WO2023232207A1

WO2023232207A1 - A robot arm joint

Info

Publication number: WO2023232207A1
Application number: PCT/DK2022/050120
Authority: WO
Inventors: Mikkel Johansen VRAA; Peter Pristed SØRENSEN; Frede Callesen
Original assignee: Universal Robots A/S
Priority date: 2022-06-03
Filing date: 2022-06-03
Publication date: 2023-12-07

Abstract

The invention relates to a robot arm joint comprising joint mechanics and joint electronics. The joint mechanics and joint electronics are enclosed in a joint housing connectable to a joint housing lid. The joint housing lid is removable fastened to said joint housing by one or more flexible arms arranged to engage with an engagement edge.

Description

A ROBOT ARM JOINT

Field of the invention

[0001] The present invention relates to a robot arm joint and a method of attaching a robot housing lid to a joint housing of the robot arm joint.

Background of the invention

[0002] In the art robot arm joints encloses joint electronics and joint mechanics in a housing closed by a lid. The lid is screwed to the housing leading to problems of holes for the screws collecting dust and dirt which is not acceptable in certain industries such as clean room applications, pharma industry and/or the medical technology industry.

Summary of the invention

[0003] The inventors have identified the above-mentioned problems and challenges related to robot arms and solved these problems by the present invention as described below.

[0004] In an aspect, the invention relates to a robot arm joint comprising joint mechanics and joint electronics, said joint mechanics and joint electronics are enclosed in a joint housing connectable to a joint housing lid, wherein said joint housing lid is removable fastened to said joint housing by one or more flexible arms arranged to engage with an engagement edge.

[0005] Such robot arm joint is advantageous in that no outer grooves in the lid or housing are needed to connect the two robot joint parts. Thereby, the risk of dust collection in such grooves is eliminated and the robot joint is both faster and easier to clean. Another effect of the present invention is that the robot arm as such becomes more clean and also easier to clean which expand the possible environments in which the robot arm is able to operate. Hence, a robot arm with joints assembled according to the present invention, can e.g. be used in clean room applications, the pharma industry and/or the medical technology industry. [0006] The robot arm joint (also sometimes referred to simply as joint) may need to be maintained or components may need to be replaced. Thus, there is a need for being able to separate the lid from the housing after they have been assembled. Therefore, the lid is removable fastened to the housing.

[0007] The joint mechanics and joint electronics should be understood as the parts comprised by a robot joint that is needed for the robot arm to work. Just to mention a few, such parts include communication interface, electric cables, sensors, encoders, motors, brackets, etc.

[0008] The flexibility of the flexible arms may origin from the arm itself i.e. the material of the arm and/or the mounting of the arm to an adaptor, housing or lid. In an embodiment, the flexibility allows to bend the arm to a position substantially perpendicular to the plan of the engagement edge. Thereby allowing an arm protruding part and an engaging edge protruding part to pass each other and thereby reach their engaged position and in that position maintain contact between the contact surfaces of the flexible arm and of the engaging edge. Note that the engaging edge may not necessarily have a protruding part.

[0009] Hence a snap or click connection of the lid to the housing is thereby established. The force needed to connect the lid and housing is limited and can easily be applied by hand of a work person.

[0010] Flexible should in this document be understood as bendable i.e. the flexible arm / finger has elastic properties in that it returns to a resting position after having been forced out of that resting position. The force required to bend the arm depends on the material and geometry of the arm. Hence one definition of a flexible arm is if it bend when a force below 100N is applied such as a force below 50N.

[0011] In an exemplary embodiment of the invention, said one or more flexible arms extend from said joint housing.

[0012] The flexible arms may be implemented as a part of the housing or as a part that can be mounted to the housing. [0013] In an exemplary embodiment of the invention, said one or more flexible arms extend from said housing lid.

[0014] The flexible arms may be implemented as a part of the lid or as a part that can be mounted to the lid.

[0015] Further it should be noted, that in an embodiment, e.g. a set of two flexible arms and two engagement edges may be implemented as part of the housing and a similar set may be implemented as part of the lid.

[0016] In an exemplary embodiment of the invention, one of said one or more flexible arms comprises at least one individual finger.

[0017] Sufficient flexibility without the risk of breaking the flexible arm when attaching the lid to the housing may be established by dividing the flexible arm into one or more so-called fingers. It should be noted, that if only one finger is present this finger could be referred to as the flexible arm.

[0018] Depending on to what extend / with which force the lid have to be attached to the housing, the number of flexible arms and fingers thereof can be determined. Hence in an embodiment, the more arms and fingers, the more difficult the lid is to remove from the housing once attached. With this said, the material and the thickness of the arms / fingers is also determining for the force needed to attach the lid.

[0019] In an exemplary embodiment of the invention, the width of said flexible arm is below 10 millimeter, such as below 7 millimeters, such as below 5 millimeters.

[0020] The flexible arm may be divided in one or more fingers (hence a reference to a finger may be a reference to an arm and vice versa) each having a width below 10 millimeters, but at the same time above 2 millimeters. This have according to an embodiment proven to be sufficiently flexible to engage with and maintain engagement with the engagement edge. It should, however, be noted that the flexibility of the fingers to a large extend depends on design hereof. Hence, if the fingers are straight or is curve, if the fingers are made of ABS (ABS; Acrylonitrile Butadiene Styrene), PLA (PLA; Polylactic acid) or other materials, etc. The resulting width should ensure a strength below the yield point so that the finger is flexible and at the same time be sufficiently strong so as to withstand a predetermined external force. In an embodiment however, the external force may be so high that dismount by destruction of a finger / arm may appear.

[0021] In an exemplary embodiment of the invention, said individual finger comprises an arm protruding part which comprises a contact surface.

