Assembly System

Abstract

An apparatus and method for placing a first object into a beveled cavity of a second object are disclosed. In some embodiments, the first object is suspended by a plurality of flexible tethers such that the flexible tethers hold the first object in an orientation suitable for insertion into the second object.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 012,363, filed April 20, 2020, entitled “Apparatus and Method of Precision Assembly of Objects Suspended with Multiple Cables”, filed under 35 USC § 119(e), the entire contents of which are incorporated herein by reference. Technical Field

[0003] The disclosed embodiments relate to assembly systems and methods, such as systems and methods for placing objects using multiple tethers. Background Technology

[0004] When assembling objects in heavy industries (e.g., aerospace, shipbuilding, mining, etc.), heavy workpieces and sub-assemblies may require precise positioning against other objects and / or structures. Often, precise positioning and / or alignment of crane-suspended objects may require specialized training and / or experience, making typical object assembly heavily reliant on skilled labor. Assembly can typically be performed by workers who stand near the crane-suspended objects and adjust the position and orientation of one or more objects by directly pushing and / or pulling them, while simultaneously adjusting the crane's height. Summary of the Invention

[0005] According to one aspect, the assembly device includes: a support structure; a plurality of tethers suspended from the support structure, the plurality of tethers configured to suspend a first object from the support structure; and one or more actuators operatively coupled to at least one selected from the group consisting of the support structure and the plurality of tethers, the one or more actuators configured to lower a portion of the first object toward a cavity formed in a second object under the influence of gravity, the second object having an inclined plane formed along at least a portion of the cavity, and wherein the one or more actuators and the plurality of tethers are configured to control the lowering of the portion of the object such that, when the portion of the first object is inserted into the cavity, the portion of the first object contacts the inclined plane and slides along the inclined plane.

[0006] According to another aspect, a method of placing an object in a cavity includes: suspending a first object on a plurality of tethers of an assembly device; lowering a portion of the first object toward a cavity formed in a second object under the influence of gravity—the second object having an inclined plane formed along at least a portion of the cavity such that at least a portion of the first object contacts the inclined plane; sliding the portion of the first object along the inclined plane; and placing the first object in the cavity of the second object.

[0007] It should be understood that the foregoing concepts and the additional concepts discussed below can be arranged in any suitable combination, as this disclosure is not limited to this aspect. Furthermore, other advantages and novel features of this disclosure will become apparent from the following detailed description of several non-limiting embodiments when considered in conjunction with the accompanying drawings. Attached Figure Description

[0008] Non-limiting embodiments of this disclosure will be described by way of example with reference to the accompanying drawings, which are schematic and not intended to be drawn to scale. In the drawings, each identical or substantially identical component is generally denoted by the same reference numeral. For clarity, not every component is labeled in every drawing, nor is every component shown in every embodiment of this disclosure, unless illustration is required for understanding of this disclosure by one of ordinary skill in the art. In the drawings:

[0009] Figure 1 This is a front view of a passive assembly device according to an illustrative embodiment;

[0010] Figure 2A This is a front view of a suspended object in contact with the inclined surface of a cavity of a stationary object, according to an illustrative embodiment.

[0011] Figure 2B This is a front view of a suspended object in point contact with the inner wall of a cavity of a stationary object, according to an illustrative embodiment.

[0012] Figure 2C This is a front view of a suspended object in contact with two points of the inner wall of a cavity of a stationary object, according to an illustrative embodiment.

[0013] Figure 3A This is a front view of an object suspended from multiple flexible ropes according to an illustrative embodiment.

[0014] Figure 3B This is a front view of an object suspended by multiple flexible ropes according to another illustrative embodiment.

[0015] Figure 4 This is a front view of an active assembly device according to an illustrative embodiment;

[0016] Figure 5 It is a flowchart illustrating a method of passively placing a first object into the cavity of a second object;

[0017] Figure 6 It is a flowchart illustrating a method for actively placing a first object into the cavity of a second object;

[0018] Figure 7 This is a front view of an exemplary assembly device according to an illustrative embodiment;

[0019] Figure 8 This is a front view of an assembly device according to an illustrative embodiment;

[0020] Figure 9 It is a graph showing the relationship between the coefficient of friction of the inclined plane of a stationary object and the initial angle of the flexible tether of the assembly equipment, based on an experiment.

[0021] Figure 10 It is a graph showing the experimentally measured relationship between the initial angle and depth of the flexible tether of the assembly equipment, and the two-point contact between the various parts of the suspended object and the inner wall of the cavity of the stationary object can be achieved at this depth.

[0022] Figure 11 It is a graph showing the experimentally measured relationship between the travel depth and the distance from the center of the suspended object and the center of the cavity;

[0023] Figure 12 It is a graph showing the relationship between the coefficient of friction of the inclined plane of a stationary object and the initial angle of the flexible tether according to one embodiment.

[0024] Figure 13 It is a graph showing the relationship between the coefficients of friction of the inclined plane of a stationary object according to another embodiment;

[0025] Figure 14 It is a graph showing the relationship between the coefficients of friction of the inclined plane of a stationary object according to yet another embodiment;

[0026] Figure 15A This is a front view of an exemplary assembly device according to an illustrative embodiment;

[0027] Figure 15B According to one implementation method Figure 15A A front view of the assembly equipment's surface contact portion and the forces generated based on the position of the instantaneous rotation center;

[0028] Figure 15C According to one implementation method Figure 15AA front view of the assembly equipment's surface contact portion and the forces generated based on the position of the instantaneous rotation center;

[0029] Figure 15D According to one implementation method Figure 15A A front view of the assembly equipment's surface-contacting parts and the forces generated based on the position of the instantaneous rotation center; and

[0030] Figure 15E According to one implementation method Figure 15A A front view of the assembly equipment's surface contact portion and the forces generated based on the position of the instantaneous rotation center. Detailed Implementation

[0031] In heavy industries (e.g., aerospace, shipbuilding, mining, etc.), assembling objects is a critical task. Assembling such objects may require accurately positioning and / or arranging heavy workpieces and / or sub-assemblies (e.g., workpieces and / or sub-assemblies weighing more than 25 kg) against other workpieces and / or sub-assemblies, which can prove challenging in many cases. Often, accurately positioning or aligning a crane-suspended object can be particularly difficult. For example, a worker may assemble a heavy object by standing near it and adjusting its position and / or orientation by directly pushing and / or pulling it while simultaneously adjusting the crane's height. The worker can steadily push specific parts of the object so that its orientation can be aligned with a reference line without overshoot. In some cases, aligning a suspended object with a second object, such as a stationary structure, can be particularly challenging. The suspended object can be lowered to a specified position and orientation so that it can be stably and with a high level of precision seated within the structure. This may involve a worker coordinating the crane to lower the suspended object while manipulating its position and / or orientation in the horizontal plane. Such precision assembly is employed in a variety of applications—including turbine generators, marine and construction machinery, and their components, including large gearboxes and motors. To perform these operations quickly, workers may require years of experience and / or extensive training.

