Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~ 17
The inve11tion relates to a gel1rlle.1c1 ~or manip~ tors hclving thc
features ~nown frol11 the preamble of the main claim of German .-\.S. 27 -~5 932.
A previously known ma]1ipulator generally has six swivelling axes of
which the last three swivelling axes are loca-ted in the area of the gearhead.
The first three swivelling axes are disposed on a base having a bogie and a
cantilever arm on which the gearhead is located. The basis for the arrange-
ment of these swivelling axes can be gleaned from the German O.S. 24 35 156.
The concentric arrangement of three drive shafts in an arm carrying the gear-
head, as is ~nown from the German A.S. 24 02 829, has proven suitable for
clriving the gearhead containing the ]ast three swivelling axes. The mobility
of a 11and is imitated by this known gear, according to whic]1 a middle housing
corresponding to the hand with the carpal joint is disposed over a cross shaft
on a front housing co-rresponding to the arm, whereby a rear housing, which
corresponds -to a fil1ger of the hand, is p:ivotably mounted on the middle housing.
The clrive of the rear housing occurs by means of bevel gear sets with -the aid
of the transverse intermediate shaft.
In this state of the art, which in principle also belongs to the
German A.S. 26 l9 336, it is considered disadvantageous that in the extended
position of the articulatecl head the rear housing cannot carry out any acute-
angled, in particular no right-angled swivelling movements with no appreciable
interruption. Rather, the front head piece must first of all carry out a
swivelling movement before the rear head piece can be brought into the desired
position. Thus, such installations are not in a position to guide the tool
along spatially curved lines without interruption and continuously.
For this reason the German O.S. 29 27 485 and the German A.S.
27 45 932 teach guiding the middle head piece rotatably along an inclined plane
772-555 str - l -
~.,D
3'~a~
on -the -Eront head piece. .~ccorclingly, the ;nte-rmed:iate sha:Ft in the gearhead
is -to be inclined to the axis o~ the concelltric drive shaEts. ~ith the con-
centric bearing arrangelnent of the rear heacl piece -to the front head piece,
the swivellillg axis of the rear head piece and thus the tool flanged th~reto
can always be perpendiclllar to a point oE a spherical section which can be
reached by the gearhead. In addition, with this known arrangement it is pos-
sible to guide the tool along syatially curved lines without interruption and
continuously, i.e. permit a continuous-pat}l control.
Ilowever, in this state of the art the swivelling axis of the rear
head piece (6th axis) in the extendecl position of the gearheacl is coaxial to
the axis of the concentric drive shaf-ts. This normal position causes dif-Ei-
culties during the computer-controlled movement of th~ man:ipulator. Rotation
of the -tool about its own swivelling ax:is ~G-th axis), as preset by the program,
leaves opell, when carrying out the computer given clata, whetller the gearllead
is to be rotated about the axis of concelltric clrive shafts (~Ith axis) or
whether the rear head piece alone should be rotated about th:is axis. This
ambiguity could so far only be overcome by program or control engineering mani-
pulations, however~ only ~msatisfactorily.
The invention is therefore based on the object of -Eirst of all
designing a gearhead for manipulators such that the above-noted ambiguities can-
not even occur. This object is new. Furthermore, it is the aim o:E the
invention to attain with the gearhead a substantially enlarged range of move-
ment with a more compact cons-truction of the gearhead.
The object according to the invention is solved by a gearhead for
manipulators comprising three head pieces disposed behind one another and
mounted about axes inclined to one another, having three drive shafts disposed
q3~
concelltrically to one allotller, o~ wllicll one of tlle inller clrive shaEts is con-
nected via bevel gear pairs ancl a tiltecl in-terllledia-te sha-ft "~h:ich Eorms the
swivellillg axis -Eor the micldle hecld p:ic~ce, to the rear head piece having a
flanged surface for carrying the tool and the o-ther inner clri~e shaft with a
bevel gear pair "~hose output gear concentrically encloses the intermediate
shaft with play, is coupled in rotationally positive manner to the middle
head piece~ characterized in that the swivelling axis of the rear head piece
lies at a 90 exclusive angle (cY) compared with the flanged surface for the
tool and at a 180 exclusive angle (e.g. 180 -c~) compared with the axis of the
drive shaf-ts, and that at least one high gear-reducing reduction gear is
arrangecl in the middle head piece for driving the rear gearhead, preferably such
a reduction gear is also provided -Eor driving the middle gearlleacl.
Due to -the inclined rotatabili-ty of the rear heacl piece compared
with that of the midclle head piece, the tool atains a substan-eially enlarged
range o-E action. ~lowever, since the oUtyllt shaft does no-t lie coax:ially to the
drive shaft, ambiguities in the comyu-ter control are avoicled.
