CN218451591U

CN218451591U - Obstacle crossing wheel and cleaning robot

Info

Publication number: CN218451591U
Application number: CN202221474280.6U
Authority: CN
Inventors: 夏建雄; 杨孜麒; 杨彦兵; 谷树森; 李冰; 邱国良; 王俊; 王铭; 张越; 王晓宁
Original assignee: Guangdong Lesheng Intelligent Technology Co ltd; Shenzhen Lesheng Robot Intelligent Technology Co ltd
Current assignee: Guangdong Lesheng Intelligent Technology Co ltd; Shenzhen Lesheng Robot Intelligent Technology Co ltd
Priority date: 2022-06-13
Filing date: 2022-06-13
Publication date: 2023-02-07
Anticipated expiration: 2032-06-13

Abstract

The utility model is suitable for a hinder technical field more, provide a hinder wheel and cleaning machines people more. The wheel of crossing barrier includes: a connecting column is arranged on one side of the face shell; the driving wheel is sleeved outside the connecting column and can rotate relative to the connecting column; the telescopic rods are uniformly distributed in the driving wheel in a telescopic manner; the first elastic piece provides pretightening force for the telescopic rod to retract into the driving wheel; the rotating piece is coaxially and rotatably arranged in the driving wheel and is matched and connected with the driving wheel, a protruding part is arranged on the circumference of the rotating piece, the telescopic rod is positioned on one side of the rotating direction of the protruding part, and the rotating piece can be separated from the driving wheel and is matched and connected with the connecting column; when rotating the piece and being connected with the spliced pole cooperation, the tip and the protruding portion butt of telescopic link, the telescopic link stretches out outside the action wheel, rotates the piece and is connected with the spliced pole separation and with the action wheel cooperation after the telescopic link stretches out outside the action wheel. The utility model discloses can increase the diameter of surmounting the wheel and adjust the ability of surmounting the obstacle according to actual need, structural design is ingenious and reliable and stable.

Description

Obstacle crossing wheel and cleaning robot

Technical Field

The utility model belongs to the technical field of hinder more, especially, relate to hinder more wheel and cleaning machines people.

Background

The obstacle crossing capability of the existing cleaning robot is limited by the diameter of a traveling wheel, namely the obstacle crossing capability is strong when the traveling wheel is large, the obstacle crossing capability is weak when the traveling wheel is small, and when the cleaning robot executes a cleaning task, a machine body cannot be far away from the ground, otherwise the cleaning robot can influence the ground garbage cleaning capability, so the diameter of the traveling wheel cannot be infinitely increased, therefore, the cleaning robot can only pass through some low obstacles, such as carpets and the like, but cannot cross over high obstacles, such as threshold and the like, so that the cleaning robot is limited in space when executing the cleaning task to generate a series of derivative problems, for example, because some special indoor spaces (kitchens, toilets and the like) need to be provided with high thresholds, the existing cleaning robot cannot cross over the spaces, a base station of the cleaning robot can only be arranged in a bedroom or a living room, the base station needs to be connected with a water source at the current position, construction difficulty and space occupation of a user are increased, and the user experience is poor.

SUMMERY OF THE UTILITY MODEL

The utility model provides a cross barrier wheel aims at solving current cleaning machines people and crosses barrier ability and hang down to lead to receiving the restriction in the space when carrying out clean task thereby makes the customer use experience not good problem.

The utility model discloses a realize like this, a hinder wheel more is applied to cleaning machines people, include:

the cleaning robot comprises a face shell, a cleaning mechanism and a control device, wherein one side of the face shell is provided with a connecting column, and the face shell is used for being fixed with the cleaning robot;

the driving wheel is sleeved outside the connecting column and can rotate relative to the connecting column;

the telescopic rods are uniformly distributed in the driving wheel in a telescopic manner;

the first elastic piece is arranged in the driving wheel and provides pretightening force for the telescopic rod to retract into the driving wheel;

the rotating piece is coaxially and rotatably arranged in the driving wheel and is matched and connected with the driving wheel, protruding parts which are in one-to-one correspondence with the telescopic rods are arranged on the circumference of the rotating piece, the telescopic rods are positioned on one side of the rotating direction of the protruding parts, and the rotating piece can be separated from the driving wheel and is matched and connected with the connecting column;

work as rotate the piece with when the spliced pole cooperation is connected, the tip of telescopic link with the protruding portion butt, the telescopic link stretches out outside the action wheel, rotate the piece and be in the telescopic link stretches out the action wheel outer back with the spliced pole separation and with the action wheel cooperation is connected.