[0032] In view of the above, the inventors have recognized the advantages associated with structures and systems that can help guide a suspended object to a desired position and / or orientation relative to a cavity of an object vertically below the suspended object when the objects are mated together. Thus, in some embodiments, the first suspended object can be suspended from the assembly device by multiple tethers. The first suspended object can then be lowered toward a second stationary object under the influence of gravity (e.g., by lowering the assembly device). The second stationary object, in turn, can include a cavity for receiving the first suspended object having a ramp extending at least partially around the periphery of the cavity. The suspended object can be roughly positioned such that a portion of the first suspended object contacts the ramp when the first suspended object is lowered toward the cavity. Once the first suspended object contacts the ramp, movement of the first suspended object can be controlled such that the portion of the suspended object contacting the ramp slides along the ramp in a direction at least partially along the ramp surface toward the cavity. Then, once the object is received in the cavity, the first suspended object can be positioned within the cavity of the second stationary object. For example, in some embodiments, the first suspended object can slide toward the cavity along the ramp before contacting the inner wall of the cavity at a single point. After contacting the inner wall of the cavity at one point, the first suspended object can then contact the inner wall of the cavity at a second point, thereby stabilizing the first object within the cavity before it is further lowered into the cavity.

[0033] To achieve the desired functionality described above, in some embodiments, the assembly apparatus according to this disclosure may include a support structure and a plurality of flexible tethers extending from the support structure. The plurality of flexible tethers may be configured to suspend a first object in a desired orientation during insertion. Furthermore, in some embodiments, the plurality of tethers may be configured to maintain a tension in each tether above a predetermined tension as the first suspended object descends toward the cavity of the second stationary object. According to a particular embodiment, this may be due to the tethers having a predetermined length. However, in other embodiments, the tension in each tether may be actively controlled by one or more actuators to maintain a tension in each tether above an associated predetermined tension, such that the first suspended object is oriented substantially upright as it descends toward the cavity of the second stationary object and slides over the inclined surface into the cavity.

[0034] Depending on the desired application and object geometry, the systems and methods disclosed herein can be used to orient and place objects into cavities in a two-dimensional reference plane and / or a three-dimensional environment.

[0035] In view of the above, in some embodiments, it may be desirable to maintain the orientation of a first suspended object relative to a cavity of a second stationary object, the second stationary object being vertically positioned below the first suspended object in two mutually perpendicular dimensions (e.g., a vertical dimension and a horizontal dimension). In this case, the assembly device may include at least two flexible tethers to which the first object may be suspended. The flexible tethers can be used to maintain the first object relative to the cavity in the desired orientation as the first object is moved by the support structure and / or the tethers. In particular, while the tethers maintain the orientation of the first object, the support structure may raise or lower the first object. Alternatively or additionally, the flexible tethers may raise and / or lower the first object by changing the length of the tethers, for example by extending and / or retracting the tethers. In either case, the tethers may be appropriately tensioned (e.g., actively or passively tensioned, as described in more detail herein) to maintain the desired orientation of the first object relative to the cavity both before and during insertion.

[0036] As described above, in some embodiments, it may be desirable to maintain the orientation of the first suspended object relative to three vertical axes in a three-dimensional direction. In this case, the assembly device may include at least three flexible tethers to properly position and maintain the orientation of the first object in three-dimensional space (e.g., the vertical X, Y, and Z axes). As further detailed below, the tension in the tethers can be appropriately maintained and / or controlled as the first suspended object is lowered into the cavity of the second object to facilitate the insertion of a portion of the first object into the cavity of the second object.

[0037] In the various embodiments described herein, including the above-described embodiments, assembly devices comprising two and three tethers are described. However, it should be understood that the assembly device according to this disclosure may include any suitable number of tethers, including four, five, six, or more tethers, and / or any other suitable number of tethers depending on the application. However, since increasing the number of tethers during assembly increases the constraint on the suspended object, using two and three tethers to position the object in a two-dimensional reference plane and three-dimensional space, respectively, may be advantageous.

[0038] In some cases, the assembly equipment can perform the insertion process in any suitable manner (e.g., as described above). For example, in some embodiments, the insertion process is performed passively. In such embodiments, the assembly equipment is configured such that a support structure moves to move an object, while a tether connected to the support structure is held at a desired tension under gravity to control the orientation of the object as it is inserted into the cavity. For example, in such embodiments, a first object may be suspended by a tether of a fixed length, the tether configured to control the movement of the object relative to the cavity as it is lowered. To lower the object, the support structure can be lowered, which lowers the tether and consequently the first object. Depending on the application, this functionality can be performed using a crane, a movable gantry crane, or any other suitable system capable of controlling the vertical displacement of the support structure and the connected object.

[0039] In some cases, or in addition to the foregoing, the assembly equipment can actively control the insertion process. Specifically, in some embodiments, while the assembly equipment inserts the first object into the cavity of the second object, one or more actuators operatively coupled to the tethers can be used to actively control the tension and / or length associated with each of the flexible tethers. For example, the tethers can be connected to a movable arm, an actuated tether reel, or other actuation systems capable of manipulating the length and / or tension of the tethers extending from the support structure to which the tethers are attached. In some embodiments, the length and / or tension of each of the multiple tethers can be controlled independently, which allows the assembly equipment to be adapted to a wide range of applications. As those skilled in the art will understand, the tethers can be actively controlled during insertion in any suitable manner, depending on the application and as detailed below.

[0040] In some cases, it may be desirable for the active control of each tether to be automated. For example, the active control of the tethers may be performed by a processor. In such an implementation, one or more processors may be operatively coupled to one or more actuators associated with multiple tethers to control the operation of one or more actuators. Specifically, one or more processors may be configured to control one or more parameters of the tethers, such as length and / or tension. In some implementations, this may include active feedback control. For example, one or more sensors may be configured to sense the tension and / or length of each tether. In some implementations, this may correspond to a separate sensor associated with each tether. In either case, a signal associated with the sensed parameters may be output to one or more processors. The one or more processors may then control the tension and / or length of the multiple tethers, at least in part, based on the sensed parameters obtained from one or more sensors.

[0041] The assembly equipment can employ any suitable type of sensor for sensing the parameters described above. For example, the tension of the tethers applied to the assembly equipment may include one or more of a load cell, force sensor, extensometer, strain gauge, and / or any other suitable sensor configured to sense the tension or load applied to the associated tethers. Regarding the extension of one or more tethers, suitable sensors may include, but are not limited to, actuator encoders and / or any other suitable type of sensor configured to sense or otherwise determine the length of the associated tether extending from the corresponding support structure. Of course, while specific sensors have been mentioned above, as those skilled in the art will understand, any suitable sensor or combination of sensors may be used in the disclosed system, as this disclosure is not limited to this approach.

[0042] In some embodiments, the flexible tether can be angled relative to the horizontal plane of the suspended object (e.g., a plane perpendicular to the direction of gravity) in any suitable manner. It should be understood that such a suitable range of angles can be based at least in part on the geometry of the object suspended by the tether. In particular, the angle can be set such that the suspended object can be oriented to limit the degree to which the suspended object tilts as it moves toward a cavity of a stationary object (e.g., along an inclined plane) and / or enters a cavity of a stationary object and transitions toward a two-point contact state (e.g., as described in more detail herein). In some cases, constructing the tether at a suitable angle can be used to prevent the suspended object from sticking and / or becoming bound within the cavity and / or along the inclined plane.

[0043] Given the above, the angle can be set such that the flexible tether causes the suspended object to rotate instantaneously about a predetermined point of rotation to prevent binding and / or adhesion. Where theoretical binding is undesirable, the suspended object may tend to rotate about an instantaneous center of rotation defined by an imaginary point where lines parallel and coaxial with the tether intersect each other. To prevent binding and / or adhesion, the instantaneous center of rotation can be located at a predetermined distance above or below the lower surface of the suspended object (e.g., a surface oriented towards a cavity of a stationary object).

[0044] Depending on the geometry of the suspended object, the angle of the tether relative to the plane perpendicular to the direction of gravity can be any suitable value, depending on the desired application detailed below for several configurations. Specifically, due to undesirable viscous and / or static behavior occurring within certain ranges of the tether angle, there can be upper and lower suitable ranges for the applied angle. Particularly long suspended objects may allow for a larger suitable angle range, while shorter objects may have a smaller suitable angle range. Exemplary ranges that can be used in some applications are provided below.

