WO2012028197A1

WO2012028197A1 - An industrial robot, a component system for a such and a method for assembling a such

Info

Publication number: WO2012028197A1
Application number: PCT/EP2010/062926
Authority: WO
Inventors: Xiaolong Feng; Jonas Larsson; Jan Larsson
Original assignee: Abb Research Ltd
Priority date: 2010-09-03
Filing date: 2010-09-03
Publication date: 2012-03-08
Also published as: CN102811843A

Abstract

The invention relates to an industrial robot with cabling and at least one semi-hollow joint. The semi-hollow joint has a drive-train with a gearbox and further operating components, including a motor. The cabling extends externally around the further components and internally within the gearbox. According to the invention the robot has at least 7 DOF and includes two joint modules (2, 3). Each of these includes a first and a second semi-hollow joint for a respective axis (A2, A3; A4, A5). The invention also relates to a component system for such a robot. The system has a set of joint modules. The invention further relates to a method for assembling an industrial robot.

Description

AN INDUSTRIAL ROBOT, A COMPONENT SYSTEM FOR A SUCH AND A METHOD FOR ASSEMBLING A SUCH

Field of invention

The present invention in a first aspect relates to an industrial robot with cabling and at least one semi-hollow joint, which semi-hollow joint has a drive-train with a gearbox and further operating components, the further operating

components including a motor, whereby the cabling extends externally around said further components and internally within the gearbox.

The invention also relates to a component system for industrial robots.

In a further aspect, the invention relates to a method for assembling an industrial robot with cabling and at least one semi-hollow joint, which semi-hollow joint has a drive-train with a gearbox and further operating components, the further operating components including a motor, whereby the cabling extends externally around said further components and internally within the gearbox, the robot having at least 7 DOF (degrees of freedom).

Background of invention

Industrial robots of the kind in question has a number of joints for achieving a corresponding number of axes of movement and which represent the number of DOF for the operation of the robot. For most industrial robots the DOF is 5 or 6. However, today also robots with a higher number of DOF, e.g. 7 DOF, are manufactured. The axes of an industrial robot are conventionally numbered as axis 1 , axis 2, axis 3 etc. Normally, by axis 1 is meant the rotational axis of the stand of the robot in relation to the robot base, and the axis most close to the tool is the one with the highest number. This terminology will be applied in the present application.

Each joint has components for performing the necessary movement related to the joint in question. These components normally include a drive-train with a gearbox and a motor. It is also necessary to provide cabling including electric cables to power actuators of each joint and process cables to transmit pressurised air or some kind of process fluid to the tool interface of the robot. The cabling has to pass through the joints in order to reach the joints more close to the work tool. Traditionally the cabling is either external, i.e. it extends outside the components of the joint, or internal through the interior of these components.

External cabling is a simple alternative but has the drawback that the cabling will be exposed to the environment, which entails the risk of damage to the cabling, and might also be hazardous to persons working close to the robot. It is therefore common that various kinds of protections are arranged around the cabling that is external of the joint components.

Internal cabling is more sophisticated and eliminates the drawbacks related to external cabling. This however requires that the components of the joint are made hollow in order to allow the cabling to extend through these. This increases the cost for these components. Examples of such hollow-shaft joints are disclosed in EP 612591 , EP 1930129 and US 5155423.

A further alternative can be considered as a hybrid between external and internal cabling, whereby the cabling extends externally of one or some of the components of the drive-train of the joint and internally in others of them. In such a solution the cabling extends internally within the gearbox of the drive-train and externally around the motor and the other components of the drive-train. To provide a hollow gearbox for internal cabling normally does not considerably increase the cost, whereas the cost increase for a hollow motor is quite high. This is because the application areas of hollow shaft motors are rather limited, which makes the cost for obtaining such motors on the market very high. Furthermore, integrated, compact and hollow-shaft gearbox + motor units can find even applications in industries and the cost to obtain such integrated and hollow-shaft power units is further increased. By integrated, it means that the gearbox, motor, brake and position sensor are all integrated into one unit. Through the hybrid solution the cabling thus will be partially internal with the advantages related thereto, but the cost will be reasonable since the motor is not hollow. Thereby an advantageous compromise between functionality and cost is achieved.

Examples of such semi-hollow joints with combined internal and external cabling are disclosed in US 5606235, US 6250174, US 2006179964, US

2008258402, US 2008264195 and US 2009124446. In some of these disclosures such a semi-hollow joint is applied at joints for two consecutive axes.

Assembling an industrial robot with many DOF is a time-consuming task requiring a precise and circumstantial mounting of its parts. In particular this is the case when the joints are made to allow partially internal cabling as described above. This results in high manufacturing cost of the robot.

Summary of invention

The object of the present invention is to address this problem and attain a robot that can be manufactured and assembled in a rational way.

