Patent Publication Number: US-2020276701-A1

Title: Modular End Effector

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the United States national phase of International Application No. PCT/EP2018/082343 filed Nov. 23, 2018, and claims priority to German Patent Application No. 10 2017 220 999.2 filed Nov. 23, 2017, the disclosures of which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to a modular end effector and a robot with such a modular end effector. 
     Known end effectors for robots exist in a variety of configurations and may as such be modeled on the human hand or be implemented as simple grippers. Here, an adaptation of the end effectors to the tasks to be solved often occurs already during the construction of the respective end effector. Thus, a specific end effector is assigned to a dedicated task or a small number of dedicated tasks. Moreover, there are also interchangeable end effectors that can be exchanged on the robot when the task is changed. However, the task is often already known in the construction of the respective end effector, so that, for example, when two tasks are to be performed by the robot, two end effectors are constructed as well which may then be exchanged when the tasks are changed. However, when new tasks are added, this usually requires a new design of a correspondingly adapted end effector, which takes into account the requirements of this new task. The capabilities of existing humanoid robotic hands are limited by the similarity to the human hand. For example, the size of the objects that can be gripped is limited. Existing simple, versatile grippers are often unable to reach the position of the gripped object with respect to the robot in a defined manner and are also unable to detect it. 
     Furthermore, it is known to provide end effectors equipped with interchangeable tools. However, also in this case, the versatility of the end effector is severely limited, since it may be possible to change the tools, yet basically different tasks cannot be  accomplished by the end effector. Thus, all tasks to be accomplished must be known at the time the end effector is designed. It is possible to use different tools within the same task to be accomplished, but changing the task to be performed usually requires a new design for the end effector. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a versatile end effector. 
     The object is achieved by a modular end effector and a robot as defined herein. 
     The modular end effector of the present invention comprises a base with at least one connection element. A manipulator is connected to the connection element. Here, the manipulator can be chosen in particular with regard to the task to be accomplished. In particular, the manipulator is designed to be exchangeable so as to be adapted to the respective task. Thus, the manipulator is detachably connected to the connection element, so that the manipulator can be changed in a simple manner. The position of the connection element can be changed so that the manipulator can be used in different positions relative to the base. As an alternative or in addition thereto, the position of the manipulator within the connection element can be changed, whereby the position of the manipulator relative to the base is also changed and, thus, the manipulator can be used in different positions relative to the base. Thereby, an increased adaptability is achieved, even to tasks unknown at the time of design of the modular end effector. The versatility of the end effector of the present invention is thereby increased, since there is a geometrical change in the position of the manipulator and, thus, for example, portions become accessible which were previously not accessible, without requiring a new design for the end effector. Rather, only the position of the connection element or the position of the manipulator in the connection element is changed such that within the framework of a new task previously not accessible portions, for example of a workpiece, are also accessible. Thus, even newly added tasks can be accomplished using the same end effector without requiring a new design.  
     Preferably, the base comprises a first segment and at least a second segment. Here, the first segment and the second segment are movably connected to each other such that the position of the first segment relative to the second segment can be changed. Furthermore, the first segment and the second segment each include at least one connection element, so that the position of the connection elements of the first segment can be changed relative to the position of the connection elements of the second segment. Thus, a change in the geometry of the base is possible, whereby the position of the connection elements on the first segment and the second segment changes relative to each other. Thereby, the versatility of the modular end effector is further increased. Such a change in the geometry of the base of the modular end effector e.g. allows a change in the opening width of the end effector so as to be able e.g. to grip larger objects. Thus, in the case of a change in the task posed, which e.g. provides for larger objects to be gripped, no new design of the end effector is required, since the requirements can be met by changing the geometry of the base of the end effector. 
     Preferably more than one manipulator can be connected to one of the respective connection elements. If in this case the position of the connection element can be changed, a simultaneous change of position of all manipulators connected to the respective connection element is effected. As an alternative or in addition thereto, it is possible to change the position of all manipulators within a respective connection element. 
