CA1108668A - Manipulator arm having co-ordinated extend/retract motion - Google Patents
Manipulator arm having co-ordinated extend/retract motionInfo
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- CA1108668A CA1108668A CA329,700A CA329700A CA1108668A CA 1108668 A CA1108668 A CA 1108668A CA 329700 A CA329700 A CA 329700A CA 1108668 A CA1108668 A CA 1108668A
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- arm member
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- arm
- wrist
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Abstract
ABSTRACT OF THE DISCLOSURE
An anthropomorphic manipulator arm assembly is dis-closed herein in which first and second arm members are connected to one another in a manner such that the distal end of one mem-ber may be moved relative to the proximal end of the other arm in a straight line. The arm assembly includes a first arm member and a second arm member. A shoulder joint is provided for connecting the first arm member to a suitable support for rotation about a first axis. An elbow joint is provided for connecting the first arm member to the second arm member for rotation about a second axis. An actuator is drivingly connected to the first arm for rotatably driving the first arm about the first axis at a first angular velocity. A first power transmission is provided for drivingly connecting the actuator means to the second arm to rotatably drive the second arm about the second axis at a second angular velocity which is twice the first angular velocity but in the opposite direc-tion. The second arm is driven in the opposite direction to that in which the first arm is driven about the first axis.
The actuator drives the first arm member about the first axis whereby the distal end of the second arm is driven in a straight path which extends radially from the first axis during both extension and retraction.
An anthropomorphic manipulator arm assembly is dis-closed herein in which first and second arm members are connected to one another in a manner such that the distal end of one mem-ber may be moved relative to the proximal end of the other arm in a straight line. The arm assembly includes a first arm member and a second arm member. A shoulder joint is provided for connecting the first arm member to a suitable support for rotation about a first axis. An elbow joint is provided for connecting the first arm member to the second arm member for rotation about a second axis. An actuator is drivingly connected to the first arm for rotatably driving the first arm about the first axis at a first angular velocity. A first power transmission is provided for drivingly connecting the actuator means to the second arm to rotatably drive the second arm about the second axis at a second angular velocity which is twice the first angular velocity but in the opposite direc-tion. The second arm is driven in the opposite direction to that in which the first arm is driven about the first axis.
The actuator drives the first arm member about the first axis whereby the distal end of the second arm is driven in a straight path which extends radially from the first axis during both extension and retraction.
Description
FIELD OF INVENTION
. _ _ This invention relates to an improved technique for co-ordinating the extend/retract motions of a manipulator arm assembly. In particular this invention relates to an anthropornorphic manipulator arm assembly in which first and second arm men~ers are connected to one another in a manner such that the distal end of one member may be moved relative to the proximal end of the other arm in a straight line.
PRIOR ART
_ In order to achieve maximum extend/retract motion for a given maximum reach, spot mounted manipulator arms commonly incorporate an elbow and discrete upper and lower arm members. There are many applications in which the operator must be able to control the motion of such a manipulator arm while looking along the arm as for ex~ample in submersible vehicles or when viewing is from a camera mounted at the proximal end of the arm. In order to facilitate the manipulation of such arms there should be no apparent wrist an~le change due to an elbow movement -20 as elbow movements are primarily commandecl in order to pro-vide extend/retract motion. Furthermore, there should be no apparent shoulder pitch or jaw movement due to an elbow movement. There should be no cross-coupling between the locator (shoulder and elbow) and orientor (wrist) movements defined relative to an operator looking down the arm from -' a point close to the spot mounting.
Considerable difficulty has been experienced in attempting to meet these practical requirements in a simple inexpensive manipulator arm assembly.
In a manipulator arm assembly described hereinafter with reference to a prefe~red embodiment there is provided a method of achieving non-coupled easily controlled arm motion on a manipulator arm assembly where the radial reach envelope has been maximised by incorporation of an elbow between equal length upper and lower arm members. The mechanism provides the control simplicity which is inherent in a telescoping arm without many of the structural dis-advantages of a conventional telescoping arm.
An important feature of the structure of the mani-pulator arm assembly described hereinafter is that the required non-cross coupled arm motions are each powered by ; discrete actuators with the result that all electrical and hydraulic control channels can also be discrete. This serves to maximise the simiplicity of the control system and simplifies servicing.
SUMMARY OF INVENTION
According to one aspect of the present invention a manipulator arm assembly comprises a first arm member having a proximal end and a distal end, a second arm member having a proximal end and a distal end, the length of said second arm member from its proximal end to its distal end being equal to that of said first arm member, a shoulder joint at said proximal end of said first arm member for supporting said first arm for extend/retract rotation about a first axis, an elbow joint connecting the distal end of said first arm to the proximal end of said second arm for extend/retract rotation about a second axis which extends parallel to said first axis, actuator means drivingly connected to said first arm for rotatably driving said first arm about said first axis at a first angular velocity, first power transmission means drivingly connecting said actuator means and said second arm to 6~8 rotatably drive said second arm about said axis, at a second angu].ar velocity which is twice said first angular velocity, but in the opposite direction to that in which the first arm is driven about said first axis, as said actuator means drives the first arm about said first axis whereby said distal end of said second arm is driven in a straight path which extends radially from said first axis during both extension and retraction.
