Active wheel assembly for moving a movable robot along a support surface, and movable robot comprising said wheel assembly

Abstract

An active wheel assembly (1) for moving a movable robot (100) along a support surface, comprising: a wheel (10) defining a wheel rotation axis (R-R) and a wheel encumbrance volume (2) delimited between two axial end planes (P1, P2) of said wheel parallel to each other and orthogonal to said wheel rotation axis (R-R) and a cylindrical radial end surface (SC) of said wheel about said wheel rotation axis (R-R), said wheel (10) comprising a central wheel body (4) coaxial with said wheel rotation axis (R-R), an annular casing body (3) fixed about said central wheel body (4) and coaxial with said wheel rotation axis (R-R), said annular casing body (3) being adapted to rest on said support surface, said wheel defining a median wheel plane (M-M) orthogonal to the wheel rotation axis (R-R) and central with respect to a width of the annular casing body (3) measured parallel to the wheel rotation axis (R-R); a support assembly (20) for connecting said wheel (10) to a base portion (101) of said movable robot (100); said support assembly (20) comprising a fixing end (28) for fixing said support assembly (20) to said base portion (101) of said movable robot (100), a support bracket (21) and an intermediate connection element (70), said wheel (10) being rotatably engaged with said intermediate connection element (70) about said wheel rotation axis (R-R), and said intermediate connection element (70) being rotatably engaged with said support bracket (21) about a steering 32 axis (S-S) orthogonal to said wheel rotation axis (R-R), said wheel rotation axis (R-R) being rotatable about said steering axis (S-S) between two angular end positions of the wheel rotation axis (R-R); said support assembly (20) comprising a rotary steering actuator assembly (50) connected to said support bracket (21) and said intermediate connection element (70) so as to rotate said intermediate connection element (70) with respect to said support bracket (21) about said steering axis (S-S), and a rotary advancement actuator assembly (80) connected to said intermediate connection element (70) and said central wheel body (4) so as to rotate said central wheel body (4) with respect to said intermediate connection element (70) about said wheel rotation axis (R-R); wherein: said rotary advancement actuator assembly (80) is contained at least partially within said wheel encumbrance volume (2); said rotary steering actuator assembly (50) is contained at least partially within said wheel encumbrance volume (2).

Description

"ACTIVE WHEEL ASSEMBLY FOR MOVING A MOVABLE ROBOT ALONG A SUPPORT SURFACE , AND MOVABLE ROBOT COMPRISING SAID WHEEL ASSEMBLY"DESCRIPTIONField of the invention

[0001] The present invention relates to an active wheel assembly for a movable robot which is easy to use , capable of supporting humans in their daily activities with a high degree of mobility, and capable of dealing with uneven or bumpy terrain, e . g . , unpaved surfaces .Background art

[0002] In the field of movable robots , the problem of providing the robot with the ability to move over a surface with high flexibility of movement is highly felt .

[0003] For this purpose , the use of motori zed wheels , sometimes having a wheel advancement motor built into the wheel itsel f , is known .

[0004] Solutions which mount wheels on the sides o f a robot base are known to allow a low positioning of the robot base with respect to a support surface . In this case , the use of a wheel support arm which extends laterally from the base of the robot is known . In order to allow steering the possibly motori zed wheel , such an arm is constrained to rotate about a steering axis which remains outside the wheel .

[0005] This configuration has the following disadvantages :

[0006] A reactive torque is generated on the steering axis when the robot accelerates or decelerates or when it moves on a slope .

[0007] Another disadvantage is that the quadrilateral support base obtained by connecting the four points of contact between the wheels and the floor varies in shape and si ze according to the steering angles of each wheel .

[0008] In the lateral movement configuration, the base rectangle is too narrow and, furthermore , the short side is parallel to the rolling direction of the wheels .

[0009] Solutions are also known in which these wheels are placed below the base of the robot in order to position the steering axis aligned with a contact point between the wheel and the floor to overcome the aforesaid disadvantages . However, this solution has the disadvantage of preventing the robot base from being placed in a position close to the floor .