     Moreover, the present invention relates to an alternative modular end effector comprising a base which includes at least two connection elements. Here, at least one manipulator can be connected to the connection elements. Specifically, the manipulator can be connected to the connection elements in an exchangeable manner, so that the manipulators can be exchanged quickly. To this end, the manipulators are in particular detachably connected to the connection elements. According to the present invention, at least one manipulator is provided, so that it is possible that a connection element does not have a manipulator depending on the task to be accomplished. According to the present invention, the base comprises a  first segment and at least one second segment, the first and second segments being movably connected to each other so that the position of the first and second segments can be changed relative to each other. Thereby, the geometry of the base can be changed. Here, at least one of the connection elements is arranged on each of the first and second segments, so that by changing the position of the first segment relative to the second segment, the position of the connection elements of the first segment relative to the position of the connection elements of the second segment can be changed. Because of the changes in the geometry of the base due to the provision of first and second segments, the modular end effector according to the present invention is easily adapted to new tasks, without the need for a new construction. 
     The following invention relates to each of the above-mentioned alternatives of the modular end effector according to the present invention. 
     Preferably, the base comprises more than two segments, which are in particular movable with respect to each other. Here, in particular, each of the segments provided comprises at least one connection element, so that by movement of the segments, the position of the respective connection elements can be suitably adapted to the task posed, thus further increasing the versatility of the modular end effector. 
     Preferably, the position of at least two segments of the base can be changed with respect to each other by shifting them towards each other. As an alternative, in the case of at least two segments, the two segments are pivoted about a common axis of rotation. However, especially if a plurality of segments is provided, a combination of shifting and pivoting is also possible in order to provide a versatile end effector which is easily adapted to the requirements of the respective tasks. 
     Preferably, the end effector comprises more than one connection element, in particular more than two connection elements and, particularly preferred, more than five connection elements, whereby it is possible in particular to achieve a non-human hand configuration. Here, at least one manipulator can be connected to each of these  connection elements, so that if more than five connection elements are provided, it is also possible to connect more than five manipulators, in particular interchangeably, to the respective connection elements. As an alternative, it is also possible to connect a plurality of manipulators to one connection element, so that an optional number of manipulators can be connected to the connection elements. 
     Preferably, the position of more than one connection element can be changed, so that it is ensured that the positions of the respective connection elements can be adapted on a large scale. In this context it is preferred that the positions of all the connection elements can be changed, so that the modular end effector can be adapted to the full extent. In particular, the positions of the connection elements can be changed independently of each other. As an alternative or in addition to this, the position of more than one manipulator within a connection element can be changed. Here, it is preferred that the position of all manipulators within a connection element is designed to be changeable so as to be able to ensure the greatest possible adaptability of the modular end effector. The positions of the manipulators within a connection element are changed in particular independently, so as to be able to ensure the highest possible degree of freedom for the required adaptability to e.g. a new task. Thus, the positions of one, a plurality or all connection elements, the positions of one, a plurality or all manipulators within a connection element and/or the positions of one, a plurality or all manipulators in each of the connection elements can be changed, so that maximum versatility with respect to the adaptability of the modular end effector is ensured. 
     Preferably, more than one manipulator and in particular more than five manipulators are provided, the number of connection elements preferably corresponding to the number of manipulators. Thus, one connection element is preferably provided for each of the manipulators. As an alternative, however, the number of manipulators can be selected higher and can be suitably adapted to the tasks posed. 
     Preferably, the manipulator is an actuated finger, a tool, a sensor or a light source. As an example of a tool, the manipulator may be a screwdriver, magnetic holder,  welding probe or the like. As an example of a sensor, the manipulator may be an optical sensor e.g. a camera, a temperature sensor, a radiation sensor, an electrical measuring device for current or voltage and the like. Specifically, the manipulator may be any active or passive component. In particular, the manipulator, if designed as an actuated finger, comprises actuation elements such as e.g. servomotors in order to change the pose of the finger. Here, the actuated finger is not restricted to a three-part human configuration, but can have a plurality of actuated and thus movable members. 