[0045] In some embodiments, the tether of the assembly device may present an appropriate tether angle (e.g., an angle formed between the tether and a plane perpendicular to the direction of gravity) within a first operating angle range to avoid sticking and / or stationary behavior of the object during insertion. These tether angles may be less than or equal to 90 degrees, 85 degrees, 80 degrees, and / or any other suitable angle. Accordingly, the tether of the assembly device may have an appropriate tether angle range greater than or equal to 75 degrees, 80 degrees, 85 degrees, and / or any other suitable angle. Combinations of the above ranges are contemplated, including but not limited to angles between 75 degrees and 90 degrees, or angles equal to 75 degrees and 90 degrees. Of course, depending on the application, any suitable tether angle range may be employed.

[0046] Alternatively or additionally, in some embodiments, the tether of the assembly device may be arranged to operate within a second operating angle range to avoid sticking and static behavior of the object during insertion. For example, depending on the geometry of the suspended object, a suitable tether angle range may be less than or equal to 70 degrees, 60 degrees, 50 degrees, and / or any other suitable angle. Accordingly, the tether of the assembly device may have a tether angle greater than or equal to 1 degree, 10 degrees, 20 degrees, and / or another suitable angle. Combinations of the above ranges are contemplated, including but not limited to tether angles between 1 degree and 70 degrees or equal to 1 degree and 70 degrees. Of course, depending on the application, any suitable tether angle range may be employed.

[0047] In some embodiments, the tether angle can be set such that the tether does not cross when the suspended object is suspended by it. Therefore, in some embodiments, a tether angle between approximately 0 degrees and 120 degrees, or equal to 0 degrees and 120 degrees, is also conceivable.

[0048] In some embodiments, the appropriate range of tether angles may depend on the total length of the suspended object. For example, in some embodiments involving a suspended object with a relatively short total length, a tether angle of less than or equal to 50 degrees or greater than or equal to 80 degrees may be used. Alternatively or additionally, in some embodiments involving a suspended object with a relatively long total length, a tether angle of less than or equal to 80 degrees may be used. Of course, embodiments with other appropriate tether angles are also conceivable depending on the geometry of the suspended object and / or other suitable factors.

[0049] It should be understood that, although in some cases each of the multiple tethers has the same angle, it is also conceivable that each tether may have a different angle, as this disclosure is not limited to this approach. Of course, any suitable combination of angles may be used depending on the application.

[0050] As described herein, the instantaneous center of rotation of a suspended object can be offset by a predetermined distance relative to the bottom surface of the suspended object in a direction parallel to the direction of gravity to prevent entrapment and / or adhesion. Furthermore, in some embodiments, the instantaneous center of rotation of the object can be positioned such that it is above the center of mass of the suspended object or below the lowest surface of the suspended object relative to the direction of gravity. In some embodiments, the offset can be a percentage of the maximum dimension of the suspended object parallel to the direction of gravity (e.g., the total length of the suspended object) before contacting a stationary object. In some embodiments, the offset distance can be greater than or equal to 50%, 60%, 70%, and / or another suitable percentage of the length of the suspended object parallel to the direction of gravity. Accordingly, the offset distance can be less than or equal to 200%, 100%, 90%, 80%, and / or any other suitable percentage of the maximum dimension of the suspended object parallel to the direction of gravity. Combinations of the above ranges are contemplated, including, but not limited to, percentages between 50% and 200% or equal to 50% and 200%. Of course, depending on the application, any suitable percentage of offset distance for the desired application can be used, including percentages smaller and larger than those described above.

[0051] The assembly apparatus according to this disclosure may include any suitable type of flexible tether, configured to support an object on a support structure to which the tether is attached. For example, the flexible tether may be a cable, wire, rope, chain, braided tape, a combination of the foregoing, and / or any other suitable elongated flexible structure capable of suspending an object on a support structure. Therefore, as those skilled in the art will understand, depending on the application, any suitable type of flexible tether or a combination of various types of flexible tethers may be employed.

[0052] The assembly apparatus according to this disclosure can be used in any suitable application. For example, in some embodiments, the assembly apparatus may be attached to a gantry crane assembly, crane, or other support structure, or otherwise incorporated as part of a gantry crane assembly, crane, or other support structure, for placing a first object into a cavity of a second object. Alternatively or additionally, the assembly apparatus according to this disclosure may be attached to or otherwise integrated into an end effector for a robot. Therefore, as those skilled in the art will understand, the assembly apparatus according to this disclosure can be used in any suitable application or combination of applications.

[0053] Turning to the accompanying drawings, specific non-limiting embodiments are described in further detail. It should be understood that the various systems, components, features, and methods described with respect to these embodiments can be used individually and / or in any desired combination, as this disclosure is not limited to the specific embodiments described herein.

[0054] Figure 1An assembly apparatus 100 for placing a suspended object 102 into a cavity 104 of a stationary object 106, according to an illustrative embodiment, is depicted. A first object is vertically positioned above the cavity of a second object relative to the direction of gravity G applied to the system and the object. Furthermore, a portion of the first object oriented toward the cavity of the second object can be sized and shaped to be received in the cavity with which it is assembled. The assembly apparatus 100 includes a support structure 110 to which two or more flexible tethers 108 are attached. The two flexible tethers 108 are configured to be attached to and support the suspended object 102 using any suitable connection to a portion of the suspended object on the opposite side of the suspended object's center of gravity, such that the suspended object 102 is suspended from the support structure 110 via the flexible tethers 108. Furthermore, the support structure 110 can be moved (e.g., upward and downward) via an actuator 112 (e.g., a bridge crane), such that the support structure and the supported object can be selectively lowered toward the cavity. In the depicted embodiment, the actuator is part of a gantry crane, allowing the supporting structure to move relative to the direction of the depicted gravity G in one or more horizontal directions to properly position the object relative to a cavity formed in a second object. Of course, it is also conceivable to include assembly equipment as part of another movable structure (e.g., a crane or other system) or a stationary structure.

[0055] In the illustrated embodiment, the assembly device 100 is configured as a passive assembly system. In other words, the tension in the flexible tether 108 is maintained solely by gravity G, and the length of the flexible tether 108 is fixed. Therefore, when the actuator 112 moves the support structure 110 upward and / or downward, the suspended object 102 moves upward and / or downward relative to the lower second object 106 and the cavity 104 formed in the second object, respectively. Specifically, when the suspended object 102 is suspended by the flexible tether 108 and the flexible tether 108 is kept taut (e.g., under gravity G), the suspended object 102 moves upward and / or downward an equal distance as the support structure 110 moves upward and / or downward.

[0056] In this way, the assembly device 100 can lower the suspended object 102 toward the cavity 104 of the stationary object 106, while the length and tension of the tether 108 are maintained under the influence of gravity G. Furthermore, the stationary object 106 includes features that can help guide the corresponding portion of the suspended object 102 into the cavity 104 during insertion. Specifically, a ramp 114 can be formed in the second object such that the ramp corresponding to the inclined surface extending between the upper surface of the object and the inner surface of the cavity can extend at least partially, and in some cases completely around the upper opening of the cavity 104, which is oriented toward the corresponding portion of the suspended object 102 and configured to receive the corresponding portion of the suspended object 102 into the cavity 104.