In a Eirst exemplary embodiment the inventioll varies Erom the teacil-
ing of the state o~ the art which permits the swivellillg axes of the gearhead
(axes ~ to 6) to intersect at a common point~ Rather, in the extended position
of the gearhead according to the invention the swivelling a.Yis of the rear
head piece (6th axis) is in an angular position compared with the axis of the
concentric drive shaft. It is accordingly imyossible for the two axes to come
into a position concentric to one another during any movement. Therefore, no
ambiguities during computer-controlled movement of the individual gear axes
can occur. This does not rule out, however, that -the work yiece can be
rotated about an axis coaxial to the axis of the drive shafts, namely because
-- 3 --
in accordance w:i-tll a ~)re~errecl Eeatu:rc o~ the inveJlt:ion the Elangecl sur:Eace o:E
the rear hc?ad piece in particular cnn be d:isl)osed perpencl:icular to the a~is
of the drive shafts. The aforenamed movement can therefore be brought about
in the extended position of the gearhead by the rotary movement of the front
head piece about the axis of the concentric drive shafts. Furthermore, the in-
vention also offers the possibility of arranging the flanged surface in other
pl anes .
Withiil the framework of an equivalent variant, it is taught how
the same effect can be achieved if the axes of the intermec.iate shaft and the
output shaft nevertheless intersect at a poin-t coaxial to the axis of the drive
shafts. Such a measure has the advantage of a less complicated calc-llation as
the basis for a continuous-path control. I-lowever, through tllis the centriilg
axis of the flanged surface is offset -to the drive axis. In orcler -to neverthe-
less attain a coaxial pOSitiOll o:f the tool to the drive axis, whic}l would be
advantageous with respect to motion -teclulology :Eor some opera-tions, measures
can be taken to guide the tool in a movable and tightenable manner along -the
flanged surface in the radial direction.
The subject matter of the invention gives the prerequisite for the
particularly compact construction of the gearhead since, in accordance with
-the invention, the reduct:ion gears can be disposed at the output end and in the
middle gearhead piece. A:Lthough the dimension of the middle gearhead piece
is necessarily increased thereby in the direction of the drive axis, a sub-
stantially enlarged range of movement o:E the gearhead piece nevertheless results,
which even makes it possible to move the flanged surface of the rear head
piece by substantially more than 90~ even up to 180 from the ex-tended
position of the gearhead.
1~;3~
It is possible, without substall-tial e~penclitllre to convert a mani-
pulator comprisillg 6 a~es to a 5-acis con-trol and thus only 5 drive motors mus-t
be used. Such maniplllators can easily be used for specific tas~s, for e.Yample
gas-sllielded welding.
Further particulars of the invention can be gleaned from the draw-
ings in which the invention is illustrated in exemplary and schematic manner,
wherein
Figure 1 shows a schematic side view of a gearhead in its e~tended
position,
Figure 2 shows a side view of the gearhead according to Figure 1 with
an angular position of the rear head piece,
Figure 3 shows a side view ot the gearheacl according to Figure 2 witl
a position of the gearheacl rotatecl 180~,
Figure ~I shows a side view of the gearlleacl accorcling to ~:igure 1 with
a tilted position of the micldle head piece,
Figure 5 shows a side view of -thc? gearhead accorcling to Figure 1 with
a tilted position of the middle and rear head pieces,
Figure 6 shows a schematic longitudinal section -throllgh the gearhead
with its drive trains corresponding to an arrangement according to Figure 1,
Figure 7 shows a longitudinal section through the gearhead according
to Figure 6 with a drive variant, and
Figure 8 shows a longitudinal section of a variant of Figure 6.
In the embodimen-t of Figure 1 -the gearhead according to the invention
in its geometric structure is illustrated entirely schematically as a tubular
body~ According to this, the gearhead has a front head piece 1, a middle head
piece 2 and a rear head piece 3. The front head piece 1 is rotatable about
the axLS -I which generally corresponds to thc longituclinal axis oE the canti-
lever arm of a manipulator. The middle head piece 2 is mounted on this front
head piece l to rotatc about the swivelling axis 5. Both axes 4, 5 intersect
at a point of intersec-tion 7. The rear head piece 3 is again mounted on the
middle head piece 2 to rotate about the swivelling axis 6. This swivelling
axis 6 intersects axis 4 at the point of intersection 8. The point of inter-
section 9 of the swivelling axes 5, 6 is, however, radially spaced from the
axis 4. The swivelling axes 5, 6 Eorm an obtuse angle ~ which results in the
separating planes of the head pieces 1, 2 or 2, 3 being at an acute angle to
one another. Preferably the angles are chosen in such a way that symmetry
results. In the example the sloping plane between the individual head pieces
l, 2 or 2, 3 forms an equal angle, howcver, in -the opposi-te inclinat:ion to -the
longitudinal ax:is 4 of the gearllead l, 2~ 3. 'I'hc invelltioll, however, ls not
restricted to an obtuse angle ~ between the swivelling axes 5, 6. The grea-ter
the total bending desired oE-the head pieces 1, 2, 3 -to one another, the small-
er the angle ~ can be selected ~even beyond the right angle).