[0010] Furthermore , for the aforesaid reasons , this solution does not allow using large-diameter wheels because this would raise the height of the center of gravity of the robot , reducing the stability thereof .

[0011] WO 2023 / 102319 shows a solution in which"Mecanum" wheels are used under the robot base .

[0012] This solution is not suitable for large-diameter wheels because it would raise the center of gravity of the robot reducing the stability thereof . Furthermore , Mecanum wheels are expensive , a source of vibration and noise , and less suitable for unpaved outdoor surfaces .

[0013] Therefore , the need is felt to provide an active wheel assembly for a movable robot capable of providing the movable robot with high stability during its movement also on an uneven and / or sloping support surface , with a high degree of mobility and flexibility of movement . Summary of the invention

[0014] It is the obj ect of the present invention to devise and provide an active wheel assembly which allows meeting the aforesaid needs and at least partially obviating the drawbacks complained of above with reference to the prior art .

[0015] In particular, it is an obj ect of the present invention to provide an active wheel assembly for a movable robot which can provide the movable robot with high stability during its movement also on an uneven and / or sloping support surface , ensuring a high degree of mobility and flexibility of movement .

[0016] In particular, it is an obj ect of the present invention to provide an active wheel assembly for a movable robot which simultaneously allows using a largewheel diameter and placing the center of gravity of the robot in a low position, close to the support surface , thus allowing the robot to move stably even in unstructured, uneven or sloping outdoor environments .

[0017] It is a further obj ect of the present invention to provide a movable robot which allows meeting the aforesaid needs and at least partially obviating the drawbacks complained of above with reference to the prior art .

[0018] These and further obj ects and advantages are achieved by an active wheel assembly according to independent claim 1 , as well as by a movable robot as described in independent claim 21 .

[0019] In a general embodiment , the active wheel assembly for a movable robot can provide the movable robot with a high degree of mobility in unstructured outdoor or indoor environments , and high stability during movement .

[0020] In particular, the active wheel assembly can make the movable robot suitable for use as a personal assistant in various human activities , such as manufacturing, healthcare , logistics , agriculture , security, and surveillance .

[0021] Further obj ects , solutions , and advantages are present in the embodiments described below and claimed inthe dependent claims .Brief description of the drawings

[0022] The invention will be shown below by the description of embodiments thereof , given by way of nonlimiting example , with reference to the accompanying drawings , in which :

[0023] - figure 1 shows an angled view of an active wheel assembly according to the invention fixed to a base portion of a movable robot ;

[0024] - figure 2 shows a rear view of the active wheel assembly in figure 1 according to the wheel rotation axis ;

[0025] - figure 3 shows a section view of the wheel assembly in figure 2 , through a section plane I I I containing the rotation axis of the wheel and the steering axis ;

[0026] - figure 4 shows a section view of the wheel assembly in figure 2 , through a section plane IV containing the wheel rotation axis and orthogonal to section plane I I I ;

[0027] figures 5 and 6 show the section view in figure 4 , in which the wheel is shown with its own wheel rotation axis in two respective angular end positions ;

[0028] - figure 7 shows an angled view of the active wheel assembly in figure 1 ;

[0029] - figure 8 shows an angled view of a movable robot according to the invention, comprising 4 active wheels as in figure 1 ;

[0030] - figure 9 shows a top view of the movable robot in figure 8 , in which the active wheels are aligned along two planes parallel to each other for moving the robot along a straight advancement direction parallel to the planes ;

[0031] figure 10 shows a top view of the movable robot in figure 8 , in which two front active wheels are rotated to vary the advancement direction of the robot with respect to the direction in figure 6 , according to the known Ackermann configuration related to the steering of a road transport vehicle , such as a car ;

[0032] figure 11 shows a top view of the movable robot in figure 8 , in which all wheels are aligned along two planes parallel to each other, which are orthogonal to those in figure 6 , to implement a movement of the movable robot in a straight direction which is orthogonal with respect to that in figure 6 ;