     Preferably, at least one connection element comprises linear mobility to change the position of the connection element. As an alternative or in addition, at least one manipulator has linear mobility within a connecting element to change the position of the manipulator. Thus, by moving the connection element or the manipulator within the connection element, a change in position can be effected in order to adapt the modular end effector to a new task. Here, e.g. low-friction sliding elements can be used to linearly change the position. Here, preferably, more than one connection element and/or more than one manipulator has linear mobility. 
     Preferably, at least one connection element has rotational mobility for the purpose of changing the position of the connection element. As an alternative or in addition, at least one manipulator within a connection element has rotational mobility for the purpose of changing the position of the manipulator. Thereby, further adaptability of the modular end effector is guaranteed. It is preferred in this context that more than one connection element and/or more than one manipulator have rotational mobility. 
     Preferably, the position of at least one connection element and/or the position of at least one manipulator within a connection element can be changed manually. Here, preferably, the positions of all connection elements and/or the positions of all manipulators within a connection element or within the respective connection element can be changed manually.  
     Preferably, the position of at least one segment and in particular the position of all segments of the base relative to each other can be changed manually. 
     Preferably, a release element arranged on at least one connection element is provided, so that by means of the release element a locking of the position of the connection element can be released and thus the position of the connection element can be changed. As an alternative or in addition, a release element is provided on the manipulator, the release element being able to release a locking of the position of the manipulator within a connecting element, so that the position of the manipulator can be changed. As an alternative or in addition, a release element is arranged on the base, so that the locking of the position of the segments of the base can be released by the release element so that the position of the segments of the base can be changed relative to each other. By providing such a release element, it is possible to quickly adapt the modular end effector and, in particular, the change in geometry of the base as well as the position of the manipulator, i.e. also during the operating time, without requiring significant redesigning. 
     Preferably, the position of at least one connection element and preferably of all connection elements can be changed automatically. Here, an automatic change in position can be effected, e.g. by means of an actuator or the like, which is addressed by a control of the end effector. As an alternative or in addition, the position of at least one manipulator within the respective connection element can be changed automatically, and preferably the position of all manipulators within a connection element or the respective connection element can be changed automatically. As an alternative or in addition, the position of at least one segment and preferably the positions of all segments of the base relative to each other can be changed automatically. Thus, it is easy to adapt the modular end effector to new tasks, even if, e.g. in space applications, no direct access to the end effector is possible. Here, the geometry or the position of the connection element or the manipulator is changed e.g. by an actuator on the basis of a control command issued by a control of the modular end effector.  
     Preferably, a release element is provided, especially when the connection elements, the manipulators and/or the segments are in an automatically changeable position, the device being in the form of a worm gear, a ratchet or a braking device. This offers the advantage of a stable fixation of the connection elements, manipulators and/or segments, thereby increasing stability. At the same time, energy consumption can be reduced since an actuator is no longer required to maintain the connection element, the manipulator and/or the segment in position. In particular, such actuators for maintaining position can be completely omitted, preferably existing actuators can be simple, so that weight can be saved. 
     Preferably, the position is changed electrically, pneumatically or hydraulically. Of course, a combination thereof is also possible, so that rapid adjustment is effected e.g. pneumatically, whereas fine adjustment is effected electrically or the like. 
     Preferably, at least one and preferably all connection elements have connections which fit a variety of different manipulators, so that it is possible to exchange the manipulators quickly. Thus, standard connections are provided which allow the manipulators to be exchanged quickly and in particular further increase the versatility of the modular end effector, since each of the possible manipulators can be attached and connected to each of the connection elements. 
