WO2014048444A1

WO2014048444A1 - Robot system for human-robot collaboration

Info

Publication number: WO2014048444A1
Application number: PCT/EP2012/003999
Authority: WO
Inventors: Björn MATTHIAS; Hao Ding
Original assignee: Abb Technology Ag
Priority date: 2012-09-25
Filing date: 2012-09-25
Publication date: 2014-04-03

Abstract

The invention is related to a robot system (10, 50) for human-robot collaboration, comprising a robot (12, 52) and a robot controller (14, 54) with data storage media (16, 56) which is provided to control movements (72, 74, 76) of the robot (12, 52) according to data of a motion program stored thereon, wherein variable motion parameters are provided to influence the motion characteristics of the robot (12, 54) when executing the robot program. Interaction means (44, 58, 60, 62) are provided for changing at least one of the variable motion parameters within predefined limits during the execution of the program and the robot controller (14, 54) is prepared to receive an get effective a changed motion parameter during and without interrupting the execution of the robot program.

Description

Robot system for human-robot collaboration

Description

The invention relates to a robot system for human-robot collaboration, comprising a robot and a robot controller with data storage media, which is provided to control movements of the robot according to data of a motion program stored thereon, wherein variable motion parameters are foreseen to influence the motion characteristics of the robot when executing the robot program.

It is known that robots are increasingly used for human-robot collaboration tasks. A human worker is then relieved of less complex parts of a chain of working steps, for example the transport of a workpiece during assembly of a product, so that he can concentrate on the demanding task of the assembly as such. Usually, the less complex parts of a chain of working steps are on the one side easy to switch over to a robot and on the other hand they are physically demanding and fatiguing for the human worker.

A robot comprises typically a robot arm with several arm segments which are connected by rotary joints, for example. A robot with 6 degrees of freedom in movement is able to reach each coordinate within its working range in every orientation with the tip of its arm. Robots might have a working range of 3m around their rotary base, but robots might also have a size similar to a human arm with a cuboid or sphere-like working range of, for example, 1m width. Robots are normally controlled by a robot controller. A robot controller comprises typically electrical amplifiers for the supply of the different drives of the robot wherein normally one drive is foreseen for each degree of freedom in movement of the robot. Furthermore a robot controller comprises a calculation device such as a computer which is able to process a software program respectively a robot program. The electrical amplifiers are driven in such a way that the robot moves accordingly. Usually robot programs define a desired movement path of the tip of the robot arm by a sequence of several coordinates with associated orientations, which are approached sequentially along linear path segments. Furthermore, robot programs define a desired movement speed between the different coordinates.

Typically a robot is arranged within a safeguarded safety zone where no worker is allowed to enter when the robot is active. In case of a violation of the safety zone by a person, an emergency stop is the normal consequence to ensure safety of the person. However, in the case of human-robot collaboration it is required that the human worker and the robot share a common working space so that, for example, a handing over of a workpiece between robot and human worker is possible without causing an emergency stop. Thus, collaboration between a human worker and a robot requires the strict observing of safety rules to ensure that the robot cannot harm the collaborating human. Such safety requirements are described in ISO 10218-1 , -2 for example.

Another aspect of human-robot collaboration consists in providing the human worker with a working place which is as ergonomic as possible. A robot normally operates according to a given motion program which defines the movement of the robot, for example a movement path and an associated movement speed for the different sections of the movement path. Thus, the robot is moving independently of the individual physical constitution of the collaborating human. Such physical constitution is, for example, the body height or the age of a collaborating human. To ensure that the motion characteristic of a robot is well-adapted to the needs of a collaborating human, so-called motion profiles might be foreseen. Before a human begins collaboration with the robot, such a motion profile, which contains basic data and requirements of the collaborating human, is loaded into the robot controller. While executing the robot program, the movement data contained in the motion program, for example movement speed or movement path, are adapted accordingly and the robot moves, for example, with reduced speed in the case that the human worker is unable to move sufficiently fast, for instance due to health problems. The German patent DE 10320343 B4 describes the possibility to adapt the motion characteristic of a robot by applying an individual motion profile before starting collaboration.