[0022] The arm protruding part is advantageous in that it comprises a contact surface which engages with a contact surface of the engagement edge. In this way due to the flexibility of the arm / fingers when pushed towards the engaging position between finger and edge, the finger bends away from the engaging edge. As the arm protruding part reaches the engaging edge the bend of the finger is increased and once the protruding part reaches the engaging edge, the finger snaps / clicks back towards the engaging edge where contact then is obtained between the contact surfaces of the finger and of the engagement edge.

[0023] In an exemplary embodiment of the invention, said contact surface decline with an angle between 0 degrees and 90 degrees such as between 25 degrees and 75 degrees, such as between 35 degrees and 65 degrees.

[0024] The declining angle is measured with respect to the plan of an adaptor if the flexible arm is part of an adaptor. Alternatively, the declining angle is measured with respect to the plan of the axis of the motor of the joint. Also, the declining angle can be measured with respect to the direction in which the robot lid is moved in relation to the robot hosing during mounting/demounting or the robot lid at the robot housing.

[0025] In an exemplary embodiment of the invention, said flexible arm / individual finger comprises a spring recess.

[0026] Preferably, the spring recess is located on the opposite side of the finger than the protruding part. The spring recess is used to hold a spring (such as a circular spring) the purpose of which is to ensure that the flexible arms / fingers is maintained in a position where contact between the contact surfaces of the flexible arm and of the engagement edge is maintained. This is especially important as time goes in that the flexibility of the fingers may increase and thus by accident, a work person may unintentionally remove the lid from the housing.

[0027] In an exemplary embodiment of the invention, said engagement edge is formed in said joint housing.

[0028] The engagement edge may be implemented as a part of the lid.

[0029] In an exemplary embodiment of the invention, said engagement edge is formed in said housing lid.

[0030] The engagement edge may be implemented as a part of the house.

[0031] In an exemplary embodiment of the invention, said engagement edge is provided as a plurality of individual engagement edges aligned with the position of said flexible arms.

[0032] This is advantageous in that no additional material is used to establish an engagement edge running all around the circumference of the lid. Further, only using the space required for the engagement edge also leave room for additional features of the lid and it reduces the weight of the lid.

[0033] In an exemplary embodiment of the invention, said engagement edge is formed at least partly by an engagement edge protruding part comprising a contact surface.

[0034] The engagement edge / individual engagement edges may comprise a protruding part that extends outwards away from the contact surface of the engagement edge at which a finger such as a protruding part of the finger is adapted to rest after click- / snap-fitting thereto.

[0035] In an exemplary embodiment of the invention, said contact surface decline with an angle between 0 degrees and 90 degrees such as between 25 degrees and 75 degrees, such as between 35 degrees and 65 degrees. [0036] The declining angle is measured with respect to the plan of an adaptor if the flexible arm is part of an adaptor. Alternatively, the declining angle is measured with respect to the plan of the axis of the motor of the joint. Also, the declining angle can be measured with respect to the direction in which the robot lid is moved in relation to the robot hosing during mounting/demounting or the robot lid at the robot housing

[0037] The angle of the contact surface is determined at least partly based on requirements to the force needed to remove the lid from the housing. Hence, the closer to 0 / 90 degrees (depending on what is used as reference), the more force is required to remove the lid.

[0038] Preferably, the angle of the contact surface of the flexible arm and of the engagement edge are the same.

[0039] In an exemplary embodiment of the invention, an adaptor is mounted to said joint housing or said joint housing lid.

[0040] The use of an adaptor is advantageous in that then no modifications are needed to the housing. Thereby the present invention can be implemented without modifying the current design of the housing of the joint. This is particularly relevant in embodiment where e.g. one of the flexible arms break during assembling or disassembling of the housing and lid. If the flexible arms are part of an adaptor, the adaptor can be replaced, and the robot arm is ready for operation without any maintenance of the housing or lid needed by the broken flexible arms. The same is true for an adaptor comprising the engagement edge.

[0041] In an exemplary embodiment of the invention, said adaptor is an arm adaptor comprising said one or more flexible arms.

[0042] An arm adaptor may be connected to either the housing or lid.

[0043] In an exemplary embodiment of the invention, said arm adaptor is a joint housing adaptor connectable to said joint housing. [0044] An arm adaptor in the form of a joint housing adaptor is connectable with an engagement edge of the lid.

[0045] In an exemplary embodiment of the invention, said arm adaptor is a housing lid adaptor connectable to said housing lid.

[0046] An arm adaptor in the form of a lid housing adaptor is connectable with an engagement edge of the housing.

[0047] In an exemplary embodiment of the invention, said adaptor is an engagement edge adaptor comprising said engagement edge.

[0048] Note that the engagement edge may be one engagement edge running continuous along e.g. the circumference of the housing or lid. Alternatively, the engagement edge is made of discontinued parts only provided where there is a need e.g. so that they are positioned where the flexible arms need an engagement edge to secure attachment of the lid to the housing.

[0049] The engagement edge adaptor may be connected to either the lid or housing.

[0050] In an exemplary embodiment of the invention, said engagement edge adaptor is a joint housing adaptor connectable to said joint housing.

[0051] An engagement edge adaptor in the form of a joint housing adaptor is connectable with a flexible arm of the lid.

[0052] In an exemplary embodiment of the invention, said engagement edge adaptor is a housing lid adaptor connectable to said housing lid.

[0053] An engagement edge adaptor in the form of a housing lid adaptor is connectable with a flexible arm of the housing.

[0054] In an exemplary embodiment of the invention, said robot arm joint comprises both of said arm adaptor and said engagement edge adaptor. [0055] Connecting a housing comprising an adaptor and a lid comprising an adaptor of a robot arm joint with two adaptors is advantageous in that it has the effect that no modification or machining of the house is necessary. Further, different materials could be chosen for the lid and for the housing.

