Rotational joint unit assembly for articulated structure

Abstract

The invention in the present application relates to a rotational joint unit assembly (100), said joint unit assembly comprising: at least one rotational joint unit (10; 10'; 10") intended for connecting a first (202, 203, 204) and a second element (202, 203, 204) of an articulated structure (200; 200'), and one, or more accessories (50) such as a brake, a motor, an encoder or a stroke limiter attached to the joint unit (10; 10'; 10") to provide the desired characteristics to the rotational joint unit assembly (100), wherein each of the accessories comprises a rotational shaft extension element (52) extending coaxially to axis A, and an accessory housing (51) surrounding said shaft extension element (52), said rotational shaft extension element (52) is attached to the rotational shaft (14) with the attachment means and the accessory housing (51) is fastened to the unit body (11; 11'; 11").

Description

[0001] ROTATIONAL JOINT UNIT ASSEMBLY FOR ARTICULATED STRUCTURE.

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a rotational joint unit assembly intended for connecting a first and a second element of an articulated structure.

[0004] BACKGROUND

[0005] Handling different types of equipment and tools during manufacturing work often involves different support structures to reduce the loads on the operator and / or robotic devices to improve the efficiency. These support structures and robotic devices are made of different structural elements that are assembled with several different types of joints to articulated structures that are adapted to the specific needs in the different applications.

[0006] To ensure the desired functionality of each support structure or robotic device several different elements and different types of rotational joints and fittings are integrated in each articulated structure. The different rotational elements and types of joints are designed for a certain application and / or purpose, with fixed dimensions and performance optimized for the specific application which makes the design and manufacturing process extensive, complex and in the end the total costs for the different support structures or robotic devices high.

[0007] The aim of the present invention is consequently to facilitate the design and manufacturing of articulated structures for supporting different types of equipment and tools and robotic devices.

[0008] SUMMARY OF INVENTION

[0009] According to the present invention, a rotational joint unit assembly intended for connecting a first and a second element of an articulated structure is provided. The rotational joint unit assembly comprising: at least one rotational joint unit intended for connecting a first and a second element of an articulated structure, said joint unit comprising: a unit body comprising: an internal recess extending along an axis A through the unit body; and first element securing means arranged in an outside surface of the unit body, said first element securing means are intended for securing the unit rotational joint unit to the first element of the articulated structure, a rotational shaft with a first and a second end arranged in the recess in the unit body and extending along axis A, at least one bearing arranged within the unit body to support the rotational axis in radial and / or axial direction, wherein the first end of the rotational shaft comprises fastening means that are intended for securing the rotational shaft to the second element of the articulated structure, and the second end of the rotational shaft comprises attachment means intended for attaching the rotational shaft to a shaft extension element of at least one accessory such as a brake, a motor, an encoder or a stroke limiter, and said unit body comprises means for securing an accessory housing surrounding said shaft extension element to the unit body, and one, or more accessories such as a brake, a motor, an encoder or a stroke limiter attached to the joint unit to provide the desired characteristics to the rotational joint unit assembly, wherein each of the accessories comprises a rotational shaft extension element extending coaxially to axis A, and an accessory housing surrounding said shaft extension element, said rotational shaft extension element is attached to the rotational shaft with the attachment means and the accessory housing is fastened to the unit body.

[0010] The claimed invention will solve, or at least reduce, the problem defined above by providing a standard rotational joint unit that could be combined with one, or more, standardized accessories to a joint unit assembly with the desired features. One end of the rotational shaft is designed to interface with a structural member or the articulated structure, i.e., the first element. The other end of the shaft is designed to interface with standardized accessories. Accessories may be brakes, motors, encoders, stroke limiters or accessories adding any other feature that could be desired to adapt the support structure or robotic device to specific needs. The possibility to use the standard rotational unit according to the invention in combination with standardized accessories will facilitate the design and manufacturing process considerably since the need for designing and producing special solutions for each support structure or robotic device is eliminated. The inventive concept based on a standardized joint unit combined with different types of accessories facilitate the aftermarket since service and repairs are facilitated and the number of required spare parts reduced considerably. Furthermore, the rotational joint unit according to the invention could be used in both support structures and robotics with articulated structures.

[0011] The claimed invention provides a standard rotational joint unit assembly with one, or more, standard accessories to provide a joint unit assembly with the desired characteristics. The standard rotational unit in combination with standardized accessories will reduce the number of different joints and the time required to design and build the different support structures and robotic considerably. Furthermore, the same rotational joint unit assembly could be used in both support structures and robotics with articulated structures.