Further, it can remove along its axis direction to rotate the piece, it is equipped with first spacing portion and the spacing portion of second respectively to rotate the relative both sides that lie in its axis direction, be equipped with on the spliced pole can with the spacing portion of first spacing portion cooperation or the spacing portion of third of separation, the inner wall of action wheel be equipped with can with the spacing portion of second separation or the spacing portion of complex fourth, hinder the wheel still includes more:

the second elastic piece is arranged in the driving wheel and provides pre-tightening force for the rotating piece to match the second limiting part with the fourth limiting part;

the first driving piece is arranged on the connecting column and can drive the rotating piece to move in the direction of the third limiting part so that the first limiting part is matched with the third limiting part.

Further, the first limiting portion, the second limiting portion, the third limiting portion and the fourth limiting portion are all teeth circumferentially arranged around the axis of the rotating shaft.

Furthermore, first driving piece is cyclic annular electro-magnet, the driving piece cover locate the axis of rotation and with the spliced pole is fixed, rotate the piece orientation one side of first driving piece is equipped with the portion of inhaling of can being inhaled by magnetism.

Further, the telescopic link can with the one end of protruding portion butt is equipped with the catch bar, the catch bar is equipped with the spacing portion of fifth at its rotation direction's end, works as the telescopic link stretches out outside the action wheel, the protruding portion with the cooperation of the spacing portion of fifth.

Furthermore, the protruding part is provided with a roller, and the roller is abutted against the push rod and can roll on the push rod.

Further, the inner wall of action wheel is equipped with the spacing portion of sixth, works as the telescopic link is received in the action wheel, the telescopic link with spacing portion butt of sixth.

Further, the inner wall of action wheel still is equipped with and ends piece and third elastic component, be equipped with the spacing portion of seventh on the circumference of rotation piece, the spacing portion circumference equipartition of seventh sets up and quantity is the same with the quantity of protruding portion, the spacing portion of seventh include with rotate the first end that the outer wall is close to and with rotate the second end that the outer wall was kept away from, the first end of rotation piece from second end circular arc transition, when the telescopic link stretches out outside the action wheel, ends the butt with the second of the spacing portion of seventh, the third elastic component to end piece provide with the pretightning force of the spacing portion butt of sixth.

Further, the action wheel includes wheel hub and cover and locates the outside wheel body of wheel hub, the telescopic link telescopic is located in the wheel hub, the telescopic link stretches out the outer one end of action wheel be equipped with the flexible piece, works as the telescopic link withdrawal when in the wheel hub, the flexible piece with the surface of wheel body flushes the setting.

The utility model also provides a cleaning robot, including organism, the aforesaid hinder wheel and the drive second driving piece that hinders the wheel motion more, hinder the panel of wheel more set firmly in on the organism.

The utility model has the advantages that by arranging the telescopic rod on the driving wheel, when obstacle crossing is not needed, the telescopic rod can be contracted in the driving wheel under the action of the first elastic part, and meanwhile, the rotating part is connected with the driving wheel in a matching way so that the rotating part can rotate along with the driving wheel and keep relatively static with the telescopic rod, the rotating part is prevented from changing the posture of the telescopic rod, and the driving wheel is kept in an initial state; when the needs organism hinders more, be connected with the spliced pole through making and keep static with relative telescopic link, the telescopic link rotates along with the action wheel and can rotate for rotating the piece, under the effect of the protruding portion of rotating the piece, the telescopic link can be by outside the ejecting action wheel of protruding portion, later make rotate the piece and be connected with the action wheel cooperation so that rotate the piece and keep at relative quiescent condition with the telescopic link, the telescopic link can keep at the current state of stretching out, the telescopic link has increased the diameter of action wheel, thereby the obstacle-crossing ability of action wheel has been increased.

