GB1568248A - Manipulator arm including a drive unit - Google Patents

Description

(54) A MANIPULATOR ARM INCLUDING A DRIVE UNIT (71) We, KERNFORSCHUNGSZENTRUM KARLSRUHE GESELLSCHAFr MIT BESCHRAENK TER HAFTUNG, formerly GESELLSCHAFT FUER KERNFORSCHUNG m.b.H. of 5 Weberstrasse, 75 Karlsruhe 1, Germany (Fed Rep); a German body corporate, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which is it to be performed, to be particularly described in and by the following statement: The present invention relates to a power driven, triplehinged. pivotal manipulating arm including a drive unit, the upper and lower portion of which each being formed of two hollow members.The hollow members accommodate power transmission elements utilised to transmit power from drive motors mounted in a base member for the arm to the joints thereof. The base member comprises a base plate having mounting elements formed thereon to which the upper arm portion is hingedly connected.

The present invention seeks to provide a drive unit for a remote-controlled or programme-controlled power driven manipulator unit, such that the unit which has a moment of inertia, and an overall height which are as low as possible. To reduce the power output from the drive unit, it is necessary to keep the moment of the masses of the arm to be accelerated and decelerated about the shoulder joint axis as low as possible.

According to the present invention, there is provided a power-driven, treble jointed, pivotal manipulating arm including a drive unit each joint having its own drive motor, the arm being divided into upper and lower portions, each of which comprise two hollow members, the hollow members accommodating the power transmitting elements for transmitting power from drive motors to the joints of the arm, the motors being mounted in a base member, the base member comprising a base plate with mounting elements formed thereon, to which the upper arm portion is hingedly connected wherein the drive motors for the shoulder and elbow joints are coaxially mounted on the base plate, the power take-off shafts from these motors extending away from one another, the common axis for the motors being located behind the axis through the shoulder joint but parallel thereto when viewed from the end of the arm remote from the shoulder joint.

Preferably, the drive motor for the wrist joint of the arm is axially mounted on the axis of the shoulder joint, the power take-off shaft of this motor being mounted in the hollow interior of one of the upper arm portions, has a gearwheel or sprocket wheel, which is located in the hollow arm portion, an axle journal being mounted on the opposite outer surface of the gearwheel or sprocket wheel for actuating the shoulder rotation movement, the journal being flanged to the hollow arm portion.

Advantageously, the drive motors for the shoulder, elbow and wrist joints are mounted on the base plate located in a first housing, which housing is rotatably mounted on a second housing, which second housing accommodates a driving motor and a reduction gear for pivotal movement of the arm, whereby the reduction gear is located on the pivotal axis and the drive motor, connected thereto by means of a toothed belt, when viewed from the end of the arm remote from the shoulder joints is located in front of this axis.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows a side view of a manipulating arm including a drive unit in accordance with the present invention, Fig. 2 is a cross-sectional view through the housing of the drive unit, on an enlarged scale relative to Fig. 1, and Fig. 3 is a horizontal section through the shoulder joint of the manipulating arm, taken along the line A-B of Fig. 2.

In Figure 1, there is shown a remotecontrolled or programme-controlled manipulating arm which is hingedly connected to a housing 1. This 1 is, itself rotatably mounted on a second housing 2, which latter contains the drive means 3, 4 for the pivotal movement. The housing 2 is secured to a base plate 5. The arm is divided into upper and lower portions, each of which is formed of two hollow members, although this cannot be seen in Fig. 1. The hollow members 6 and 7 of the upper arm portion are mounted in slots formed in the housing 1 and are pivotal about the shoulder joint axis 8. The lower arm 9, as aforementioned, also comprises two hollow members which are pivotal with respect to the members 6 and 7 about an elbow joint 10.On the free end of the lower arm portion 9, there is mounted a hand portion 11 which is inclinable and pivotal about an universal joint and having gripping tongs 12, pivotal about its longitudinal axis, mounted thereon.

