Wheel-foot transition robot

Abstract

The present application relates to the field of mobile robots, in particular to a wheel-foot switching robot, comprising a body carrying a controller, and a plurality of foot-wheel mechanisms respectively connected to opposite sides of the body. The foot-wheel mechanism comprises a base plate connected to the body and controllably rotatable, and a plurality of mechanical legs connected to the side of the base plate away from the body. The mechanical leg comprises a connecting rod and a circular arc-shaped supporting foot, and the two ends of the connecting rod are controllably rotatably connected to the base plate and the supporting foot respectively. The mechanical leg is switched between the foot type and the wheel type under the control of the controller. When each mechanical leg is in the wheel type, the edges of each mechanical leg together enclose a circular wheel shape, and controllably rotate with the base plate to perform wheel movement. When each mechanical leg is in the foot type, the body is supported by the end of each mechanical leg away from the connecting rod, and performs foot movement. The two movement modes are realized by the deformation of the foot-wheel mechanism, and the two movement modes are realized by a relatively simple mechanical structure.

Description

Technical Field

[0001] This invention relates to the field of mobile robots, and in particular to a wheel-leg switching robot. Background Technology

[0002] Mobile robots are automated machines that perform tasks and are often used as the core carriers of intelligent equipment. Currently, mobile robots are widely used in industrial logistics, service robots, medical inspection, and special operations. Based on their means of movement, mobile robots are mainly classified into legged robots and wheeled robots. Legged robots have a larger contact area and can move stably on uneven terrain such as steps, but require complex software programs to operate. In contrast, wheeled robots can operate stably under the drive of simpler programs, but are only suitable for relatively flat surfaces.

[0003] To combine the advantages of legged and wheeled robots, researchers have combined their structures, giving the robot both wheels and legs, and switching between these locomotion mechanisms via a control program. However, this combination results in a bulky structure, hindering the simplification of the mechanical design. Summary of the Invention

[0004] The purpose of this invention is to provide a wheel-leg switching robot that can switch between wheeled and legged robots and has a relatively simple structure.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A wheel-leg switching robot, comprising:

[0007] The main body, which houses the controller;

[0008] The footwheel mechanism comprises multiple footwheels connected to opposite sides of the main body. It includes a base plate connected to the main body and controllably rotatable, and multiple sets of mechanical legs connected to the sides of the base plate away from the main body. Each mechanical leg includes a connecting rod and an arc-shaped support foot. The two ends of the connecting rod are controllably rotatably connected to the base plate via a first servo motor and to the support foot via a second servo motor. Driven by a controller, the footwheel mechanism switches between a foot-type and a wheel-type configuration. When in wheel-type mode, the edges of all the mechanical legs together form a circular wheel shape, surrounding the edge of the base plate and rotating with the base plate. When all the mechanical legs are in foot-type mode, the end of each mechanical leg away from the connecting rod supports the main body, and each mechanical leg independently flexes and extends, causing displacement of the main body.

[0009] Optionally, the body includes a housing and an axle. An extension passage is formed on the housing. The axle passes through the extension passage and slides controllably along the extension passage. The center of the base plate is connected to the axle and controlslably moves closer to or further away from the housing along with the axle. A female magnetic interface electrically connected to the controller is formed on the side of the housing near the base plate. A female magnetic interface that mates with the female magnetic interface is formed on the side of the base plate near the body. The female magnetic interface is electrically connected to the first servo and the second servo.

[0010] Optionally, the main body further includes a telescopic motor, a rotating component, and a push-pull component electrically connected to the controller. Each of the base plates is connected to one of the axles. The rotating component is built into the housing and includes a rotation center connected to the telescopic motor and several pulling parts away from the rotation center. The two ends of each push-pull component are rotatably connected to the pulling parts of the rotating component and the end of the axle away from the base plate. The turntable is controllably rotated along the rotation center under the drive of the rotating component, causing the axle to slide in the extension passage.