Furthermore, in the interests oE symmetry it is assumed that the axes
5 and 6 are at an equal angle ~ to the longitudinal axis 4.
On the rear head piece 3 there is a flanged plate lQ with a flanged
surface 12 for fastening the tool not illustrated~ -for example, a welding tool.
~eference numeral 11 symbolically identifies a marking pin which shows the
position of the tool as a function of the swivelling possibilities described
later.
In the example of Figure 2 the first simple swivelling possibility
is illustrated according to which the rear head piece 3 is rotated 180 about
the swivelling axis 6. On the assumption that the swivelling planes between
-the individuaL heacl pieces 1, 2, 3 are symmc?trical to OnC? .Inother .ITId form tlle
angle 90 -~ to thc? axis ~, t'ne rota-tion o:E the renr head piecc 3 about its
swivelling axis 6, namely by lS0, results in the d:isplacement of this heacl
piece 3 by the angle 2c~.
If the gearheacl in the position shown in Figure 2 is rotated lS0
about axis 4, as is illustrated in Figure 3, the mirror-inverted position of
the rear head piece 3 compared to the position in Figure 2 results. From the
position of the axes 5, 6 it can be seen that the swivelling axis 6 does not
come to lie coaxially to the axis ~ in any position since in every case the
;10 point of intersection 9 of the axes 5, 6 moves in an orbit about the axis 4.
Consequently, ambiguity of the axis position is ruled out. .~ccordingly, no
program or control engineering manipulations need be carried out as in the
state of the art.
The arrangement according to -the :invention oE r:;gllre 1 moreover
offers fur-ther possibilities o-E movement oE the art;culated head which can ex-
tend beyond that o:E the state oE the ar-t. ~igure ~ shows that when pivoting
the middle head piece 2 about the swivelling axis 5 an angular position results
which corresponds to that of Figure 3 withou-t, however, -the front head piece
1 being rotated. In the position shown in Figure ~ the rear head piece 3 can
be rotated about the swivelling axis 6 so that an angle oE rotation of the
rear head piece 3 compared to the front head piece 1 by the amount ~cY results.
If, in this position, the front head piece 1 is rotated about the axis ~, then
a maximum range of movemen-t results for the symbolically illustrated marking
pin 11 ~Figure 5).
This range of movement is larger than that of the obvious state of
the art. In addition, the arrangement according to the invention results in
the aclv1ntagc that the d.ll~ger of acckle1lt during swiv~ lg of the pieces 1
2 3 rela-tivc to onc allother coulcl be reclucecl substclntillly b~ avoic1ing ~arrow
and constricted poillts~ On -the other hand the subject matter of the invention
is in a position to s~ivel the work piece in the e~ctended position of the
gearhead about the axis 4 oE the drive shafts as is shown in Figure 1. For
this purpose the flanged plate 10 need merely be disposed perpendicular to the
axis 4 on the rear head piece 3. If this concentrici-ty of the pin 11 to the
axis ~ of the drive shafts is not desired then one is at liberty to position
the flanged plate 10 in a different angle.
The cxemplary embodime11t according to Figure 6 shows the struc-tural
design of the gearhead according to the invention in the extenclecl position o~
its pieces. According to this an inner drive shaft 13 is connected by means
of bevel gears 1~ 15 to a hollow sha-Et 16 whic11 is conllected in rotationally
positive manner to the midclle head piece 2 hy means oE a recluc-tioll gcar 17.
This middle head piece 2 is rotated abou-t the swivelling axis 5 via -this bevel
gear arrangement 14 15. It is guided over suitable bearings 011 the -Eront
head piece 1 about a plane perpendicular to the swivelling axis 5.
