WO1995005975A1

WO1995005975A1 - Coupling and robotic engagement fixture and jaws

Info

Publication number: WO1995005975A1
Application number: PCT/CA1994/000450
Authority: WO
Inventors: King-Heng Liu; Gordon Rife
Original assignee: Canadian Space Agency
Current assignee: Canadian Space Agency
Priority date: 1993-08-24
Filing date: 1994-08-24
Publication date: 1995-03-02
Anticipated expiration: 1996-02-24
Also published as: AU7487394A

Abstract

A coupling interface (1) for grasping by a robotic end effector comprises a body (2) and two pairs of fingers (4, 5 and 6, 7) extending outwardly from opposite sides of the body, each pair of fingers (4, 5 and 6, 7) providing a bifurcation between their inner sides (8, 9 and 10, 11) in the form of an inwardly tapering recess (12, 14). All of the inner sides of the fingers are bevelled for aligning a complementary shaped anvil with the tapering recess. The anvil (29) is also provided with a central, chamfered, 'V' shaped recess (48) to engage with the corners of a square-waisted microfixture interface.

Description

Title: COUPLING AND ROBOTIC ENGAGEMENT FIXTURE AND JAWS

Field of the Invention

This invention relates to connector interfaces whereby an object can be seized and manipulated by a tool, such as by the end effector of a robot. More particularly, it relates to an interface fixture and gripping anvil for such fixture that allows the gripping anvil to be compatible with engagement of another form of connector interface. The invention is particularly suited to space applications.

Background to the Invention

In the field of materials handling, many types of "handles" have been conceived. With the advent of robotics, new types of handles or connector interfaces suited for grasping by a robotic end-effector have become required. Such interfaces should be easily graspable, provide a degree of self-alignment and enable the manipulated article to be transposed and rotated with precision.

These requirements are especially present in the case of space application where orbital replacement (or replaceable) units - "ORU's" - are attached to space vehicles and satellites, but are removable for servicing. Satellites themselves some times need to be grasped and manipulated by robotic machines.

One type of interface has been designed for the retrieval and perhaps the replacement of small component parts - ORU's - as a means of servicing a satellite. This interface is described in Patent Cooperation Treaty Application No. PCT/CA91/0035, filed 3 October, 1991. This "microfixture" interface is square in cross-section in plan view, and from the a side view has a profile defined by upper and lower chamfered walls that taper into a waist, also square in a cross-sectional plan view, defining two pairs of opposed corners. This specific shape allows gripping anvils to receive and engage one pair of the opposed, chamfered corners provided by this square-waisted interface.

While the square-shaped microfixture interface is useful for manipulating smaller objects, it is not as satisfactory for gripping, holding and retrieving, for example, an entire orbiting satellite as when the satellite must be held for a servicing operation.

Previous attempts to provide an interface which can be gripped sufficiently as, for example, transporting or servicing a satellite, have been found to be prone to jam and to be damaged, resulting in difficulties in releasing the interface and to loss of accuracy in alignment with the gripping anvils after repeated use. There is a need for a robust interface which can be gripped sufficiently for, for example, transporting or servicing a satellite, and which is not prone to jam to be damaged. There is also a need for an interface which will provide no backlash when gripped firmly by gripping anvils, and yet which will align with the gripping anvils in all of the axis x, y and z axes. The present invention provides such an interface. There is further a need for gripping anvils which can grip both the pre-existing design of microfixture interface and the new robust interface disclosed below, without the need for an adjustment being made to one or both of the anvils. The invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments are intended to demonstrate the principle of the invention, and the manner of its implementation. The invention in its broadest and more specific forms will then be further described, and defined, in each of the individual claims which conclude this Specification. Summary of the Invention

Accordingly to the present invention there is provided a bifurcated connector interface suitable for use with articles to be grasped, and particularly orbital replacement units, comprising:

(1) an interface body; and

(2) two pairs of fingers extending outwardly from opposite sides of the body, each pair of fingers defining a bifurcation between their inner sides in the form of a bifurcating recess which tapers inwardly towards the body the inner sides of the fingers being bevelled for aligning with a pair of correspondingly shaped gripping anvils that can enter the respective bifurcating recesses for engagement with the interface.

Preferably, the bevelled inner sides of each of the fingers define a shape for the fingers that is in the form of a truncated triangle in cross-section. Such truncated triangle shape may be that of isosceles triangle.