[0056] In an exemplary embodiment of the invention, said adaptor is a multi-adaptor comprising at least one flexible arm and at least one engagement edge.

[0057] In an exemplary embodiment of the invention, said joint housing and said joint housing lid are connected by two of said multi -adaptors.

[0058] Having two multi -adaptors i.e. two adaptors both having flexible arms and engaging edges, is advantageous in that one of the two can be used opposite the other so that flexible arms of one multi-adaptor can connect to engagement edges of the other multi-adaptor. In this way it is only needed to produce one adaptor which can be mounted upside-down relative to each other and still facilitate to removable fasten to housing and the lid.

[0059] In an exemplary embodiment of the invention, said arm adaptor and / or said engagement edge adaptor is connectable to said joint housing and / or to said joint housing lid via a set of flexible arms and an engagement edge.

[0060] An adapter may be connected to the housing and / or to the lid via a clicksystem similar to the click-system provided by the flexible arms and the engagement edge used to mount the lid to the housing.

[0061] In an exemplary embodiment of the invention, said arm adaptor and / or said engagement edge adaptor is connectable to said joint housing and / or joint housing lid via screws.

[0062] An adapter may alternatively be connected to the housing and / or lid via screws. This is advantageous in that screws are ensuring a fixed and firm connection of the adaptor. Further, the screw receivers used in the old design to fasten lid to the housing may be used. [0063] In an exemplary embodiment of the invention, one or more spacers are physically connecting said joint housing with said arm adaptor or with said engagement edge adaptor.

[0064] In an exemplary embodiment of the invention, two of said one or more spacers have a different length.

[0065] Using spacers is advantageous in that it is possible to predetermine the orientation / inclination of the adapter thereby ensuring precise engagement between contact surfaces of the flexible arm and the engagement edge.

[0066] In an exemplary embodiment of the invention, said robot arm joint comprising a gasket positioned between said joint housing and said joint housing lid.

[0067] In an exemplary embodiment of the invention, said gasket is forming part of the outer surface of said robot arm joint when said joint housing is connected with said joint housing lid.

[0068] In an exemplary embodiment of the invention, said gasket is deformable.

[0069] A deformable gasket is advantageous in that when a force is applied to it, it deforms in the direction of the applied force. Hence, if force is applied from a lid towards a housing, the gasket size therebetween is reduced due to the fact that a the gasket (e.g. made of rubber) behaves like a fluid in that it “flows” away from the force. Once the force is removed, the gasket resizes. This feature of a deformable gasket may be used to maintain a desired tension / friction / hold between the contact surfaces of the flexible arms and of the engagement edge(s).

[0070] In an exemplary embodiment of the invention, said gasket is a liquid gasket.

[0071] A liquid gasket is advantageous in that it may comprise an adhesive component ensuring a gluing effect of the attachment between the lid and the housing. A liquid gasket is typically used as a one-time gasket which may require destruction of the lid if the lid is to be removed from the housing. [0072] In an exemplary embodiment of the invention, said gasket is L-shaped.

[0073] In an exemplary embodiment of the invention, said gasket is T-shaped.

[0074] An advantage with an L or T-shaped gasket, is that when inserted in the housing and lid sealing recesses the gasket contributes to align the outer surface of lid and housing with the gasket and align arm and engagement edge when the lid is attached to the housing.

[0075] In an exemplary embodiment of the invention, said joint housing lid is made of Aluminium.

[0076] An aluminium lid is advantageous in that aluminium is more durable / stronger and more chemically inert than plastic.

[0077] In an exemplary embodiment of the invention, said joint housing lid comprises a lid sealing recess, preferably an L-shaped sealing recess.

[0078] An L-shaped sealing recess of the lid together with similar shaped sealing recess of the housing provides T-shaped sealing recess which is advantageous in that it has the effect that it positions the sealing better to the edges.

[0079] In an exemplary embodiment of the invention, said joint housing lid comprises lid/adaptor guide part for aligning said flexible arms with said engagement edge.

[0080] This is advantageous in that thereby is ensured that the individual fingers of the arms fit the individual recess when mounting. This is especially true when the arms are provided on an adaptor.

[0081] In an exemplary embodiment of the invention, said joint housing lid comprises steering tabs for aligning the form of said joint housing lid with the form of said joint housing. [0082] This is advantageous in that the form of the lid adapts to the form of the house and thereby it is ensured e.g. that the width of the part of the gasket that is visible is substantially the same all the way around the housing of the joint.

[0083] In an exemplary embodiment of the invention, said joint housing comprises a housing sealing recess, preferably an L-shaped sealing recess.

[0084] In an exemplary embodiment of the invention, said arm adaptor or said engagement edge adaptor comprises guide parts arranged to receive said lid/adaptor guide part.

[0085] The guide parts of the adapter may be implemented e.g. as holes, notches, etc. and used to ensure fingers / arms meet with engagement edges and thereby correct mounting of the lid to the housing. This is obtained when the lid/adaptor guide part and the guid part meet.

[0086] In an exemplary embodiment of the invention, the robot arm joint according to any of the paragraphs [0004] - [0085] is assembled according to the method described in any of the paragraphs [0087] - [0108],

[0087] In an aspect, the invention relates to a method of assembling a robot arm joint by mounting a joint housing lid to a joint housing, the method comprising the steps of:

• providing a gasket in one of a lid sealing recess and a housing sealing recess,

• aligning a flexible arm with an engagement edge,

• deforming said gasket by applying a force from said joint housing lid to said gasket,

• by said applied force, push said flexible arm towards said engagement edge and thereby bend said flexible arm before establishing engagement between a contact surface of said flexible arm and a contact surface of said engagement edge (19), and release said applied force. [0088] In an exemplary embodiment of the invention, said bend of said flexible arm is established by a movement of one of an engagement edge protruding part and a arm protruding part of said flexible arm relative to the other.