Drawings

Fig. 1 is an exploded schematic view of an obstacle crossing wheel provided by the present invention in an initial state;

FIG. 2 is a schematic view of a rotating member of an obstacle detouring wheel according to the present invention;

fig. 3 is a cross-sectional view of an obstacle crossing wheel provided by the present invention in an initial state;

FIG. 4 is an enlarged view at A in FIG. 3;

FIG. 5 is an exploded view of the obstacle crossing wheel provided by the present invention, wherein the retractable rod extends out of the driving wheel;

fig. 6 is a cross-sectional view of the obstacle crossing wheel provided by the utility model, wherein the telescopic rod extends out of the driving wheel;

fig. 7 is an enlarged view at B in fig. 6.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example one

Referring to fig. 1-2, the embodiment of the present invention provides a wheel for obstacle crossing, which is applied to a cleaning robot, and comprises a surface shell 1, a driving wheel 2, a telescopic rod 3, a rotating member 4 and a first elastic member 5. Wherein, one side of the face shell 1 is provided with a connecting column 11, the face shell 1 is used for being fixed with a cleaning robot, a driving wheel 2 is sleeved outside the connecting column 11 and can rotate relative to the connecting column 11, so that the driving wheel 2 can not drive the face shell 1 to rotate when rotating, telescopic rods 3 are evenly distributed in the driving wheel 2 in a telescopic and circumferential manner so that the telescopic rods 3 can be contracted in the driving wheel 2 when not required to be extended to ensure that the driving wheel 2 walks in an initial posture, a first elastic part 5 is arranged in the driving wheel 2 and provides a pretightening force for the telescopic rods 3 to be contracted in the driving wheel 2 to ensure that the telescopic rods 3 can be contracted in the driving wheel 2, a rotating part 4 is coaxially and rotatably arranged in the driving wheel 2 and is matched and connected with the driving wheel 2, so that the rotating part 4 can be driven to rotate when the driving wheel 2 rotates, thereby ensuring that the telescopic rods 3 and the rotating part 4 are kept in a relatively static initial state, the circumference of the rotating piece 4 is provided with the protruding parts 41 which are in one-to-one correspondence with the telescopic rods 3, the telescopic rods 3 are positioned on one side of the rotating direction of the protruding parts 41, the rotating piece 4 can be separated from the driving wheel 2 and is in fit connection with the connecting column 11 so that the rotating piece 4 is separated from the driving wheel 2 and is connected with the connecting column 11 so as to keep static, when the rotating piece 4 is in fit connection with the connecting column 11, the end part of the telescopic rod 3 is abutted against the protruding parts 41, namely under the condition that the rotating piece 4 keeps static, when the telescopic rod 3 which always rotates along with the driving wheel 2 rotates relative to the rotating piece 4, the telescopic rod 3 can be gradually close to the protruding parts 41 and is ejected by the protruding parts 41 so that the telescopic rod 3 extends out of the driving wheel 2, the rotating piece 4 is separated from the connecting column 11 and is in fit connection with the driving wheel 2 after the telescopic rod 3 extends out of the telescopic rod 22, even if the rotating piece 4 rotates along with the driving wheel 2 so as to keep in a relative static state with the telescopic rod 3, so that the telescopic rod 3 is kept in the extended state.

By arranging the telescopic rod 3 on the driving wheel 2, when obstacle crossing is not needed, the telescopic rod 3 can be contracted in the driving wheel 2 under the action of the first elastic part 5, and meanwhile, the rotating part 4 is matched and connected with the driving wheel 2 so that the rotating part 4 can rotate along with the driving wheel 2 and keep relatively static with the telescopic rod 3, the rotating part 4 is prevented from changing the posture of the telescopic rod 3, and the driving wheel 2 is kept in an initial state; when needing the organism to hinder more, keep static with relative telescopic link 3 through making rotation piece 4 be connected with spliced pole 11, telescopic link 3 can rotate for rotating piece 4 along with action wheel 2 rotates, under the effect of the protruding portion 41 that rotates piece 4, telescopic link 3 can be outside protruding action wheel 2 of protruding portion 41, later make rotation piece 4 be connected with action wheel 2 cooperation so that rotate piece 4 and telescopic link 3 and keep at relative static state, telescopic link 3 can keep at the current state of stretching out, telescopic link 3 has increased the diameter of action wheel 2, thereby the ability of hindering more of action wheel 2 has been increased.