Figures 2 and 3 show, on an enlarged scale relative to Fig. 1, sections through the housings 1 and 2. On a base plate 13 of the housing 1 drive motors 14, 15 and 16 for the respective movements of the arm are mounted. The motor 14 produces the movement or rotation of the shoulder joint about the axis 8, the motor 15 that of the elbow joint 10 and the motor 16 the rotation of the wrist joint 17. The motors 14 and 15 are mounted on a common axis 18, which axis is located parallel to the axis 8 of the shoulder joint and, as seen from the hand end of the arm (in the direction of the arrow 34), is located behind it. The motors 14 and 15 are fitted with reduction gears 19 and 20 respectively. On the driven shafts of these motors, sprocket 21 and 22 for toothed belts 23 and 24 respectively are mounted.The disposition of the axis 18 is therefore such that the power take-off of the motors 14 and 15, at the toothed belts 23 and 24, are located at the lateral edges of the driving unit.

On the shoulder joint axis 8, the drive motor 16 for movement of the hand portion 11 about the wrist joint 17 is located. On the motor 16, a reduction gear 25 is flangeconnected, the driven shaft 26 of which carries -a sprocket 27. The sprocket 27 is located in the interior space 28 of the upper arm portion 6 and is mounted therein by means of a roller bearing 29. The arm portion 6 is, in turn, mounted on an axle journal 30 which is mounted on the outer wall 31 of the housing by means of a bearing 32. This supports a sprocket 33, aligned with the sprocket 21, for the toothed belt 23. On the opposite wall 52 of the housing, a stub shaft 36 carrying a sprocket 37 is mounted by means of a roller bearing 38 in a bearing bush 35.The free end of the stub shaft 36 supports a further sprocket 40 for the drive of the elbow joint 10 and which is aligned with the driven sprocket 22 of the motor 15. The other upper arm portion 7 is mounted on the stub shaft 36 by means of a roller bearing 39, in a similar manner to that in which upper arm portion 6 on the bearing 29. The sprocket 37 is thus located in the interior of the upper arm portion 7. The motors 14 and 15 are flanged to the outer walls 31 and 52 of the housings by means of their gears 19 and 20 in such a manner that their driven shafts, and the sprockets 21 and 22 respectively project outwards through the respective wall. The toothed belts 23 and 24 therefore assume positions on each outer surface of the driving unit.

As already mentioned, the pivotal movement of the manipulating arm is effected by rotating the housing 1 on the housing 2. The pivotal or rotary movement, as can be seen in Figure 2, takes place about the axis 41. The pivot shaft 42 located in this axis 41 is rigidly secured at its upper end to the base plate 13, which latter is mounted on the lower housing 2 by means of bearings 43 and 44. The lower end of the shaft is flanged to the gearing 4 of the drive means. The driven shaft 45 of the gearing supports a pinion 46 for a sprocket chain 47, which chain is driven by the driven gear 48 of the motor 3. The motor 3 and its driven gear 48 is thus located both downward of and in front of the axis 41, when viewed in the direction of the arrow 34.The housing 1 is mounted on the housing 2 by means of the ball bearing 49, the inner race 50 of which is associated with the upper housing 1, and the other race 51 with the housing 2.

The present invention provides a readily programmable manipulating arm with spot control for various uses. The apparatus, besides standard gripping tongs, may be provided with different tongs or tools for particular uses. Thus, the tongs may be capable of effecting spot-welding tongs. The mechanical manipulating arm has three separate joints and, in all, six possible movements independent of one another are possible. Due to the design of both the upper arm and lower arm as two hollow members, the considerable spacing between the bearings permits a high degree of rigidity of the arm when under load. This improves the accuracy obtainable in positioning the device. The weight of the arm itself is reduced and the pivotal behaviour is thus favourably affected.

This construction permits a simple mounting of the device, provides accommodation of the power transmitting elements within the arms themselves and provides protection for the electrical supply cables. By arranging two motors behind, when viewed from the hand end of the device, the shoulder joint, there is attained a device having a reduced width, a reduced swivel circle and a low moment of inertia relative to known devices. Moreover, .the motors act as counterweights, the third driving motor, due to its mounting on the pivot axis, not substantially increasing the moment of inertia. By so doing, a reduction in the necessary power output is attained. More over, by arranging the joint drives at the level of the shoulder joint, a substantially lower overall height of the device is attained.

The method of construction shown, during inclination of the lower arm, causes the hand to be guided in parallel and during inclination of the upper arm, causes the hand and the lower arm to be guided in parallel that is to say, the spatial angle is retained.