[0033] figure 12 shows a top view of the movable robot in figure 8 , in which the four active wheels are arranged tangent to a circle having its center in the center of the base element of the movable robot to allow a rotation of the robot on the support plane about such acenter point ;

[0034] figure 13 shows a top view of the movable robot in figure 8 , in which the four wheels are arranged at angles such as to perform a generic curved traj ectory, in which each of the front wheel pair and the rear wheel pair are actuated in the Ackermann configuration . Description of preferred embodiments

[0035] Hereafter, reference will be made to the term " axial" direction, or " axially" with reference to the wheel , to indicate a direction coincident with or parallel to the wheel rotation axis R-R .

[0036] Furthermore , reference will be made to the term " radial" direction, or " radially" with reference to the wheel , to indicate a direction orthogonal to and passing through the wheel rotation axis R-R .

[0037] An active wheel assembly according to the invention is shown in the figures and indicated by reference numeral 1 as a whole .

[0038] "Active" wheel means a motori zed wheel .

[0039] The active wheel assembly 1 is configured to move a movable robot 100 along a support surface , e . g . , a hori zontal or sloping floor .

[0040] The active wheel assembly 1 comprises a wheel 10 defining a wheel rotation axis R-R and a wheel encumbrance volume 2 delimited between two axial endplanes Pl , P2 of said wheel parallel to each other and orthogonal to said wheel rotation axis R-R and a cylindrical radial end surface SC of said wheel about said wheel rotation axis R-R .

[0041] The wheel 10 comprises an annular casing body 3 coaxial with said wheel rotational axis R-R, and adapted to rest on said support surface and coaxial with said wheel rotation axis R-R, and a central wheel body 4 about which said annular casing body 3 is fixed .

[0042] The wheel 10 defines a median wheel plane M-M orthogonal to the wheel rotation axis R-R and central with respect to a width L of the annular casing body 3 measured parallel to the wheel rotation axis R-R .

[0043] Furthermore , the wheel assembly 1 comprises a support assembly 20 for connecting the wheel 10 to a base portion 101 of the movable robot 100 .

[0044] The support assembly 20 comprises a fixing end 28 for fixing said support assembly 20 to said base portion 101 of said movable robot 100 , a support bracket 21 and an intermediate connection element 70 .

[0045] The wheel 10 is rotatably engaged to the intermediate connection element 70 about the wheel rotation axis R-R, and the intermediate connection element 70 is rotatably engaged to said support bracket 21 about a steering axis S-S .

[0046] The wheel rotation axis R-R is orthogonal to the steering axis S-S at an incidence point C and rotatable about the steering axis S-S between two angular end positions of the wheel rotation axis R-R .

[0047] According to an embodiment , said angular end positions of the wheel rotation axis define an angular steering sector having angular amplitude greater than 90 ° .

[0048] According to an embodiment , the support assembly 20 defines a longitudinal support plane L-L containing the steering axis S-S and passing through said fixing end 28 .

[0049] According to an embodiment , said longitudinal support plane lies between said two angular end positions of the wheel rotation axis R-R .

[0050] According to an embodiment , the longitudinal support plane lies at a central angular position between said two end angular positions of the wheel rotation axis R-R .

[0051] Preferably, in use , the steering axis S-S is arranged orthogonally to the support surface and the wheel rotation axis R-R is arranged parallel to the support surface .

[0052] The support assembly 20 comprises a rotary steering actuator assembly 50 connected to the supportbracket 21 and the intermediate connection element 70 so as to rotate the intermediate connection element 70 with respect to the support bracket 21 about said steering axis S-S .

[0053] The support assembly 20 further comprises a rotary advancement actuator assembly 80 connected to the intermediate connection element 70 and to the central wheel body 4 so as to rotate the central wheel body 4 with respect to the intermediate connection element 70 about the wheel rotation axis R-R .