According to a further aspect oft~e present inven~ion, a manipulator arm assembly comprises a first arm member having a proximal end and a distal end, a second arm member having a proximal end and a distal end, a wrist member having a proximal end and a distal end, a shoulder joint at said proximal end of said first arm mem-ber for supporting said first arm member for extend/retract rotation about a first axis, an elbow joint connecting the distal end of said first arm member to the proximal end of said second arm member for extend/retract rotation about a second axis which extends parallel to said first axis, a wrist joint connecting said distal end of said second arm member to said proximal end of said wrist member for extend/retract rotation about a third axis, at the distal end of said arm member, said first and third axes being equally spaced from said second axis, said wrist member pro-jecting outwardly from said third axis in a first radial direction with respect to said third axis, actuator means drivingly connected to said first arm member for rotatably driving sai.d first arm member about said first axis at a first angular velocity, first power transmission means drivingly connecting said actuator means and said second arm member to rotatably drive said second arm about said second axis, at a second angular velocity which is twice said first angular velocity but in the opposite direction to that in which said first arm member is driven about said first axis, as said actua~or means drives said first arm member about said first axis, second power trans-mission means drivingly connecting said extend/retract actuator means and said wrist member to rotatably drive said wrist member about said third axis at an angular velocity equal to said first angular velocity and in the same angular direction as said first direction, as said first power transmission means drives said second arm about said second axis whereby the wrist joint at the distal end of said second arm member is driven in a straight path which extends radially from said first axis during both extension and retraction of said arm assembly and said wrist ntember is driven relative to said second arm member so as to be retained in a position extending in said first radlal direc-tion relative to said third axis as said arm assembly is extended and retracted in use.
The invention will be more clearly understood after reference to the following detailed specification read in conjunction with the drawings wherein, Figure 1 is a diagrammatic plan view of a ~:
manipulator arm constructed in accordance with an embodi-ment of the present invention;
Figure 2 is a diagrar,tmatic plan view of a manipulator arm constructed in accordance with a further embodiment of the present invention;
Figure 3, 3a, 3b, 3c, 3d, 3e, and 3f are diagrammatic side views showing various positions which 6~
the arm will assume in response to discrete operation of the arm's pitch joint actuators (shoulder pitch, extend/
retract, wri~t pitch);
Figure 4 is a diagrammatic illustration of a manipulator arm and a portion of its actuator mechanism;
Figure 5 is a vector diagram which provides an analysis of the structure illustrated in Figure 4;
Figure 6 is a view similar to Figure 4 which includes the power transmission means for operating the distal end of the outer arm;
Figure 7 is an exploded pictorial view of an underwater manipulator arm assembly incorporating a pitch joint arrangement.
With reference to Figure 1 of the drawings, the reference numeral 10 refers generally to a manipulator arm assembly which comprises a first arm member 12 and a second arm member 14. The first arm member 12 has its proximal end mounted and fixed on the housing of extend/
retract actuator 24. The drive shaft 16 of the extend/
retrac~ actuator is coupled to the output drive shaft of a shoulder pitch actuator 22 which is in turn mounted on a support structure 20. A sprocket 26 is keyed to the shaft 16 for rotation therewith. A second sprocket 28 is mounted on a second drive shaft 30 which is located at .
the distal end of the first arm 12. The shaft 30 is secured with respect to the proximal end of the arm 14 for rotation therewith relative to the distal end of the arm 12. A sprocket 32 is secured against movement relative to the distal end of the arm 12 and has its central axis co-incident with the axis of the shaft 30. A second shaft 34 is mounted for rotation about its longitudinal axis at the distal end of the arm 14. A sprocket 36 is keyed to and rotatably drives the shaft 34 about its longitudinal axis. A wrist pitch actuator 38 is drivingly rotatable on the shaft 34 to control the pitch of the wrist member 40 with respect to the distal end of the arm 14. A first drive chain 42 extends between sprocket 26 and 28 and a second drive chain 44 extends between sprocket 32 and 36.
As will be described hereinafter in order to obtain ~he required straight line motion of the distal end of the arm 14, the arms 12 and 14 are of equal length between shafts 16, 30 and 34. Furthermore, the sprockets 26 and 36 must have twice as many teeth as sprockets 28 and 32 respectively.
Figure 2 shows an equivalent arrangement where wrist pitch actuator 38 has been moved up to the elbow where it is fixed with respect to the distal end of first arm member 12. In tllis arrangement the output shaft 35 of the wrist pitch actuator 38 drives wrist member 40 through the transmission comprising sprockets 32a and 36b and chain 44.
The operation of the manipulator arm of Figure 1 can thus be understood with reference to an analysis of the relative motion which occurs as a result of activating the extend/retract actuator 24 with reference to Figures 3, 4 and 5 of the drawings.
With reference to Figures 1 and 4 of the drawings consider what happens when the proximal end of the arm 12 is driven about the shoulder pitch axis 50 at an angular velocity w~R by activating the extend/retract actuator 24. Thus, with reference to Figure 3 of the 8~8 drawings, it will be seen that C VB (VC) relB .L
where B _ER ~ 1 _ 2 ( c)relB WBC ~ A2 Where WBC Efl (~ C)relAB
_ER 2~ER
_ ~R . _ 4 Substituting 4 in 3 ( c)relB _E~ ~ _2 _ 3 A :~
Substituting 3 A and 2 in 1 Vc = __ER A _1 W~R ~ 2 _E~ ~ (Al A2) With reference to Figure 5 of the drawings, it will be seen that since Al A2 ~ the construction in the figure shows Al- A2 is perpendicular to Al + A2 (the _ vector along the line joining the shoulder and wrist pitch axis) and since ~E~ iS perpendicular to the plane containing Aland A2 and therefore also perpendicular to Al - A2 ~ it fo~lows from the definition of a vector product that Vc lies along Al + A2 i.e. along the line AC. Thus actuation of the extend/retract actuator results in pure extend/
retract motion.
