which is transmitted to the reducer 103 via the coupling 102. After reduction, the power is transmitted to the Mecanum wheel 100, which has a variable-thickness elastic coating and double-layer rollers. A connecting plate connects the suspension to the reducer via bolts; bolts are provided on the upper surface of the suspension for connecting to the platform 300.

[0043] Figure 7 A mobile platform 300 is shown, implemented using the Mecanum wheelset 200 provided in this embodiment. The mobile platform 300 is rectangular, and its lower surface has bolt holes corresponding to the upper surface of the suspension, through which the Mecanum wheelset 200 is connected.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A Mecanum wheel with vibration damping function, characterized in that, The device includes a rim for mounting a double-layer roller assembly, the rim being mounted on a hub. The rim includes an inner roller mounting frame, a middle roller mounting frame, and an outer roller mounting frame arranged in parallel. Multiple rollers are evenly distributed circumferentially between the inner and middle roller mounting frames to form an inner roller assembly. Multiple rollers are evenly distributed circumferentially between the middle and outer roller mounting frames to form an outer roller assembly. Each roller has an elastomer layer on its outer periphery. Each installed roller axis is at a 45° angle to the hub axis; the central angle between two adjacent inner roller axes is 360 / n degrees, the central angle between two adjacent outer roller axes is 360 / n degrees, and the central angle between adjacent inner roller axes and outer roller axes is 180 / n degrees. The inner roller mounting frame has 8 roller shaft mounting holes evenly distributed around its periphery, the outer roller mounting frame has 8 roller shaft mounting holes evenly distributed around its periphery, and the middle roller mounting frame has 16 roller shaft mounting holes evenly distributed around its periphery. The central angle between the axes of the roller shafts of two adjacent inner rollers is 45°, the central angle between the axes of the roller shafts of two adjacent outer rollers is 45°, and the central angle between the axes of the roller shafts of adjacent inner rollers and the axes of the roller shafts of outer rollers is 22.5°. Eight of the roller shaft mounting holes face inward and correspond to the roller shaft mounting holes on the inner roller mounting frame, and are used to install the inner rollers. The other eight roller shaft mounting holes face outward and correspond to the roller shaft mounting holes on the outer roller mounting frame, and are used to install the outer rollers. The two ends of the roller shaft of each roller are fixedly connected to the corresponding roller shaft mounting holes of two adjacent roller mounting frames. The outer surface of the roller has a generatrix that meets the tangency requirement, and the radius of curvature of the outer surface of the roller is the same as that of the contact point with the ground. To ensure that the radius of curvature of the outer surface of the roller is the same as that of the contact point with the ground, a vector projection method is used to project the roller axis onto the cylindrical surface of the design circle, so that the outer surface of the roller is tangent to the cylindrical surface of the design circle at every point. The generatrix equation of the roller is constructed as follows: In this system, a rectangular coordinate system is established with the cross-section of the hub where the convergence point A at one end of the roller generatrix is ​​located as the xoy plane. The intersection of the xoy plane and the hub axis is the center point O. The line connecting OA is the x-axis, and the direction of the hub axis toward the other convergence point B of the roller generatrix is ​​the z-axis. x, y, and z represent the x, y, and z coordinates of any point F on the roller generatrix, respectively. This represents the angle between any point F on the roller generatrix and the x-axis. The range of values ​​is ; This is the minimum distance between the roller axis and the hub axis; Where is the hub radius.

2. A Mecanum wheel with vibration damping function according to claim 1, characterized in that, The roller includes a roller shaft, bearings, a roller steel core, and an elastomer layer. The roller steel core is sleeved on the outside of the roller shaft, and its two ends are rotatably connected to the roller shaft through bearings. The elastomer layer covers the outer periphery of the roller steel core.

3. A Mecanum wheel with vibration damping function according to claim 2, characterized in that, The roller also includes a bushing, a bearing retaining ring, and an elastic retaining ring. The bearings include a thrust bearing and a needle roller bearing. The roller shaft is a stepped shaft with a stepped protrusion in the middle section. The bushing is installed on the outside of the stepped protrusion. Needle roller bearings are installed on the left and right ends of the stepped protrusion and the bushing to bear radial loads and provide radial positioning. Thrust bearings are installed beside the needle roller bearings to bear axial loads. The left and right ends of the roller core are both installed on the needle roller bearings and the thrust bearings, and there is a gap between the roller core and the bushing to reduce wear. A bearing retaining ring is installed beside the thrust bearing to limit the axial position of the bearing on the roller shaft. An elastic retaining ring is installed beside the bearing retaining ring to fix the various components.

4. A Mecanum wheel with vibration damping function according to claim 1, characterized in that, The thickness of the elastomer layer of the roller varies on the cross-section at different positions of the roller, so that the contact area between the Mecanum wheel and the ground is the same during rolling and the rolling radius of the Mecanum wheel is a constant value.

5. A Mecanum wheel with vibration damping function according to claim 1, characterized in that, The elastomer layer is made of a hyperelastic material.

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