[0054] The rotary advancement actuator assembly 80 is contained at least partially within said wheel encumbrance volume 2 , preferably the rotary advancement actuator assembly 80 is contained entirely within said wheel encumbrance volume 2 .

[0055] The rotary steering actuator assembly 50 is contained at least partially in the wheel encumbrance volume 2 , preferably the steering rotary actuator assembly 50 is contained within the wheel encumbrance volume 2 for most of its si ze .

[0056] According to an embodiment , the rotary steering actuator assembly 50 comprises a steering stator 51 fixed to the support bracket 21 and a steering rotor 52 fixed to the intermediate connection element 70 .

[0057] According to an embodiment , the steering rotor52 is coaxial with the steering axis S-S .

[0058] According to an embodiment , the rotary advancement actuator assembly 80 comprises an advancement stator 81 fixed to said intermediate connection element 70 and an advancement rotor 82 fixed to the central wheel body 4 .

[0059] According to an embodiment , the advancement stator 82 is coaxial with the wheel rotation axis R-R .

[0060] The active wheel assembly 1 having the steering rotor 52 coaxial with the steering axis S-S and the advancement rotor 82 coaxial with the wheel rotation axis R-R, is thus constructionally and kinematically simple and compact .

[0061] According to an embodiment , the rotary steering actuator assembly 50 is a steering electric motor 53 , or the steering actuator assembly 50 comprises a steering electric motor 53 .

[0062] According to an embodiment , the electric steering motor is arranged at least partially within the wheel encumbrance volume 2 .

[0063] In other words , the rotary steering actuator assembly 50 is preferably formed by an electric motor contained at least partially, preferably for most of its si ze , even more preferably contained completely, within the wheel encumbrance volume 2 , having its stator fixedto the support bracket 21 and its rotor fixed to the intermediate connection element 70 .

[0064] A compact , sel f-contained configuration of the wheel assembly 1 is thus obtained .

[0065] According to another embodiment , the rotary steering actuator assembly 50 comprises an electric motor contained at least partially, preferably for most of its si ze , even more preferably contained completely, within the wheel encumbrance volume 2 . In this case , in addition to the electric motor, there may be a speed reduction unit external to the electric motor and mounted thereon .

[0066] According to an embodiment , the rotary advancement actuator assembly 80 is an electric advancement motor 83 , or the rotary advancement actuator assembly 80 comprises an electric advancement motor 83 .

[0067] According to an embodiment , the electric advancement motor is arranged at least partially within the wheel encumbrance volume 2 .

[0068] In other words , the rotary advancement actuator assembly 80 preferably consists of an electric motor contained at least partially, preferably for most of its si ze , even more preferably contained completely, within the wheel encumbrance volume 2 , having its stator fixed to the intermediate connection element 70 and its rotor fixed to the central wheel body 4 .

[0069] A compact , sel f-contained configuration of the wheel assembly 1 is thus obtained .

[0070] According to another embodiment , the rotary advancement actuator assembly 80 comprises an electric motor contained at least partially, preferably for most of its si ze , even more preferably contained completely, within the wheel encumbrance volume 2 .

[0071] In this case , in addition to the electric motor, there may be a speed reduction unit external to the electric motor and mounted thereon .

[0072] According to an embodiment , the central wheel body 4 has a central cavity 5 open towards the support assembly 20 , the central cavity 5 containing at least partially said rotary steering actuator assembly 50 and said rotary advancement actuator assembly 80 therein .

[0073] According to a preferred embodiment , the electric steering motor 53 is contained at least partially, preferably for most of its si ze , even more preferably contained completely, within the central cavity 5 .

[0074] According to a preferred embodiment , the electric advancement motor 83 is contained at least partially, preferably for most of its si ze , even more preferably contained completely, within the central cavity 5 .

[0075] According to an embodiment , the central wheel body 4 has a central body wall 6 which at least partially surrounds said central cavity 5 .