If the sprockets 32 and 36 and their associated chain 44 are added to the system as shown in Figure 5, a symmetry argument becomes apparent in that the mechanism appears identical when viewed from either side. It follows that the shoulder connection at the proximal end of the arm member 12 and the wrist connection at the distal end of the arm member 14 are mirrored and there is therefore no change in the orientation of the wrist member 40 as the arm is extended or retracted.
Referring once again to Figures 1 and 2 of the drawings, it will be seen that operation of the shoulder pitch actuator 22 to rotatably drive the shaft 16 will cause simultaneous rotation of the sprocket 26 and extend/
retract actuator 24 about the axis of the shaft 16 with the result that the power transmission means associated with the sprocket 26 will not move relative to the first arm member 12 and consequently the pitch of the arm may be varied without extending or retracting the arms by rotatably driving the shoulder pitch actuator 22.
The advantages to be derived by employing the technique for coordinating the extend/retract motion according to the structures illustrated in Figures 1 and
. _ _ This invention relates to an improved technique for co-ordinating the extend/retract motions of a manipulator arm assembly. In particular this invention relates to an anthropornorphic manipulator arm assembly in which first and second arm men~ers are connected to one another in a manner such that the distal end of one member may be moved relative to the proximal end of the other arm in a straight line.
PRIOR ART
_ In order to achieve maximum extend/retract motion for a given maximum reach, spot mounted manipulator arms commonly incorporate an elbow and discrete upper and lower arm members. There are many applications in which the operator must be able to control the motion of such a manipulator arm while looking along the arm as for ex~ample in submersible vehicles or when viewing is from a camera mounted at the proximal end of the arm. In order to facilitate the manipulation of such arms there should be no apparent wrist an~le change due to an elbow movement -20 as elbow movements are primarily commandecl in order to pro-vide extend/retract motion. Furthermore, there should be no apparent shoulder pitch or jaw movement due to an elbow movement. There should be no cross-coupling between the locator (shoulder and elbow) and orientor (wrist) movements defined relative to an operator looking down the arm from -' a point close to the spot mounting.
Considerable difficulty has been experienced in attempting to meet these practical requirements in a simple inexpensive manipulator arm assembly.
In a manipulator arm assembly described hereinafter with reference to a prefe~red embodiment there is provided a method of achieving non-coupled easily controlled arm motion on a manipulator arm assembly where the radial reach envelope has been maximised by incorporation of an elbow between equal length upper and lower arm members. The mechanism provides the control simplicity which is inherent in a telescoping arm without many of the structural dis-advantages of a conventional telescoping arm.
An important feature of the structure of the mani-pulator arm assembly described hereinafter is that the required non-cross coupled arm motions are each powered by ; discrete actuators with the result that all electrical and hydraulic control channels can also be discrete. This serves to maximise the simiplicity of the control system and simplifies servicing.
SUMMARY OF INVENTION
According to one aspect of the present invention a manipulator arm assembly comprises a first arm member having a proximal end and a distal end, a second arm member having a proximal end and a distal end, the length of said second arm member from its proximal end to its distal end being equal to that of said first arm member, a shoulder joint at said proximal end of said first arm member for supporting said first arm for extend/retract rotation about a first axis, an elbow joint connecting the distal end of said first arm to the proximal end of said second arm for extend/retract rotation about a second axis which extends parallel to said first axis, actuator means drivingly connected to said first arm for rotatably driving said first arm about said first axis at a first angular velocity, first power transmission means drivingly connecting said actuator means and said second arm to 6~8 rotatably drive said second arm about said axis, at a second angu].ar velocity which is twice said first angular velocity, but in the opposite direction to that in which the first arm is driven about said first axis, as said actuator means drives the first arm about said first axis whereby said distal end of said second arm is driven in a straight path which extends radially from said first axis during both extension and retraction.
According to a further aspect oft~e present inven~ion, a manipulator arm assembly comprises a first arm member having a proximal end and a distal end, a second arm member having a proximal end and a distal end, a wrist member having a proximal end and a distal end, a shoulder joint at said proximal end of said first arm mem-ber for supporting said first arm member for extend/retract rotation about a first axis, an elbow joint connecting the distal end of said first arm member to the proximal end of said second arm member for extend/retract rotation about a second axis which extends parallel to said first axis, a wrist joint connecting said distal end of said second arm member to said proximal end of said wrist member for extend/retract rotation about a third axis, at the distal end of said arm member, said first and third axes being equally spaced from said second axis, said wrist member pro-jecting outwardly from said third axis in a first radial direction with respect to said third axis, actuator means drivingly connected to said first arm member for rotatably driving sai.d first arm member about said first axis at a first angular velocity, first power transmission means drivingly connecting said actuator means and said second arm member to rotatably drive said second arm about said second axis, at a second angular velocity which is twice said first angular velocity but in the opposite direction to that in which said first arm member is driven about said first axis, as said actua~or means drives said first arm member about said first axis, second power trans-mission means drivingly connecting said extend/retract actuator means and said wrist member to rotatably drive said wrist member about said third axis at an angular velocity equal to said first angular velocity and in the same angular direction as said first direction, as said first power transmission means drives said second arm about said second axis whereby the wrist joint at the distal end of said second arm member is driven in a straight path which extends radially from said first axis during both extension and retraction of said arm assembly and said wrist ntember is driven relative to said second arm member so as to be retained in a position extending in said first radlal direc-tion relative to said third axis as said arm assembly is extended and retracted in use.