[0012] The different types of accessories will be described more in detail in the detailed description, but they all comprise a rotational shaft extension element that, when it is secured to the rotational shaft, will extend coaxially to axis A such that the functionality of the selected accessory is also affecting the rotational shaft of the joint unit.

[0013] In one embodiment of the rotational joint unit assembly, the unit body furthermore comprises a second securing means arranged in the outside surface of the unit body, said second securing means are intended for securing a first component of the articulated structure. This embodiment is advantageous since the possibility to add further components makes it possible to add further functionalities to the joint unit and the structure it is fitted in thereby reducing the need for individual solutions.

[0014] In one embodiment of the rotational joint unit assembly, the first element securing means are configured such that the first element of the articulated structure will extend in substantially transverse direction from axis A. This embodiment is favourable since this configuration will provide a simple and reliable structure where the angle between the rotational axis A and the longitudinal direction of the first element is substantially 90°.

[0015] In one embodiment of the rotational joint unit assembly, the fastening means comprises at least two recesses with internal threads arranged in the rotational shaft. At least two fastening points arranged at different locations in the end surface of the rotational shaft will ensure a fastening that is able to stand repeated operation cycles and transfer the necessary momentum and forces that are generated during use.

[0016] In one embodiment of the rotational joint unit assembly, the attachment means comprises at least two recesses with internal threads arranged in the rotational shaft. At least two attachment points arranged at different locations in the end surface of the rotational shaft will ensure a fastening that is able to stand repeated operation cycles and transfer the necessary momentum and forces that are generated during use.

[0017] In one embodiment of the rotational joint unit assembly, the attachment means comprises guiding elements intended to guide the accessory to the intended position in relation to the rotational joint unit to facilitate the attachment of the accessory to the joint unit.

[0018] In one embodiment of the rotational joint unit assembly, the first and / or the second end of the rotational shaft has a surface structure that will prevent movement between the rotational shaft and the first element and / or the rotational shaft and the accessory. The surface structure could for example be an undulating structure, teeth, splines or any other surface structure that increase the friction or mechanically locks the contact surfaces to each other to prevent movements between the rotational shaft and the and structure element or accessory attached to the joint unit. In one embodiment of the rotational joint unit assembly, at least a section of the rotational shaft is hollow, said section is arranged in the centre of the rotational shaft to reduce the weight of the joint unit. The hollow section could furthermore be used for cables or wires for supplying power and / or data as well as hoses for pressurized air to and from the rotational joint unit.

[0019] In one embodiment of the rotational joint unit assembly, each of the rotational shaft extension elements in the accessories comprises a first and a second end, said first end is provided with an interface configured to be attached to the fastening means on the rotational shaft, and the second end comprises identical fastening means as the rotational shaft such that the interface on the second end of the rotational shaft extension element of an accessory attached to the rotational joint unit is identical as the one of the rotational joint unit to make it possible to attach further accessories to the accessory fitted to the rotational joint unit. This embodiment is very favourable since it provides a simple and reliable solution that makes it possible to attach several different accessories to the joint unit and change or extend the functionality of the rotational joint unit assembly if the desired functionality is changed.

[0020] One embodiment of the rotational joint unit assembly further comprises a control unit configured to monitor and / or operate the rotational joint unit and / or the one or more accessories, said control unit is either arranged as an integrated part in the joint unit assembly or externally and communicating with the joint unit and or the attached assembly or assemblies.

[0021] In one embodiment of the rotational joint unit assembly, the rotational shaft and the rotational shaft extension element have substantially the same radius.

[0022] In one embodiment of the rotational joint unit assembly, the fastening means on the rotational joint unit and the accessories have identical male / female configuration. The male / female configuration could for example be treaded holes in the rotational shaft and the shaft extension element and corresponding screws or bolts extending through the shaft extension element to attach the accessories to the rotational shaft of the joint unit.

[0023] In one embodiment of the rotational joint unit assembly, each of the accessories comprises a housing with a shape in the plane transvers to axis A corresponding to the shape of the rotational joint unit body. The housing of the accessories preferably has a shape and size that is substantially the same, or smaller, than the joint unit housing to provide a joint unit assembly with smooth peripheral shape that will not interfere more than necessary with surrounding structures and equipment. Each accessory housing preferably has a substantially circular shape in the plane transvers to axis A and substantially the same radius, so they are easy to attach to each other.