[0089] The bend of the flexible arm is established by the movement of the flexible arm relative to the engagement edge or vice versa. At least one of the flexible arm and the engagement edge comprises a protruding part which facilitates the bend of the flexible arm and the subsequent snap-lock of the lid to the housing when the protruding part is passed, and the flexible arm returns to its rest position. In this rest position, there is established contract / friction / hold between the contact surfaces of the flexible arm and the engagement edge.

[0090] Upon release of the force, the gasket reshapes at least partly thereby helping to increase the friction between the contact surfaces of the flexible arm and engagement edge or to hold the engaged position between the flexible arms and the engagement edge.

[0091] In an exemplary embodiment of the invention, said applied force is applied by hand.

[0092] In an exemplary embodiment of the invention, said applied force is above 50N, preferably above 75N most preferably above 85N.

[0093] In an exemplary embodiment of the invention, said step of aligning includes aligning lid/adapter guide parts with guide parts.

[0094] The lid/adapter guide parts and the guiding parts may be part of the housing, housing lid or adaptor. In the embodiment where there is no adaptor between the housing and the lid, if the lid/adapter guide parts are part of the housing, the guiding parts is part of the lid and vice versa.

[0095] In an exemplary embodiment of the invention, said method further comprises the step of mounting an adaptor to at least one of said joint housing and said joint housing lid. [0096] The adapter is advantageous in that it provides freedom in the location and orientation of the flexible arms so that they do not collide with any of the joint electronics or joint mechanics. Further, no machining of the housing and lid is needed if adaptor is used.

[0097] In an exemplary embodiment of the invention, said method further comprises the step of mounting a spring in a spring recess of a plurality of flexible arms comprised by said adaptor.

[0098] Such spring is advantageous in that it help to maintain the flexible arms in correct position holding the flexible arm and the engagement edge and thereby maintain the friction / connection between the contact surfaces of the arms and engagement edges.

[0099] In an exemplary embodiment of the invention, said method further comprises the step of mounting one or more spacers to one of said joint housing and said joint housing lid.

[0100] In an exemplary embodiment of the invention, said method further comprises the step of mounting said adaptor to said one or more spacers.

[0101] The spacers are advantageous in that by adjusting their length, the orientation of the adapter can be adjusted. Hence, the spatial angle of flexible arms of an adapter relative to e.g. the joint motor axis can be determined by the length of the spacers.

[0102] Further, by using spacers, the contact between the housing and the lid can be moved outwards from the housing center to a distance from the center where no joint electronics or joint mechanics takes up the space.

[0103] In an exemplary embodiment of the invention, said method further comprises the step of dismantle said joint housing from said joint housing lid, wherein said dismantle is a destructive process including applying a dismantle force to said lid resulting in breaking said flexible arm. [0104] Destruction of a flexible arm is especially advantageous if the flexible arm is part of an adaptor. This is because the adaptor can be replaced fast and cheap without damaging any parts of the housing or lid.

[0105] In an exemplary embodiment of the invention, said breaking flexible arm is predetermined from a plurality of flexible arms.

[0106] The flexible arm of a plurality of flexible arm the breaks as consequence of the applied dismantle force may be predetermined e.g. by designing on of the plurality of flexible arms weaker than the rest.

[0107] In an exemplary embodiment of the invention, said dismantle force is applied substantially perpendicular to the axis of a motor comprised by said robot arm joint.

[0108] In an exemplary embodiment of the invention, said dismantle force is at least 100N.

[0109] In an exemplary embodiment of the invention, the method according to any of the paragraphs [0087] - [0108] is used to assemble a robot arm joint according to any the paragraphs [0004] - [0085],

The drawings

[0110] For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts. The drawings illustrate embodiment of the invention and elements of different drawings can be combined within the scope of the invention:

Fig. 1 illustrates a prior art robot arm,

Fig. 2a, 2b illustrates a prior art robot joint,

Fig. 3a, 3b illustrates a robot joint according to an embodiment of the invention,

Fig. 4a, 4b illustrates a robot joint assembled by an adaptor according to an embodiment of the invention,

Fig. 5a, 5b illustrates an exploded view of a robot joint according to an embodiment of the invention,

Fig. 5c illustrates an enlarged view of detail E of fig. 5a,

Fig. 5d illustrates an enlarged view of detail F of fig. 5b,

Fig 6a illustrates a top view of a robot joint according to an embodiment of the invention,

Fig. 6b illustrates cross-sectional view along line C-C of fig. 6a,

Fig. 6c illustrates an enlarged view of detail D of fig. 6b

Fig. 7a illustrates a side of view of a robot joint according to an embodiment of the invention,

Fig. 7b illustrates cross-sectional view along line A-A of fig. 7a,

Fig. 8a illustrates a side view of a lid according to an embodiment of the invention, Fig. 8b illustrates cross-sectional view along line E-E of fig. 8a,

Fig. 9a-9f illustrates variations of the flexible fingers and the engagement edge according to embodiments of the invention.

Detailed description

[0111] The present invention is described in view of exemplary embodiments only intended to illustrate the principles and implementation of the present invention. The skilled person will be able to provide several embodiments within the scope of the claims.