The invention will be more clearly understood after reference to the following detailed specification read in conjunction with the drawings wherein, Figure 1 is a diagrammatic plan view of a ~:
manipulator arm constructed in accordance with an embodi-ment of the present invention;
Figure 2 is a diagrar,tmatic plan view of a manipulator arm constructed in accordance with a further embodiment of the present invention;
Figure 3, 3a, 3b, 3c, 3d, 3e, and 3f are diagrammatic side views showing various positions which 6~
the arm will assume in response to discrete operation of the arm's pitch joint actuators (shoulder pitch, extend/
retract, wri~t pitch);
Figure 4 is a diagrammatic illustration of a manipulator arm and a portion of its actuator mechanism;
Figure 5 is a vector diagram which provides an analysis of the structure illustrated in Figure 4;
Figure 6 is a view similar to Figure 4 which includes the power transmission means for operating the distal end of the outer arm;
Figure 7 is an exploded pictorial view of an underwater manipulator arm assembly incorporating a pitch joint arrangement.
With reference to Figure 1 of the drawings, the reference numeral 10 refers generally to a manipulator arm assembly which comprises a first arm member 12 and a second arm member 14. The first arm member 12 has its proximal end mounted and fixed on the housing of extend/
retract actuator 24. The drive shaft 16 of the extend/
retrac~ actuator is coupled to the output drive shaft of a shoulder pitch actuator 22 which is in turn mounted on a support structure 20. A sprocket 26 is keyed to the shaft 16 for rotation therewith. A second sprocket 28 is mounted on a second drive shaft 30 which is located at .
the distal end of the first arm 12. The shaft 30 is secured with respect to the proximal end of the arm 14 for rotation therewith relative to the distal end of the arm 12. A sprocket 32 is secured against movement relative to the distal end of the arm 12 and has its central axis co-incident with the axis of the shaft 30. A second shaft 34 is mounted for rotation about its longitudinal axis at the distal end of the arm 14. A sprocket 36 is keyed to and rotatably drives the shaft 34 about its longitudinal axis. A wrist pitch actuator 38 is drivingly rotatable on the shaft 34 to control the pitch of the wrist member 40 with respect to the distal end of the arm 14. A first drive chain 42 extends between sprocket 26 and 28 and a second drive chain 44 extends between sprocket 32 and 36.
As will be described hereinafter in order to obtain ~he required straight line motion of the distal end of the arm 14, the arms 12 and 14 are of equal length between shafts 16, 30 and 34. Furthermore, the sprockets 26 and 36 must have twice as many teeth as sprockets 28 and 32 respectively.
Figure 2 shows an equivalent arrangement where wrist pitch actuator 38 has been moved up to the elbow where it is fixed with respect to the distal end of first arm member 12. In tllis arrangement the output shaft 35 of the wrist pitch actuator 38 drives wrist member 40 through the transmission comprising sprockets 32a and 36b and chain 44.
The operation of the manipulator arm of Figure 1 can thus be understood with reference to an analysis of the relative motion which occurs as a result of activating the extend/retract actuator 24 with reference to Figures 3, 4 and 5 of the drawings.
With reference to Figures 1 and 4 of the drawings consider what happens when the proximal end of the arm 12 is driven about the shoulder pitch axis 50 at an angular velocity w~R by activating the extend/retract actuator 24. Thus, with reference to Figure 3 of the 8~8 drawings, it will be seen that C VB (VC) relB .L
where B _ER ~ 1 _ 2 ( c)relB WBC ~ A2 Where WBC Efl (~ C)relAB
_ER 2~ER
_ ~R . _ 4 Substituting 4 in 3 ( c)relB _E~ ~ _2 _ 3 A :~
Substituting 3 A and 2 in 1 Vc = __ER A _1 W~R ~ 2 _E~ ~ (Al A2) With reference to Figure 5 of the drawings, it will be seen that since Al A2 ~ the construction in the figure shows Al- A2 is perpendicular to Al + A2 (the _ vector along the line joining the shoulder and wrist pitch axis) and since ~E~ iS perpendicular to the plane containing Aland A2 and therefore also perpendicular to Al - A2 ~ it fo~lows from the definition of a vector product that Vc lies along Al + A2 i.e. along the line AC. Thus actuation of the extend/retract actuator results in pure extend/
retract motion.
If the sprockets 32 and 36 and their associated chain 44 are added to the system as shown in Figure 5, a symmetry argument becomes apparent in that the mechanism appears identical when viewed from either side. It follows that the shoulder connection at the proximal end of the arm member 12 and the wrist connection at the distal end of the arm member 14 are mirrored and there is therefore no change in the orientation of the wrist member 40 as the arm is extended or retracted.
Referring once again to Figures 1 and 2 of the drawings, it will be seen that operation of the shoulder pitch actuator 22 to rotatably drive the shaft 16 will cause simultaneous rotation of the sprocket 26 and extend/
retract actuator 24 about the axis of the shaft 16 with the result that the power transmission means associated with the sprocket 26 will not move relative to the first arm member 12 and consequently the pitch of the arm may be varied without extending or retracting the arms by rotatably driving the shoulder pitch actuator 22.
The advantages to be derived by employing the technique for coordinating the extend/retract motion according to the structures illustrated in Figures 1 and
2 of the drawings are readily apparent with reference to Figures 3 to 3f inclusive.