This object is according to the first aspect of the invention achieved in that an industrial robot of the initially specified kind includes the specific features that the robot has at least 7 DOF and includes at least two joint modules, whereby each of said joint modules includes a first and a second semi-hollow joint for a respective rotation axis.

Since the robot has 7 DOF it will be more flexible regarding operation range and operation tasks than the conventional 5 or 6 DOF robot. The increased assembling complexity of the robot due to the increased number of DOF and the use of semi-hollow joints is to a large extent reduced by forming modules for the joints, where each module includes two axes. A robot having two such two-axes modules can be assembled very rationally and with a high accuracy in the relation between adjacent axes. The modules also reduce the risk for mounting mistakes. The invented robot thus has high performance quality and the advantage of partial internal cabling without considerably increasing its manufacturing costs.

According to one embodiment of the invented robot, the robot includes three such modules.

This further contributes to a rational manufacturing of the robot in robot applications where the relations between the axes are such that a third two-axis module can be used and other considerations do not prevent this. The three joint modules may be for the axes 2 + 3, axes 4 + 5 and axes 6 + 7.

According to a further embodiment, each joint module includes a protective cover enclosing the externally extending cabling.

With the modules of the invented robot the need for protecting the cabling from affecting the environment is reduced, but not completely eliminated. A protective cover for a semi-hollow joint, however, will be less complicated than for a joint with solely external cabling, and incorporating the protective cover as an integrated part of the module represents a further step to a high degree of rationalization. The protective cover may be separated into two or more cover units.

According to a further embodiment one joint module includes axis 2 and axis 3, and another joint module includes axis 4 and axis 5.

These two pairs of axes are normally those that are most appropriate for the modulization according to the principle of the present invention. The

advantages of the present invention will also be more prominent when the joint modules are two adjacent modules due to the synergy when connecting these joints to each other.

According to a further embodiment at least two of the joint modules have the same configuration, i.e. are identical or scaled in relation to each other.

Thereby an increased standardization is obtained which further simplifies the assembly as well as the stock keeping of the modules.

According to a further embodiment, the joint modules are identical to each other.

This is a further step towards simplification and rationalization.

According to another embodiment, the joint modules differ from each other only by the size.

This embodiment is not as simple as the one mentioned next above, but it is better adapted for a robot where the joint module for axes with higher numbers can be made smaller than the joint module for axes with lower numbers, which often is the case. Since the joint modules are equal in all respects except the size, the standardization advantages will still be present.

The object of the invention is achieved also in that a component system for industrial robots includes a set of joint modules, each module including a first and a second semi-hollow joint for a respective rotation axis.

By such a system the assembly of the robot can be rationalized to a high degree.

According to an embodiment of the invented system all the joint modules in the set have the same configuration.

According to a further embodiment the set includes joint modules that are identical to each other and/or includes joint modules that differ from each other only by the size. These preferred embodiments of the system offer a very rational way of assembling a robot, since the appropriate joint modules will be at hand ready to be connected to the other parts of the robot. In many cases robots of different sizes are to be manufactured, whereby the set of joint modules is of particular advantage. For example, a joint module of one and the same size can be used for one joint module, e.g. the one applied for axes 2 and 3, in the smaller robot, and for another joint module, e.g. the one applied for axes 4 and 5, in the larger robot.

According to the further aspect of the invention, the object is achieved in that a method of the kind introductionally specified includes the specific measures of assembling the robot by providing at least two joint modules, each joint module including a first and a second semi-hollow joint for a respective rotation axis and by connecting the joint modules to other parts of the robot.

According to an embodiment of the invented method, a set of joint modules is provided, and the at least two joints are selected from the set.

According to a further embodiment, the set includes joint modules of the same configuration. The joint modules may be identical to each other or be of different size in relation to each other.

According to a further embodiment, the method is applied for assembling a plurality of robots of different sizes.

According to a further embodiment, the plurality of robots include robots in which the two joint modules include a larger and a smaller module, whereby for two robots of different sizes, a joint module of the same size is selected for axis 2 and axis 3 of the smaller robot and for axis 4 and axis 5 of the larger robot.

The invented method and the embodiments thereof have advantages of the same kind as those of the invented robot and the component system and the embodiments of these, and which have been described above.

The above described embodiments of the invention are defined in the dependent claims. It is to be understood that further embodiments naturally can be constituted by any possible combination of the embodiments above and by any possible combination of these and features mentioned in the description of examples below.

The invention will be further explained through the following detailed description of examples thereof and with reference to the accompanying drawings. Short description of the drawings

Fig 1 is a perspective view of an industrial robot according to the invention,

Figs. 2 and 3 are perspective views of further examples of an industrial robot according to the invention,

Figs. 4 to 7 are different perspective views of a detail of the robot in fig. 1 according to an example of the invention,

Figs. 8 to 13 are different perspective views of a detail corresponding to the one of Figs. 4 to 7 but illustrate an alternative example.