[0112] Fig. 1 discloses a prior art robot arm 1 comprising a number of robot joints 2 connecting a robot base 3 to a robot tool flange 4, where the robot arm 1 is controlled by a robot controller 5 that can be programmed via a user interface 6, as known in the art. The robot joints 2 comprise a joint housing 7 (also simply referred to as housing) having an opening closed by a joint housing lid 8 (also referred to simply as lid, cover or end cap) that is secured to the joint housing 7 via a number of screws 9.

[0113] Fig. 2a illustrates the joint housing 7 of the robot arm illustrated in fig. 1 with the joint housing lid 8 in a side view and fig. 2b illustrates the joint housing 7 in a top view where the four screws 9 securing the lid 8 to the housing 7 are clearly seen both with a flange 10 at the bottom. The screws are each arranged in a cavity, and both the cavities, and the head of the screws can collect dust / dirt and can be hard to clean. Also, some prior art housing may comprise a connecting edge 11 where the lid 8 and the housing 7 meet, this is clearly seen at fig. 2a and 2b.

[0114] As described above, the problem of dust collection and cleaning of the housing 7 is solved by the present invention by a new way of attaching the lid 8 to the housing 7. Fig. 3a illustrates the principles of the housing 7 according to the present invention, namely the flexible arms 12 that are engaging with one or more engagement edges 13 (illustrated as one stipulated line in fig. 3a and 3b).

[0115] As illustrated in fig. 3a and fig 3b, the flexible arms 12 can point towards the housing 7 and towards the lid 8 respectively. This is just one example of the flexibility of the design of the housing 7 of the present invention, namely that the flexible arms 12 and thus the engagement edge 13 can be part of either one of the parts of the housing 7. Note that the lid 8 and the housing 7 may both comprise both arms 12 and engagement edges 13. [0116] It should be noted that the flexible arms 12 and / or the engagement edge 13 can also be implemented as an adaptor 14 connectable to one of the housing 7 or the lid 8. Fig. 4a illustrates an embodiment of the invention where an arm adaptor 15 comprising flexible arms 12 are to be mounted in the housing 7 and subsequently, the lid 8, comprising engagement edges 13 is forced towards the arms 12 and thereby attach the lid 8 to the housing 7.

[0117] Fig. 4b illustrates an embodiment of the invention where two adaptors are used, a so-called arm adaptor 15 and a so-called engagement edge adaptor 16. In this embodiment where two adaptors 15, 16 are used, the arm adaptor 15 can be mounted to the housing 7 whereas the engagement edge adaptor 16 can be mounted to the lid 8 and vice versa.

[0118] Fig. 5a and fig. 5b illustrates a more detailed embodiment of the invention where an arm adaptor 15 comprising four flexible arms 12 connectable to a housing 7. The housing 7 illustrated in fig. 5a is stripped for all joint electronics such as wires, sensors, etc. and all joint mechanics such as motor, brackets, etc. The arm adaptor 15 may be screwed to the housing 7 and / or lid 8 by the already existing screw receivers 17 used in the prior art robot arms to attach lid 8 to housing 7. The use of existing screw receivers 17 is advantageous in that then no machining or adaption of the housing 7 are needed to connect the lid 8 to the housing 7 according to the present invention. It should be noted that the arm adaptor 15 can be replaced by an engagement adaptor.

[0119] To ensure correct positioning of the arm adaptor 15, spacers 18 are used between the arm adapter 15 and the screw receivers 17. Spacers 18 may be hollow tube-like structures through which screws connecting the arm adaptor 15 to the screw receivers 17 may pass. Alternatively, the spacers 18 may be screwed to the screw receivers 17 and the screws connecting the arm adaptor 15 to the housing is then received by the spacers 18.

[0120] Fig. 5a illustrates four flexible arms 12 each part of the arm adaptor 15 and each connected with a circular spring 19. The tension of the spring 19 is sufficiently high to assist the flexible arms 12 in maintaining their position when clicked on to the engaging edges 13. At the same time, the tension of the spring 19 is sufficiently low to allow bend of the flexible arms 12 when the protruding parts 22 hereof, as they (or the engaging edges) are moved towards the point where the contact surfaces 24, 25 meet.

[0121] The detailed view E of fig. 5a illustrated in fig. 5c illustrates one flexible arm 12 in more details. It is noted that this flexible arm 12 comprises two individual fingers 26 spaced apart. These fingers may be identical i.e. both part of the arm adaptor 15 and having a spring recess 21 for connection to the spring 19. Both fingers 26 preferably have a protruding part 22 including a contact surface 24.

[0122] The angle of the contact surface 24 relative to the longitudinal direction of the finger 26 is at least partly, together with the gasket 29 and spring 19, responsible for establishing the friction or static position required between the contact surface 24 and the contact surface of the engaging edge 19 to maintain the lid attached to the housing. To ensure sufficient attachment, four flexible arms may be chosen in one embodiment other numbers of flexible arms may be chosen in other embodiments.

[0123] Where the view of fig. 5a is so that the interior of the housing 7 is visible, although stripped for most interior, the view of fig. 5b is so that the interior of the lid 8 is visible.

[0124] Fig. 5b illustrates one example of how an engaging edge 13 can be implemented. More specific the detailed view denoted F and illustrated in fig. 5d of the engaging edge 13 illustrates a protruding part 23 having a contact surface 25. Hence, when the flexible arm 12 and the engaging edge 13 of fig. 5b are forced to pass each other the protruding parts 22, 22 facilitates a bend of the flexible arms 12 and subsequently, friction between and / or hold of the contact surfaces 24, 25. In an embodiment the force needed to separate the lid from the housing is between 75N and 125N, such as 100N. The force required to bed the arm would typically be less than 100N such as between 25N and 50N. Hence, in an embodiment if e.g. the arms are designed to break if 130N is applied to the lid. Then, if during service a broken arm is found, this may indicate that the lid has been exposed to a force above the 130N. However, this depends on material and design of the flexible arms. Hence, depending on if the flexible arms are positioned in a straight line or in a curved line, if the flexible arms are one finger or divided in several fingers, etc. the force to mount and dismount is applied. Mounting and dismounting would in most embodiments include applying a force that is able to bend the flexible arms so that the contact surfaces 24, 25 meet or separate.