With reference to these figures, it will be seen that the proximal end of the arm member 12 is mounted for rotation about the shoulder pitch axis 16a, the distal end of the arm member 12 is pivotally connected to the proximal end of the arm mem~er 14 for rotation about elbow axis 30a and the wrist member 40 is connected at the distal end of the arm member 14 for rotation about -~ ~t~ 8 wrist pitch axis 34a.
By activating the wrist pitch actuator 38 (Fig. 1) the wrist member 40 may be progressively driven about the wrist axis 34a as shown in Figures 3a and 3b of the drawings.
It will be noted that the wrist member 40 may be moved independently of any movement of the arms 12 and 14. By activating the shoulder pitch actuator 22 (Fig. 1) the arm members 12 and 14 may be rotated about the shoulder axis 16a as shown in Figures 3c and 3d without any resultant change in the relative positions of the axm mcmbers 12, 14 and wrist member 40. By activating the extend/retract actuator 24, the arm members 12 and 14 are caused to move progressively from the extended position shown in Figure
With reference to these figures, it will be seen that the proximal end of the arm member 12 is mounted for rotation about the shoulder pitch axis 16a, the distal end of the arm member 12 is pivotally connected to the proximal end of the arm mem~er 14 for rotation about elbow axis 30a and the wrist member 40 is connected at the distal end of the arm member 14 for rotation about -~ ~t~ 8 wrist pitch axis 34a.
By activating the wrist pitch actuator 38 (Fig. 1) the wrist member 40 may be progressively driven about the wrist axis 34a as shown in Figures 3a and 3b of the drawings.
It will be noted that the wrist member 40 may be moved independently of any movement of the arms 12 and 14. By activating the shoulder pitch actuator 22 (Fig. 1) the arm members 12 and 14 may be rotated about the shoulder axis 16a as shown in Figures 3c and 3d without any resultant change in the relative positions of the axm mcmbers 12, 14 and wrist member 40. By activating the extend/retract actuator 24, the arm members 12 and 14 are caused to move progressively from the extended position shown in Figure
3 to the intermediate position shown in Figure 3e and the retracted position shown in Figure 3f, it will be noted that the wrist member 40 remains in the same plane in all positions of the arms during the extend/retract motion.
By incorporating this pitch coordinating mechanism and actuator arrangement in an arm having the morphology shown in Figure 7 an arm with both the control advantages of a telescoping arm and the reach envelope advantages of an articulated arm is achieved. A further advantage of the apparatus of the invention described above is that it permits the extend/retract actuator and wrist pitch actuator to be located closer to the proximal end of the arm than can be achieved with the conventional arm joint actuation arrangements. This serves to reduce the arm dead weight contribution to actuator loading for a given arm lift capability and minimises wrist length.
Various modifications of the present invention will be apparent to those skilled in the art. For example, the mounting at the shoulder may be varied so as to provide a single actuator which will selectively effect a shoulder pitch movement or the extend/retract movement. ,This structure may be used to advantage in order to provide a minimum weight arm for application where a simultaneous actuation of the arm extend/retract and shoulder pitch (or yaw) is not required. In a further modified structure, the wrist pitch actuator may be located at the shoulder with a sprocket mounted for free rotation on the shaft 30 drivingly engaging a further sprocket keyed to the shaft 34, each of these sprockets having a one to one ratio. The second design variation will provide a spatially stable wrist pitch axis, i.e. the wrist side of the wrist pitch joint will ~main at the same fixed orientation in space regardless of shoulder pitcll and extend/retract tions. This may be desirable in situations where, for example, an inspection probe held by the arm is being scanned vertically up the leg of an offshore structure.
Figure 7 illustrates a modular underwater arm of a type which may incorporate the pitch jointarrangement described above. The arm includes an interface mounting plate 100 upon which a support member 102 is coupled by means of an arm jettison assembly 104. A shoulder yaw actuator has a splined shaft 108 mounted in a splined passage 110 in the support 102. The shoulder yaw actuator 106 is rotatable about the axis of the shaft 108. A shoulder pitch actuator 113 is mounted on the shoulder yaw actuator.
The output shaft of this actuator is connected through ; 30 couplers 115 and 117 to the output shaft of the extend/retract ~86~8 actuator 124 which is located at the proximal end of the first arm 112. The proximal end of the second arm memher 114 is pivotally connected to the distal end of the first arm 112 for rotation about shaft 130. A sprocket 126 is drivingly connected to the extend/retract actuator shaft coupling and a chain 142 drivingly connacts the sprocket 126 to a sprocket 128 which is fixed with respect to the shaft 130 which in turn is fixed with respect to arm member 114. ~ sprocket 132 is drivingly connected to a wrist pitch actuator mounted within the distal end of the arm member 112 and is connected to a sprocket 136 at the - distal end of the arm member 114 by means of a chain 145 A wrist member 138 is mounted for rotation about the wrist axis and is drivingly engaged by the sprocket 136.
The wrist memher 138 is in the form of a wrist yaw actuator which supports a wrist extend/retract mechanism 140 which in turn supports a wrist roll actuator 142, a rotary union 143, a tool engage/disengage mechanism 144, and a hook hand 146. By activating the extend/retract actuator 124 of Figure 7, the arm of Figure 7 may be caused to operate in the manner previously described with reference to Figures 3, 3e and 3f. By operating the wrist pitch actuator (not shown) which is located within the distal end of the first arm 112 the wrist member 140 may be moved as shown with reference to Figure 3, 3a and 3b of the drawings. By operating the shoulder pitch actuator 113 the arm assembly may be moved as shown in Figure 3, 3c and 3d of the drawings.