[0024] One embodiment of the rotational joint unit assembly, comprises air; power and / or data communication supply to the joint unit and an air, power and / or data connection point arranged in a second side surface on the unit body such that air, power and / or data can be transferred to a corresponding air, power and / or data connection point in a first side wall of the accessory facing the second side surface when the accessory is attached to the joint unit, and a second end wall, on opposite side of the accessory, comprises an identical connection point as the joint so that power can be supplied to further accessories. This embodiment makes easy to provide air, power and / or data communication to the joint unit and the one or more accessories of the rotational joint unit assembly.

[0025] In one embodiment of the rotational joint unit assembly, the rotational joint unit assembly comprises at least two accessories and the attachment means comprises at least two screws extending through the at least two accessory housings to attach the accessories to the rotational joint unit. This embodiment reduces the number of screws and facilitates the assembly.

[0026] Whilst the invention is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings as herein described in detail. It should be understood, however, that the detailed description herein and the drawings attached hereto are not intended to limit the invention to the particular form disclosed. Rather, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the appended claims.

[0027] Any reference to prior art documents or comparative examples in this specification is not to be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.

[0028] As used in this specification, the words “comprise”, “comprising”, and similar words are not to be interpreted in the exclusive or exhaustive sense. In other words, they are intended to mean “including, but not limited to”.

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] One or more embodiments will be described, by way of example only, and with reference to the following figures, in which:

[0031] Figure 1 A schematically illustrates a perspective view of a first embodiment of a support structure or robotic device according to the invention.

[0032] Figure IB schematically illustrates a perspective view of a second embodiment of a support structure or robotic device according to the invention.

[0033] Figure 2 illustrates a perspective view of a rotational joint unit assembly according to the invention.

[0034] Figure 3 illustrates an exploded perspective view of the joint unit assembly in figure 2.

[0035] Figure 4A illustrates a perspective view of a rotational joint unit according to the invention.

[0036] Figure 4B illustrates a partly exploded perspective view of the joint unit in figure 4A.

[0037] Figure 4C illustrates a perspective view of a second embodiment of a rotational joint unit according to the invention.

[0038] Figure 4D illustrates a perspective view of the joint unit in figure 4C.

[0039] Figure 4E illustrates a perspective view of a third embodiment of a rotational joint unit according to the invention.

[0040] Figure 4F illustrates a perspective view of the joint unit in figure 4E.

[0041] Figure 5A illustrates a first perspective view of an accessory.

[0042] Figure 5B illustrates a second perspective view of the accessory in figure 5A. DETAILED DESCRIPTION

[0043] The present invention is described in the following by way of several illustrative examples. It will be appreciated that these examples are provided for illustration and explanation only and are not intended to be limiting on the scope of the present invention. Instead, the scope of the present invention is to be defined by the appended claims. Furthermore, although the examples may be presented in the form of individual embodiments, it will be recognised that the invention also covers combinations of the embodiments described herein.

[0044] In figure 1 an example of a support structure / robotic device 200 comprising several rotational joint units 10 according to the invention is illustrated. The lower end 201 of the support structure / robotic device 200 is intended to be reliably anchored to a rigid foundation, only schematically illustrated. The illustrated support structure / robotic device 200 comprises three elongated straight elements 202, 203, 204 that are connected by rotational joint units 10 according to the invention to form an articulated structure. The number of elongated elements, the lengths, dimensions, and the cross-sectional shape of the elongated elements are adapted to the intended use of the support structure / robotic device 200 and the expected loads that the support structure / robotic device 200 is expected to be exposed to.

[0045] The elongated elements 202, 203, 204 are connected in their respective ends to the adjacent elongated element by one, or two, rotational joint units depending on the desired characteristics of the support structure / robotic device 200. If one rotational joint unit is used in the connection between the two elongated elements the second elongated element will be rotatable around one axis A of rotation as in the first connection 205. If two rotational joint units are used in the connection between the two elongated elements, the second elongated element will be rotatable around two axes A of rotation as in the second connection 206 of the illustrated support structure / robotic device 200.

[0046] Consequently, the possibility of adapting the characteristics of the elongated elements in combination with the rotational joint units and the joint unit assemblies according to the invention makes it possible to adapt the support structure / robotic device to the specific needs. In the illustrated embodiment, no working tool or tool support is illustrated in the outer end of the support structure or robotic device but is selected depending on the intended work that is intended to be conducted by the installation.

[0047] In Figure IB a second embodiment of a support structure / robotic device 200' according to the invention is illustrated to give a clearer understanding of the flexibility of the joint unit 10 and joint unit assembly 100 according to the invention.