The embodiment of the utility model provides a hinder wheel more, can hinder the diameter of wheel more and adjust obstacle ability more according to the increase of actual need, structural design is ingenious and reliable and stable.

Further, telescopic link 3 is the contained angle setting with the radius of action wheel 2, and telescopic link 3 sets up for the radius slope of action wheel 2 promptly, so can increase telescopic link 3's flexible stroke, the diameter of increase action wheel 2 that can bigger degree to the feasible obstacle crossing ability of surmounting the wheel is higher.

In this embodiment, the first elastic member 5 may be, but is not limited to, a coil spring.

Example two

Referring to fig. 3 to 7, on the basis of the first embodiment, further, the rotating member 4 can move along the axis direction thereof, the rotating member 4 is provided with a first limiting portion 42 and a second limiting portion 43 at two opposite sides of the axis direction thereof, the connecting column 11 is provided with a third limiting portion 111 capable of being matched with or separated from the first limiting portion 42, the inner wall of the driving wheel 2 is provided with a fourth limiting portion 2111 capable of being separated from or matched with the second limiting portion 43, the obstacle crossing wheel further includes a second elastic member 6 and a first driving member 7, the second elastic member 6 is disposed in the driving wheel 2 and provides a pre-tightening force for the rotating member 4 to match the second limiting portion 43 with the fourth limiting portion 2111, and the first driving member 7 is disposed on the connecting column 11 and can drive the rotating member 4 to move towards the third limiting portion 111 so that the first limiting portion 42 is matched with the third limiting portion 111.

Thus, under the action of the second elastic element 6, the second limiting portion 43 of the rotating element 4 is matched with the fourth limiting portion 2111, so that the driving wheel 2 can drive the rotating element 4 to rotate when rotating, and when the telescopic rod 3 is required to extend, the first driving element 7 drives the rotating element 4 to move in the direction away from the second limiting portion 43, so that the first limiting portion 42 is matched with the third limiting portion 111, and the rotating element 4 can keep a static state.

Further, the first stopper portion 42, the second stopper portion 43, the third stopper portion 111, and the fourth stopper portion 2111 are all teeth provided circumferentially around the axis of the rotating shaft 23. Therefore, the rotating part 4 can be ensured to be matched with the first limiting part 42 and the third limiting part 111 after rotating for any angle, and the second limiting part 43 is matched with the fourth limiting part 2111.

In the present embodiment, the second elastic member 6 may employ, but is not limited to, a coil spring.

EXAMPLE III

Referring to fig. 5, on the basis of the second embodiment, further, the first driving member 7 is an annular electromagnet, the driving member is sleeved on the rotating shaft 23 of the driving wheel 2 and fixed to the connecting column 11 so as to keep the first driving member 7 stationary, thereby preventing the wire of the first driving member 7 from being wound due to the rotation of the first driving member 7 along with the driving wheel 2, and a magnetic attraction portion 44 capable of being magnetically attracted is disposed on one side of the rotating member 4 facing the first driving member 7. First driving piece 7 adopts the electro-magnet, can simplify the structural mounting of first driving piece 7, and the little energy consumption of electro-magnet can reach great suction simultaneously, and is with low costs, rotates piece 4 and sets up magnetism portion 44 of inhaling, can guarantee that the electro-magnet is to the mobility control who rotates piece 4.

Example four

Referring to fig. 1-2, on the basis of any one of the first to third embodiments, further, a push rod 31 is disposed at one end of the telescopic rod 3, which can abut against the protrusion 41, the push rod 31 can increase the abutting area of the telescopic rod 3 and the protrusion 41, so that the protrusion 41 and the telescopic rod 3 are more reliably engaged, a fifth limiting portion 311 is disposed at the end of the push rod 31 in the rotation direction, and when the telescopic rod 3 extends out of the driving wheel 2, the protrusion 41 and the fifth limiting portion 311 are engaged. Thus, the fifth limiting portion 311 is arranged to be matched with the protruding portion 41, so that the protruding portion 41 can stably push the telescopic rod 3, and the protruding portion 41 is prevented from being separated from the telescopic rod 3, so that the telescopic rod 3 extends out of the driving wheel 2 and fails.