From the foregoing it will be apparent that the present invention provides a simple and efficient mechanism for achieving a coordinated extend/retract motion of a manipulator arm.
By incorporating this pitch coordinating mechanism and actuator arrangement in an arm having the morphology shown in Figure 7 an arm with both the control advantages of a telescoping arm and the reach envelope advantages of an articulated arm is achieved. A further advantage of the apparatus of the invention described above is that it permits the extend/retract actuator and wrist pitch actuator to be located closer to the proximal end of the arm than can be achieved with the conventional arm joint actuation arrangements. This serves to reduce the arm dead weight contribution to actuator loading for a given arm lift capability and minimises wrist length.
Various modifications of the present invention will be apparent to those skilled in the art. For example, the mounting at the shoulder may be varied so as to provide a single actuator which will selectively effect a shoulder pitch movement or the extend/retract movement. ,This structure may be used to advantage in order to provide a minimum weight arm for application where a simultaneous actuation of the arm extend/retract and shoulder pitch (or yaw) is not required. In a further modified structure, the wrist pitch actuator may be located at the shoulder with a sprocket mounted for free rotation on the shaft 30 drivingly engaging a further sprocket keyed to the shaft 34, each of these sprockets having a one to one ratio. The second design variation will provide a spatially stable wrist pitch axis, i.e. the wrist side of the wrist pitch joint will ~main at the same fixed orientation in space regardless of shoulder pitcll and extend/retract tions. This may be desirable in situations where, for example, an inspection probe held by the arm is being scanned vertically up the leg of an offshore structure.
Figure 7 illustrates a modular underwater arm of a type which may incorporate the pitch jointarrangement described above. The arm includes an interface mounting plate 100 upon which a support member 102 is coupled by means of an arm jettison assembly 104. A shoulder yaw actuator has a splined shaft 108 mounted in a splined passage 110 in the support 102. The shoulder yaw actuator 106 is rotatable about the axis of the shaft 108. A shoulder pitch actuator 113 is mounted on the shoulder yaw actuator.
The output shaft of this actuator is connected through ; 30 couplers 115 and 117 to the output shaft of the extend/retract ~86~8 actuator 124 which is located at the proximal end of the first arm 112. The proximal end of the second arm memher 114 is pivotally connected to the distal end of the first arm 112 for rotation about shaft 130. A sprocket 126 is drivingly connected to the extend/retract actuator shaft coupling and a chain 142 drivingly connacts the sprocket 126 to a sprocket 128 which is fixed with respect to the shaft 130 which in turn is fixed with respect to arm member 114. ~ sprocket 132 is drivingly connected to a wrist pitch actuator mounted within the distal end of the arm member 112 and is connected to a sprocket 136 at the - distal end of the arm member 114 by means of a chain 145 A wrist member 138 is mounted for rotation about the wrist axis and is drivingly engaged by the sprocket 136.
The wrist memher 138 is in the form of a wrist yaw actuator which supports a wrist extend/retract mechanism 140 which in turn supports a wrist roll actuator 142, a rotary union 143, a tool engage/disengage mechanism 144, and a hook hand 146. By activating the extend/retract actuator 124 of Figure 7, the arm of Figure 7 may be caused to operate in the manner previously described with reference to Figures 3, 3e and 3f. By operating the wrist pitch actuator (not shown) which is located within the distal end of the first arm 112 the wrist member 140 may be moved as shown with reference to Figure 3, 3a and 3b of the drawings. By operating the shoulder pitch actuator 113 the arm assembly may be moved as shown in Figure 3, 3c and 3d of the drawings.
From the foregoing it will be apparent that the present invention provides a simple and efficient mechanism for achieving a coordinated extend/retract motion of a manipulator arm.
Claims (2)
1. A manipulator arm assembly comprising;
(a) a first arm member having a proximal end and a distal end, (b) a second arm member having a proximal end and a distal end, (c) a wrist member having a proximal end and a distal end, (d) a shoulder shaft at said proximal end of said first arm member supporting said first arm member for extend/retract rotation relative thereto about a first axis, (e) an elbow shaft connecting the distal end of said first arm member to the proximal end of said second arm member, said elbow shaft being fixed against rotation relative to said second arm member and being rotatable relative to said first arm member to permit extend/retract rotation of said second arm member relative to said first arm member about a second axis which extends parallel to said first axis, (f) a wrist shaft connecting the distal end of said second arm member to the proximal end of said wrist member, said wrist shaft being rotatable relative to said second arm during extend/retract rotation about a third axis at the distal end of said second arm member and means for releasably securing the wrist member against rotation relative to said wrist shaft, said first and third axes being equally spaced from the second axis, said wrist member projecting outwardly from said third axis in a first radial direction with respect to said third axis, (g) extend/retract actuator means mounted on said first arm member and drivingly connected to said shoulder shaft for rotatably driving said first arm member relative to said shoulder shaft for rotation about said first axis at a first angular velocity, (h) integrated first and second power transmission means for effecting extension and retraction of said arms in response to operation of said extend/retract actuator means, (i) said first power transmission means extending from said shoulder shaft and drivingly connecting said shoulder shaft and said elbow shaft to rotatably drive said second arm member about said second axis, at a second angular velocity which is twice said first angular velocity but in the opposite direction to that in which said first arm member is driven about said first axis, as said actuator means drives said first arm member about said first axis, (j) said second power transmission means drivingly connecting said elbow shaft and said wrist shaft to rotatably drive said wrist member about said third axis at an angular velocity equal to said first angular velocity but in the same angular direction as said first power transmission means drives said second arm member about said second axis whereby the wrist joint at the distal end of said second arm member is driven in a straight path which extends radially from said first axis during both extension and retraction of said arm assembly and said wrist member is driven relative to said second arm member so as to be retained in a position extending in said first radial direction relative to said third axis as said arm assembly is extended and retracted in use, (k) shoulder pitch means mounted on said shoulder support and drivingly engaging said shoulder shaft in advance of said first power transmission means whereby said shoulder shaft may be rotated to adjust the pitch of said first arm member without effecting movement of said first transmission means relative to said shoulder shaft, and (l) wrist pitch drive means mounted on said wrist member and drivingly engaging said wrist shaft, said wrist pitch drive means being operable to drive said wrist member about said wrist shaft to effect adjustment of the angular disposition of the wrist member with respect to said second arm member,