[0057] The interaction between the inclined plane 114 and the portion of the contacting inclined plane of the suspended object 102 can help guide a portion of the suspended object into the cavity. For example, Figure 2A The diagram illustrates a suspended object 102 positioned such that its lower portion initially contacts a portion of an inclined plane 114 located below the portion of the object to be inserted into the cavity. As the suspended object 102 contacts the inclined plane 114, the force distribution among the flexible tethers 108 may change, resulting in a change in the angle of the associated tethers as the orientation of the suspended object changes with tilting to one side. Simultaneously, by appropriately controlling the length, angular orientation, and / or the force applied to a given object, the portion of the suspended object 102 in contact with the inclined plane can slide along the inclined plane surface toward the cavity 104. In some cases, each tether can be kept taut during this initial contact and sliding using a non-zero tension applied to each tether, in which case the suspended object 102 can function as if it were connected to the support structure 110 via a rigid linkage. For example, in Figure 1 In the system shown, the suspended object can move and rotate as if it were attached to a support structure via a rigid four-bar linkage, where the object itself acts as one of the linkages. However, implementations where one or more tethers can be slack, i.e., subjected to approximately zero tension, are also conceivable. In either case, the suspended object 102 can be guided toward the cavity 104 via the inclined plane 114 and the flexible tether 108, such that the overall direction of motion of the portion of the suspended object 102 in contact with the inclined plane is at least partially oriented inward toward the cavity 104 of the stationary object 106, which could correspond to the contact portion of the suspended object sliding inward toward the cavity along the inclined plane surface.

[0058] As stated above, and as Figures 2A to 2C As illustrated, the suspended object 102 can be positioned in its final position within the cavity 104 by sliding along the surface of the inclined plane 114 into the cavity 104. Specifically, as... Figure 2A As shown, when the suspended object 102 contacts the inclined plane 114, the suspended object 102 slides along the inclined plane 114 until at least a portion of the suspended object 102 enters the cavity 104. Figure 2B As shown, the suspended object 102 can initially contact the inner wall of the cavity 104 at a single point. As the suspended object 102 continues to descend into the cavity 104 (e.g., by lowering the support structure 110), as Figure 2CAs shown, the suspended object 102 can then contact the inner wall of the cavity 104 at two points. Once the suspended object 102 contacts the cavity 104 at both points, the reaction force provided by the inner wall of the cavity 104 can be used to provide orientation and two points of insertion for the portion of the suspended object to be inserted into the cavity. The corresponding portions of the cavity and the suspended object can be sized and shaped to allow the object to slide unrestrained into the cavity after the two-point contact engagement has occurred, as the suspended object continues to be lowered for insertion. This allows the suspended object 102 to be positioned in the final desired position within the cavity 104.

[0059] Once the suspended object 102 achieves a two-point contact state (e.g., as described herein), one of the flexible tethers 108 can be slackened while the other remains taut. Therefore, the combination of the reaction force from the inner wall of the cavity 104 and the tension in the remaining tauts can be used to control the descent of the suspended object 102 into the cavity 104 until the suspended object 102 achieves the desired position within the cavity 104. In a satisfactory embodiment, tension is maintained in the remaining tauts due to the force G acting on the tether.

[0060] Alternatively or additionally, in some embodiments, the flexible tether 108 can be actively controlled (e.g., as described in more detail herein). In such embodiments, one or more actuators can actively control the tension in the flexible tether 108 when a two-point contact state is achieved, allowing the suspended object 102 to move toward a desired orientation. In such embodiments, the tension in the flexible tether 108 can be controlled together or individually depending on the application. In some embodiments, the assembly device 100 may include a feature that allows the assembly device 100 to hold the suspended object 102 in a generally upright position when it is inserted into the cavity 104. In particular, the flexible tether 108 can be used to minimize the angle between the longitudinal axis of the suspended object 102 and the vertical axis A during insertion. For example, as... Figure 2A As shown, the suspended object can be approximately aligned with the vertical axis A (e.g., when the flexible tether 108 is kept taut under the influence of gravity G). However, as Figure 2B As shown, when the suspended object 102 slides along the inclined plane 114, the suspended object 102 can be displaced at an angle relative to the central axis A, for example, by a first angle α1. Furthermore, the suspended object 102 can be displaced at an angle relative to the central axis A by a second angle α2 during final insertion into the cavity. The flexible tether 108 can be configured to orient the suspended object 102 such that the angular displacement of the suspended object 102 remains less than a threshold angle, facilitating the sliding of the object along the inclined plane surface and its insertion into the cavity unrestrained, as described above.

[0061] To help avoid restraint during insertion of a portion of the object into the cavity, a flexible tether can be further used to hold the suspended object 102 in an orientation such that, when the suspended object 102 is lowered into the cavity 104, it can be fitted within the cavity 104. Specifically, the flexible tether 108 can hold the suspended object 102 in an orientation such that, when the suspended object 102 slides along the inclined plane 114 and / or enters the opening of the cavity 104 oriented toward the suspended object, the horizontal lateral dimension of the suspended object 102 is less than or equal to the horizontal lateral dimension of the opening of the cavity 104. In particular, in Figure 2A In the inclined plane contact position shown, the horizontal lateral dimension H1-A of the suspended object 102 is less than or equal to the horizontal lateral dimension H2 of the cavity 104. Relatedly, in Figure 2B In the shown point contact position, the horizontal lateral dimension H1-B of the suspended object 102 is less than or equal to the horizontal lateral dimension H2 of the cavity 104, such that the desired portion of the suspended object can be inserted into the opening of the cavity. Furthermore, in Figure 2C In the two-point contact positions shown, the horizontal lateral dimension H1-C of the suspended object 102 is less than or equal to the horizontal lateral dimension H2 of the cavity 104.

[0062] Although the above considerations have been described in relation to a passive system with an unacted tether, these concepts for facilitating partial sliding of the contact ramp and eventual insertion into the cavity are applicable to all embodiments described herein. Therefore, actively controlled assembly equipment can also be suitably controlled to provide the aforementioned functionality, as this disclosure is not limited to this approach.

[0063] As understood from the above, when the suspended object 102 contacts and slides across the surface of the inclined plane 114 to reach its final position within the cavity 104, the suspended object 102 can rotate (e.g., shift at an angle). This rotation can occur about an instantaneous rotation center P1, which can be related to the corresponding angle of the flexible tether 108 relative to the suspended object 102, see [reference needed]. Figures 3A to 3B P1 and P2 in the diagram. The instantaneous center of rotation can correspond to an imaginary point where lines parallel and coaxial with the tether intersect each other. Depending on the orientation of the tether, the instantaneous center of rotation can be located above, below, or coincide with the bottom surface of the suspended object. In particular, in Figure 3A In the depicted configuration, the lines coaxial with the flexible tether 108 intersect at point P1, which can be vertically positioned below the bottom surface of the suspended object oriented towards another object. Therefore, the suspended object 102 will tend to rotate about point P1. Relatedly, in Figure 3B In the configuration shown, the line coaxial with the flexible tether 108 intersects at point P2. Therefore, the suspended object 102 will tend to rotate about point P2.

[0064] As previously mentioned, in some cases, it may be desirable for the tether to be oriented within a specific angular range such that the instantaneous center of rotation of the object is offset by a predetermined distance relative to the bottom surface of the object, so that the object can slide into contact with the corresponding inclined plane and be inserted into the cavity of the second object. For example, points P1 and P2 can be selected such that the corresponding suspended object in each figure can be appropriately oriented to fit into the corresponding cavity. In particular, the suspended object 102 can be oriented to fit into the cavity when points P1 and P2 are outside the lower region ab of the object. Thus, as shown in the figures, pivot points P1 and P2 can be vertically positioned above or below the lower region ab of the object.