The middle drive shaft 18 acts via the bevel gears 19 20 on the
intermediate shaft 21 which lies on the swivelling axis 5. Bevel gears 22 33
are provided at the end of the intermediate shaEt 21 to drive the output
shaft 24 located in the rear head piece 3 which for its part is rotatably mount-
ed in comparison to the micldle head piece 2 namely abou-t the swivelling axis
6. A reduction gear 25 is also provided here between the output shaft 2~l and
the rear head piece 3.
The outer drive shaft 26 acts via the reduction gear 27 directly
on the front head piece 1 which is disposed coaxially to -the cantilever arm
_ ~ _
a~3~3~
2S and is rotatably mounted on lt.
~ 11 recluction gc-?ars 17, 25, 27 are consequently disposed at thc-? ou-t-
put end which results in a gearhead construction extc?nsively free Erom play,
spatially comr)act ancl thus constructc?d small. These reduction gc-?ars 17, 25,
27 are provided for high gear reductions.
Surprising variants can be derived when starting with this arrange-
ment. It is thus illustrated in Figure 7, for example, that a drive motor
can be dispensed with if the middle and rear head pieces 2, 3 are driven by
the same drive shaft 13. The bevel gear 1~l thc?reby drives the hollow shaft
16 which acts on the output shaEt 24 via bevel gears 22, 23. The gear ratio
of the bevel gears 22, 23 should preferably be 1 : 1 and the reduction ratio
of the gears 17, 25 should be equal.
I~ith a corrc~sponcling indicatioll oE the clirec-tion oE rotation
through the drive train 1~, 16, 22, 23, 2~, 25 :it Eollows from this tha-t -the
rear head piece 3 rota-tes in the oppos:ite direction to thc? middle head piece
2. Thus, an overlap can be controlled, as can be sec?n in Figure 5, althougll
one less drive motor is available. Such arrangements are adequate and suitable,
for example, for gas-shielded welding.
If the rear head piece 3 is to be moved in the same direction of
rotation to the middle head piece 2, then a corresponding direction of rotation
in the drivetrainl~, 16, 22, 23, 2~, 25, for example by means of an inter-
mediate gear, must be spec:ified. Such a case results in the same overlapping
of space, however, the programmer can survey the course of movement less
easily. The orientation of the rear head piece 3, changed in the intermediate
area vis-à-vis the first possibility, can, however, also oEfer advantages to
skilled programmers, depending on the spatial conditions.
3~
If one ~ishes to ta~e advalltage of both poss-ihil-itics, the arrange-
men-t o-E a change-speed gear between the head pieces 2, 3 would be necessary,
said change-speed gear yermitting, with the aid oE a coupling (as is common
with machine tools), the rotary movement of these head pieces 2, 3 to be
switched in the same or opposite direc-tion.
Finally, the llead pieces 2, 3 can also be connected by means of
a coupling to a holding brake in that the middle and rear head pieces 2, 3 are
held in rotationally positive malmer to one another by means oE a suitable
switching arrangement through which movements according to the state of the
art are also possible.
In the embodiment of the invelltioll accorcling to Figure S the poin-t
of intersection 9' of axis 5 oE the intermecliate sha-Et 2l with the axis 6 of
the output shaft 24 lies coaxial to the commorl axis ~ oE the drive shaEts L3,
18, 26. For this purpose the head piece l ln the examl)le is divided into
Elanged parts 30, 31 o-f which -Elanged part 30 is -ro-tatably mountecl on the
cantilever arm 28; flanged part 31 silpports the bearing Eor the middle head
piece 2. With the lateral misaligmnent o-E-the Elanged par-t 31, the position
of -the axis 5 is offset at right angles to the axis 4 so that the point of in-
tersection 9' oE axes 5 and 6 comes into the desired coaxial position to axis
In the embodiment the flanged surface 12 is aligned radially to the
axis 4. If a tool is to rotate coaxially to the axis ~, it need only be dis-
placed radially along the flanged surface 12 until concentricity is given. In
this case the drive of the intermediate shaEt 21 and the output shaft 24 is
blocked.
Under the condition that the flanged surface 12 is radial to the
- 10 -
a~is 1~ i-t is possib:Le in -this way to move the tooL connecte~ to the ~langecl
surface 1~ coa.~ial:ly to the a.~is ~1 (or d:isL~Lacecl ~arallc?l to the a.~cis)l whicll
is of particular importance for those mallipulators wllose -indiv:iducll members are
movably guided according to the rect~ngular space coordinates and l~hich carry
a gearhead clesiglled in accordance Wit}l the invention.
It is to be noted that both gear}leads according to the e~cemplary
embodiments in Figures 6 and 8 are in a position to avoid ambiguities in the
computer control and, according to Figure 5, reach a subs-tan-tially enlarged
radius of action co~npared with the state of the art.
