Crawler suspension assembly for walking robot
By setting a sliding ridge and elastic suspension structure on the inner side of the track, the problem of insufficient adhesion of the track on the outer arch surface is solved, achieving better fit and walking accuracy.
Patent Information
- Application Number
- CN202520541677.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2035-03-26
AI Technical Summary
When existing belt-driven walking robots pass through arched surfaces, the two ends of the track surface are prone to separation, resulting in reduced adhesion and walking accuracy, and posing a risk of slippage.
A raised ridge is provided on the inner side of the track plate. The raised ridge can slide and be locked in the slot of the cantilever bracket. The spring provides elastic lifting force, so that the lower track surface forms an inward arc structure, which enhances the fit with the outer arch walking surface.
It improves the fit and adhesion between the track and the outer arch surface, prevents slippage, and enhances walking accuracy and safety.
Smart Images
Figure CN223891089U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to the field of belt type robot, especially relates to a track suspension assembly for walking robot. BACKGROUND
[0002] The belt type walking robot is a common robot structure, and its walking part is usually composed of a base, a belt wheel and a track, the two ends of the track are tensioned and driven by the belt wheel, and the robot is driven to walk by the friction force generated between the lower track surface of the track and the walking surface. However, the existing belt type walking robot usually has the following problems when passing through the outwardly arched curved surface: because the belt wheels at the two ends of the track are in a tensioned state, the lower track surface of the track has a large tension and is in a straight line shape, when driving on the outwardly arched curved surface, the track surfaces at the two ends of the track have a tendency to separate from the walking surface, that is, the two ends of the track are upwardly curved, so that the adhesion between the lower track surface of the track and the walking surface cannot be guaranteed, the contact area and the friction force are reduced, the driving force and the walking accuracy are affected, and the skidding phenomenon and other dangerous situations are prone to occur.
[0003] In the patent document with the application number "CN2024209472261", a simple robot for rust removal of ship body curved surface with magnetic track is disclosed, which comprises a rack and a control box fixedly arranged on the back of the rack, and a magnetic track mechanism for the rust removal robot to move closely to the ship body curved surface is installed on both sides of the rack. Although the track mechanism is composed of three tensioning wheels and a track assembly, the lower track surface is still tensioned by the two sides of the end portion, and when driving on the outwardly arched walking surface, the two ends of the lower track surface still have a tendency to separate from the walking surface, so that the adhesion is reduced, and the driving force and the walking accuracy are still affected.
[0004] The disclosure of the above background technology is only used to assist in understanding the utility model concept and technical scheme of the utility model, and it does not necessarily belong to the prior art of the present patent application. In the absence of explicit evidence that the above content has been disclosed on the filing date of the present patent application, the above background technology should not be used to evaluate the novelty and inventiveness of the present application. UTILITY MODEL CONTENT
[0005] The utility model aims to provide a track suspension assembly for walking robot, so as to improve the adhesion between the track and the outwardly arched curved surface, ensure strong adhesion, and overcome the defects of poor adhesion and adhesion of the existing robot track mechanism when walking on the outwardly arched curved surface.
[0006] In order to achieve the above object, the utility model provides a track suspension assembly for walking robot, including track and mounting seat, a plurality of rotatable suspension arms are equipped on the mounting seat, the swing end of the suspension arm is in abutment with the inner side of the lower belt surface of the track, and the spring is equipped between the suspension arm and the mounting seat, the inner side of the belt plate of the track is equipped with the ridge, both sides of the ridge are equipped with the recessed clamping groove, the swing end of the suspension arm is equipped with rotatable clamping seat, the bottom of the clamping seat is equipped with the accommodation slot, the accommodation slot is penetrated both ends of the clamping seat, and the ridge can be clamped in the accommodation slot in a slidable mode, both sides of the accommodation slot are equipped with the protruding clamping claw, and the clamping claw is clamped in the clamping groove in a slidable mode.