[0048] In figure 1 an example of a support structure / robotic device 200 comprising several rotational joint units 10 according to the invention is illustrated. The lower end 201 of the support structure / robotic device 200 is intended to be anchored to a rigid foundation. The foundation could also be arranged at an elevated position and the support structure / robotic device extending downwards from the foundation. This embodiment of the support structure / robotic device 200' comprises a rigid elongated element 300 that is extending in two directions from a first joint unit 301 secured to the lower end 201 such that each end of the elongated element is support rotational units 10 and structural elements 302 such that one articulated structure is formed in each end of the elongated element 300. The design of the articulated structure, i.e. the angles between the different elements as well as the dimensions of the different elements, could however be modified in several different ways without departing form the scope of the present invention.

[0049] In figure 2, a perspective view of a rotational joint unit assembly 100 according to the invention is illustrated and if figure 3 an exploded view of the same joint unit assembly is presented. The illustrated rotational joint unit assembly 100 comprises a rotational joint unit 10 and four accessories 220, 230, 240, 250, 260 attached to the rotational joint unit 10 to illustrate the general concept of the invention that is to combine the rotational joint unit 10 according to the invention with on, or more, accessories to adapt the characteristics of the rotational joint unit assembly.

[0050] The rotational joint unit 10 is intended to be used either as a separate joint unit between two structural elements or in combination with one, or more standardized accessories 220, 230, 240, 250 such as a brake, a motor, an encoder, a stroke limiter or any other desired type of functionality. All these accessories as well as the technical solutions to achieve the desired functionality are well known within technical field. Once the desired accessories are attached to the joint unit, the outer end of the last accessory is closed by a cover plate 270 to seal the joint unit assembly protect the interior of the joint unit assembly.

[0051] In figure 4 A and 4B a first embodiment of a rotational joint unit 10 according to the invention is illustrated. The rotational joint unit comprises a unit body 11 and an internal recess 12 extending along an axis A through the unit body 11. In the recess 12, a bearing 13 is arranged to support a rotational shaft 14 with a first end 17 and a second end 18 extending along axis A in radial and / or axial direction. The bearing 13 could be embodied in different ways as long as the expected radial and axial forces that the rotational shaft is exposed to are handled in an efficient way and the rotational shaft 14 is able to rotate in the unit body as intended. The illustrated bearing 13 comprises a roller bearing that will take care of the radial forces and a slide bearing arranged to handle the axial forces on the rotational shaft.

[0052] The unit body is adapted to the type of bearing that is used in the joint unit. Either the unit body is formed in one piece of material and the bearing press fitted into the intended position within the unit body. If more than one bearing is fitted within the recess these are either fitted from the same side or from the different sides of the unit body into the intended position within the recess. In an alternative embodiment of the unit body, the unit body is divided into two body sections in order to access the recess and make it possible to fit the bearing in the recess before the two sections are fitted together.

[0053] In figure 4C and 4D a second embodiment of a rotational joint unit 10' according to the invention is illustrated. This embodiment comprises the same main components but have a different type of bearing fitted within the recess in the unit body. In figure 4C and 4D the same reference numerals as for the first embodiment have been used with the addition of a ' to the reference numeral. In this embodiment a shoulder is formed within the recess. The bearing comprises a corresponding flange extending from the outside surface of the bearing and when fitted in the recces the flange is resting against the shoulder such that the bearing is maintained in the desired axial position within the unit body. This embodiment of the joint unit comprises a bearing with larger axial extension along axis A which makes it more adapted to withstand larger radial loads than the first embodiment of the joint unit. In figure 4E and 4F a third embodiment of a rotational joint unit 10" according to the invention is illustrated. This embodiment comprises the same main components as both previous embodiments but in figure 4E and 4F the reference numerals have the addition ' to the reference numeral.

[0054] Depending on the intended use of the joint unit the unit body, the bearing and the rotational shaft will have different configuration and dimensions. For example, if the expected momentum and forces are high the axial length of the bearing must be increased, and the type of bearing selected to withstand the expected forces. Consequently, different types of bearings such as crossed roller bearings, taper roller bearings and roller bearings could be used depending on the required strength and characteristics of the joint unit. Furthermore, the cost aspect and the expected working conditions for the articulated structure are aspects to take in consideration.