Disadvantageously within the state of the art is that collaborative robots that fulfil the necessary safety requirements may not be "pleasant" to work with for any given individual worker, who might be subject to daily variations in his performance or his subjective feeling of well-being respectively comfort level during work. A feeling of well- being, on the other hand, is important for a higher productivity and fewer faults during robot-human collaboration.

Based on this state of the art, it is the objective of the invention to provide a robot system for human-robot collaboration that provides the possibility to improve the feeling of comfort of the individual worker while upholding or even increasing his productivity.

This problem is solved by a robot system for human-robot collaboration of the aforementioned kind. This is characterized in that interaction means are provided for changing at least one of the variable motion parameters within predefined limits during the execution of the program and in that the robot controller is able to receive and get effective a changed motion parameter during and without interrupting the execution of the robot program.

The basic idea of the invention consists not only in providing an individual and fixed motion profile for a worker, moreover a possibility of an easy and individual adaptation of the belonging profile during runtime of the motion program is provided. This enables the human collaborator - preferably based on his already personalized load- ed motion profile - to easily adjust the motion parameters of the robot according to his current requirements and needs without any complex programming effort or interruption of the motion program.

Since a motion program comprises a sequence of fixed commands, it is in principal not expected to be modified during runtime. The motion parameters define intentional deviations between the robot movement according to the data of the robot program and the real executed robot movement.

It is as well possible to have some motion parameters which can be directly provided to the robot controller, so that the robot changes his movement behavior automatically while executing the unmodified motion program. This could be in a simple case, for example, a speed limiting behavior wherein the maximum speed can be adapted by an associated variable motion parameter. All movement speeds lower than the current speed limit, for example 500mm/s, will be executed according to the motion program and all other, i.e. higher speeds will be limited to 500mm/s. But also a predefined value for the acceleration is thinkable, for example a given acceleration of 5m/s². If the robot is physically able to accelerate with the given value of acceleration, it will move accordingly, otherwise it will accelerate with a lower value. A limited movement speed or acceleration behavior is suitable to give the collaborating human an increased feeling of safety. It is also possible to define a zone around a coordinate of the movement path, for example with a certain radius. Instead of moving exactly linearly between the different coordinates, the robot controller can control the robot automatically in such a way that the tip of the robot arm moves along a curve within such a zone to gain a smoother movement behavior, which might give the collaborating human a feeling of higher safety. A radius of such a zone is also an example for a motion parameter. Thus, according to a variant of the invention it is foreseen that the motion parameters influence at least the robot movement speed or acceleration behavior.

But it is also possible to modify automatically the motion program according to certain rules and provide this modified motion program to the robot controller for further execution. In a simple case the movement speed can be multiplied by a certain predefined factor, for example 0.7, so that each robot movement is slower than basically defined within the motion program by this factor. Such an adaptation of the motion program could be executed by an additional adaptation task running on the robot controller. Of course both methods for applying the movement parameters can be applied at the same time, for example an adaptation of the movement speed to a higher value and afterwards limiting the maximum speed with a speed limiting value.

According to the invention, a change of a motion parameter becomes effective immediately during the runtime of the robot program and without interrupting it. Nevertheless it is also within the scope of the invention that a change of motion parameter might cause a temporary slowing down of the movement speed during the change phase, whereas the new motion parameters become effective immediately after the change phase.

To not exceed a reasonable range of motion parameters, the motion parameters are only changeable within predefined limits, which are given for example by the manufacturer of the robot and which are not subject to be modified by the human collaborator. Since safety for the human collaborator has the highest priority, all predefined limits have to be given in such a way that each changeable variant of motion parameters ensures a safe human-robot collaboration and complies to the relevant safety requirements. Thus, according to a variant of the invention, at least a high and a low level access mode are foreseen for configuration or programming the robot system wherein an adaptation of the limits for variable motion parameters is restricted to the high level access mode.