     Preferably, the base has a surface element forming the inner surface of the end effector, i.e. precisely the gripping surface. Here, the surface element is at least partially interchangeable. Thereby, the surface element can also be adapted to the task of the modular end effector to be accomplished. As an alternative or in addition, the surface element has different areas, wherein individual areas have different materials. Thus, the surface element can be adapted in a purposeful manner to the areas to be obtained, so that, e.g. one area comprises a hard surface for precise gripping, whereas another area comprises an elastic surface that additionally has an anti-slip effect to guarantee a secure grip. Here, it is particularly preferred that individual areas are interchangeable, in order to further increase the adaptability of the modular end effector.  
     Preferably, when actuated fingers are used as manipulators, the position of the connection elements and/or the manipulators within the connection elements can be adjusted such that there is more than one pair of manipulators acting against each other. There is only one pair in the human hand, e.g. made up of the index finger and thumb. In the present modular end effector it is possible to form a further pair by means of further manipulators, with one of the manipulators taking over the function of another thumb and another manipulator assuming e.g. the function of the middle finger. Thus, two pairs of manipulators acting against each other are provided, whereby e.g. two or more objects can be gripped simultaneously or a gripped object can be manipulated by the second pair of manipulators acting against each other. Here, for example, a gripped object can be easily rotated in the hand or be brought into another orientation without requiring a second hand or putting the object down. 
     Preferably, when using actuated fingers as manipulators, the position of the connection elements and/or the manipulators within the connection elements can be adjusted such that at least two actuated fingers can be combined, so that the two combined actuated fingers perform their movement in synchronized manner, i.e. simultaneously and uniformly, for mutual reinforcement. Thus, e.g. if a greater force is required, the position of the connection elements and/or the manipulators within the connection elements can be adapted such that the movement requiring said force is effected simultaneously by two actuated fingers and their force is thus added. Hereby, it is also possible to avoid damage to the actuated fingers, since stability is increased by combining the two actuated fingers. 
     Preferably, when using actuated fingers as manipulators, the position of the connection elements and/or the manipulators within the connection elements can be adjusted such that the position of the actuated fingers corresponds to a humanoid configuration. This facilitates transmission in a teleoperation mode as a control element in a human-machine interface, in which the movement of a human hand is detected and then transmitted to the end effector. A complicated conversion of the movement of the human hand to a non-human configuration is omitted, since the actuated fingers are arranged as manipulators in a humanoid configuration.  
     Preferably, the base comprises at least one position sensor for detecting the position of the segments of the base. As an alternative or in addition, the base includes at least one force sensor for detecting the forces acting on the base. Preferably, a plurality of position sensors is provided, specifically a position sensor for each of the segments provided, for the purpose of an exact determination of the position of the segments of the base. 
     Preferably, when using actuated fingers as manipulators, these actuated fingers include position sensors as well as force sensors for carrying out and monitoring an exact movement. 
     Moreover, the present invention relates to a robot with at least one modular end effector as described above. 
     Preferably, the robot is a robot arm with in particular six and preferably seven degrees of freedom. 
     The invention will be explained in more detail below based on preferred embodiments and with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic illustration of a first embodiment of the modular end effector in a first configuration, 
         FIG. 2  shows the modular end effector of  FIG. 1  in a second configuration, 
         FIG. 3  shows a detailed view of the locking device, 
         FIG. 4  shows a further embodiment of the modular end effector in a first configuration, 
         FIG. 5  shows the modular end effector of  FIG. 4  in a second configuration,  
         FIG. 6  shows a further embodiment of the modular end effector in a first configuration, 
         FIG. 7  shows the modular end effector of  FIG. 6  in a second configuration, 
         FIG. 8  shows a further embodiment of the modular end effector according to the invention, 
         FIG. 9  shows a further embodiment of the modular end effector according to the invention, 
         FIG. 10  shows a further embodiment of the modular end effector, and 
         FIG. 11  shows a further embodiment of the modular end effector according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The modular end effector  10  according to the present invention comprises a base  12  having a first connection element  14  and a second connection element  16 . Here, a first manipulator  18 , illustrated as an actuated finger in  FIG. 1 , is connected to the first connection element  14 . However, the first manipulator  18  is not limited to this, so that it can also be e.g. a tool, a sensor such as e.g. a movable camera or a movable light source. In general, the manipulator  18  can be any active or passive element required in the context of the task to be accomplished by the modular end effector. The actuated finger is also not restricted to a three-part structure and may have more or fewer actuated limbs. 