[0055] The three presented embodiments have a unit body with substantially the same configuration and the detailed description and reference numerals could be found in figure 4A and 4B. The unit body has a first flat side 30 that is substantially parallel to axis A. The first flat side 30 is intended to bear against an outer end surface of the adjacent structural element of the supports structure / robotic device. The rotational joint unit 10 is secured to the structural element of the supports structure / robotic device by first element securing means 31, i.e., four screws 32 extending through holes 33 in the unit body transvers to the plane of the first flat side and into the outer end surface of the adjacent structural element. In the illustrated embodiment of the joint unit, the first element securing means are configured such that the first element of the articulated structure will extend in substantially transverse direction from axis A.

[0056] The unit body 11 furthermore has a first end surface 34 surrounding the first end 17 of the rotational shaft, and a second end surface 35 surrounding the second end 18 of the rotational shaft 14. The first end surface 34 is substantially flat and configured such that the first end 17 of the rotational axis extends outside the first end surface along axis A not to limit the rotation of the structural element secured to the rotational shaft 14 in relation to the joint unit 10. The unit body could furthermore be provided with sealing / sealing rings arranged around each end of the rotational shaft to seal the passage through the unit body and protect the bearing and possible other components within the unit body.

[0057] The second end surface 35 of the unit body 11 comprises means for securing an accessory housing to the unit body 11. The accessory housing is secured to the unit body by screws (not illustrated) extending through the accessory housing parallel to axis A and into threaded holes 65 in second end surface 35 of the unit body 11.

[0058] The unit body 11 furthermore comprises a second securing means embodied as two flat side surfaces 36, 37 substantially parallel to axis A, transverse to the first flat surface 30 on opposite sides of the unit body 11, i.e., on the outside surface of the unit body 11. The second securing means are intended for securing one or more additional components (not illustrated) of the articulated structure to the joint unit 10 which could be advantageous if further structural members are needed to achieve the desired functionality of the support structure / robotic device 200. An example of this configuration is illustrated in figure IB where the side surfaces 36 and 37 are used for securing flat elements of the articulated structure to the joint unit.

[0059] The remaining side of the unit body 11, the side opposite the flat first side 30 has a substantially half cylindrical shape corresponding to the shape and dimensions of the recess and bearing extending through the joint body. The dimensions of the joint body are determined by the expected forces on the joint unit. The substantially half cylindrical side of the unit body extend between the two flat side surfaces 36, 37.

[0060] In the illustrated embodiment of the joint unit 10, a shoulder 15 is formed in the recess 12 and a corresponding groove 16 in the bearing 13 to maintain the bearing in the intended axial position within the unit body 11. This design could however by modified depending on the bearing type selected in the rotational joint.

[0061] The rotational shaft 14 has a first end 17 and a second end 18. The first end 17 of the rotational shaft 14 comprises fastening means 19 that are intended for securing the rotational shaft 14 to an adjacent elongated element of the articulated structure. The fastening means 19 are embodied as several screws 21 extending parallel to axis A from the second end 18 through holes 20 in the rotational shaft to the first end 17 to be securable in the adjacent element of the articulated structure, illustrated in figure 1. The fastening means could be modified in different ways and for example the number of screws could be changed depending on the expected forces that the joint unit will be exposed to. If two or more screws are used, they arranged at different positions around the end surface in the first end of the rotational axis. An alternative configuration would be to use one singe screw arranged in the centre of the rotational axis.

[0062] In figure 1, the first end 17 of the rotational shaft 14 is fastened to an end fitting 210 secured in the end of the structural element 203. These end fittings could be modified in many ways, alternatively the first end 17 of the rotational shaft could be fastened directly to structural element and the end fitting eliminated.

[0063] If two joint units are combined in one connection point of the articulated structure, as in connection point 206 in the articulated structure in figure 1, the first end 17 of the rotational shaft is secured in a connection plate 211 and the unit body 11 of the second joint unit 10 could be attached to the connection plate 211. This connection provides rotatability around two axes.

[0064] The second end 18 of the rotational shaft 14 comprises attachment means 22 intended for attaching the rotational shaft 14 to one, or more, standardized accessory such as a brake, a motor, an encoder, or a stroke limiter. The attachment means comprises three recesses 57 with internal threads arranged in the rotational shaft 14. The recesses extend parallel to axis A and are arranged at substantially equal distances from each other around the second end surface of the rotational shaft 14 to form an attachment interface for an accessory. The attachment means consequently have a male / female configuration with recesses 57 and corresponding screws 56 arranged to attach an accessory 220, 230, 240, 250 to the joint unit 10.