[0065] Without being bound by theory, the positions of the instantaneous rotation centers P1 and P2 of the suspended object relative to the depicted region ab can be a function of the angle between the flexible tether 108 and a portion of the suspended object to which the tether is connected, and the length of the suspended object 102 relative to the vertical direction parallel to the local gravitational direction G. For example, in Figure 3A In the configuration shown, the suspended object 102 has a relatively small length L1, and the region ab extends along most of the length L1. Therefore, the angle between the flexible tether 108 and the horizontal plane perpendicular to the direction of gravity... 1 can be set relatively large (e.g., close to 90 degrees or another suitable angle as detailed above) such that the pivot point P1 falls outside region ab. Relatedly, in Figure 3B In the configuration shown, the suspended object 102 has a relatively long length L2 in the vertical direction, and the region ab extends only along a small portion of the length L2. Therefore, the angle between the flexible tether 108 and the horizontal plane... 2 can be set to various suitable values ​​so that the pivot point P2 falls outside the region ab. Specifically, in Figure 3B In the embodiments shown, angle 2 is set to be relatively small, such that pivot point P2 is located above region ab in the vertical direction.

[0066] While the above embodiments illustrate a static tether length, it should be understood that tethers with dynamically varying lengths and / or angles during operation using one or more actuators are also conceivable. Therefore, the above discussion relating to the instantaneous center of rotation and its correspondence can be applied to both passively actuated and actively actuated assembly equipment, as this disclosure is not limited thereto.

[0067] Alternatively or in addition to the above, in some embodiments, the assembly device 100 includes features that allow active control of one or more parameters of the flexible tether 108. For example, such as Figure 4 As shown, the assembly equipment may include one or more actuators 118, depicted as actuated arms, configured to actively control the flexible tether 108. Specifically, the actuators 118 are capable of controlling the extension and retraction of the flexible tether 108 relative to the support structure 110 to which the actuators and tethers are connected. Therefore, the actuators can be used to lower or raise the suspended object 102 relative to the support structure.

[0068] As described above, in some cases, it may be desirable to maintain a predetermined tension applied to the multiple tethers supporting the object when the object is lowered into the corresponding cavity. Therefore, in some embodiments, the assembly device 100 may include a plurality of sensors 116 configured to sense the tension and / or extension of the tether 108. In the depicted embodiments, the sensors are depicted as sensors positioned in line with or attached to the tether. Regardless of the specific configuration, the multiple sensors may be operatively coupled to a processor 120 configured to control one or more actuators 118, such that the sensors can output one or more sensing parameters to the processor. The processor may be operatively coupled to an associated non-transitory processor-readable memory including processor-executable instructions that, when executed by the processor, can perform any of the methods disclosed herein. The processor 120 may control one or more actuators 118 at least in part based on one or more parameters sensed by the sensors. The processor 120 may then command the actuators to perform one or more functions on the flexible tether 108. For example, as the suspended object 102 is lowered relative to the support structure 110, the actuator can be controlled to maintain a tension in each tether greater than or equal to a predetermined tension. For example, the tethers can extend relative to the support structure while maintaining tension in each tether, or the tethers can be operated to maintain a desired tension in each tether while the support structure is lowered. In either case, during insertion of the object into the cavity, the suspended object can be lowered toward the cavity while maintaining tension in each tether. However, embodiments that allow one or more tethers to slacken during the insertion process are also conceivable, as this disclosure is not limited thereto.

[0069] Figure 5 One embodiment of a method for placing a first object into a cavity of a second object using assembly equipment is described, the method including passive operation wherein the length of a tether can be fixed as the object is lowered toward the cavity of the object, which includes an inclined plane extending at least partially around the cavity. Figure 5In step 500, a first object is suspended relative to the cavity of the object below the suspended object by a flexible tether of the assembly device in a desired orientation and horizontal position, such that the portion of the suspended object inserted into the cavity is generally positioned and oriented toward the cavity. Once the object is suspended in the desired orientation and position, in step 502, the object is lowered until it contacts the inclined surface of the cavity. Then, in step 504, the flexible tether (e.g., tension) facilitates the rotation of the object and the sliding of the portion of the suspended first object in contact with the inclined surface toward the cavity until the object is seated in the cavity. Finally, in step 506, the first object slides across the surface of the inclined surface such that the object makes a first contact with one or more inner surfaces of the cavity before sliding to the desired final position within the cavity, and subsequently a second contact. In this passive arrangement, the operation of the system can simply involve lowering a support structure from which the tether extends, and the overall configuration of the tether and the object can help ensure that the object properly slides across the various surfaces during insertion without being restrained, stuck, or moving in an undesirable direction.

[0070] Figure 6 This is a flowchart illustrating an exemplary method for actively controlling the tension of a tether applied to a first suspended object when it is inserted into a cavity of a second object positioned vertically below the first object relative to the direction of gravity. Similar to the embodiments described above, at step 600, an assembly device can be used to position and orient the first object toward a corresponding cavity formed in the second object below the first object when suspended by the flexible tether. This can be done manually and / or using one or more corresponding actuators to move the support structure of the device to a desired position and orientation, as this disclosure is not limited to how the first object is positioned and oriented relative to the second object. In either case, at step 602, one or more actuators of the assembly device can be appropriately controlled to extend the flexible tether (i.e., lengthen the flexible tether) to lower the first object toward the second object. As the first object lowers, tension in each tether can be sensed at 604, enabling a force-based control loop to control the actuators associated with the tether. For example, in some embodiments, the actuators can be operated to extend the associated tether whenever the sensed tension in the tether is greater than or equal to a predetermined threshold. Correspondingly, the extension of a particular tether can be stopped, and in some cases, the tether can retract when the sensed tension is less than a predetermined threshold. In this way, at 606, tension can be maintained in each of the flexible tethers as the object is lowered into the cavity. Similarly, this facilitates the sliding of the portion of the first suspended object that contacts the inclined surface around the cavity toward the cavity and facilitates the subsequent insertion of this portion of the first suspended object into the cavity.

[0071] Example 1: Conditions for successful insertion without relaxation / stickiness

[0072] Reference Figure 15A Furthermore, without being bound by theory, in the depicted embodiment, the suspended object 102 is held by only two tethers 108. Therefore, in the depicted embodiment, neither of the two flexible tethers 108 is slack (e.g., as...). Figures 3A to 3B As shown, by making the ropes at an angle, each rope does not fall into area ab.

[0073] Without being bound by theory, the quasi-static motion of the suspended object 102 can be determined kinematically under this "no-slack" condition. Since both flexible tethers 108 are taut, they can be considered as a pair of rigid linkages. The support structure 100, the two taut flexible tethers 108, and the suspended object 102 form a four-bar linkage mechanism with only one degree of freedom in the vertical plane.

[0074] Figure 7 and Figure 15A The diagram illustrates the insertion of such a suspended object 102 under the aforementioned "no slack" conditions. When the suspended object 102 is placed on the surface of the inclined plane 114, it is constrained by contact with the inclined plane 114. The position and orientation of the suspended object can be geometrically determined without being bound by theory. As the support structure 110 is lowered, the position and orientation of the suspended object 102 can vary relative to the height of the support structure 110. After reaching the bottom edge of the cavity 104, the suspended object 102 can contact the edge of the cavity 114 at its side, thus making a point contact with a portion of the cavity 104. In this point-contact state, the position and orientation of the suspended object 102 can be kinematically determined without being bound by theory. This continues until the suspended object 102 makes two-point contact with the inner wall of the cavity 104, thus achieving a two-point contact state. In the two-point contact state, the suspended object 102 can be constrained on at least both sides of the cavity 104. Once the suspended object 102 is thus constrained, a four-bar linkage is no longer formed. In cases where it is undesirable to be bound by theory, at least one flexible tether 108 can be relaxed to satisfy the constraint condition of two-point contact. In this case, the unidirectional nature of the tension in the flexible tether (e.g., the ability of the flexible tether 108 to be tensioned by gravity) allows the tension in one or more flexible tethers 108 to be released, so that the suspended object 102 is not over-constrained.