[0007] Preferably, in the above technical solution, the mounting seat comprises a seat plate and a connecting column, the number of the seat plate is two and the seat plates are arranged in parallel, the number of the connecting column is three or more and both ends of the connecting column are fixedly connected with a seat plate, and a reinforcing plate is further connected between the two seat plates, and a weight-reducing hole is formed in the reinforcing plate.
[0008] Preferably, in the above technical solution, the suspension arm comprises a first suspension arm and a second suspension arm, the number of the first suspension arm is two, the rotating ends of the two first suspension arms are rotatably connected with the seat plates and the rotating axes of the two first suspension arms coincide, and the number of the second suspension arm is an even number and the second suspension arm is symmetrically arranged on both sides of the first suspension arm.
[0009] Preferably, in the above technical solution, a first ear plate is arranged on the seat plate, one end of the first ear plate extends outward in a direction perpendicular to the seat plate and is provided with a first mounting hole and a second mounting hole, a second ear plate extending outward is arranged on the middle part of the first suspension arm, a third mounting hole is formed in the second ear plate, a third ear plate extending outward is arranged on the rotating end of the second suspension arm, a fourth mounting hole is formed in the third ear plate, and both ends of the spring are connected between the first mounting hole and the third mounting hole or between the second mounting hole and the fourth mounting hole.
[0010] Preferably, in the above technical solution, a fourth ear plate and a fifth ear plate are further arranged, one end of the fourth ear plate is fixedly connected with the seat plate, the other end of the fourth ear plate extends outward in a direction perpendicular to the seat plate and is provided with a fifth mounting hole, one end of the fifth ear plate is fixedly connected with the middle part of the first suspension arm, the other end of the fifth ear plate extends outward in a direction perpendicular to the seat plate and is provided with a sixth mounting hole, both ends of the spring can be fixedly connected with the fifth mounting hole and the sixth mounting hole, the distance from the fifth mounting hole to the seat plate is greater than the distance from the first mounting hole and the second mounting hole to the seat plate, and the number of the fourth ear plate is two and the fourth ear plates are symmetrically arranged on both sides of the first ear plate.
[0011] Preferably, in the above technical solution, a sensor support mounting hole is arranged on the seat plate, and the first ear plate and the fourth ear plate are arranged around the periphery of the sensor support mounting hole.
[0012] Preferably, in the above technical solution, one end of the clamping jaw is detachably connected with the clamping seat through a screw, the other end of the clamping jaw is bent towards the gap slot, both ends of the clamping seat are provided with first arc surfaces, both sides of the clamping jaw are provided with second arc surfaces and third arc surfaces, the first arc surfaces and the second arc surfaces face the gap slot, and the third arc surfaces face the inner side of the track plate of the track.
[0013] Preferably, in the above technical solution, the ridge is composed of a support part and a clamping block, one end of the support part is fixedly connected with the inner side of the track plate, the clamping block is fixedly connected with the other end of the support part and is perpendicular to the support part, the edges of the clamping block are all provided with chamfers, the width of the clamping block is greater than the width of the support part, and the bottom of the clamping block and the track plate form the clamping groove.
[0014] Preferably, in the above technical solution, one end of the clamping block is provided with an inwardly recessed notch, the other end of the clamping block is provided with an outwardly protruding protrusion, and the protrusion can be movably clamped in the notch.
[0015] Preferably, in the above technical solution, the other end of the support part is inclined to the front side of one end of the support part, so that the position of the notch corresponds to the position of the rotating shaft of the track link.
[0016] Compared with the prior art, the track suspension assembly for the walking robot has the following beneficial effects:
[0017] 1. The track suspension assembly for the walking robot in the utility model is provided with a ridge on the inner side of the track plate of the track, the ridge can be movably clamped in the gap slot of the swing clamping seat of the cantilever, and a spring is arranged between the swing arm and the clamping seat, so that an upward elastic pulling force can be applied to the middle part of the lower track surface of the track, the lower track surface of the track forms an inwardly recessed arc structure, the walking surface has better adhesion and better adhesion with the outwardly arched walking surface, slipping during walking is prevented, and walking precision and safety are improved.