     A second manipulator  20  is connected to the second connection element  16 , also shown schematically as an actuated finger in  FIG. 1 . Here, the second manipulator  20  can be displaced linearly within the second connection element  16  in accordance with the arrow  22  illustrated in  FIG. 2 , so that the position of the second manipulator  20  changes and can thus be adapted to a new task without requiring a new design of  the modular end effector  10 . To obtain the linear mobility of the second manipulator  20 , for example, linear sliding elements  24  ( FIG. 3 ) can be provided, within which the second manipulator  20  can be displaced so as to be moved to a different position. The linear change in position can be caused e.g. by turning a grub screw  26  meshing with a tooth element  28  of the second manipulator  20 . In addition, the tooth element  28  is spring-loaded in the direction of the grub screw  26  by a spring  30 . Here, the toothed element  28  can be moved along the arrow  32  against the spring load, so that the toothed element  28  is no longer in engagement with the grub screw  26 . It is then possible to move the second manipulator  20  freely within the linear sliding element  24 . Thereby, a quick manual change of the position of the manipulator is possible. 
     As an alternative, however, it is also possible for the position change of the second manipulator  20  to happen automatically, e.g. by means of an electrical actuator or e.g. by means of a motor-operated grub screw which is in engagement with a toothed element of the second manipulator element  20 . Then, an automatic change in the position of the second manipulator element  20  can be achieved by moving the actuator (not shown) or by rotating the grub screw via the motor. 
     Hereinafter, identical or similar components are identified by the same reference numerals. 
     In the embodiment of the end effector  36  illustrated in  FIG. 4 , the position of the second manipulator element  20  can also be changed corresponding to the arrow  34 , the second manipulator element  20  being provided with linear mobility for this purpose. In addition, the modular end effector  36  of  FIG. 4  comprises a third connection element  38  to which a third manipulator  40  is connected. Here, the third manipulator  40  is in turn designed as an actuated finger, which again is only an example. The third manipulator element  40  has rotational mobility corresponding to the arrow  42  ( FIG. 5 ), so that the position of the third manipulator  40  can be adjusted. Thus, it is possible e.g. due to the rotational adaptability of the position of the third manipulator  40  to grasp elements that the modular end effector  36  was previously  not able to grasp. Thus, if the task to be accomplished is changed, it is no longer necessary to redesign the modular end effector. 
     In the embodiment of  FIG. 6 , the modular end effector  44  comprises a fourth manipulator  46 . The same is connected to the second connection element  16 . Here, the position of the fourth manipulator  46  can be adapted to the respective requirements corresponding to the arrow  48 . Thus, both the second manipulator  20  and the fourth manipulator  46  are connected to the second connection element  16  and are movable within this connection element  16 , so that the position can be adapted to the tasks to be accomplished. 
     In the embodiment of the modular end effector  50  illustrated in  FIG. 7 , the third manipulator  40  has, in addition to the rotary mobility for adapting the position of the manipulator, linear mobility corresponding to the arrows  52 , as already described above. Thus, the position of the third manipulator  40  can be adjusted both in a rotary manner and in a linear manner, whereby a high degree of adaptability and thus a great versatility of the modular end effector  50  is achieved. Moreover, the position of the first connection element  14  can be changed corresponding to the arrow  54 . Thereby, the position of the first manipulator  18  also changes corresponding to the arrow  56 . Here, the change in the position of the first connection element  14  can be supplemented by a mobility of the first manipulator  18 , e.g. in relation to the second and third manipulators, in the manner described above. 