[0076] According to an embodiment , the central body wall 6 has a plurality of ventilation openings 7 configured to cool said rotary advancement actuator assembly 80 and said rotary steering actuator assembly 50 .

[0077] According to an embodiment , the central body wall 6 is devoid of ventilation openings .

[0078] According to an embodiment , the central wheel body 4 is substantially cup-shaped, or bell-shaped .

[0079] In other words , the central wheel body 4 has a cross section taken along a section plane containing the wheel rotation axis R-R, shaped like the letter "C" .

[0080] According to an embodiment , the steering axis S- S lies along the median wheel plane M-M .

[0081] The steering axis S-S thus falls in the center of the contact area between the annular casing body 3 and the support surface .

[0082] In other words , the point defined as the intersection of the steering axis S-S and the support surface is located at the center of the Hertzian pressure area generated between each wheel and the support surface .

[0083] In other words , the incidence point , or intersection point , C between the wheel rotation axis R-R and the steering axis S-S is located in the center of the annular casing element 3 , and thus in the center of gravity of the annular casing element 3 .

[0084] These features result in the advantage that during the steering action, only a small contact area of the annular casing body 3 with the support surface is subj ected to torsion, thus preserving the annular casing body 3 from wear .

[0085] In particular, this configuration further solves some dynamic problems of the robot to which the active wheels 1 are connected during its movement .

[0086] Indeed, when the robot accelerates or decelerates , or when it moves on a slope , this configuration avoids generating reactive torque on the steering axis S-S , which would inevitably be generated i f the steering axis were outside the median plane M-M .

[0087] Furthermore , in the case of movable robot having four active wheels 1 , this configuration allows avoiding changing, during steering, the shape and si ze of the support quadrilateral formed by the four contact points of the four active wheels on the support surface .

[0088] Furthermore , in the case of a movable robot having four active wheels 1 , this configuration allowsavoiding excessively narrowing the aforementioned support quadrilateral according to one direction at given angular wheel steering positions .

[0089] In the case of movable robot having four active wheels 1 , since the steering axis S-S passes through the center of the annular casing element , the two dimensions of the ideal rectangle obtained by connecting the four contact points of each wheel with the floor do not depend on the steering angle configuration . This allows the movable robot to maintain good stability even during lateral movement .

[0090] One of the most interesting advantages due to the position of point "C" in the center of the wheel is that when the forward actuator assemblies are stationary and the steering actuator assemblies rotate , the robot frame , and thus the payload, does not move .

[0091] The steering axis S-S passing through the center of the annular casing element simpli fies the control system and reduces the reactive torque applied to the steering motors to zero when the robot accelerates or when it moves down a slope . This feature also has the signi ficant advantage that the support base is a rectangle the shape and si ze of which does not change during the operation of the steering actuators .

[0092] The large wheel diameter allows maximi zingcompactness , agility, stability . This was made possible by the special design of the wheels with the steering actuator assembly and the forward actuator assembly integrated into the wheel volume .

[0093] According to an embodiment , the annular casing element 3 has a maximum diameter having a value between 300 mm and 500 mm, preferably between 370 mm and 400 mm .

[0094] Thus , the active wheel assembly 1 allows dealing with uneven terrain and small obstacles .

[0095] According to an embodiment , the annular casing element 3 is made of rubber .

[0096] According to an embodiment , the support bracket 21 extends along the longitudinal support plane L-L .

[0097] According to an embodiment , the support bracket 21 has a first free end 21 ' fixed to the steering stator 51 and an opposite second free end 21 ' ' , and wherein the intermediate connection element 70 is hinged to the second free end 21 ' ' of the support bracket 21 about the steering axis S-S , on the side opposite to the steering actuator assembly 50 , with respect to the wheel rotation axis R-R .

[0098] According to an embodiment , the support bracket 21 has a symmetrical shape with respect to the wheel rotation axis R-R .

[0099] According to an embodiment , the support bracket21 is substantially shaped like the letter "C" .

[0100] This allows for a compact wheel assembly design .