[0018] 2. The mounting seat of the utility model adopts the lightweight structure design of mutual assembly of the seat plate, the connecting column and the reinforcing plate, and is respectively provided with the second lug plate and the fifth lug plate on the first cantilever, the directions of the fifth lug plate and the second lug plate are opposite, when the sensor mounting hole does not install the sensor, the spring can be installed between the first lug plate and the second lug plate, and the installation position is inward to the spring and has good protective property; when the sensor mounting hole needs to install the sensor, the spring can be installed between the fifth lug plate and the fourth lug plate, so that the sensor can be given way and can be disposed in dislocation with the spring on the second cantileaver.
[0019] 3. The end of the clamping seat and the two sides of the clamping claw are respectively provided with the first arc surface, the second arc surface and the third arc surface, when the ridge passes through the giving way slot, can play a guiding role, and one end of the clamping block in the ridge is provided with a notch and the other end is provided with a protrusion, the protrusion can be clamped in the notch to limit the transverse dislocation between the clamping blocks during track driving, affecting the passability of the ridge in the giving way slot. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 It is the structure diagram of the track suspension assembly of the utility model walking robot.
[0021] Figure 2 It is the structure diagram of the mounting seat.
[0022] Figure 3 It is the structure diagram of the belt plate of the track.
[0023] Figure 4 It is the structure diagram of the clamping seat.
[0024] Figure 5 It is the structure diagram of the first cantilever.
[0025] Figure 6 It is the structure diagram of the second cantilever.
[0026] MAIN REFERENCE NUMERALS EXPLANATION:
[0027] 100 - track, 110 - ridge, 111 - support part, 112 - clamping block, 113 - notch, 114 - protrusion, 120 - clamping slot;
[0028] 200 - mounting seat, 210 - seat plate, 211 - first lug plate, 212 - first mounting hole, 213 - second mounting hole, 220 - connecting column, 230 - reinforcing plate, 240 - weight reduction hole, 250 - fourth lug plate, 251 - fifth mounting hole, 260 - fifth lug plate, 261 - sixth mounting hole, 270 - sensor support mounting hole;
[0029] 300 - first cantilever, 301 - second lug, 302 - third mounting hole, 310 - second cantilever, 311 - third lug, 312 - fourth mounting hole;
[0030] 400 - spring;
[0031] 500 - card seat, 501 - first arc surface, 510 - accommodation slot, 520 - clamping jaw, 521 - second arc surface, 522 - third arc surface. DETAILED DESCRIPTION
[0032] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.
[0033] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "top", "bottom", "top surface", "bottom surface", "inner", "outer", "inner side", "outer side" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.
[0034] In the description of the present application, the meaning of "several" is one or more, the meaning of "multiple" is two or more, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If the terms "first", "second", "third" are described, they are only for the purpose of description and for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of indicated technical features.
[0035] In the description of the utility model, it is necessary to explain, unless another explicit provision and limitation, the term "installation", "connection", "connect", "set" should do broad sense understanding, for example, can be fixed connection, also can be detachable connection, or integrally connected;Can be mechanical connection, also can be electrical connection;Can be directly connected, also can be indirectly connected through the intermediate medium, can be two elements inside the communication。For ordinary skilled in the art, the above-mentioned terms can be understood according to the specific meaning of the utility model in the specific situation。Below, according to the overall structure of the utility model, its embodiment is explained.
[0036] As Figures 1 to 6 The track 100 suspension assembly for the walking robot in the embodiment includes: a track 100, a ridge 110, a support part 111, a clamping block 112, a notched 113, a protruding block 114, a clamping groove 120, a mounting seat 200, a seat plate 210, a first ear plate 211, a first mounting hole 212, a second mounting hole 213, a connecting column 220, a reinforcing plate 230, a weight-reducing hole 240, a fourth ear plate 250, a fifth mounting hole 251, a fifth ear plate 260, a sixth mounting hole 261, a sensor support mounting hole 270, a first cantilever 300, a second ear plate 301, a third mounting hole 302, a second cantilever 310, a third ear plate 311, a fourth mounting hole 312, a spring 400, a clamping seat 500, a first arc surface 501, a give-way slot 510, a clamping jaw 520, a second arc surface 521, and a third arc surface 522.