[0075] exist Figure 7 and Figure 15AIn the illustrated embodiment, the "no slack" condition described above can be maintained throughout the insertion process until two-point contact occurs, allowing for kinematic control of the movement of the suspended object 102, as detailed above. This is achieved by employing an appropriate tether angle. , The attachment position of the tether allows the instantaneous rotation center P3 to be positioned away from region ab, and the suspended object 102 can be guided through a quasi-static process to achieve a two-point contact state within cavity 104 at a depth sufficient for successful insertion.

[0076] This "no relaxation" condition can be satisfied in two ranges of tether orientation: small angles and large angles. In some cases, using a medium angle may cause the instantaneous rotation center P3 to fall into region ab, thus violating the "no relaxation" condition.

[0077] If one does not wish to be bound by theory, the choice of the tether angle can depend on the size of the suspended object 102. Figures 3A to 3B Two such examples are illustrated. If the suspended object 102 has a relatively short total length L1, a large tether angle can be used. 1. For example, to position the instantaneous center of rotation of the suspended object 102 below region ab. On the other hand, if the suspended object 102 has a relatively long total length L2, a smaller tether angle can be used. 2. For example, to position the instantaneous rotation center of the suspended object 102 above region ab.

[0078] During the insertion process, it may be desirable to prevent the suspended object 102 from sticking to the surface of the inclined plane 114. To control this, the inventors first considered the conditions required for the suspended object 102 to stick to the surface of the inclined plane 114. This could occur at the moment a portion of the suspended object 102 contacts the surface of the inclined plane 114 or when the suspended object 102 slides along the inclined plane 114. When the suspended object 102 sticks to the surface of the inclined plane 114, the suspended object 102 may lose two degrees of freedom. In this case, where it is not desirable to be bound by theory, the suspended object 102 may only rotate about the point of contact, meaning that at least one tether is slack. Alternatively, if the flexible tether 108 is set at an appropriate angle such that the instantaneous center of rotation P3 does not fall within region ab, the suspended object 102 can avoid sticking to the surface of the inclined plane 114 during insertion.

[0079] Used in Figure 7 The parameter d, which is limited in the middle, has no relaxation condition regarding the cable angle, given by the following equation:

[0080]

[0081] Without being bound by theory, the above equations can be used to determine two sets of tether angle ranges that can be associated with two conditions: when the tether is stuck on the surface of the inclined plane 114 during insertion and when it slides along the surface of the inclined plane 114 during insertion. Without being bound by theory, the static friction coefficient can be used to determine the stickiness upon initial contact with the inclined plane 114, and the dynamic friction coefficient can be used when sliding downwards along the inclined plane 114. Similar equations can be derived to determine the stickiness conditions during a single point of contact.

[0082] However, it should be noted that the "non-viscous" condition described above alone does not guarantee that the suspended object 102 will slide downwards along the inclined plane 114. The suspended object 102 can remain on the surface of the inclined plane under certain kinematic conditions. For example, Figure 15B Case (B) shows that the suspended object 102 can remain on the inclined plane 114 without sliding.

[0083] exist Figure 15B In configuration (B), the instantaneous rotation center P3-B is located at the end of the suspended object 102, where the extensions of the two tethering ropes 108 intersect. Without being bound by theoretical constraints, assume the left corner of the suspended object 102... Figure 7 Point A contacts the inclined plane. When the suspended object 102 rotates about P3-B, point A moves upward. If this upward movement is equal to the downward movement of the supporting structure 110, the two displacements cancel each other out, and the suspended object 102 can remain stationary on the inclined plane 114 without sliding. Figure 15A As shown, this stationary behavior can be a function of the tether angle, the relative position of point A with respect to the instantaneous center of rotation, and / or the slope angle α. Relative to the location... Figure 15C The instantaneous center of rotation P3-C, located slightly above the bottom surface of the object, is situated at... Figure 15D The instantaneous center of rotation P3-D at a relatively large distance above the bottom surface of the object and Figure 15E The position of the instantaneous center of rotation P3-E, located below the bottom surface of the object, determines other conditions. As can be seen in these figures, the position of the instantaneous center of rotation at a greater distance above and below the bottom surface of the portion of the object to be inserted into the cavity may cause rotation of the portion in contact with the inclined plane, which points inward toward the inward of the inclined plane where the cavity is located. Therefore, the tether of the assembly device can be suitably constructed and / or controlled such that the instantaneous center of rotation of the object can be suitably positioned to provide sliding movement of the portion of the object in contact with the inclined plane surface toward the opening of the cavity.

[0084] Without being bound by theory, if the "no viscosity" and "no stationary" conditions described above are met, it can be expected that the suspended object 102 will slide along the inclined plane 114.

[0085] After the suspended object 102 passes over the inclined plane 114, the opposite side of the bottom surface of the suspended object 102 (e.g., Figure 7 Point B in the diagram can clearly define the width of cavity 104 (e.g., Figures 2A to 2C (H2 in the text). Without being bound by theory, a four-bar linkage analysis can be used to estimate the tilt angle of the suspended object 102 at the point where it has reached the end of the inclined plane 114 and just before transitioning to the point-contact state described herein. Without being bound by theory, as described in the following equation, if the predicted tilt angle of the suspended object 102 satisfies the specified constraints, the opposite side of the bottom surface of the suspended object 102 can clearly define the corresponding edge of the cavity 104, such as... Figure 7 As shown.

[0086]

[0087] Subsequently, when at least opposite sides of the bottom surface of the suspended object 102 contact the corresponding edge of the cavity 104, the suspended object 102 can achieve a two-point contact state. Without being bound by theory, the depth of the initial two-point contact position can determine whether the suspended object 102 becomes stuck inside the cavity 104, for example, wedged into the cavity 104. Wedging is unlikely to occur when the depth of the initial two-point contact position within the cavity 104 is sufficiently deep. Depending on the given geometry of the suspended object 102, certain tether angles can produce a deeper initial two-point contact position compared to other tether angles, thus making wedging unlikely. This parameter can be selected to make the depth of the initial two-point contact position as deep as possible. Without being bound by theory, the depth of the initial two-point contact position can be determined kinematically and geometrically.

[0088] Example 2: Experimental Verification

[0089] The analytical results associated with the implementation of the devices and methods disclosed herein are verified through experiments using both 2D and 3D scale models. For example, as Figure 8As shown, a steel pin 126 (0.76 kg) is manufactured to slide into a steel hole 132 with a 45-degree bevel angle. To avoid nonlinearity associated with sharp edges, the bottom corner of pin 126 is given a 0.6 mm radius. Pin 126 is connected to a mounting system via a low-strength polyester cord 134, and the mounting system is attached to a linear guide 122 powered by a lead screw. An April tag is attached to the mounting system, pin 126, and hole 132 to provide relative position data for calculation and to indicate the pin's tilt angle. An indicator LED 128 provides a trigger for when a two-point contact state (e.g., as described in more detail herein) is achieved. Various types of materials are placed on the bevel surface to vary the coefficient of friction of the interaction between the pin and the bevel (e.g., material 130). The coefficient of friction is measured by placing a piece of material 130 on a steel block and resting pin 126 on top of the surface. The angle of the steel block is raised until pin 126 begins to slide along the surface. The angle at which sliding begins is measured as the friction coefficient angle fs, where m = tan(fs). In this experiment, the length L of pin 126 was set to 127 mm, and the width d of pin 126 was set to 50.8 mm. Furthermore, the inclined plane angle α was set to 45 degrees, and the lengths l1 and l2 of the flexible tether 134 were set to 203.2 mm. The diameter D of the hole... h It is set to 51.82 mm, which means that the gap between pin 126 and the hole is 1.02 mm.