[0011] Optionally, when the wheel-leg switching robot stops working, the sub-magnetic interface is electrically connected to the female magnetic interface, and the mechanical leg is in the wheel-like shape.

[0012] Optionally, multiple sets of sub-magnetic interfaces correspond one-to-one with each of the mechanical legs, and each set of sub-magnetic interfaces includes a first interface electrically connected to the first servo motor and a second interface electrically connected to the second servo motor.

[0013] Optionally, the substrate is constructed as a circular plate structure, and the axle includes a rotary motor. The rotary motor is slidably connected to the inner wall of the extended passage, and its motor shaft is connected to the substrate, driving the substrate to rotate controllably around its center.

[0014] Optionally, a first alignment member is provided on the substrate, and a second alignment member is provided on the side of the housing near the substrate. When the positions of the first alignment member and the second alignment member correspond to each other, the position of the sub-magnetic interface corresponds to the position of the female magnetic interface.

[0015] Optionally, the wheel-foot switching robot also includes several auxiliary wheels. When the foot wheel mechanism is in the wheel form, the lowest height of the foot wheel mechanism is lower than the height of the bottom of the auxiliary wheels, which are used to assist in supporting the main body.

[0016] Optionally, the main body includes a placement platform located on its top and a main control board disposed on the side of the placement platform. The main control board is electrically connected to the controller and includes several external interfaces and a battery compartment for accommodating batteries.

[0017] Optionally, the outer edge of the support foot is wrapped with a flexible structure.

[0018] The beneficial effects of this invention are as follows: The outer contours of multiple support legs connected to the base plate are constructed in an arc shape, allowing the multiple support legs to be arranged end-to-end to form a circular wheel-like structure, thus achieving switching between wheel-like and multi-legged structures. Through linkages, a first servo motor, and a second servo motor, the mechanical legs possess a high degree of freedom, enabling the wheel-leg switching robot to achieve stable legged movement through the support and shape changes of multiple mechanical legs. By controllably rotating the base plate, the wheel-leg switching robot can achieve wheeled movement by rotating the base plate. Achieving two movement modes through the deformation of the same foot-wheel mechanism helps to realize both legged and wheeled movement functions with a relatively simple mechanical structure.

[0019] Furthermore, by controllably sliding the axle along the extended path, the wheel mechanism is moved away from the main body during wheeled movement, preventing interference between the base plate and the main body and thus affecting the base plate's movement. Electrical connections between the first and second servos and the controller are achieved through mutually cooperating female and female magnetic interfaces, preventing data cables used for electrical connections from becoming tangled during base plate rotation, and reducing the risk of failure with a simple structure.

[0020] Furthermore, by rotating the rotating component and driving the sliding of the wheel axle through the transmission of the push-pull component, the synchronous sliding of multiple wheel axles is achieved with a simple structure and has high movement accuracy, which helps to ensure the accurate connection between the female magnetic interface and the female magnetic interface.

[0021] Furthermore, when the wheel-foot switching robot stops working, making its structure different from both the wheeled and footed movement types, it helps reduce the risk of erroneous movement caused by system failure and improves the working accuracy of the wheel-foot switching robot.

[0022] Furthermore, electrically connecting multiple mechanical legs to the controller and allowing them to move independently, as well as electrically connecting the first and second servo motors to the controller and allowing them to move independently, both help reduce erroneous movements caused by signal transmission or reception errors.

[0023] Furthermore, the cooperating first and second alignment components help ensure accurate alignment of the female and female magnetic interfaces. After alignment, the sliding of the wheel axle allows the female and female magnetic interfaces to connect, which helps ensure the electrical connection between the caster mechanism and the controller, preventing connection failure due to alignment errors from causing the caster mechanism to be unable to deform.

[0024] Furthermore, the auxiliary wheels can assist the wheeled foot mechanism in providing support. In addition, when the wheel-foot switching robot moves forward or backward, the auxiliary wheels touching the ground first helps to stabilize its posture.