(a) a first arm member having a proximal end and a distal end, (b) a second arm member having a proximal end and a distal end, (c) a wrist member having a proximal end and a distal end, (d) a shoulder shaft at said proximal end of said first arm member supporting said first arm member for extend/retract rotation relative thereto about a first axis, (e) an elbow shaft connecting the distal end of said first arm member to the proximal end of said second arm member, said elbow shaft being fixed against rotation relative to said second arm member and being rotatable relative to said first arm member to permit extend/retract rotation of said second arm member relative to said first arm member about a second axis which extends parallel to said first axis, (f) a wrist shaft connecting the distal end of said second arm member to the proximal end of said wrist member, said wrist shaft being rotatable relative to said second arm during extend/retract rotation about a third axis at the distal end of said second arm member and means for releasably securing the wrist member against rotation relative to said wrist shaft, said first and third axes being equally spaced from the second axis, said wrist member projecting outwardly from said third axis in a first radial direction with respect to said third axis, (g) extend/retract actuator means mounted on said first arm member and drivingly connected to said shoulder shaft for rotatably driving said first arm member relative to said shoulder shaft for rotation about said first axis at a first angular velocity, (h) integrated first and second power transmission means for effecting extension and retraction of said arms in response to operation of said extend/retract actuator means, (i) said first power transmission means extending from said shoulder shaft and drivingly connecting said shoulder shaft and said elbow shaft to rotatably drive said second arm member about said second axis, at a second angular velocity which is twice said first angular velocity but in the opposite direction to that in which said first arm member is driven about said first axis, as said actuator means drives said first arm member about said first axis, (j) said second power transmission means drivingly connecting said elbow shaft and said wrist shaft to rotatably drive said wrist member about said third axis at an angular velocity equal to said first angular velocity but in the same angular direction as said first power transmission means drives said second arm member about said second axis whereby the wrist joint at the distal end of said second arm member is driven in a straight path which extends radially from said first axis during both extension and retraction of said arm assembly and said wrist member is driven relative to said second arm member so as to be retained in a position extending in said first radial direction relative to said third axis as said arm assembly is extended and retracted in use, (k) shoulder pitch means mounted on said shoulder support and drivingly engaging said shoulder shaft in advance of said first power transmission means whereby said shoulder shaft may be rotated to adjust the pitch of said first arm member without effecting movement of said first transmission means relative to said shoulder shaft, and (l) wrist pitch drive means mounted on said wrist member and drivingly engaging said wrist shaft, said wrist pitch drive means being operable to drive said wrist member about said wrist shaft to effect adjustment of the angular disposition of the wrist member with respect to said second arm member,
Claim 2. A manipular arm assembly comprising;
(a) a first arm member having a proximal end and a distal end, (b) a second arm member having a proximal end and a distal end, (c) a wrist member having a proximal end and a distal end, (d) a shoulder shaft at said proximal end of said first arm member supporting said first arm member for extend/retract rotation relative thereto about a first axis, (e) a compound elbow shaft connecting the distal end of said first arm member to the proximal end of said second arm member for extend/retract rotation about a second axis which extends parallel to said first axis, said compound elbow shaft comprising a first section and a second section which are axially aligned and independently rotatable about said second axis, said first section being rotatable relative to said first arm member and secured against rotation relative to said second arm member, (f) wrist pitch drive means mounted on said first arm member and normally securing said second section of said elbow shaft against rotation relative to said first arm member, said wrist pitch drive means being operable to rotatably drive said second section relative to said first arm member and said second arm member, (g) a wrist shaft connecting the distal end of said second arm member to the proximal end of said wrist member, said wrist shaft being rotatable relative to said second arm member for rotation about a third axis at the distal end of said second arm member, said first and third axes being equally spaced from said second axis, said wrist member projecting outwardly from said third axis in a first radial direction with respect to said third axis, (h) extend/retract actuator means mounted on said first arm member and drivingly connected to said shoulder shaft for rotatably driving said first arm member relative to said shoulder shaft for rotation about said first axis at a first angular velocity, (i) integrated first and second power transmission means for effecting extension and retraction of said first and second arm members in response to operation of said extend/retract actuator means, (i) said first power transmission means extending from said shoulder shaft and drivingly connecting said shoulder shaft and said first section of said elbow shaft to rotatably drive said second arm member about said second axis at a second angular velocity which is twice said first angular velocity but in the opposite direction to that in which said first arm member is driven about said first axis, as said extend/retract actuator means drives said first arm member about said first axis, (k) said second power transmission means drivingly connecting said second section of said elbow shaft and said wrist shaft to rotatably drive said wrist member about said third axis at an angle of velocity equal to said first angular velocity but in the same angular direction as said first power transmission means drive said second arm member about said second axis whereby the wrist joint at the distal end of said second arm member is driven in a straight path which extends radially from said first axis during both extension and retraction of said arm assembly and said wrist member is driven relative to said second arm member so as to be retained in a position extending in said first radial direction relative to said third axis as said arm assembly is extended and retracted in use, (l) shoulder pitch drive means mounted on said shoulder support and drivingly engaging said shoulder shaft in advance of said wrist powered transmission means whereby said shoulder shaft may be rotated to adjust the pitch of the first arm without effecting movement of the first transmission means relative to said shoulder shaft, (m) said wrist pitch drive means being operably connected to said wrist shaft by said second power transmission means whereby said wrist pitch drive means is operable to rotatably drive the wrist pitch shaft about said third axis to effect adjustment of the angular disposition of the wrist member with respect to said second arm member.