[0037] The track 100 includes two chains composed of chain links, the two chains are arranged in parallel, and a chain plate is installed between two chain links corresponding in position of the two chains, the track 100 is provided with the ridge 110 on the inner side of the track plate, the two sides of the ridge 110 are provided with the clamping groove 120 recessed inward, so that the cross section becomes a "T" structure;The mounting seat 200 is arranged in the area enclosed by the track 100, a plurality of rotatable cantilevers are installed on the mounting seat 200, a rotatable clamping seat 500 is installed at the swing end of the cantilever, the bottom of the clamping seat 500 is provided with the give-way slot 510, the two ends of the clamping seat 500 are penetrated by the give-way slot 510, and the ridge 110 can be clamped in the give-way slot 510 in a slidable manner, the two sides of the give-way slot 510 are provided with the clamping jaw 520 protruding outward, and the clamping jaw 520 is clamped in the clamping groove 120 in a slidable manner.
[0038] In more detail, the mounting seat 200 comprises seat plates 210 and connecting columns 220, the number of the seat plates 210 is two and they are arranged in parallel, the number of the connecting columns 220 is three or more and both ends of each connecting column are fixedly connected with a seat plate 210, a reinforcing plate 230 is further connected between the two seat plates 210, and the reinforcing plate 230 is provided with weight-reducing holes 240; the cantilever comprises first cantilevers 300 and second cantilevers 310, the number of the first cantilevers 300 is two, the rotating ends of the two first cantilevers 300 are simultaneously rotatably connected with the seat plates 210 and the rotating axes coincide, the number of the second cantilevers 310 is two and they are symmetrically arranged on the two sides of the first cantilevers 300, and the length of the second cantilevers 310 is greater than that of the first cantilevers 300; the seat plates 210 are provided with first ear plates 211, the number of the first ear plates 211 is two and they are arranged side by side at a certain interval, one end of each first ear plate 211 extends outward in a direction perpendicular to the seat plate 210 and is provided with a first mounting hole 212 and a second mounting hole 213; the middle part of each first cantilever 300 is provided with a second ear plate 301 extending outward, the second ear plate 301 is provided with a third mounting hole 302, the distance from the third mounting hole 302 to the seat plate 210 is consistent with that from the first mounting hole 212 to the seat plate 210, the rotating end of each second cantilever 310 is provided with a third ear plate 311 extending outward, the third ear plate 311 is provided with a fourth mounting hole 312, the distance from the fourth mounting hole 312 to the seat plate 210 is consistent with that from the second mounting hole 213 to the seat plate 210, the second ear plates 301 and the third ear plates 311 are parallel to the seat plates 210, and both ends of the spring 400 are connected between the first mounting hole 212 and the third mounting hole 302 or between the second mounting hole 213 and the fourth mounting hole 312.
[0039] In addition, the seat plates 210 are further provided with fourth ear plates 250, and the first cantilevers 300 are further provided with fifth ear plates 260, one end of each fourth ear plate 250 is fixedly connected with a seat plate 210, the other end of each fourth ear plate 250 extends outward in a direction perpendicular to the seat plate 210 and is provided with a fifth mounting hole 251, one end of each fifth ear plate 260 is fixedly connected with the middle part of a first cantilever 300, the other end of each fifth ear plate 260 extends outward in a direction perpendicular to the seat plate 210 and is provided with a sixth mounting hole 261, both ends of the spring 400 can be fixedly connected with the fifth mounting hole 251 and the sixth mounting hole 261, the distance from the fifth mounting hole 251 to the seat plate 210 is greater than that from the first mounting hole 212 and the second mounting hole 213 to the seat plate 210, the number of the fourth ear plates 250 is two and they are symmetrically arranged on the two sides of the first ear plates 211, and the outer sides of the two fourth ear plates 250 are downwardly deflected; the seat plates 210 are provided with sensor bracket mounting holes 270, the first ear plates 211 and the fourth ear plates 250 are arranged around the periphery of the sensor bracket mounting holes 270, and the rotating connection ends of the first cantilevers 300 and the second cantilevers 310 are located below the sensor mounting holes.