[0101] According to an embodiment , the support bracket 21 is substantially shaped like the letter "C" and the central wheel body 4 has a cross section obtained by means of a section plane containing the wheel rotation axis R-R, shaped like the letter "C" , in which these shapes are opposed to each other, so that the support bracket 21 is partially inside the central wheel body 4 .

[0102] These special geometries allow the rotary advancement actuator assembly 80 to rotate about the steering axis S-S within the support bracket 21 , and the support bracket 21 , oriented in the opposite direction, can rotate within the wheel encumbrance volume when the steering angle is large .

[0103] According to an embodiment , the support bracket 21 comprises two mutually identical flat-plate bracket elements 21A, 21B parallel to the longitudinal support plane L-L, arranged on opposite sides with respect to the longitudinal support plane L-L and equidistant from the longitudinal support plane L-L .

[0104] According to an embodiment , the support assembly 20 comprises an articulated parallelogram mechanism 23 interposed between said fixing end 28 and said support bracket 21 , configured to allow a translation of thesupport bracket 21 along the longitudinal support plane L-L .

[0105] According to an embodiment , the articulated parallelogram mechanism 23 comprises two hal f articulate parallelogram mechanisms 23A and 23B mutually identical and parallel to the longitudinal support plane L-L, arranged on opposite sides with respect to said longitudinal support plane L-L and equidistant from said longitudinal support plane L-L .

[0106] In this case , the articulated parallelogram mechanism 23 comprises four bars hinged at their respective ends . Such a configuration allows movement of the steering axis S-S with respect to the fixing end 28 , only along the longitudinal support plane L-L .

[0107] In other words , the articulated parallelogram mechanism 23 allows the movement of the steering axis S-S in the longitudinal support plane L-L, so that the steering axis always remains orthogonal to the support surface .

[0108] According to an embodiment , the support assembly 20 comprises a shock-absorber device 24 associated with the articulated parallelogram mechanism 23 arranged so as to elastically counteract the movements of the support bracket 21 from an equilibrium position thereof .

[0109] The shock-absorber device 24 allows using aharder material to make the annular casing element 3 , thereby increasing ef ficiency and therefore the battery li f e .

[0110] According to an embodiment , the intermediate connection element 70 comprises a sleeve portion 71 coaxial with said wheel rotation axis R-R containing said rotary advancement actuator 80 therein .

[0111] According to an embodiment , the electric advancement motor 83 is contained, preferably completely, within said sleeve portion 71 .

[0112] According to another aspect of the present invention, the aforesaid obj ects and advantages are achieved by a movable robot 100 capable of moving on a support surface .

[0113] The movable robot 100 comprises a base structure 102 adapted to support one or more loads , at least two active wheel assemblies 1 according to any of the features described above , in which each wheel assembly 1 is fixed to a respective portion 101 of the base structure 102 of the movable robot 100 .

[0114] The movable robot 100 further comprises an electronic control unit 105 , e . g . programmable , connected to said rotary steering actuator 50 and said rotary advancement actuator 80 of each of said at least two active wheel assemblies 1 .

[0115] The movable robot 100 comprises an electric battery connected to said electronic control unit .

[0116] According to an embodiment , said at least two active wheel assemblies 1 are mounted laterally with respect to said base structure 102 of said movable robot 100 .

[0117] A wider support base and a lower height of the center of gravity of the robot , and therefore high stability, are thus obtained .

[0118] According to an embodiment , said at least two active wheel assemblies 1 are arranged with their respective , mutually orthogonal longitudinal support planes L-L .

[0119] According to an embodiment , the movable robot 100 comprises four active wheel assemblies 1 according to any of the features described above .

[0120] For example , the four active wheel assemblies 1 are fixed in the four vertices of a quadrilateral , preferably rectangular, base structure 102 .

[0121] According to an embodiment , all said wheel assemblies are mutually equal , or have mutually equivalent features , e . g . they are configured in right configuration or left configuration, in a mutually specular shape .