[0065] The different types of accessories that are intended to be used in combination with the rotational joint unit 10 according to the invention are all embodied comprising a substantially cylindrical housing 51 with the same radius as the half cylindrical part of the unit body 11. The different accessories, i.e., the brake, the motor, the encoder, and stroke limiter, of course have different component configuration inside the cylindrical housing 51 to ensure the desired functionality of the different accessories. However, the length of the housing 51 of the different types of accessories along axis A is adapted to ensure the required space for the components inside the housing 51.

[0066] Each type of accessory comprises a rotational shaft extension element 52 arranged in the centre of the cylindrical housing 51 co-axially to the cylindrical housing. The rotational shaft extension elements 52 have substantially the same radius as the rotational shaft 14 of the rotational joint unit 10 and a first end 53 and a second end 54.

[0067] The cylindrical housing 51 comprises a first end wall 61 surrounding the first end 53 of the rotational shaft extension element 52, and a second end wall 62 surrounding the second end 54 of the rotational shaft extension element 52. The first end wall 61 is substantially flat and intended to bear against the second end surface 35 of the unit body 11. The first and second end wall 61 and 62 together with possible sealings are intended to seal the accessory and protect the bearing and possible other components within the accessory housing 51. Several holes 63 extend through the cylindrical housing between the first and the second end wall parallel to axis A such that the accessory housing can be secured to the unit body or adjacent accessory housing by corresponding screws 64 extending from the second end wall via the holes 63 to the means 65 for securing and accessory housing to the unit body, alternatively in an adjacent accessory housing 51.

[0068] In an alternative embodiment an elongated screw extending through the holes 63 of all the assembled accessories are used to secure the accessories to the joint unit. This embodiment facilitates the assembly and saves time since the number of screws are reduced considerably.

[0069] The first end 53 of the rotational shaft extension element is intended to bear against the second end 18 of the rotational shaft 14 and attached to the rotational shaft 14 by attachment means embodied as three screws 55 extending parallel to axis A, and the rotational shaft extension element from the second end 54 through holes 56 in the rotational shaft extension element to the first end 53 to attach the rotational shaft extension element 52 to the rotational shaft 14.

[0070] The second end 54 of the rotational shaft extension element 52 comprises attachment means identical to the attachment means in the second end 18 of the rotational shaft 14 of the joint unit 10, i.e. three recesses 60 with internal threads arranged in the rotational shaft extension element 52 parallel to axis A substantially equal distances from each other around the second end surface of the rotational shaft extension element 52, such that a further accessory could be attached to the accessory already attached to the joint unit 10.

[0071] In other words, each accessory is designed with the same male / female interface such that the interface is brought forward to make is possible to attach further standardized accessories.

[0072] If the accessories in the joint unit assembly requires power to power one or more of the accessories wires or hoses could be arranged either internally or externally along the structural elements and the schematically illustrated accessory in figure 5A and 5B is provided with a power and / or data contact 68 arranged in the outside surface of the accessory housing 51

[0073] In one preferred embodiment, power is supplied to the joint unit via a similar air, power or data contact 68 arranged in the outside surface of the joint body and lead to each of the accessories attached to the joint unit. The air, power or data is transferred via a connection point 66 arranged on the second side surface on the unit body to a corresponding connection point 66 in the first side wall of the accessory attached to the joint unit. The second end wall of each accessory comprises an identical connection point 66 as the joint unit in the second side wall so that the air, power or data interface is brought forward from the joint unit to the accessories. The connection points preferably have a male / female configuration to provide a reliable connection between the joint unit and the accessory, alternatively between two accessories. Corresponding connections could also be provided for data to transfer data back and forth between a control unit 280, schematically illustrated in figure 2, and the joint unit and the one, or more accessories of the rotational joint unit assembly. The control unit is configured to monitor and control the operation of the rotational joint unit assembly such as for example activate and deactivate the motor and / or brake based on predetermined operation cycles and monitor the operation of the different accessories by sensors in the different accessories.

[0074] Communication between the control unit 280 and the joint unit, and the attached accessories could also be achieved by wireless communication and the joint unit and the respective accessory are then provided with the required technology to ensure transmittal and receival of the desired data to and from the control unit 280.

[0075] To facilitate the attachment of accessories to the joint unit, or an already fitted accessory, the second end of the rotational shaft and / or the second end surface of the unit body could be provided with guiding elements, alternatively a geometrical design, that guides the adjacent accessory to the intended position in relation to the joint unit, or already fitted accessory, to facilitate the attachment of the desired accessories to the joint unit. One embodiment of a guiding element is illustrated in for example figure 4A, 4D and 4F where an annular flange 71, 71 ', 71", 71 '" is extending from the second end surface of the unit body. The annular flange is intended to fit in a corresponding annular recess 72 formed in the first end wall of the accessories to guide the adjacent accessory into the intended position when attached.