[0125] Further, it is noted, that the lid 8 may comprise lid/adaptor guide parts 28 which together with guide parts 20 of the arm adaptor 15 ensure correct alignment of the flexible arms 12 of the arm adaptor 15 to the engagement edge 13 and thereby correct mounting of the lid to the arm adaptor 15. The alignment of the lid/adaptor guide parts 28 with the guide parts 20 is illustrated by stipulated lines of fig. 5b.

[0126] Further, it is noted, that the lid 8 may comprise steering tabs 27 which are used to ensure to maintain the correct shape of the lid 8. When mounted, the steering tabs 27 may be in physically contact with the housing 7 thereby it is ensured that e.g. the visible part of the gasket 29 has the same thickness from any view of the housing 7.

[0127] Together the lid/adaptor guide part 28 and the steering tabs 27 are collaborating in aligning and positioning the lid 8 correct when the lid is being and after the lid 8 is mounted to the housing 7.

[0128] Fig. 6a illustrates a robot arm joint 2 in a top view. Fig. 6b illustrates a cross sectional view of the arm joint 2 illustrated in fig. 6a at line C-C. Fig. 6c illustrates an enlarged detailed view of the features in the circle denoted D of fig. 6b.

[0129] Fig. 6c illustrates an example of how the flexible arm 12 engage with the edge 13. In the cross-sectional view, the engaging edge 13 is illustrated as part of the lid 8. The engaging edge 13 comprises a protruding part 23 and a contact surface 25 which is in contact with the contact surface 24 of the one finger 26 of a flexible arm 12. The finger 26 is part of an arm adaptor 15 and comprises in addition to the contact surface 24 of the protruding part 22 a spring recess 21. [0130] A “contact surface angle” range is illustrated between 0 degrees and 90 degrees where 0 degrees is measured along the joint motor axis and the 90 degrees is measured along the orientation of the adaptor 15. The contact surface angle may be determined by the design of the flexible arms 12 / fingers 26 and the engagement edge 13. Hence in an embodiment where the flexible arms 12 are implemented as a hook, the contact surface angle may e.g. be 90 degrees or out of the specified range.

[0131] Further Fig. 6c illustrates an example of the gasket 29 positioned in a lid sealing recess 30 and between the housing 7 and the lid 8. As illustrated, the gasket 29 is part of the outer surfaces of the joint 2. The gasket 29 is illustrated as only extending into the lid sealing recess 30 and not into the housing sealing recess 31. However, in other embodiments, the gasket 29 is a T-shaped gasket and thus also extend into the housing sealing recess 31 or the gasket 29 is deformed so that it is present in both the lid sealing recess 30 and in the housing sealing 31.

[0132] The gasket 29 may be made of standard deformable rubber / gasket material such as nitrile butadiene rubber (NBR; Nitrile Butadiene Rubber). However, it should be noted that if the robot arm has to be used in e.g. a medical technology, the gasket material should be resistant to different chemicals.

[0133] Fig. 7a illustrates a side view of robot arm joint 2 according to an embodiment of the present invention and fig. 7b illustrates a cross-sectional view of the robot arm joint 2 at line A-A of fig. 7a.

[0134] Fig. 8a illustrated a lid 8 according to an embodiment of the present invention and fig. 8b illustrates a cross-sectional view of the lid 8 at line B of fig. 8a

[0135] Fig. 9a-9f illustrates different cross-sectional views of implementations of how the lid 8 can be assembled with the housing 7 all within the scope of the present invention. It should be noted that the embodiments illustrated in fig. 9a-9f are exemplary thus not detailed i.e. the above description of features also applies to the features of fig. 9a-9f. A joint motor 32 and a motor axel 33 rotating a flange 10 are illustrated in structural form. [0136] Fig. 9a illustrated the engagement edge 13 as a flange such as an annual flange or individual flanges of the lid 8 located where / aligned with the position of the flexible arms 12 at an adaptor (not shown) or housing 7.

[0137] Fig. 9b illustrates the engagement edge 13 as a recess such as an annual recess or individual recesses of the lid 8 located where / aligned with the position of the flexible arms 12 at an adaptor (not shown) or housing 7.

[0138] Fig. 9c illustrates the engagement edge 13 as a protrusion such as an annual protrusion or individual protrusions of the lid 8 located where / aligned with the position of the flexible arms 12 at an adaptor (not shown) or housing 7.

[0139] Fig. 9d illustrates the engagement edge 13 as a recess such as an annual recess or individual recesses of the housing 7 located where / aligned with the position of the flexible arms 12 at an adaptor (not shown) or lid 8.

[0140] Fig. 9e illustrated the engagement edge 13 as a flange such as an annual flange or individual flanges of the housing 7 located where / aligned with the position of the flexible arms 12 at an adaptor (not shown) or lid 8.

[0141] Fig. 9f illustrates the engagement edge 13 as a protrusion such as an annual protrusion or individual protrusions of the housing 7 located where / aligned with the position of the flexible arms 12 at an adaptor (not shown) or lid 8.

[0142] It should be mentioned that within the scope of the present invention, different implementation of the click-lock of the lid 8 to the housing 7 may exist other than those illustrated in fig. 9a-9f. One such alternative is a so-called hook embodiment where the flexible arms are formed as hooks engaging with the engaging edge. The engaging edge may be adapted to the hook shape of the flexible arm and thus connection of the lid 8 and housing 7 may be maintained by gravity and / or by the hooked connection.