[0122] According to an embodiment , the wheel rotationaxis R-R can rotate about the steering axis S-S between two angular end positions which define an angular steering sector having angular amplitude greater than 90 ° .

[0123] This allows the following types of movements for the robot :- translation with fixed orientation- single or double Ackermann steering- pivoting in position, i . e . , rotation with zero radius- lateral translation .

[0124] Note that this kinematic arrangement is very di f ferent from that of a holonomic or omnidirectional robot because they do not allow all directions of motion for every j oint configuration . Omnidirectional robots are usually equipped with four "Mecanum" wheels , the steering system is needed i f standard wheels are used, which means that eight active j oints are needed, i . e . , four drive wheels + four steering systems , instead of only four active j oints .

[0125] Those skilled in the art may make changes and adaptations to the embodiments of the device described above or replace elements with others which are functionally equivalent in order to meet contingent needs without departing from the scope of the following claims . Each of the features described as belonging to a pos sibleembodiment can be made irrespective of the other embodiments described .

Claims

CLAIMS1. An active wheel assembly (1) for moving a movable robot (100) along a support surface, comprising:- a wheel (10) defining a wheel rotation axis (R-R) and a wheel encumbrance volume (2) delimited between two axial end planes (Pl, P2) of said wheel parallel to each other and orthogonal to said wheel rotation axis (R-R) and a cylindrical radial end surface (SC) of said wheel about said wheel rotation axis (R-R) , said wheel (10) comprising a central wheel body (4) coaxial with said wheel rotation axis (R-R) , an annular casing body (3) fixed about said central wheel body (4) and coaxial with said wheel rotation axis (R-R) , said annular casing body (3) being adapted to rest on said support surface, said wheel defining a median wheel plane (M-M) orthogonal to the wheel rotation axis (R-R) and central with respect to a width of the annular casing body (3) measured parallel to the wheel rotation axis (R-R) ,- a support assembly (20) for connecting said wheel (10) to a base portion (101) of said movable robot (100) ;- said support assembly (20) comprising a fixing end (28) for fixing said support assembly (20) to said base portion (101) of said movable robot (100) , a support bracket (21) and an intermediate connection element (70) , said wheel (10) being rotatably engaged with saidintermediate connection element (70) about said wheel rotation axis (R-R) , and said intermediate connection element (70) being rotatably engaged with said support bracket (21) about a steering axis (S-S) orthogonal to said wheel rotation axis (R-R) , said wheel rotation axis (R-R) being rotatable about said steering axis (S-S) between two angular end positions of the wheel rotation axis (R-R) ;- said support assembly (20) comprising a rotary steering actuator assembly (50) connected to said support bracket (21) and said intermediate connection element (70) so as to rotate said intermediate connection element (70) with respect to said support bracket (21) about said steering axis (S-S) , and a rotary advancement actuator assembly (80) connected to said intermediate connection element (70) and to said central wheel body (4) so as to rotate said central wheel body (4) with respect to said intermediate connection element (70) about said wheel rotation axis (R-R) ; wherein : said rotary advancement actuator assembly (80) is contained at least partially within said wheel encumbrance volume (2) ; said rotary steering actuator assembly (50) is contained at least partially within said wheelencumbrance volume (2) .

2. An active wheel assembly (1) according to claim 1, wherein said rotary steering actuator assembly (50) comprises a steering stator (51) fixed to said support bracket (21) and a steering rotor (52) fixed to said intermediate connection element (70) .

3. An active wheel assembly (1) according to claim 2, wherein said steering rotor (52) is coaxial with said steering axis (S-S) .

4. An active wheel assembly (1) according to claim 1, wherein said rotary advancement actuator assembly (80) comprises an advancement stator (81) fixed to said intermediate connection element (70) and an advancement rotor (82) fixed to said central wheel body (4) .

5. An active wheel assembly (1) according to claim 4, wherein said advancement rotor (82) is coaxial with said wheel rotation axis (R-R) .