[0076] Furthermore, the first and / or the second axial end of the rotational shaft as well as the first and / or second end of the rotational shaft extension elements could have a surface structure that increases the friction between the contact surfaces to prevent movement between the rotational shaft and the attached rotational shaft extension element of the accessory. The surface structure could for example be an undulating structure, teeth, splines or any other surface structure that increase the friction or mechanically locks the contact surfaces to each other to prevent movements between the rotational shaft and the and structure element or accessory attached to the joint unit.

[0077] As a further alternative, one or more splines arranged in corresponding grooves in the peripheral surface of the rotational shaft and the shaft extension element could be used to ensure a mechanically reliable and precise attachment between the rotational join unit and the one, or more accessories. In this embodiment the splines extend substantially parallel to axis A and the length selected depending on the expected momentum that will be transferred between the joint unit and the accessory. The same configuration could also be used in the fastening of the first end of the rotational shaft to the structural element of the articulated structure, i.e. a spline extending in a groove in the peripheral surface of the rotational shaft and a corresponding groove in the structural element.

[0078] As a further alternative, the attachment means of the joint unit can be embodied with a male / female configuration. For example, the second end of the rotational shaft could have a recess with a geometrical shape like for example a star, a triangle, etc extending into the rotational shaft and the first end of the shaft extension element a corresponding geometrical protrusion extending from the first end of the rotational shaft such that the protrusion is fitted in recess to transfer momentum between the rotational shaft and the shaft extension element. The male / female part could of course be switched between the rotational shaft and the shaft extension element.

[0079] In an alternative configuration, a thin washer, illustrated in figure 4 with reference numeral 74, with a thickness in the range of 0.05 mm to 1 mm is arranged between the contact surfaces of the rotational shaft and the shaft extension element. The washer is sometimes referred to as a friction shim. Both sides of the washer are covered by a friction coating that increases the friction between the contact surfaces. The increased friction makes it possible to reduce the size of the contact surfaces still ensuring that the surfaces are maintained in the intended position relative each other. This type of washer could also be used between the unit body and the first element of the articulated structure and the first end of the rotational shaft and the second element of the articulated structure. If the washer is used between the unit body and the first element the washer has a shape corresponding to the size and dimensions of the first flat side 30 of the unit body. An example of this type of washer 73 is illustrated in figure 3.

[0080] The concept of the mechanical structures of the rotational joint unit and the rotational joint unit assembly have been described in relation to the presented illustrations. However, the configuration of the fastening means and the attachment means could be modified in many ways without departing from the inventive concept described above.

[0081] Although specific examples have been referred to in the figures, it should be appreciated that these are not intended to limit the scope of the invention, which instead is intended to be defined by the scope of the appended claims.

Claims

CLAIMS1. A rotational joint unit assembly (100), said joint unit assembly comprising: at least one rotational joint unit (10; 10'; 10") intended for connecting a first (202, 203, 204) and a second element (202, 203, 204) of an articulated structure (200; 200'), said joint unit (10; 10'; 10") comprising: a unit body (11; 11 '; 11") comprising: an internal recess (12) extending along an axis A through the unit body (11; 11 '; 11"); and first element securing means (30, 31, 32, 33) arranged in an outside surface of the unit body (11; 11 '; 11"), said first element securing means (30, 31, 32, 33) are intended for securing the unit rotational joint unit (10; 10'; 10") to the first element (202, 203, 204) of the articulated structure, a rotational shaft (14) with a first (17; 17'; 17") and a second end (18; 18'; 18") arranged in the recess (12) in the unit body (11; 11 '; 11") and extending along axis A, at least one bearing (13) arranged within the unit body (11; 11 '; 11") to support the rotational shaft (14) in radial and / or axial direction, wherein the first end (17; 17'; 17") of the rotational shaft (14) comprises fastening means (20, 21) that are intended for securing the rotational shaft (14) to the second element (202, 203, 204) of the articulated structure, and the second end (18; 18'; 18") of the rotational shaft (14) comprises attachment means (57) intended for attaching the rotational shaft (14) to a shaft extension element (52) of at least one accessory (50) such as a brake, a motor, an encoder or a stroke limiter, and said unit body (11; 11 '; 11") comprises means (65) for securing an accessory housing (51) surrounding said shaft extension element (52) to the unit body (11; 11 '; 11"), and one, or more accessories (50) such as a brake, a motor, an encoder or a stroke limiter attached to the joint unit (10; 10'; 10") to provide the desired characteristics to the rotational joint unit assembly (100), wherein each of the accessories comprises a rotational shaft extension element (52) extending coaxially to axis A, and an accessory housing (51) surrounding said shaft extension element (52), said rotational shaft extension element (52) isattached to the rotational shaft (14) with the attachment means and the accessory housing (51) is fastened to the unit body (11; 11 '; 11").