[0025] Furthermore, by constructing the top of the housing as a flat platform, it facilitates the placement and handling of materials. Positioning the main control board on the side of the platform, along with several external interfaces and a battery compartment, facilitates maintenance and repair of the wheel-leg switching robot, and provides information interfaces and power when carrying equipment requiring electrical connection.

[0026] Furthermore, by encasing the flexible structure to enhance the shock absorption capability of the caster mechanism, it helps to ensure the smooth movement of the main body.

[0027] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0028] Figure 1 This is a front view of the wheel-leg switching robot shown in Embodiment 1 of the present invention during wheeled movement;

[0029] Figure 2 This is a side view of the wheel-leg switching robot shown in Embodiment 1 of the present invention during wheeled movement;

[0030] Figure 3 This is a top view of the wheel-leg switching robot shown in Embodiment 1 of the present invention during wheeled movement.

[0031] Figure 4 This is a schematic diagram of the wheel-leg switching robot shown in Embodiment 1 of the present invention when it is moving in groups.

[0032] Legend: 1-Main body, 11-Shell, 111-Placement platform, 112-Connecting surface, 113-Directional surface, 114-Extension path, 12-Axle, 13-Telescopic motor, 14-Rotating component, 15-Push-pull component, 16-Main control board, 17-Female magnetic interface, 181-Central shaft, 182-Auxiliary wheel, 2-Foot wheel mechanism, 21-Base plate, 22-Mechanical leg, 221-First servo motor, 222-Linkage, 223-Supporting foot, 224-Second servo motor, 225-Wheel belt, 23-Sub-magnetic interface, 231-First interface, 232-Second interface. Detailed Implementation

[0033] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] Please see Figure 1 and Figure 4 The wheel-leg switching robot claimed in this invention includes a body 1 carrying a controller and multiple wheel mechanisms 2 respectively connected to opposite sides of the body 1. Each wheel mechanism 2 includes a base plate 21 connected to the body 1 and controllably rotatable, and multiple sets of mechanical legs 22 connected to the sides of the base plate 21 away from the body 1. Each mechanical leg 22 includes a connecting rod 222 and an arc-shaped support foot 223. The two ends of the connecting rod 222 are controllably rotatably connected to the base plate 21 via a first servo motor 221 and controllably rotatably connected to the support foot 223 via a second servo motor 224. The mechanical legs 22 switch between a legged form and a wheeled form under the control of the controller. When all mechanical legs 22 are in wheel form, the edges of all mechanical legs 22 together form a circular wheel shape, surrounding the edge of the base plate 21 and rotating with the rotation of the base plate 21. When all mechanical legs 22 are in foot form, the end of each mechanical leg 22 away from the connecting rod 222 supports the body 1. Each mechanical leg 22 can bend and extend independently, causing the body 1 to move.

[0038] The outer contours of multiple support legs 223 connected to the base plate 21 are constructed in an arc shape, allowing the multiple support legs 223 to be arranged end-to-end to form a circular wheel-like structure, realizing the switching between wheel-like and multi-legged structures. Through the link 222, the first servo motor 221, and the second servo motor 224, the mechanical legs 22 have a high degree of freedom, enabling the wheel-leg switching robot to achieve stable legged movement through the support and shape changes of multiple mechanical legs 22. By controllably rotating the base plate 21, the wheel-leg switching robot can achieve wheeled movement by rotating the base plate 21. Achieving two movement modes through the deformation of the same foot-wheel mechanism 2 helps to realize both legged and wheeled movement functions with a relatively simple mechanical structure.

[0039] Please refer to the following examples for details.

[0040] Example 1:

[0041] Please see Figure 1 , Figure 2 The preferred embodiment of this application shows a wheel-foot switching robot including a body 1 and two sets of foot wheel mechanisms 2 connected to the body 1.