(a) a first arm member having a proximal end and a distal end, (b) a second arm member having a proximal end and a distal end, (c) a wrist member having a proximal end and a distal end, (d) a shoulder shaft at said proximal end of said first arm member supporting said first arm member for extend/retract rotation relative thereto about a first axis, (e) a compound elbow shaft connecting the distal end of said first arm member to the proximal end of said second arm member for extend/retract rotation about a second axis which extends parallel to said first axis, said compound elbow shaft comprising a first section and a second section which are axially aligned and independently rotatable about said second axis, said first section being rotatable relative to said first arm member and secured against rotation relative to said second arm member, (f) wrist pitch drive means mounted on said first arm member and normally securing said second section of said elbow shaft against rotation relative to said first arm member, said wrist pitch drive means being operable to rotatably drive said second section relative to said first arm member and said second arm member, (g) a wrist shaft connecting the distal end of said second arm member to the proximal end of said wrist member, said wrist shaft being rotatable relative to said second arm member for rotation about a third axis at the distal end of said second arm member, said first and third axes being equally spaced from said second axis, said wrist member projecting outwardly from said third axis in a first radial direction with respect to said third axis, (h) extend/retract actuator means mounted on said first arm member and drivingly connected to said shoulder shaft for rotatably driving said first arm member relative to said shoulder shaft for rotation about said first axis at a first angular velocity, (i) integrated first and second power transmission means for effecting extension and retraction of said first and second arm members in response to operation of said extend/retract actuator means, (i) said first power transmission means extending from said shoulder shaft and drivingly connecting said shoulder shaft and said first section of said elbow shaft to rotatably drive said second arm member about said second axis at a second angular velocity which is twice said first angular velocity but in the opposite direction to that in which said first arm member is driven about said first axis, as said extend/retract actuator means drives said first arm member about said first axis, (k) said second power transmission means drivingly connecting said second section of said elbow shaft and said wrist shaft to rotatably drive said wrist member about said third axis at an angle of velocity equal to said first angular velocity but in the same angular direction as said first power transmission means drive said second arm member about said second axis whereby the wrist joint at the distal end of said second arm member is driven in a straight path which extends radially from said first axis during both extension and retraction of said arm assembly and said wrist member is driven relative to said second arm member so as to be retained in a position extending in said first radial direction relative to said third axis as said arm assembly is extended and retracted in use, (l) shoulder pitch drive means mounted on said shoulder support and drivingly engaging said shoulder shaft in advance of said wrist powered transmission means whereby said shoulder shaft may be rotated to adjust the pitch of the first arm without effecting movement of the first transmission means relative to said shoulder shaft, (m) said wrist pitch drive means being operably connected to said wrist shaft by said second power transmission means whereby said wrist pitch drive means is operable to rotatably drive the wrist pitch shaft about said third axis to effect adjustment of the angular disposition of the wrist member with respect to said second arm member.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA329,700A CA1108668A (en) | 1979-06-13 | 1979-06-13 | Manipulator arm having co-ordinated extend/retract motion |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA329,700A CA1108668A (en) | 1979-06-13 | 1979-06-13 | Manipulator arm having co-ordinated extend/retract motion |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1108668A true CA1108668A (en) | 1981-09-08 |
Family
ID=4114449
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA329,700A Expired CA1108668A (en) | 1979-06-13 | 1979-06-13 | Manipulator arm having co-ordinated extend/retract motion |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1108668A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4865514A (en) * | 1986-10-03 | 1989-09-12 | Hitachi, Ltd. | Manipulator system with small arm removably attachable at points along large arm |
| US4978274A (en) * | 1985-09-16 | 1990-12-18 | R. De Groot Holding Laag-Zuthem B.V. | Manipulator |
| US5064340A (en) * | 1989-01-20 | 1991-11-12 | Genmark Automation | Precision arm mechanism |
| US5102280A (en) * | 1989-03-07 | 1992-04-07 | Ade Corporation | Robot prealigner |
-
1979
- 1979-06-13 CA CA329,700A patent/CA1108668A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4978274A (en) * | 1985-09-16 | 1990-12-18 | R. De Groot Holding Laag-Zuthem B.V. | Manipulator |
| US4865514A (en) * | 1986-10-03 | 1989-09-12 | Hitachi, Ltd. | Manipulator system with small arm removably attachable at points along large arm |
| US5064340A (en) * | 1989-01-20 | 1991-11-12 | Genmark Automation | Precision arm mechanism |
| US5102280A (en) * | 1989-03-07 | 1992-04-07 | Ade Corporation | Robot prealigner |
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