[0040] More specifically, one end of the claw 520 is detachably fixed to the bottom of the card holder 500 by a screw, and the other end of the claw 520 is bent into an "L" shape towards the relief groove 510. The two claws 520 and the bottom of the card holder 500 form the relief groove 510. The card holder 500 has a first arc surface 501 at both ends, and the claws 520 have a second arc surface 521 and a third arc surface 522 on both sides. The first arc surface 501 and the second arc surface 521 face the relief groove 510, and the third arc surface 522 faces the relief groove 510. The arc surface 522 faces the inner side of the track plate of the track 100; the ridge 110 is composed of a support part 111 and a locking block 112. One end of the support part 111 is fixedly connected to the inner side of the track plate, and the locking block 112 is fixedly connected to the other end of the support part 111 and is perpendicular to the support part 111. The edges of the locking block 112 are all chamfered. The width of the locking block 112 is greater than the width of the support part 111, so that the cross-section of the ridge 110 forms a "T" shaped structure. The bottom of the locking block 112 forms a locking groove 120 between the track plate of the track 100.
[0041] In addition, one end of the locking block 112 is provided with an inwardly recessed notch 113, and the other end of the locking block 112 is provided with an outwardly protruding protrusion 114. The width of the notch 113 is consistent with the width of the protrusion 114, so that the protrusion 114 can be locked in the notch 113 and can rotate and slide. The other end of the support part 111 is inclined to the front side of one end of the support part 111, so that the side cross section of the support part 111 forms a parallelogram structure, which makes the position of the notch 113 correspond to the position of the rotation axis of the track link 100.
[0042] Next, the working principle of the track 100 suspension assembly for a walking robot in this embodiment will be described in detail to enable those skilled in the art to better understand this utility model:
[0043] The mounting base 200 is installed on the robot's chassis and located in the area between the drive wheels at both ends of the track 100. A rotatable rotating arm is provided on the mounting base 200. The rotating end of the rotating arm has a retaining groove 510 and a claw 520 on its retaining seat 500. The ridge 110 on the inner side of the track plate of the track 100 is in a "T" shape. The ridge 110 can be slidably engaged in the retaining groove 510, and the claw 520 can engage with the retaining groove 120. This can generate a lifting force on the lower surface of the track 100, so that the lower surface of the track 100 forms an upward arched structure, which can have better fit with the outer arched walking surface and can eliminate the tendency of the two ends of the track 100 to separate from the walking surface, so that the robot has better adhesion when walking.
[0044] In summary, the track 100 suspension assembly for the walking robot in this embodiment has a ridge 110 on the inner side of the track plate of the track 100. The ridge 110 can be slidably engaged in the relief groove 510 of the swing arm's swing bracket 500. A spring 400 is installed between the swing arm and the bracket 500, thereby providing an upward elastic lifting force on the middle of the lower surface of the track 100. This makes the lower surface of the track 100 form a concave arc-shaped structure, which has better fit and adhesion with the outer arched walking surface, preventing slippage during movement and improving walking accuracy and safety.
[0045] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the present invention to the precise forms disclosed, and it is obvious that many changes and variations can be made based on the above teachings. Although embodiments of the present invention have been shown and described, these specific embodiments are merely explanations of the present invention and are not intended to limit the invention. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. The purpose of selecting and describing exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art, after reading this specification, can make modifications, substitutions, variations, and various choices and changes to the embodiments as needed without departing from the principles and spirit of the present invention, provided that such modifications, substitutions, variations, and choices and changes are within the scope of the claims of the present invention and are protected by patent law.