Specifically, the fifth limiting portion 311 is an arc-shaped recessed portion, so that the protruding portion 41 can be inserted into or separated from the fifth limiting portion 311 when the telescopic rod 3 rotates with the driving wheel 2.

Further, the roller 20 is provided on the protruding portion 41, and the roller 20 abuts against the push rod 31 and can roll on the push rod 31. This can reduce friction between the protrusion 41 and the telescopic rod 3, thereby avoiding wear between the protrusion 41 and the telescopic rod 3 to cause a reduction in accuracy.

EXAMPLE five

Referring to fig. 1-2, in any one of the first to fourth embodiments, a sixth limiting portion 2112 is further disposed on an inner wall of the driving wheel, and when the telescopic rod 3 is retracted into the driving wheel 2, the telescopic rod 3 abuts against the sixth limiting portion 2112, that is, the push rod 31 on the telescopic rod 3 abuts against the sixth limiting portion 2112. Thus, under the action of the first elastic element 5, the sixth limiting portion 2112 can limit the position of the telescopic rod 3 in the driving wheel 2.

EXAMPLE six

Referring to fig. 1-2, in any one of the first to fifth embodiments, further, the inner wall of the driving wheel 2 is further provided with a locking piece 8 and a third elastic piece 9, the circumference of the rotating member 4 is provided with a seventh limiting portion 45, the seventh limiting portions 45 are uniformly distributed circumferentially and have the same number as the number of the protruding portions 41, the seventh limiting portion 45 includes a first end close to the outer wall of the rotating member 4 and a second end far from the outer wall of the rotating member 4, the first end of the rotating member 4 is transited from the second end in an arc shape, so that when the rotating member 4 rotates in the forward direction (referring to the direction in which the rotating member 4 rotates along with the driving wheel 2), the locking piece 8 can move from the first end to the second end of the seventh limiting portion 45 without interfering with the forward rotation of the rotating member 4, when the telescopic rod 3 extends out of the driving wheel 2, the locking piece 8 abuts against the second end of the seventh limiting portion 45, and the third elastic piece 9 provides a pre-tightening force for the locking piece 8 to abut against the sixth limiting portion 2112. Thus, when the protrusion 41 pushes the telescopic rod 3, the engagement between the locking member 8 and the seventh limiting portion 45 can prevent the rotating member 4 from rotating in the opposite direction, so that the protrusion 41 is separated from the telescopic rod 3, and the telescopic rod 3 retracts into the driving wheel 2 under the action of the first elastic member 5.

In the present embodiment, the third elastic member 9 may be a torsion spring, but is not limited thereto.

EXAMPLE seven

Referring to fig. 1-2, in any one of the first to sixth embodiments, further, the driving wheel 2 includes a hub 21 and a wheel body 22 sleeved outside the hub 21, the telescopic rod 3 is telescopically disposed in the hub 21, an end of the telescopic rod 3 extending out of the driving wheel 2 is provided with a flexible member 10, and when the telescopic rod 3 is retracted into the accommodating cavity 211, the flexible member 10 is flush with a surface of the wheel body 22. Therefore, when the telescopic rod 3 extends out, the flexible part 10 can buffer one end of the telescopic rod 3 contacting with the ground, so that abrasion caused by hard contact between the telescopic rod 3 and the ground is avoided, and when the telescopic rod 3 retracts into the wheel hub 21, the flexible part 10 can be integrated with the wheel body 22 to keep the consistency of the external structure of the wheel body 22, and the gap between the wheel body 22 and the wheel body 22, which is penetrated by the telescopic rod 3, can be sealed to prevent sundries from entering the wheel hub 21.

In this embodiment, the flexible member may be made of soft glue, such as one of silicone and rubber.

Referring to fig. 4 and 6, in detail, the hub 21 includes a first side plate 21a and a second side plate 21b which are oppositely disposed and cover the accommodating cavity 211, the telescopic rod 3, the first elastic member 5, the first driving member 7, the second elastic member 6, the rotating member 4, the locking member 8, and the third elastic member 9 are all disposed in the accommodating cavity 211, the connecting rod 11 penetrates through the first side plate 21a and extends into the accommodating cavity 211, the first side plate 21a can rotate relative to the connecting rod 11, the second side plate 21b is connected with a rotating shaft 23 and extends through the face shell 1 toward the connecting rod 11, the rotating shaft 23 is driven by the second driving member 30 to rotate so as to drive the second side plate 21b, the first side plate 21a, and the wheel body 22 to rotate, wherein the locking member 8 and the third elastic member 9 are fixed to the second side plate 21b, so as to prevent the interference rotating member 4 from moving on the axis thereof toward the first side plate 21a direction to cooperate with the connecting rod 11.