2. A rotational joint unit assembly (100) according to claim 1, wherein the unit body (11; 11 '; 11") furthermore comprises a second securing means (36, 37) arranged in the outside surface ofthe unit body (11; 11 '; 11 "), said second securing means are intended for securing a first element of the articulated structure.

3. A rotational joint unit assembly (100) according to claim 2, wherein the first element securing means are configured such that the first element (202, 203, 204) of the articulated structure will extend in substantially transverse direction from axis A.

4. A rotational joint unit assembly (100) according to claim 1, 2 or 3, wherein the fastening means comprises at least two recesses (20) with internal threads arranged in the rotational shaft (14).

5. A rotational joint unit assembly (100) according to anyone of the previous claims, wherein the attachment means comprises at least two recesses (57) with internal threads arranged in the rotational shaft (14).6 A rotational joint unit assembly (100) according to anyone of the previous claims, wherein the attachment means comprises guiding elements (71) intended to guide the accessory (50) to the intended position in relation to the rotational joint unit (10; 10'; 10").

7. A rotational joint unit assembly (100) according to anyone of the previous claims, wherein the first (17; 17'; 17") and / or the second end (18; 18'; 18") of the rotational shaft (14) has a surface structure that will prevent movement between the rotational shaft (14) and the first element (202, 203, 204) and / or the rotational shaft (14) and the accessory.

8. Rotational joint unit (10; 10'; 10") according to anyone of the previous claims, wherein at least a section of the rotational shaft (14) is hollow, said section is arranged in the centre of the rotational shaft (14).

9. Rotational joint unit assembly (100) according to anyone of the previous claims, wherein each of the rotational shaft extension elements (52) in the accessories (50) comprises a first (53) and a second end (54), said first end (53) is provided with an interface configured to be attached to the fastening means on the rotational shaft (14), and the second end (54) comprises identical fastening means as the second end of the rotational shaft (14) such that the interface on the second end (54) of the rotational shaft extension element (52) of an accessory(50) attached to the rotational joint unit (10; 10'; 10") is identical as the one of the rotational joint unit (10; 10'; 10") to make it possible to attach further accessories (50) to the accessory (50) fitted to the rotational joint unit (10; 10'; 10").

10. Rotational joint unit assembly (100) according to anyone of the previous claims, wherein the rotational joint unit assembly (100) further comprises a control unit configured to monitor and / or operate the rotational joint unit (1010; 10'; 10") and / or the one or more accessories (50), said control unit is either arranged as an integrated part in the joint unit assembly (100) or externally and communicating with the joint unit (10; 10'; 10") and / or the attached assembly (50), or assemblies (50).

11. Rotational joint unit assembly (100) according to anyone of the previous claims, wherein the rotational shaft (14) and the rotational shaft extension elements (52) have substantially the same radius.

12. Rotational joint unit assembly (100) according to anyone of the previous claims, wherein fastening means on the rotational joint unit (10; 10'; 10") and the accessories (50) have identical male / female configuration.

13. Rotational joint unit assembly (100) according to anyone of the previous claims, wherein each of the accessories (50) comprises a housing (51) with a shape in the plane transvers to axis A corresponding to the shape of the rotational joint unit body (11; 11 '; 11").

14. Rotational joint unit assembly (100) according to anyone of the previous claims, further comprises air, power and / or data communication supply to the joint unit and an air, power and / or data connection point (66) arranged in a second side surface on the unit body (11; 11 '; 1") such that air, power and / or data can be transferred to a corresponding air, power and / or data connection point (66) in a first side wall of the accessory facing the second side surface when the accessory is attached to the joint unit, and a second end wall, on opposite side of the accessory, comprises an identical connection point (66) as the joint unit so that power can be supplied to further accessories.

15. Rotational joint unit assembly (100) according to anyone of the previous claims, wherein the rotational joint unit assembly (100) comprises at least two accessories (50) and the attachment means comprises at least two screws extending through the at least two accessory housings (51) to attach the accessories (50) to the rotational joint unit (10; 10'; 10").

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