[0042] Please see Figure 1 and Figure 3 The main body 1 includes a housing 11, an axle 12, a telescopic motor 13, a rotating component 14, and a push-pull component 15. The housing 11 is a hollow isosceles trapezoidal columnar structure with a horizontally positioned rectangular platform 111 at the top, vertically connected connecting surfaces 112 on opposite sides of the platform 111, and inclined directional surfaces 113 on the other two sides of the platform 111. Both connecting surfaces 112 of the housing 11 have a significant thickness, and a horizontal extension passage 114 is formed along the centerline of each connecting surface 112. Both extension passages 114 connect the inside and outside of the housing 11 and are located on the same straight line. The axle 12 is a rotary motor, its outer casing slidably connected to the inner wall of the extension passage 114, allowing it to slide freely within the extension passage 114. The telescopic motor 13 is fixedly connected inside the housing 11. The circular plate-shaped rotating component 14 is horizontally positioned and connected to the telescopic motor 13, and can be controllably rotated around its center under the drive of the telescopic motor 13. Two horizontally extending elongated push-pull members 15 are rotatably connected at one end to the radially opposite edges of the rotating member 14, and at the other end to the ends of the axle 12. When the rotating member 14 rotates, the push-pull members 15 rotate in the horizontal plane, causing the axle 12 to slide along the extension passage 114. In this embodiment, a horizontally extending sliding track is formed on the inner wall of the extension passage 114, which matches the shape of the stepper motor housing.

[0043] The main body 1 also includes a main control board 16. The main control board 16 is embedded in any surface 113 of the main body 1, and has various external interfaces of different specifications, a controller, and a battery compartment. The battery compartment is used to house the battery, and the controller is electrically connected to the interfaces on the main control board 16, the battery compartment, and the telescopic motor 13. The main control board 16 is fitted into the surface of the housing 11 of the main body 1, facilitating inspection and maintenance, and enabling easy command input. When the platform 111 of the main body 1 carries equipment requiring power, it facilitates information exchange and power transmission through external interfaces.

[0044] Please see Figure 1 , Figure 2 and Figure 4The footwheel mechanism 2 includes a base plate 21 and multiple sets of mechanical legs 22 connected to the side of the base plate 21 away from the main body 1. The base plate 21 has an outer circular plate structure, and its center is connected to the motor shaft of a rotary motor, which can controllably rotate around the center under the drive of the rotary motor. In this embodiment, the rotary motor is a stepper motor. The mechanical legs 22 include connecting rods 222 and arc-shaped support feet 223. Three first servo motors 221 are fixedly connected to the upper and lower semicircular areas of the base plate 21. The ends of the connecting rods 222 of the three mechanical legs 22 are respectively connected to the three first servo motors 221, so that the connecting rods 222 can be controllably rotated in the vertical plane. Each support foot 223 is rotatably connected to the end of the connecting rod 222 away from the first servo motor 221 through three second servo motors 224. The support feet 223 are arc-shaped with rounded edges to increase the contact area with the ground. The support foot 223 has a hollow shell structure. The second servo motor 224 is built into the inside of the support foot 223, and the edge of the support foot 223 is wrapped with a flexible rubber belt 225 to improve the cushioning capacity. When the two sets of upper mechanical legs 22 rotate to the top and fold, and the set of lower mechanical legs 22 rotates to the side and folds, the support feet 223 of the three sets of mechanical legs 22 are arranged end to end, forming a circle with a large diameter and coaxial with the base plate 21. At this time, the wheel mechanism 2 is in wheel form. When all three sets of mechanical legs 22 rotate to the bottom, with the end of the support foot 223 away from the connecting rod 222 supporting the ground, the wheel mechanism 2 is in leg form. Three sets of female magnetic attraction interfaces 17 electrically connected to the controller are formed on the connecting surface 112 of the housing 11. The central angle between adjacent sets of female magnetic attraction interfaces 17 is different to prevent the female magnetic attraction interface 23 from being incorrectly connected to the female magnetic attraction interface 17. Each set of female magnetic attraction interfaces 17 includes two interface units. The base plate 21 has sub-magnetic interfaces 23 on its side near the housing 11, each corresponding to a set of female magnetic interfaces 17. Each sub-magnetic interface 23 includes a first interface 231 and a second interface 232 corresponding to two interface units. Each sub-magnetic interface 23 is electrically connected to each mechanical leg 22, with the first interface 231 electrically connected to the first servo motor 221 and the second interface 232 electrically connected to the second servo motor 224. When the wheel-leg switching robot moves in wheel mode, the telescopic motor 13 drives the base plate 21 away from the housing 11 to prevent interference between the housing 11 and the base plate 21 and to prevent the base plate 21 from rotating. When the wheel-leg switching robot moves in leg mode, the telescopic motor 13 drives the base plate 21 closer to the housing 11, so that each female magnetic interface 17 and the sub-magnetic interface 23 are aligned, thereby electrically connecting the first servo motor 221 and the second servo motor 224 to the controller and the battery, realizing the deformation of the leg mechanism 2.