Strengthening webs may extend along the sides of the body, joining the outer sides of the fingers.

The body is preferably pierced centrally, perpendicularly to the plane of the fingers, by a fastener access opening, whereby bolts and the like may be accessed. Such opening may also provide a seat for such fasteners.

Mounting ribs may be provided on the underside or base-end of the body for engagement with indexing slots on the body, or ORU, to which the interface is attached. Attachment is effected by attachment means that may include mounting screw passages extending downwardly through the body or strengthening portions of the interface, preferably at positions adjacent the outer, base or root-end sides of the fingers.

To complement the interface of the present invention and, as well, serve as grippers for interfaces of the microfixture type, gripping anvils may be provided, each anvil comprising: (a) an anvil body portion;

(b) a pair of splayed protuberances extending from the anvil body portion for engaging an article of complementary form, each pair of protuberances having: (i) opposed, inner sides defining between them a converging recess formed by top and bottom, chamfered, inner sides of the protuberances, for mating with complementary-shaped, converging, top and bottom, inwardly chamfered walls, defining a waist, that meet to form a corner on an article to be grasped; and

(ii) opposed, outer, notched sides with the notches diverging rearwardly from one another on the exterior portion of each side of the recess, the notches being positioned for mating with a pair of diverging, top and bottom, bevelled bifurcated fingers on an article to be grasped.

Preferably, the central portions of the top and bottom, chamfered, inner sides of the converging recess are planar, and extend substantially vertically between their chamfers to accurately align with similar, planar, waist portions between the chamfers of the walls on the micro-interface.

Preferably, the notches on the exterior sides of the pairs of protuberances on the anvil each comprise two, inwardly tapering, planar sides leading to a flat bottom which accurately aligns with a flattened crest between the top and bottom bevelled sides of the bifurcated fingers on the article to be grasped.

The protuberances may have truncated ends to reduce the risks of interferences and ensure mating in both of the above (i) and (ii) modes. The foregoing summarizes the principal features of the invention and some of its optional aspects. The invention may be further understood by the description of the preferred embodiments, in conjunction with the drawings, which now follow.

Summary of the Figures

In the accompanying drawings which illustrate, by way of example, an embodiment of the present invention. Figure 1 is an oblique view of the connector interface of the invention.

Figure 2 is an oblique view of one of a pair of similar gripping anvils for gripping therebetween the interface shown in Figure 1.

Figure 3 is an oblique view of a variant of the anvil of Figure 2, carried on a mount for engagement with a robotic machine.

Figure 4 is an oblique view of a prior art micro-fixture connector interface.

Figure 5 is a top view of Figure 4. Figure 6 is a side view of Figure 4.

Description of the Preferred Embodiment

In Figure 1 there is shown a bifurcated, connector interface, generally designed 1, comprising a body 2, and two pairs of splayed fingers 4,5 and 6,7, extending outwardly from opposite sides of the body 2. Each pair of fingers 4,5 and 6,7 provides a bifurcation between their inner sides 8,9 and 10,11 respectively, in the form of a recess, 12 and 14 respectively, which tapers inwardly towards the centre of the body 2. All of the inner sides 8 to 11 of the fingers 4 to 7 are bevelled for aligning with gripping anvils of complementary shape (to be described later) that will enter the recesses 12 and 14. The bevelled inner sides 8 to 11 of the fingers

4 to 7 provide a shape to the inner portions of the fingers 4 to 7 that is that of truncated triangles in cross-section. This is apparent from the end view of the finger designated 7 where the truncated triangle is shown to be an isosceles triangle. (The apparent curvature of the lines defining the end of such finger 7 is due to the curved end face 7a that terminates the outer end of the finger 7.)

Strengthening webs, such as that designated 16, may extend along the sides of the body 2, joining outer sides of the unit, such as between fingers 4 and 7.

A base portion 18 of relatively larger cross-section of the body 2 extends beneath the fingers 4 to 7 and the strengthening webs, such as web 16, to serve as a base 18 for the body 2. Mounting ribs, such as those designated 20 and 22, are provided on the underside of the body 2, and mounting screw passages 24, 25 extend downwardly through the strengthening webs, such as web 16, and through the base portion 18 of the body 2, preferably at positions adjacent the outer sides of the fingers 4 to 7.

The interface 1 may be provided with lightening recesses in the form of indentations or blind-holes 36, 37.