[0143] In yet another alternative, the engaging edge 13 is implemented as a series of subsequent edges 23 which each may sustain the protruding parts 22 of associated flexible arms 12 / fingers 26. Such zip tie like fastening of an arm 12 to an engaging edge 13 is advantageous in that different pressures towards the gasket can be established and maintained.

[0144] In yet another alternative, an adaptor 14 may be mounted in the housing 7. The adaptor 14 may in one part of its circumference comprise a receiving part of a substantially rigid part of the lid 8. Opposite this receiving part, an engaging edge 13 may be positioned. Thus, the lid 8 may be connected to the receiving part of the adaptor 14 and subsequently forced towards the adaptor 14 so that the flexible arm 12 engage with the engaging edge 13 as described above.

[0145] In yet another alternative, the lid 8 is connected to the housing by means of an adhesive. Gluing the lid and housing together is advantageous in that less mechanics are needed such as the adaptor, flexible arms and engaging edges.

[0146] From the above it is now clear that the invention relates to a robot arm 1 comprising a robot arm joint 2 which comprises a joint housing 7 closed with a lid 8. The closure / assembly of lid 8 and housing 7 is made by means of flexible arms 12 engaging with engaging edges 13 when a force is applied to the lid forcing the lid towards the housing.

[0147] As described a gasket 29 is positioned between the lid 8 and the housing 7 and is forming part of the outer surface of the joint 1.

[0148] The invention has been exemplified above with the purpose of illustration rather than limitation with reference to specific examples of methods and robot systems. Details such as a specific method and system structures have been provided in order to understand embodiments of the invention. Note that detailed descriptions of well-known systems, devices, circuits, and methods have been omitted so as to not obscure the description of the invention with unnecessary details. List

1. Robot arm

2. Robot arm joint

3. Robot base

4. Robot tool flange

5. Robot controller

6. User interface

7. Joint housing

8. Joint housing lid

9. Screw

10. Flange

11. Connecting edge

12. Flexible arm

13. Engaging edge

14. Adaptor

15. Arm adaptor

16. Engagement edge adaptor

17. Screw receiver

18. Spacer

19. Spring

20. Guide part

21. Spring recess

22. Arm protruding part

23. Engagement edge protruding part

24. Contact surface of flexible arm

25. Contact surface of engaging edge

26. Fingers

27. Steering tab

28. Lid/adapter guide part

29. Gasket

30. Lid sealing recess

31. Housing sealing recess

32. Joint motor

33. motor axel

Claims

Patent claims

1. A robot arm joint (2) comprising joint mechanics and joint electronics, said joint mechanics and joint electronics are enclosed in a joint housing (7) connectable to a joint housing lid (8), wherein said joint housing lid (8) is removable fastened to said joint housing (7) by one or more flexible arms (12) arranged to engage with an engagement edge (13).

2. A robot arm joint (2) according to claim 1, wherein said one or more flexible arms (12) extend from said joint housing (7).

3. A robot arm joint (2) according to claim 1 or 2, wherein said one or more flexible arms (12) extend from said housing lid (8).

4. A robot arm joint (2) according to any of the preceding claims, wherein one of said one or more flexible arms (12) comprises at least one individual finger (26).

5. A robot arm joint (2) according to claim 4, wherein the width of said individual finger (26) is below 10 millimeter, such as below 7 millimeters, such as below 5 millimeters.

6. A robot arm joint (2) according to any of the preceding claims, wherein said flexible arm (12) comprises an arm protruding part (22) which comprises a contact surface (24).

7. A robot arm joint (2) according to any of the preceding claims, wherein said contact surface (24) decline with an angle between 0 degrees and 90 degrees such as between 25 degrees and 75 degrees, such as between 35 degrees and 65 degrees.

8. A robot arm joint (2) according to any of the preceding claims, wherein said flexible arms (12) / individual finger (26) comprises a spring recess (21).

9. A robot arm joint (2) according to any of the preceding claims, wherein said engagement edge (13) is formed in said joint housing (7).

10. A robot arm joint (2) according to any of the preceding claims, wherein said engagement edge (13) is formed in said housing lid (8).

11. A robot arm joint (2) according to any of the preceding claims, wherein said engagement edge (13) is provided as a plurality of individual engagement edges (13) aligned with the position of said flexible arms (12).

12. A robot arm joint (2) according to any of the preceding claims, wherein said engagement edge (13) is formed at least partly by an engagement edge protruding part (23) comprising a contact surface (25).

13. A robot arm j oint (2) according to any of the preceding claims, wherein said contact surface (25) decline with an angle between 0 degrees and 90 degrees such as between 25 degrees and 75 degrees, such as between 35 degrees and 65 degrees.

14. A robot arm joint (2) according to any of the preceding claims, wherein an adaptor (14) is mounted to said joint housing (7) or said joint housing lid (8).

15. A robot arm joint (2) according claim 14, wherein said adaptor (14) is an arm adaptor (15) comprising said one or more flexible arms (12).

16. A robot arm joint (2) according to claim 15, wherein said arm adaptor (14) is a joint housing adaptor connectable to said joint housing (7)

17. A robot arm joint (2) according to claim 15 or 16, wherein said arm adaptor (14) is a housing lid adaptor connectable to said housing lid (8).

18. A robot arm joint (2) according to claim 14, wherein said adaptor (14) is an engagement edge adaptor (16) comprising said engagement edge (13).

19. A robot arm joint (2) according to claim 18, wherein said engagement edge adaptor (16) is a joint housing adaptor connectable to said joint housing (7)

20. A robot arm joint (2) according to claim 18 or 19, wherein said engagement edge adaptor (16) is a housing lid adaptor connectable to said housing lid (8).