Fig. 14 schematically illustrates a system according to the invention, and Figs. 15 and 16 schematically illustrate a principle for assembling industrial robots according to the invention.

Description of examples

In Fig. 1 is illustrated an industrial robot according to the invention. The robot has 7 DOF. The seven rotation axes of the robot are marked with broken lines and indicated as A1 to A7, consecutively numbered from the base towards the tool end of the robot. In comparison with a conventional 6 DOF robot, the robot in the figure differs in that the extra axis A3 is present. However, the terminology in the present application does not label this as the seventh axis but as the third axis A3 to achieve contextual clarity.

Axis A1 thus is the axis of the rotational joint related to the base 1 and axes A6 and A7 are the axes of the wrist 4. Axes A2 and A3 are arranged together in a first joint module 2, and axes A4 and A5 are arranged in a second joint module 3. The first joint module 2 has one interface for connecting it to the base 1 and another interface for connecting it to the second joint module 3. Similarly the second joint module has one interface for the connection to the first module and another interface for connecting it to the wrist 4.

The modules 2, 3 can be prefabricated and when assembling the robot they are simply connected to each other and to the base 1 and the wrist 4, respectively.

In the illustrated example, the modules 2 and 3 have principally the same configuration, but differ from each other in size. Alternatively modules that are equal also in size can be used. Within the scope of invention the modules can also be of different construction. In the example of Fig. 1 the wrist 4 is a module with integrated hollow- shaft servo actuator, where gearbox, motor, brake and position sensor all are of hollow design. Thereby a well protected cabling is present all the way from the base 1 to the tool end of the robot, since the cabling extends internally of all gearboxes and otherwise is protected by the covers of each of the modules 2 and 3.

The wrist 4 can, however, optionally be of another type than according to the semi-hollow concept and for example be of the full hollow shaft type. Figs. 2 and 3 illustrate two further examples, where the wrist is of another kind. In Fig. 2 the wrist 4a is a traditional wrist for low material cost and compactness. In Fig. 3 the wrist 4b is of a more simple design, with a lower number of components when compared to traditional wrists.

The construction of the joint modules will be explained more in detail with reference to Figs. 4 to 7, which show various perspective views of the first module 2 of the robot in Fig. 1 . The views of Figs. 4 and 5 are from the same view point. In the view of Fig. 6 the module is turned 180 ° around a vertical axis and in Fig. 7 the module is turned about 45° from the position in Fig. 6, while the protective cover is made transparent.

The joint module 2 has a first connection portion 22 by means of which the module is connected to the base 1 (see Fig. 1 ) and a second connection portion 28, by means of which the module 2 is connected to the 4/5 axis module 3 (see Fig. 1 ). A first section 23 houses the motor of axis A2 and a second section 24 houses the gearbox 35 of that axis. These two sections 23, 24 belong to the same structural part. The motor 31 of axis A2 is visible in Fig. 5 and is provided with an integrated brake and a position sensor. Section 23 is covered by a cover unit 29. Inside the cover unit 29 the cabling extends around the motor 31 and into the central hole 32 of the gearbox 35 in section 24. For clarity reason the cabling is not present in the figures. Axis A2 is a pitch axis around which a third section 25 is turnable. Section 25 is connected to a fourth section 26 which houses the motor 36 (see Fig. 7) for the third axis A3. A fifth section 27 is connected to section 26. In section 27 the gearbox 34 of the third axis A3 is mounted. These sections 25, 26, 27 belong to the same structural part. This third axis is a roll axis around which the outer parts of the robot is rotatable. The gearbox 34 terminates into the connection portion 28. The cabling coming from the central hole 32 of the gearbox 35 of A2 passes through the section 25, around the motor within section 26, through the hole 33 in the gearbox 34 of A3 and then further in to the next joint module. A cover unit 30 protects the cabling within section 25.

The joint module 3 is basically of the same configuration as joint module 2 described above, but with the difference that the end portions instead are adapted for connection to the second joint module and to the wrist, respectively.

Naturally, the joint modules in the robot of the present invention may be constructed and configured in many various ways. In Figs. 8 to 13 another example of such a joint module is illustrated and which can be used for the joint modules 2, 3 of the robot in Fig. 1 . The figures show the same joint module in perspective views from different directions, and in some of the figures some parts are left out.

The joint module of Figs. 8 to 13 is an alternative for the joint module 2 of the robot in Fig. 1 . A first section 43 is provided with a connection portion 42, by means of which the module is connected to the base 1 and it has a cover unit 49 for protecting the cabling. At the other end of the module there is a second connection portion 48 for connection to module 3, which may be similarly configured.