[0045] The caster mechanism 2 also includes a first alignment member disposed on the connecting surface 112 of the housing 11 and a second alignment member disposed on the side of the base plate 21 near the housing 11. When the positions of each sub-magnetic interface 23 correspond one-to-one with the positions of each female magnetic interface 17, the positions of the first alignment member and the second alignment member correspond to each other, preventing misalignment between the sub-magnetic interfaces 23 and each female magnetic interface 17, which would lead to connection failure. In this embodiment, the first and second alignment members are through-beam sensors.

[0046] When the wheel-foot switching robot shown in this embodiment stops running, the base plate 21 is close to the shell 11 and each female magnetic interface 17 is connected to each female magnetic interface 23 one by one, and the foot wheel mechanism 2 is in a wheel state, which makes it easy for the wheel-foot switching robot to start moving after deformation.

[0047] The wheel-foot switching robot shown in this embodiment also includes auxiliary wheels 182. The auxiliary wheels 182 are rotatably connected to a central shaft 181 fixed to the bottom of the main body 1. Each set of auxiliary wheels 182 includes two auxiliary wheels 182 connected to the same central shaft 181 and respectively close to the two foot wheel mechanisms 2, and the two sets of auxiliary wheels 182 are respectively arranged on both radial sides of the foot wheel mechanism 2. When the foot wheel mechanism 2 is in wheel mode, the lowest height of the foot wheel mechanism 2 is lower than the height of the bottom of the auxiliary wheels 182. The wheel-foot switching robot in this embodiment has a two-wheel structure. Through structural design, the weight is symmetrical, so that when the wheel-foot switching robot moves in wheel mode, the platform 111 remains horizontal, at which time the auxiliary wheels 182 are separated from the ground. However, when the speed of the wheel-foot switching robot changes, the main body 1 sways under the action of inertia. At this time, the auxiliary wheels 182 touch the ground, assisting the foot wheel mechanism 2 in providing support.

[0048] By enabling mobile robots to possess both wheeled and legged locomotion through structural deformation, it is possible to expand the functionality of mobile robots while maintaining a relatively simple mechanical structure.

[0049] Example 2:

[0050] The only difference between this embodiment and Embodiment 1 is that a compensation part is also connected to the base plate 21. The compensation part is offset from each support foot 223 and does not interfere with each support foot 223. When the wheel mechanism 2 is in the form of a wheel, the compensation part and each support foot 223 together form a circle to prevent bumps caused by the rounded corner structure at the end of the support foot 223.