     The modular end effector  58  illustrated in  FIG. 8  includes a base  12  having a first segment  60  and a second segment  62 . Here, the first segment  60  and the second segment  62  are movably connected to each other via a common pivot point  64 , so that the first segment  60  and the second segment  62  can be pivoted against each other corresponding to the arrow  66 . In the embodiment illustrated, the first segment  60  comprises a first manipulator  68 . Likewise, the second segment  62  comprises a second manipulator  70 . By changing the position of the first segment  60  and the second segment  62  relative to each other, the positions of the first manipulator  68   and the second manipulator  70  also change, so that their positions can be adapted to a modified task and a versatile end effector is thus provided. 
     In the embodiment illustrated in  FIG. 9 , the modular end effector  72  includes a base with a first segment  60  and a second segment  62 . Here, two manipulators  68  are connected to the first segment  60  and are illustrated as actuated fingers in the example depicted. Likewise, two manipulators  70  are connected to the second segment  62 , which are also illustrated as actuated fingers. Here, both the manipulators  68  of the first segment  60  and the manipulators  70  of the second segment  62  can have translational or rotational mobility to ensure a further improved adaptability of the modular end effector  72 . Moreover, in the modular end effector  72  of  FIG. 9 , a third segment  74  of the base  12  is provided, which is connected to the first segment  60  and the second segment  62  via a pivot point  76 . Thus, the position of the third segment  74  of the base  12  can be changed and can thus be adapted to new or modified tasks. The third segment  74  of the base  12  comprises a manipulator  78 , which in turn is implemented as an actuated finger. 
     Moreover, the end effector  72  of  FIG. 9  comprises an exchangeable surface element  80 , wherein the surface element  80  is able to be adapted to the respective task. Here, the surface element  80  can be divided so that different portions have functionally different materials, depending on the task to be accomplished. 
     Because of the changeability of the position of the connection elements and/or the position of the manipulators within the connection elements, together with the possibility of changing the geometry of the base, a modular end effector is provided that is easily adapted to changing tasks. In this context, it is understood that the features of the above embodiments can be freely combined with each other to further increase the maximum adaptability of the modular end effector. Specifically, the invention is not restricted to a specific number of manipulators or segments of the base. Furthermore, the invention is not restricted to the type of manipulators used.  
     The modular end effector illustrated in  FIG. 10  is constructed as described above with reference to  FIG. 9 . In addition, however, the former has a second rotatable manipulator  79 . Thus, non-human configurations/arrangements of the manipulators can be provided by the existing manipulators. In particular, several force pairs can be formed, so that it is possible to simultaneously grip more than one object or to simultaneously grip and process an object. The manipulators  70 , which are connected to the second segment  62 , and/or the manipulators  68  of the first segment  60  can each cooperate, so that the force of the manipulators is added or a higher stability of the manipulators is achieved. Here, the manipulators  70  of the second segment are moved synchronously. If also the manipulators  68  of the first segment are provided so as to cooperate, the manipulators  68  of the first segment are also moved synchronously. Of course, the movements of the manipulators of the first or second segment are independent of each other. 
     The modular end effector illustrated in  FIG. 10  is constructed as described above with reference to  FIG. 9 . In addition, the end effector has the possibility of rotating the segments  60 ,  62  of the base  12  relative to each other corresponding to the arrow  63 , so that the configuration/geometry of the base can be adapted. 
     The embodiments illustrated herein are mere examples of the present invention and should therefore not be construed as being limiting. Alternatives provided by a skilled person in consideration of the embodiments are likewise encompassed by the scope of protection of the present invention. Accordingly, the foregoing description is intended to be illustrative rather than restrictive. The invention described hereinabove is defined by the appended claims and all changes to the invention that fall within the meaning and range of equivalency of the claims are to be embraced within their scope.