21. A robot arm joint (2) according to any of the preceding claims, wherein said robot arm joint (2) comprises both of said arm adaptor (15) and said engagement edge adaptor (16).

22. A robot arm joint (2) according to any of the preceding claims, wherein said adaptor (14) is a multi-adaptor comprising at least one flexible arm (12) and at least one engagement edge (13).

23. A method according to claim 22, wherein said joint housing (7) and said joint housing lid (8) are connected by two of said multi -adaptors.

24. A robot arm joint (2) according to any of the claims 15-23, wherein said arm adaptor (15) and / or said engagement edge adaptor (16) is connectable to said joint housing (7) and / or to said joint housing lid (8) via a set of flexible arms and an engagement edge.

25. A robot arm joint (2) according to any of the claims 15-24, wherein said arm adaptor (15) and / or said engagement edge adaptor (16) is connectable to said joint housing (7) and / or joint housing lid (8) via screws.

26. A robot arm joint (2) according to any of the preceding claims, wherein one or more spacers (18) are physically connecting said joint housing (7) with said arm adaptor (15) or with said engagement edge adaptor (16).

27. A robot arm joint (2) according to claim 26, wherein two of said one or more spacers (18) have a different length.

28. A robot arm joint (2) according to any of the preceding claims, wherein said robot arm joint (2) comprising a gasket (29) positioned between said joint housing (7) and said joint housing lid (8).

29. A robot arm joint (2) according to claim 28, wherein said gasket (29) is forming part of the outer surface of said robot arm joint (2) when said joint housing (7) is connected with said joint housing lid (8).

30. A robot arm joint (2) according to claim 28 or 29, wherein said gasket (29) is deformable.

31. A robot arm joint (2) according to any of the claims 28-30, wherein said gasket (29) is a liquid gasket.

32. A robot arm joint (2) according to any of the claims 28-31, wherein said gasket (29) is L-shaped.

33. A robot arm joint (2) according to any of the claims 28-32, wherein said gasket (29) is T-shaped.

34. A robot arm joint (2) according to any of the preceding claims, wherein said joint housing lid (8) is made of Aluminium.

35. A robot arm joint (2) according to any of the preceding claims, wherein said joint housing lid (8) comprises a lid sealing recess (30), preferably an L-shaped sealing recess.

36. A robot arm joint (2) according to any of the preceding claims, wherein said joint housing lid (8) comprises lid/adaptor guide part (28) for aligning said flexible arms (12) with said engagement edge (13).

37. A robot arm joint (2) according to any of the preceding claims, wherein said joint housing lid (8) comprises steering tabs (27) for aligning the form of said joint housing lid (8) with the form of said joint housing (7).

38. A robot arm joint (2) according to any of the preceding claims, wherein said joint housing (7) comprises a housing sealing recess (31), preferably an L-shaped sealing recess.

39. A robot arm joint (2) according to any of the preceding claims, wherein said arm adaptor (15) or said engagement edge adaptor (16) comprises guide parts (20) arranged to receive said lid/adaptor guide part (28).

40. A robot arm joint (2) according to any of the preceding claims, wherein the robot arm joint (2) according to any of the claims 1-39 is assembled according to the method described in any of the claims 41-53.

41. A method of assembling a robot arm joint (2) by mounting a joint housing lid (8) to a joint housing (7), the method comprising the steps of:

• providing a gasket (29) in one of a lid sealing recess (30) and a housing sealing recess (31),

• aligning a flexible arm (12) with an engagement edge (13),

• deforming said gasket (29) by applying a force from said joint housing lid (8) to said gasket (29),

• by said applied force, push said flexible arm (12) towards said engagement edge (13) and thereby bend said flexible arm (12) before establishing engagement between a contact surface of said flexible arm (18) and a contact surface of said engagement edge (19), and

• release said applied force.

42. A method according to claim 41, wherein said bend of said flexible arm (12) is established by a movement of one of an engagement edge protruding part (23) and a arm protruding part (22) of said flexible arm (12) relative to the other.

43. A method according to claim 41 or 42, wherein said applied force is applied by hand.

44. A method according to any of the preceding claims 41-43, wherein said applied force is above 50N, preferably above 75N most preferably above 85N.

45 wherein said step of aligning includes aligning lid/adapter guide parts (28) with guide parts (20).

46. A method according to any of the preceding claims 41-45, wherein said method further comprises the step of mounting an adaptor (14) to at least one of said joint housing (7) and said joint housing lid (8).

47. A method according to any of the preceding claims 41-46, wherein said method further comprises the step of mounting a spring (19) in a spring recess (21) of a plurality of flexible arms (12) comprised by said adaptor (14).

48. A method according to any of the preceding claims 41-47, wherein said method further comprises the step of mounting one or more spacers (18) to one of said joint housing (7) and said joint housing lid (8).

49. A method according to any of the preceding claims 41-48, wherein said method further comprises the step of mounting said adaptor (14) to said one or more spacers.

50. A method according to any of the preceding claims 41-49, wherein said method further comprises the step of dismantle said joint housing (7) from said joint housing lid (8), wherein said dismantle is a destructive process including applying a dismantle force to said lid resulting in breaking said flexible arm (12).

51. A method according to claim 50, wherein said breaking flexible arm (12) is predetermined from a plurality of flexible arms (12).

52. A method according to claim 50 or 51, wherein said dismantle force is applied substantially perpendicular to the axis of a motor comprised by said robot arm joint (2).

53. A method according to any of the preceding claims 50-52, wherein said dismantle force is at least 100N.

54. A method according to any of the claims 41-53 is used to assemble a robot arm joint (2) according to any the claims 1-40.