The interface 1 may also be provided with a pair of tab-engaging recesses 42 on opposite sides of the top of the body 2, and jaw engaging notches 46 for the interface 1 to be gripped by a hand tool (not shown) .

A central attachment aperture 40 extends entirely through the body 2 to provide access to attachment means (not shown) such as bolts and machine screws or other rotational fasteners. Such fasteners may attach an ORU to an orbital body. If the aperture 40 has a seating rim (not shown) near its bottom within the body

2, the fastener may seat on the interface. By placing the attachment aperture centrally in the body 2, robotic end-effectors that rotate fasteners can anchor themselves against the connector interface 1, using it to absorb torque.

Fins 28 may extend from the base 18 of the body 2 beneath the fingers 4 to 7 in order to form curtains that will exclude tether-lines from snagging on the interface.

While the interface 1 has been described in an application suitable for an orbiting body, it is equally suited to any application whereby it is desired to provide a connector interface to grasp any object with gripping jaws.

In Figure 2, there is shown one of a pair of similar gripping anvils for gripping the interface shown in Figure 1. This anvil 29 comprises:

(a) a body portion 30;

(b) a pair of splayed protuberances 46, 47 extending from the body portion 30, each pair of protuberances 46, 47 forming: (i) a rearwardly converging central recess 48 between them, formed by top and bottom chamfered, inner sides 45 and 49, for, in operation, receiving, mating with and gripping converging, inwardly chamfered walls 51 and 52 (Figures 4 to 6) that meet at a corner 53 on an alternate coupling interface 54; and (ii) opposed, outer, notched sides 55 and 56 having notches 57, 58 formed therein, such notches 57, 58 diverging rearwardly from one another on each side of the central recess 48, the notches 57, 58 in operation, entering between, mating with diverging, outwardly bevelled fingers 7, 8, 9, 10 on connector interface 1 (Figure 1)

The inner sides 45, 49 of the central recess 48 of the anvil 29 are planar between the chamfers and extend substantially vertically, to accurately locate with similar, planar waist portions 59, 66 between the chamfers of the walls 51, 52 on the alternate interface article 54.

The notches 57, 58 of the opposed, outer notched sides 55, 56 of the pair of protuberances 46, 47, each comprises two inwardly tapering, plane sides 60, 61 leading to a flat bottom 62 which accurately locates with a flattened crest 50 between the top and bottom bevelled sides 8, 9, 10, 11 of the bifurcated fingers 4, 5, 6, 7 on the connector interface 1.

The protuberances 46, 47 preferably have truncated ends 63, 64 to ensure mating in the previously described modes (i) and (ii) .

In operation, two of the anvils 29 are mounted facing one another on the ends of a robotic arm for movement towards and away from one another. Figure 3 shows a variant 65 of the anvil 31 formed with a base 66 for connection to a robotic arm. In this variant 65 the truncated ends 63, 64 are not present. Extensions 69 to the body 2 protect the anvil engagement surfaces 60, 61 at the top corner of each protuberance.

When, for example, the alternate micro- interface 54 (Figures 4 to 6) is to be gripped between the anvils 29, the anvils 29 are moved towards one another with the corner 53 of the micro-interface 54 roughly aligned between the inwardly chamfered sides 51, 52 on the micro-interface 54 defining the waist portion 59. Within its range of action, the respective chamfered surfaces then rotatably align the sides 45, 49 of the central recess 48 of the anvil 29 until the top and bottom chamfers 67, 68 of the inner sides 51, 52 of the micro-interface 54 are brought into vertical alignment with the chamfered portion of the sides 45, 49 of the central recess 48 in the anvil 29. With the protuberances 46, 47 and micro-interface 54 mated in this manner, the micro-interface 54 can then be firmly gripped between the anvils 29. When, for example, the connector interface 1

(Figure 1) is to be gripped between the anvils 29, the anvils 29 are moved towards one another with one of the finger pairs 4, 5 and 6, 7 of the connector interface 1 roughly aligned between the protuberances 46 and 47 of each anvil 29. This movement causes the protuberances 46, 47 to enter between the protrusions 4, 5, 6, 7 so that the outer, notched sides 55, 56 mate with the outwardly chamfered protrusions 4, 5, 6, 7. This mating rotatably aligns the outer, notched sides 57, 58 with the protrusions 4, 5, 6, 7, while, at the same time, causing vertical alignment between the anvils 29 and the connector interface 1. With the connector interface 1 held in this manner, it can be firmly gripped between the anvils 29.