[0051] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A wheel-leg switching robot, characterized in that, include: The main body (1) carries the controller; The footwheel mechanism (2) is provided with multiple footwheels and is respectively connected to the opposite sides of the main body (1). It includes a base plate (21) connected to the main body (1) and controllably rotatable, and multiple sets of mechanical legs (22) connected to the side of the base plate (21) away from the main body (1). The mechanical leg (22) includes a connecting rod (222) and an arc-shaped support foot (223). The two ends of the connecting rod (222) are controllably rotatably connected to the base plate (21) through a first servo motor (221) and controllably rotatably connected to the support foot (223) through a second servo motor (224). 23), the foot wheel mechanism (2) switches between foot-type and wheel-type modes under the drive of the controller. When the foot wheel mechanism (2) is in the wheel-type mode, the edges of each mechanical leg (22) together form a circular wheel shape, surrounding the edge of the base plate (21) and rotating with the rotation of the base plate (21). When each mechanical leg (22) is in the foot-type mode, the body (1) is supported by the end of each mechanical leg (22) away from the connecting rod (222). Each mechanical leg (22) flexes and extends independently, driving the body. (1) Displacement occurs. The body (1) includes a housing (11) and an axle (12), and also includes a telescopic motor (13), a rotating component (14), and a push-pull component (15) electrically connected to the controller. An extension passage (114) is formed on the housing (11). The axle (12) passes through the extension passage (114) and slides controllably along the extension passage (114). The center of the base plate (21) is connected to the axle (12), and it controlslably moves closer to or further away from the housing (11) along with the axle (12). Each base plate (21) is divided into A wheel axle (12) is connected to the rotating member (14) which is built into the housing (11). The rotating member (14) includes a rotation center connected to the telescopic motor (13) and a plurality of pulling parts away from the rotation center. The two ends of each push-pull member (15) are respectively rotatably connected to the pulling part of the rotating member (14) and the end of the wheel axle (12) away from the base plate (21). The rotating member (14) rotates controllably along the rotation center under the drive of the telescopic motor (13), causing the wheel axle (12) to slide in the extension passage (114).

2. The wheel-leg switching robot as described in claim 1, characterized in that, The housing (11) has a female magnetic interface (17) that is electrically connected to the controller on the side near the base plate (21), and the base plate (21) has a female magnetic interface (23) that is matched with the female magnetic interface (17) on the side near the body (1), and the female magnetic interface (23) is electrically connected to the first servo (221) and the second servo (224).

3. The wheel-leg switching robot as described in claim 2, characterized in that, When the wheel-leg switching robot stops working, the sub-magnetic interface (23) is electrically connected to the mother magnetic interface (17), and the mechanical leg (22) takes the shape of a wheel.

4. The wheel-leg switching robot as described in claim 2, characterized in that, Multiple sets of sub-magnetic interfaces (23) correspond one-to-one with each of the mechanical legs (22). Each set of sub-magnetic interfaces (23) includes a first interface (231) electrically connected to the first servo motor (221) and a second interface (232) electrically connected to the second servo motor (224).

5. The wheel-leg switching robot as described in claim 2, characterized in that, The substrate (21) is constructed as a circular plate structure. The axle (12) includes a rotary motor. The rotary motor is slidably connected to the inner wall of the extension passage (114), and its motor shaft is connected to the substrate (21), driving the substrate (21) to rotate controllably around its center.

6. The wheel-leg switching robot as described in claim 2, characterized in that, A first alignment member is provided on the substrate (21), and a second alignment member is provided on the side of the housing (11) near the substrate (21). When the positions of the first alignment member and the second alignment member correspond to each other, the position of the sub-magnetic interface (23) corresponds to the position of the female magnetic interface (17).

7. The wheel-leg switching robot as described in claim 1, characterized in that, It also includes several auxiliary wheels (182). When the foot wheel mechanism (2) is in the wheel form, the lowest height of the foot wheel mechanism (2) is lower than the height of the bottom of the auxiliary wheel (182). The auxiliary wheel (182) is used to assist in supporting the body (1).

8. The wheel-leg switching robot as described in claim 1, characterized in that, The main body (1) includes a placement platform (111) located on its top and a main control board (16) disposed on the side of the placement platform (111). The main control board (16) is electrically connected to the controller and includes several external interfaces and a battery compartment for accommodating batteries.

9. The wheel-leg switching robot as described in claim 1, characterized in that, The outer edge of the support foot (223) is wrapped with a flexible structure.

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