[0090] First, experiments were conducted using three different coefficients of friction to verify that the flexible tether angle is within the permissible range (e.g., as mentioned above regarding...). Figures 3A to 3B As described, the pivot point is located outside region ab) and prohibited regions (e.g., as mentioned above regarding Figures 3A to 3B As described, this results in a successful ramp intersection of pin 126 when the pivot point is located within region ab. Figure 9 As shown, the permissible initial angle range decreases sharply with increasing friction coefficient of the pin-hole system. This experiment verifies that pin 126 will slide within the permissible range.

[0091] Secondly, experiments were conducted comparing quasi-static inclined plane crossing simulations with actual pin crossings under different initial pin level errors. Returning to... Figure 7 The e0 values ​​were tested at 1.27 mm, 2.54 mm, and 5.08 mm, representing 2.5%, 5%, and 10% of the diameter of the test pin, respectively. Figure 10As shown, data points indicate experimentally measured data, and lines indicate predicted values ​​from simulations. The root mean square error (RMSE) between the measured and predicted results was calculated. For a horizontal error e0 = 1:27 mm, the RMSE was 0.5 degrees; for e0 = 2:54 mm, the RMSE was 1 degree; and for e0 = 5:08 mm, the RMSE was 2.4 degrees. This indicates that kinematic analysis can be used to predict the final angle of the pin at the end of the ramp crossing within 2.4 degrees for approximately all ranges of flexible tether angles.

[0092] Third, experiments were conducted in which the depth of the first two-point contact was measured based on different horizontal displacement errors of the pin and different flexible tether installation angles (e.g., as part of the trajectory associated with insertion, as described herein). The root mean square error (RMSE) between the measured and predicted results was calculated. For a horizontal error of e0 = 1:27 mm, the RMSE was 8.9 mm; for e0 = 2:54 mm, the RMSE was 4.2 mm; and for e0 = 5:08 mm, the RMSE was 8.6 mm. This indicates that for the maximum amount of horizontal displacement error the pin may be expected to experience, the kinematic model can be used to predict the depth of the first two-point contact within 7.5% of the pin length. Figure 10 As shown, the depth l* associated with achieving two-point contact decreases as the angle of the flexible tether increases. Furthermore, as... Figure 10 As shown, the depth l* increases as the flexible tether angle approaches 90 degrees. This means that in order to construct the assembly device as an insertion pin to achieve the appropriate two-point contact depth l*, the flexible tether angle can be as small as possible (e.g., as shown in the figure). Figure 3B (as shown) or as close to 90 degrees as possible (e.g., as shown) Figure 3A (As shown).

[0093] Fourth, additional experiments were conducted using 3D settings, such as... Figure 11 As shown, it includes a 3.5 kg aluminum round pin with a diameter of 101.7 mm and a length of 152.4 mm, an aluminum hole with an inner diameter of 101.85 mm, a low-strength polyester rope with lengths of 457 mm and 609.6 mm, and a mounting plate with a diameter of 203.2 mm.

[0094] Figure 11 The experimental results depicted in the figure show that, for certain cable angles, the pin will not successfully cross the ramp and enter the hole. The figure depicts the travel trajectory where the cable installation angle falls within the unacceptable area predicted for a specific pin geometry (e.g., as shown in the figure). Figures 3A to 3B The area shown (ab) is inside. In these cases, the pin may tilt forward and fall over. Therefore, Figure 11The diagram shows the minimum variation in the distance from the center of the pin to the center of the hole and the depth of the pin within the hole within such a region. In particular, successful pin insertion was found when the flexible tether was outside this range, especially when the flexible tether was installed at 76 degrees and / or 38 degrees relative to the horizontal.

[0095] Example 3: Parameter Study

[0096] In situations where one does not wish to be bound by theory, the mechanical behavior of a suspended object, such as a pin, can be determined by applying kinematic principles associated with a four-bar linkage. Specifically, the effects of varying the length L, width d, and slope angle α of the suspended object 102 were investigated. The trajectory of the suspended object 102 with varying geometric parameters and a varying initial cable placement angle was determined, and the instantaneous slope at the point of first contact with the slope 114 was calculated. A configuration is considered permissible if the slope of the instantaneous trajectory favors the sliding of the suspended object 102 down the slope. Figures 12 to 14 The results of the parameter study are described in the text.

[0097] The inventors observed that as the length L of the suspended object 102 increases, the area where the pin will remain stationary increases, and the area where sticking might occur shifts towards the area with a higher cable angle. Therefore, the inventors understand that a smaller cable angle may be associated with successful insertion (e.g., as...). Figure 3B (As shown). Furthermore, the inventors observed that as the width of the suspended object 102 increases, the area where adhesion may occur increases, while the area where the suspended object 102 may remain stationary appears to remain approximately the same. Additionally, the inventors observed that as the slope angle α becomes less steep, the effective mounting configuration range decreases.

[0098] The embodiments of the technology described herein can be implemented in any of a variety of ways. For example, the embodiments can be implemented using hardware, software, or a combination thereof. When implemented in software, the software code can execute on any suitable processor or set of processors, whether located in a single computer device or distributed across multiple computer devices. Such a processor can be implemented as an integrated circuit, wherein one or more processors in the integrated circuit components include commercially available integrated circuit components known in the art as, for example, CPU chips, GPU chips, microprocessors, microcontrollers, or coprocessors. Alternatively, the processor can be implemented in custom circuitry such as ASICs or semi-custom circuitry resulting from configuring programmable logic devices. As yet another alternative, whether commercially available, semi-custom, or custom, the processor can be part of a larger circuit or semiconductor device. As a specific example, some commercially available microprocessors have multiple cores, such that one or a subset of these cores can constitute a processor. However, the processor can be implemented using circuitry in any suitable form.

[0099] In addition, the processor may have one or more input and output devices. Among other things, these devices may also be used to present a user interface. Examples of output devices that can be used to provide a user interface include a display screen for visual presentation of output and a speaker or other sound-generating device for auditory presentation of output. Examples of input devices that can be used for a user interface include a keyboard, individual buttons, and clicking devices such as a mouse, touchpad, and digitizer. As another example, the computing device may receive input information via voice recognition or in other audible formats.

[0100] Such processors can be interconnected via one or more networks of any suitable form, including local area networks (LANs) or wide area networks (WANs), such as enterprise networks or the Internet. Such networks can be based on any suitable technology and can operate according to any suitable protocol, and can include wireless networks, wired networks, or fiber optic networks.

[0101] Furthermore, the various methods or processes outlined in this paper can be encoded as software that can execute on one or more processors employing any of a variety of operating systems or platforms. Additionally, such software can be written using any of a number of suitable programming languages ​​and / or programming or scripting tools, and can also be compiled into executable machine language code or intermediate code that executes on an architecture or virtual machine.