Thus, by providing the anvil 29 with both inner chamfered walls 45, 49 and outer chamfered, notched protrusions 46, 47, then the protrusions 46, 47 of anvil 29 can mate with both types of interfaces 1, 54.

Conclusion

The foregoing has constituted a description of specific embodiments showing how the invention may be applied and put into use. These embodiments are only exemplary. The invention in its broadest, and more specific aspects, is further described and defined in the claims which now follow. These claims, and the language used therein, are to be understood in terms of the variants of the invention which have been described. They are not to be restricted to such variants, but are to be read as covering the full scope of the invention as is implicit within the invention and the disclosure that has been provided herein.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY IS CLAIMED ARE FOLLOWS:

1. A bifurcated connector interface 1 suitable for use with orbital replacement units comprising: (1) an interface body 2; and

(2) two pairs of fingers 4, 5 and 6, 7 extending outwardly from opposite sides of the interface body 2, each pair of fingers 4, 5 and 6, 7 defining a bifurcation between their inner sides in the form of a bifurcating recess 12,

14 which tapers inwardly towards the interface body 2; the inner sides 8, 9 and 10, 11 of the finger pairs being bevelled for aligning with a pair of correspondingly shaped gripping anvils 29 that can enter the respective bifurcating recesses 12, 14 for engagement with the interface 1.

2. An interface 1 as in claim 1 wherein the bevelled inner sides 8, 9 and 10 11 of each of the fingers 4, 5 and 6, 7 define a shape for the fingers that is in the form of a truncated triangle in cross-section.

3. An interface 1 as in claim 2 wherein the shape for the cross-section of the fingers 4, 5 and 6,7 is that of an isosceles triangle.

4. An interface 1 as in claim 1 comprising strengthening webs 16 extending along the sides of the interface body 2, joining the outer sides of the fingers

4. 5 and 6, 7.

5. An interface 1 as in claim 1 wherein the interface body 2 is pierced centrally, perpendicularly to the plane of the fingers 4, 5 and 6, 7 by a fastener access opening 40.

6. An interface 1 as in claim 1 comprising mounting ribs 20, 22 provided on the underside or base- end 18 of the interface body 2 for engagement with indexing slots on an object to which the interface 1 is to be attached.

7. An interface 1 as in claim 1 comprising attachment means in the form of fastener passageways 24 extending downwardly through the interface body 2 to the base portion 18 thereof.

8. An interface 1 as in claim 1 wherein said fastener passageways 24 are located at positions adjacent the outer, root-end sides of the fingers 4, 5 and 6, 7.

9. A gripping anvil 29 for engagement with the interface 1 of claim 1 comprising:

(a) an anvil body portion 30;

(b) a pair of splayed protuberances 46, 47 extending from the anvil body portion 30 for engaging an article of complementary form, each of said pair of protuberances 46, 47 having:

(i) opposed, inner sides 45, 49 defining between them a converging recess 48, such inner sides 45, 49 having top and bottom, chamfered, inner side portions for mating with complementary-shaped, converging, top and bottom, inwardly chamfered walls 67, 68, defining a waist 59, 60 that meet to form a corner 53 on an article 54 to be grasped; and

(ii) opposed, outer, notched sides 55, 56 with notches 57, 58 diverging rearwardly from one another on the exterior portion of each protuberance 46, 47, the notches 57, 58 being positioned for mating with a pair of diverging, top and bottom, bevelled, bifurcated fingers 4, 5 and 6, 7 on an article 1 to be grasped.

10. A gripping anvil 29 as in claim 11 wherein the central portions of the top and bottom, chamfered, inner sides 45, 49 of the converging recess 48 are planar and extend substantially vertically between their chamfered side portions to accurately align with similar, planar, waist portion 59 between the inwardly directed chamfered sides 51, 52 of the walls on an article 54 to be grasped.

11. A gripping anvil 29 as in claim 9 wherein the notches 57, 58 on the exterior sides of the pairs of protuberances 46, 47 each comprise two, inwardly tapering, planar sides 60, 61 leading to a flat bottom 62 for alignment with a flattened crest 50 between the top and bottom bevelled sides 8, 9 and 10, 11 of the bifurcated fingers 4, 5 and 6, 7 on an article 1 to be grasped.

12. A gripping anvil 29 as in claim 9 wherein the protuberances 46, 47 have truncated ends 63, 64.