Example eight

Referring to fig. 1-2, 4 and 6, an embodiment of the present invention further provides a cleaning robot, including a body (not shown in the figure), the obstacle crossing wheel and a second driving member 30 for driving the obstacle crossing wheel to move, wherein a surface shell 1 of the obstacle crossing wheel is fixedly disposed on the body. Specifically, the driving end of the second driving element 30 is provided with a transmission set 301, the transmission set 301 may be a gear transmission set 301, and the transmission set 301 is connected to the rotating shaft 23 to drive the rotating shaft 23 to rotate.

The embodiment of the utility model provides a cleaning robot can increase the diameter of hindering the wheel more and adjust the ability of hindering more according to actual need, and structural design is ingenious and reliable and stable.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.

Claims

1. The utility model provides an obstacle crossing wheel is applied to cleaning machines people which characterized in that includes:

2. The obstacle crossing wheel as claimed in claim 1, wherein the rotating member is movable in an axial direction thereof, the rotating member is provided with a first position-limiting portion and a second position-limiting portion at opposite sides of the axial direction thereof, respectively, the connecting column is provided with a third position-limiting portion engageable with or disengageable from the first position-limiting portion, the inner wall of the driving wheel is provided with a fourth position-limiting portion disengageable from or engageable with the second position-limiting portion, and the obstacle crossing wheel further comprises:

3. The obstacle crossing wheel of claim 2 wherein the first, second, third and fourth limiting portions are teeth disposed circumferentially about an axis of rotation.

4. The obstacle crossing wheel as claimed in claim 2, wherein the first driving member is an annular electromagnet, the first driving member is sleeved on the rotating shaft and fixed to the connecting post, and a magnetic attraction portion capable of being magnetically attracted is disposed on a side of the rotating member facing the first driving member.

5. The obstacle crossing wheel as claimed in claim 1, wherein a push rod is provided at an end of the telescopic bar, which is capable of abutting against the protrusion, and a fifth stopper is provided at an end of the push rod in a rotation direction thereof, and the protrusion is engaged with the fifth stopper when the telescopic bar is extended out of the driving wheel.

6. The obstacle crossing wheel of claim 5 wherein the nose has a roller wheel thereon, the roller wheel abutting and rolling on the push bar.

7. The obstacle crossing wheel according to claim 1 or 5, wherein a sixth limiting part is arranged on the inner wall of the driving wheel, and when the telescopic rod is retracted into the driving wheel, the telescopic rod is abutted against the sixth limiting part.

8. The obstacle crossing wheel as claimed in claim 7, wherein the inner wall of the driving wheel is further provided with a locking member and a third elastic member, the rotating member is provided with a seventh limiting portion on the circumference thereof, the seventh limiting portion is circumferentially and uniformly arranged and has the same number as the number of the protrusions, the seventh limiting portion includes a first end close to the outer wall of the rotating member and a second end far from the outer wall of the rotating member, the first end of the rotating member is circularly transited from the second end, when the telescopic rod extends out of the driving wheel, the locking member abuts against the second end of the seventh limiting portion, and the third elastic member provides a pre-tightening force for the locking member to abut against the sixth limiting portion.

9. The obstacle crossing wheel as claimed in claim 1, wherein the driving wheel includes a wheel hub and a wheel body sleeved outside the wheel hub, the retractable rod is telescopically disposed in the wheel hub, a flexible member is disposed at an end of the retractable rod extending out of the driving wheel, and the flexible member is disposed flush with a surface of the wheel body when the retractable rod is retracted into the wheel hub.

10. A cleaning robot comprising a body, an obstacle crossing wheel according to any one of claims 1 to 9, and a second driving member for driving the obstacle crossing wheel to move, wherein a panel of the obstacle crossing wheel is fixed to the body.