[0102] In this regard, the embodiments described herein can be implemented as a computer-readable storage medium (or multiple computer-readable media) (e.g., computer memory, one or more floppy disks, compact discs (CDs), optical discs, digital video discs (DVDs), magnetic tape, flash memory, RAM, ROM, EEPROM, circuit configurations in field-programmable gate arrays or other semiconductor devices, or other tangible computer storage media) encoding one or more programs that, when executed on one or more computers or other processors, perform methods implementing the various embodiments discussed above. It is apparent from the foregoing examples that a computer-readable storage medium can retain information for a sufficient time to provide computer-executable instructions in a non-transitory form. Such a computer-readable storage medium or medium can be transportable, such that one or more programs stored thereon can be loaded onto one or more different computer devices or other processors to implement the various aspects of this disclosure discussed above. As used herein, the term "computer-readable storage medium" includes only non-transitory computer-readable media that can be considered as a product (i.e., an article of manufacture) or a machine. Alternatively or additionally, this disclosure can be implemented as a computer-readable medium other than a computer-readable storage medium, such as a propagating signal.

[0103] As used herein, the terms "program" or "software" generally refer to any type of computer code or set of computer-executable instructions that can be used to program a computer device or other processor to implement the various aspects of this disclosure as discussed above. Furthermore, it should be understood that, according to one aspect of this embodiment, one or more computer programs that perform the methods of this disclosure when executed do not need to reside on a single computer device or processor, but can be distributed in a modular manner across many different computers or processors to implement the various aspects of this disclosure.

[0104] Computer-executable instructions can take many forms, such as program modules executed by one or more computers or other devices. Typically, a program module contains routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. In different implementations, the functionality of a program module can usually be combined or distributed as desired.

[0105] The various aspects of this disclosure can be used individually, in combination, or in various arrangements not specifically discussed in the embodiments described above, and therefore are not limited to the details and arrangements of the components set forth in the foregoing description or shown in the drawings. For example, aspects described in one embodiment can be combined in any way with aspects described in other embodiments.

[0106] The embodiments described herein can be embodied in the methods for which examples have been provided. The actions performed as part of this method can be ordered in any suitable manner. Therefore, embodiments can be constructed that perform actions in an order different from the order shown, and even if actions are shown as sequential in the illustrative embodiments, the embodiments may include the simultaneous execution of some actions.

[0107] Furthermore, some actions are described as being performed by a “user.” It should be understood that a “user” does not necessarily have to be a single individual, and in some implementations, actions attributable to a “user” may be performed by a team of individuals and / or individuals in combination with computer-aided tools or other mechanisms.

[0108] The use of ordinal terms such as "first," "second," and "third" in the claims to modify a claim element does not imply any priority, order of precedence, or sequence of actions of a method relative to another claim element. Rather, it is merely used as a marker to distinguish one claim element with a certain name from another element with the same name (if not using ordinal terms), thus differentiating the claim elements.

[0109] Furthermore, the wording and terminology used herein are for descriptive purposes and should not be considered restrictive. The use of “including,” “contains,” or “has,” “includes,” “involves,” and variations thereof in this document means to cover the items listed thereafter and their equivalents, as well as any additional items.

[0110] Although this teaching has been described in conjunction with various embodiments and examples, it is not intended to be limited to such embodiments or examples. Rather, as those skilled in the art will understand, this teaching includes various alternatives, modifications, and equivalents. Therefore, the foregoing description and figures are merely illustrative.

Claims

1. An assembly apparatus, comprising: Support structure; Multiple flexible tethers are suspended from the support structure, and the multiple flexible tethers are configured to suspend a first object from the support structure; as well as One or more actuators, operatively coupled to at least one of the group consisting of the support structure and the plurality of flexible tethers, the actuators being configured to lower a portion of the first object under the influence of gravity toward a cavity formed in a second object, the second object having an inclined surface formed along at least a portion of the cavity, and wherein the actuators and the flexible tethers are configured to control the lowering of the portion of the first object such that, upon insertion of the portion of the first object into the cavity, the portion of the first object contacts and slides along the inclined surface. The one or more actuators include a plurality of actuators configured to extend the plurality of flexible tethers to lower the first object.

2. The assembly equipment according to claim 1, wherein, The plurality of actuators are configured to maintain a predetermined tension in each of the plurality of flexible tethers as the portion of the first object is lowered into the cavity.

3. The assembly equipment according to claim 1, wherein, The plurality of actuators are configured to lower the support structure.

4. The assembly equipment according to claim 1, wherein, The plurality of flexible tethers include one or more sensors configured to sense the tension of the plurality of flexible tethers.

5. The assembly equipment according to claim 4, wherein, The plurality of actuators are configured to change the tension of the plurality of flexible tethers at least in part based on the sensed tension.

6. The assembly equipment according to claim 5, wherein, The plurality of actuators are configured to be controlled by the processor at least in part based on the sensed tension.

7. The assembly equipment according to claim 1, wherein, The plurality of actuators and the plurality of flexible tethers are configured to keep the first object substantially upright as it is lowered into the cavity of the second object.

8. The assembly equipment according to claim 1, wherein, The plurality of flexible tethers includes two flexible tethers configured to move the first object in two dimensions.

9. The assembly equipment according to claim 1, wherein, The plurality of flexible tethers include three flexible tethers configured to move the first object in three dimensions.

10. The assembly equipment according to claim 1, wherein, The plurality of actuators are configured to move the first object such that, as the first object slides along the inclined plane of the second object, the portion of the first object moves toward the cavity of the second object by a greater amount than the portion of the first object moves away from the cavity of the second object.

11. The assembly equipment according to claim 1, wherein, The lines extending coaxially with the plurality of flexible tethers intersect at an intersection point, wherein the intersection point is offset by a predetermined distance in the vertical direction relative to the bottom surface of the portion of the first object oriented toward the cavity, wherein the vertical direction is parallel to the direction of gravity.

12. The assembly equipment according to claim 11, wherein, The predetermined distance is at least 50% of the total length of the first object offset from the bottom surface, wherein the total length is parallel to the direction of gravity.

13. The assembly equipment according to claim 11, wherein, The assembly equipment also includes a processor configured to control the plurality of actuators such that the length of each of the plurality of flexible tethers is set such that the intersection point is offset relative to the bottom surface by at least the predetermined distance.

14. A method of placing a first object in a cavity, comprising: The first object is suspended by multiple flexible tethers of the assembly equipment; A portion of the first object is lowered towards a cavity formed in the second object under the influence of gravity, such that at least a portion of the first object contacts an inclined surface, and the second object has the inclined surface formed along at least a portion of the cavity; The portion of the first object is made to slide along the inclined plane; as well as The first object is placed in the cavity of the second object. Lowering the first object includes extending the plurality of flexible tethers via a plurality of actuators in the assembly equipment to lower the first object.

15. The method according to claim 14, wherein, Lowering the first object into the cavity of the second object includes lowering the plurality of flexible tethers.

16. The method according to claim 15, wherein, Lowering the plurality of flexible tethers includes maintaining a predetermined tension in each of the plurality of flexible tethers when the portion of the first object is lowered into the cavity of the second object.

17. The method of claim 14, wherein, Lowering the first object into the cavity includes keeping the first object substantially upright.

18. The method according to claim 14, wherein, Sliding the portion of the first object along the inclined plane includes moving the first object such that the portion of the first object moves toward the cavity of the second object by a greater amount than the portion of the first object moves away from the cavity of the second object.

19. The method of claim 14, wherein, The plurality of flexible tethers suspending the first object on the assembly device include suspending the first object such that lines extending coaxially with the plurality of flexible tethers intersect at an intersection point, wherein the intersection point is offset vertically by a predetermined distance relative to the bottom surface of the portion of the first object oriented toward the cavity, wherein the vertical direction is parallel to the direction of gravity.

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