The gearbox 55 which is mounted in a second section 44 provides rotation relative to the first section 43 around pitch axis A2. In a third section 45, the motor 51 for axis A2 is located. In a fourth section the motor 56 for axis A3 is located. Section 45 is covered by a cover unit 50 and the sections 45 and 46 together form a common housing for the two motors 51 , 56. In a fifth section 47, the gearbox of axis A3, which is a roll axis, is mounted. Sections 44, 45, 46, 47 all belong to the same structural part.

The cabling (not shown) extends from the base, through section 43 inside the protecting cover unit 49. Thereafter the cabling extends through the hole 52 of the gearbox 55 for axis A2, through sections 45, 46 externally of the motors 51 , 56 in these and then through the hole 53 of the gearbox 54 for axis A3, from where the cabling reaches the next joint module 3.

The module principle of a robot according to the present invention offers a rational way of manufacturing and assembling robots. To this end it is

advantageous to keep a stock of a set of pre-assembled joint modules. Fig. 14 schematically illustrates such a set 100 of joint modules. The set includes a first group of identical joint modules 101 and a second group of identical joint modules 102. The modules 101 in the first group are of larger size than the modules 102 in the second group but are similar in construction and configuration.

When manufacturing robots of the same construction but of different sizes, the invented robot offers a very rational way to do that, thanks to the module concept. Figs. 15 and 16 schematically illustrate a larger and a smaller robot, respectively. The larger robot in Fig. 15 has a base B1 , a first joint module M1 for axes 2 and 3, a second joint module M2 for axes 4 and 5 and a wrist W1 . The smaller robot in Fig. 16 has corresponding parts. The joint module M2 for axes 2 and 3 of the smaller robot is identical to the joint module M2 for axes 4 and 5 of the larger robot, i.e. not only of the same configuration but also of the same size.

The assembling concept illustrated by Figs. 15 and 16 can of course be further developed and be more sophisticated. It can be used for robots of more than two different sizes in one series and may be applied to a larger extent than in the illustrating example where only one of the modules is identical.

Claims

PATENT CLAIMS

1 . An industrial robot with cabling and at least one semi-hollow joint, which semi-hollow joint has a drive-train with a gearbox (34, 35, 54,55) and further operating components, the further operating components including a motor (31 , 36, 51 , 56), whereby the cabling extends externally around said further

components and internally within the gearbox (34, 35, 54, 55), characterized in that the robot has at least 7 DOF and includes at least two joint modules (2, 3), whereby each of said joint modules (2, 3) includes a first and a second semi- hollow joint for a respective rotation axis (A2, A3; A4, A5).

2. An industrial robot according to claim 1 , characterized in that the robot includes three such joint modules.

3. An industrial robot according to claim 1 or 2, characterized in that each joint module (2, 3) includes a protective cover (29, 30, 49, 50) enclosing said externally extending cabling.

4. An industrial robot according to claim 1 or 3, characterized in that one joint module (2) includes axis 2 and axis 3, and another joint module (3) includes axis 4 and axis 5.

5. An industrial robot according to any of claims 1 -4, characterized in that at least two of said joint modules (2, 3) have the same configuration.

6. An industrial robot according to claim 5, characterized in that said joint modules (2, 3) are identical to each other.

7. An industrial robot according to claim 5, characterized in that said joint modules (2, 3) are of different size.

8. A component system for industrial robots, characterized in that the system includes a set (100) of joint modules (101 , 102), each module including a first and second semi-hollow joint for a respective rotation axis.

9. A system according to claim 8, characterized in that all the joint modules (101 , 102) in the set (100) have the same configuration.

10. A system according to claim 9, characterized in that the set (100) includes joint modules that are identical to each other and/or includes joint modules that differ from each other only by the size.

1 1 . A method for assembling an industrial robot with cabling and at least one semi-hollow joint, which semi-hollow joint has a drive-train with a gearbox and further operating components, the further operating components including a motor, whereby the cabling extends externally around said further components and internally within the gearbox, the robot having at least 7 DOF, characterized by assembling the robot by providing at least two joint modules, each joint module including a first and a second semi-hollow joint for a respective rotation axis and by connecting the joint modules to other parts of the robot.

12. A method according to claim 1 1 , characterized by providing a set of joint modules and selecting said at least two joint modules from said set.

13. A method according to claim 12, characterized in that said set includes joint modules of the same configuration.

14. A method according to claim 13, characterized in that said set includes joint modules that are identical.

15. A method according to claim 13 or 14, characterized in that the set of joint modules includes joint modules that are of different size.

16. A method according to any of claims 12-15, characterized in that the method includes assembling a plurality of robots of different sizes.

17. A method according to claim 16, characterized in that the plurality of robots include robots in which the two joint modules include a larger and a smaller module, whereby for two robots of different sizes, a joint module of the same size is selected for axis 2 and axis 3 of the smaller robot and for axis 4 and axis 5 of the larger robot