Claims
1. A track suspension assembly for a walking robot, comprising a track and a mounting base, wherein the mounting base is provided with a plurality of rotatable cantilever arms, the swinging ends of the cantilever arms abutting against the inner side of the lower surface of the track, and a spring is provided between the cantilever arms and the mounting base; characterized in that: The inner side of the track plate is provided with a ridge, and the two sides of the ridge are provided with inwardly recessed grooves; the swing end of the cantilever is provided with a rotatable seat, the bottom of the seat is provided with a relief groove, the relief groove passes through both ends of the seat and the ridge can be slidably locked in the relief groove, the two sides of the relief groove are provided with outwardly protruding claws, and the claws are slidably locked in the groove.
2. The track suspension assembly for a walking robot according to claim 1, characterized in that, The mounting base includes a base plate and connecting columns. There are two base plates arranged in parallel. There are three or more connecting columns, each with its two ends fixedly connected to one of the base plates. A reinforcing plate is also connected between the two base plates, and the reinforcing plate has weight-reducing holes.
3. The track suspension assembly for a walking robot according to claim 2, characterized in that, The cantilever includes a first cantilever and a second cantilever. There are two first cantilevers, and the rotating ends of the two first cantilevers are simultaneously rotatably connected to the seat plate and their rotation axes coincide. There is an even number of second cantilevers, which are symmetrically arranged on both sides of the first cantilever.
4. The track suspension assembly for a walking robot according to claim 3, characterized in that, The base plate is provided with a first ear plate, one end of which extends outward in a direction perpendicular to the base plate and is provided with a first mounting hole and a second mounting hole; the middle part of the first cantilever is provided with an outwardly extending second ear plate, which is provided with a third mounting hole; the rotating end of the second cantilever is provided with an outwardly extending third ear plate, which is provided with a fourth mounting hole; the two ends of the spring are respectively connected between the first mounting hole and the third mounting hole or between the second mounting hole and the fourth mounting hole.
5. The track suspension assembly for a walking robot according to claim 4, characterized in that, It also includes a fourth ear plate and a fifth ear plate. One end of the fourth ear plate is fixedly connected to the base plate, and the other end of the fourth ear plate extends outward in a direction perpendicular to the base plate and is provided with a fifth mounting hole. One end of the fifth ear plate is fixedly connected to the middle part of the first cantilever, and the other end of the fifth ear plate extends outward in a direction perpendicular to the base plate and is provided with a sixth mounting hole. Both ends of the spring can be fixedly connected to the fifth mounting hole and the sixth mounting hole. The distance from the fifth mounting hole to the base plate is greater than the distance from the first mounting hole and the second mounting hole to the base plate. There are two fourth ear plates, which are symmetrically arranged on both sides of the first ear plate.
6. The track suspension assembly for a walking robot according to claim 5, characterized in that, The base plate is provided with sensor bracket mounting holes, and the first ear plate and the fourth ear plate surround the sensor bracket mounting holes.
7. The track suspension assembly for a walking robot according to claim 1, characterized in that, One end of the claw is detachably connected to the card holder by a screw, and the other end of the claw is bent toward the relief groove. The card holder has a first arc surface at both ends, and the claw has a second arc surface and a third arc surface on both sides. The first arc surface and the second arc surface face the relief groove, and the third arc surface faces the inner side of the track plate.
8. The track suspension assembly for a walking robot according to claim 7, characterized in that, The ridge is composed of a support and a locking block. One end of the support is fixedly connected to the inner side of the belt plate, and the locking block is fixedly connected to the other end of the support and perpendicular to the support. The edges of the locking block are chamfered, and the width of the locking block is greater than the width of the support. The bottom of the locking block forms the locking groove between itself and the belt plate of the track.
9. The track suspension assembly for a walking robot according to claim 8, characterized in that, One end of the card block has an inwardly recessed notch, and the other end of the card block has an outwardly protruding protrusion. The protrusion can be movably engaged in the notch.
10. The track suspension assembly for a walking robot according to claim 9, characterized in that, The other end of the support is tilted towards the front of one end of the support, so that the position of the notch corresponds to the position of the rotation axis of the track link.