6. An active wheel assembly (1) according to at least one preceding claim, wherein said rotary steering actuator assembly (50) is, or comprises, an electric steering motor ( 53 ) .

7. An active wheel assembly (1) according to claim 6, wherein said electric steering motor is arranged at least partially within said wheel encumbrance volume (2) .

8. An active wheel assembly (1) according to at least onepreceding claim, wherein said rotary advancement actuator assembly (80) is, or comprises, an electric advancement motor ( 83 ) .

9. An active wheel assembly (1) according to claim 8, wherein said electric advancement motor is arranged at least partially within said wheel encumbrance volume (2) .

10. An active wheel assembly (1) according to at least one preceding claim, wherein said steering axis (S-S) lies along said median wheel plane (M-M) .

11. An active wheel assembly (1) according to at least one preceding claim, wherein said central wheel body (4) has a central cavity (5) open towards said support assembly (20) , said central cavity (5) containing at least partially said rotary steering actuator assembly (50) and said rotary advancement actuator assembly (80) therein .

12. An active wheel assembly (1) according to claim 11, wherein said central wheel body (4) has a central body wall (6) at least partially surrounding said central cavity (5) , wherein said central body wall (6) has a plurality of ventilation openings (7) configured to cool said rotary advancement actuator assembly (80) and said rotary steering actuator assembly (50) .

13. An active wheel assembly (1) according to at least one preceding claim, wherein said support assembly (20)defines a longitudinal support plane (L-L) containing said steering axis (S-S) and passing through said fixing end (28) , wherein said central support plane (L-L) lies between said two angular end positions of the wheel rotation axis (R-R) .

14. An active wheel assembly (1) according to claim 13, wherein said support bracket (21) extends along said longitudinal support plane (L-L) .

15. An active wheel assembly (1) according to claim 2, wherein said support bracket (21) has a first free end (21' ) fixed to said steering stator (51) and an opposite second free end (21' ' ) , and wherein said intermediate connection element (70) is hinged to said second free end (21' ' ) of said support bracket (21) about said steering axis (S-S) , on the side opposite to said steering actuator assembly (50) , with respect to said wheel rotation axis (R-R) .

16. An active wheel assembly (1) according to claim 15, wherein said support bracket (21) is substantially shaped like the letter "C" and / or is symmetrical in shape with respect to the wheel rotation axis (R-R) .

17. An active wheel assembly (1) according to claim 15 or 16, wherein said support bracket (21) comprises two mutually identical flat-plate bracket elements (21A, 21B) parallel to the longitudinal support plane (L-L) ,arranged on opposite sides with respect to said longitudinal support plane (L-L) and equidistant from said longitudinal support plane (L-L) .

18. An active wheel assembly (1) according to at least one preceding claim, wherein said support assembly (20) comprises an articulated parallelogram mechanism (23) interposed between said fixing end (28) and said support bracket (21) , configured to allow a translation of the support bracket (21) along the longitudinal support plane (L-L) .

19. An active wheel assembly (1) according to claim 18, wherein said support assembly (20) comprises a shock- absorber device (24) associated with said articulated parallelogram mechanism (23) arranged so as to elastically counteract the movements of the support bracket (21) from an equilibrium position thereof.

20. An active wheel assembly (1) according to at least one preceding claim, wherein said intermediate connection element (70) comprises a sleeve portion (71) coaxial with said wheel rotation axis (R-R) containing said rotary advancement actuator (80) therein.

21. A movable robot (100) capable of moving on a support surface, comprising:- a base structure (102) adapted to support one or more loads ;- at least two active wheel assemblies (1) according to at least one of the preceding claims, each wheel assembly (1) being fixed to a respective portion (101) of said base structure (102) of said movable robot (100) ; an electronic control unit (105) connected to said rotary steering actuator (50) and said rotary advancement actuator (80) of each of said at least two active wheel assemblies ( 1 ) ; an electric battery connected to said electronic control unit.

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