Moreover, this permits approximate translatory movements to be effected from a basic position in both X and Z directions. This property facilitates the definition of the starting positions during programming.

Furthermore, this method of construction mutually supports the joints. By so doing, the drive means to be installed are reduced and permits a substantially unitary structure, at least for the drive units for the X and Z movement.

WHAT WE CLAIM IS: 1. A power-driven, treble jointed, pivotal manipulating arm including a drive-unit, each joint having its own drive motor, the arm being divided into upper and lower portions, each of which comprises two hollow members, the hollow members accommodating the power transmitting elements for transmitting power from drive motors to the joints of the arm, the motors being mounted in a base member, the base member comprising a base plate with mounting elements formed thereon, to which the upper arm portion is hingedly connected wherein the drive motors for the shoulder and elbow joints are coaxially mounted on the base plate, the power take-off shafts from these motors extending away from one another, the common axis for the motors being located behind the axis through the shoulder joint but parallel thereto when viewed from the end of the arm remote from the shoulder joint.

2. A manipulating arm including a drive unit as claimed in claim 1, wherein the drive motor for the wrist joint of the arm is axially mounted on the axis of the shoulder joint, the power take-off shaft of this motor being mounted in the hollow interior of one of the upper arm portions, has a gearwheel or sprocket wheel, which is located in the hollow arm portion, an axle journal being mounted on the opposite outer surface of the gearwheel or sprocket wheel for actuating the shoulder rotational movement, the journal being flanged to the hollow arm portion.

3. A manipulating arm including a drive unit as claimed in claim 1 or claim 2, wherein the drive motors for the shoulder, elbow and wrist joints are mounted on the base plate located in a first housing, which housing is rotatably mounted on a second housing, which which second housing accommodates a driving motor and a reduction gear for pivotal movement of the arm, whereby the reduction gear is located on the pivotal axis and the drive motor, connected thereto by means of a toothed belt, when viewed from the end of the arm remote from the shoulder joint is located in front of this axis.

4. A manipulating arm including a drive unit constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. lower overall height of the device is attained. The method of construction shown, during inclination of the lower arm, causes the hand to be guided in parallel and during inclination of the upper arm, causes the hand and the lower arm to be guided in parallel that is to say, the spatial angle is retained. Moreover, this permits approximate translatory movements to be effected from a basic position in both X and Z directions. This property facilitates the definition of the starting positions during programming. Furthermore, this method of construction mutually supports the joints. By so doing, the drive means to be installed are reduced and permits a substantially unitary structure, at least for the drive units for the X and Z movement. WHAT WE CLAIM IS:

1. A power-driven, treble jointed, pivotal manipulating arm including a drive-unit, each joint having its own drive motor, the arm being divided into upper and lower portions, each of which comprises two hollow members, the hollow members accommodating the power transmitting elements for transmitting power from drive motors to the joints of the arm, the motors being mounted in a base member, the base member comprising a base plate with mounting elements formed thereon, to which the upper arm portion is hingedly connected wherein the drive motors for the shoulder and elbow joints are coaxially mounted on the base plate, the power take-off shafts from these motors extending away from one another, the common axis for the motors being located behind the axis through the shoulder joint but parallel thereto when viewed from the end of the arm remote from the shoulder joint.

2. A manipulating arm including a drive unit as claimed in claim 1, wherein the drive motor for the wrist joint of the arm is axially mounted on the axis of the shoulder joint, the power take-off shaft of this motor being mounted in the hollow interior of one of the upper arm portions, has a gearwheel or sprocket wheel, which is located in the hollow arm portion, an axle journal being mounted on the opposite outer surface of the gearwheel or sprocket wheel for actuating the shoulder rotational movement, the journal being flanged to the hollow arm portion.

3. A manipulating arm including a drive unit as claimed in claim 1 or claim 2, wherein the drive motors for the shoulder, elbow and wrist joints are mounted on the base plate located in a first housing, which housing is rotatably mounted on a second housing, which which second housing accommodates a driving motor and a reduction gear for pivotal movement of the arm, whereby the reduction gear is located on the pivotal axis and the drive motor, connected thereto by means of a toothed belt, when viewed from the end of the arm remote from the shoulder joint is located in front of this axis.

4. A manipulating arm including a drive unit constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.