Interaction means are foreseen to enable the human collaborator to easily adapt the motion parameters according to his actual personal requirements. Those interaction means do not correspond to the standard programming means such as a control computer at a production line or a standard teach pendant. Moreover, dedicated input means are foreseen for quick and easy adaptation of the motion parameters. Thus it might be foreseen, that one interaction means is provided for the input of one dedicated motion parameter. This enables an easy interaction with the operator. Of course, those dedicated input means can be implemented into already existing control means. Thus, it is thinkable to provide a dedicated slider or similar means as additional control elements within a standard teach pendant.

Following a further embodiment of the invention, the motion parameters are intended to influence the motion characteristic movement path according to, for example, one of the criteria of 'closest distances of approach to a collaborating human' or 'angular direction of approach towards a collaborating human'. The closer a robot moves to a human collaborator, the lesser might be his comfort level. Also, the angular direction of the robot movement towards the human collaborator is a motion behavior of the robot that might influence the comfort level of the human collaborator. It is reasonable to assume that a typical human collaborator has the highest degree of comfort when the robot moves directly face to face towards him instead from the side.

In this case it is required that the current position of the human collaborator relative to the collaborating robot is known. Thus, the robot system according to the invention comprises means for detecting the actual position of a collaborating human. Those means could be a vision system with camera and analysis system, for example, which determines the position of the human collaborator and which provides the associated position to the robot controller. In this case, the robot controller has an adaptation task running thereon, which modifies the current movement path in such a way that the preferences of the human collaborator are fulfilled within the given boundary conditions. As mentioned before, unavoidable boundary conditions, which must be fulfilled in any case, are given by the safety requirements and regulations. But also the physical limitations of the robot or its working range cannot be exceeded.

According to a further embodiment of the invention, the interaction means are suitable for manual and preferably intended interaction with a collaborating human. Thus, the interaction means comprise physical control elements such as a slider, a potentiometer, a button, a foot pedal or a touch screen. Of course, those interaction means have to be arranged within reaching distance of the human collaborator respectively within his workspace. They are mounted, for example, on a working bench or integrated as a separate element within a teach pendant or similar device. According to another embodiment of the invention, the interaction means comprise means for voice recognition and/or means for image recognition. This type of interaction means are preferably provided for audio- or video- surveillance of the human collaborator within his workspace. The measured audio- or video data are permanently analyzed by an evaluation system, wherein any gesture or speech of the human collaborator is sought to be interpreted as a sign of comfort or discomfort. In case of an interpreted evidence of discomfort, the evaluation system automatically changes an associated motion parameter in such a way that the comfort level of the human collaborator is expected to rise. Hence, according to a further variant of the invention, it is foreseen to permanently observe a human collaborator, wherein in case of a detection of an abnormal state of the human collaborator at least one motion parameter is changed automatically towards its lower limit. "Lower limit" does not necessarily mean a lower number value. Moreover, "lower limit" means a less challenging motion parameter for the human collaborator, which typically is also not in conflict with the maximum admissible safety limit. A typical example would be to slow down the robot speed in case of any doubtful situation.

Following a further embodiment of the invention, a set of initial individual motion parameters is loadable from a data storage media to the robot controller before starting the execution of the robot program. Thus, a human collaborator can initialize the robot with a set of motion parameters, which are basically comfortable for him. Dependent on his actual individual feeling, he can adjust those parameters during runtime of the robot program. According to the invention it is also foreseen that a modified set of motion parameters is stored on the data storage media of the robot controller.

Following another embodiment of the invention, the robot system comprises at least two robots respectively robot controllers with variable motion parameters. It is either possible that each robot is controlled by a dedicated controller, but it is also possible that one robot controller controls more than one robot. This is advantageous for an improved coordination between several robots. As a variant of the invention, it is foreseen to change the motion parameters of at least two robots synchronously by use of the same interaction means. Thus, a person collaborating synchronously with, for example, two robots has to adjust the motion parameters for the two robots only once.

Further advantageous embodiments of the invention are mentioned in the dependent claims.

The invention will now be further explained by means of an exemplary embodiment and with reference to the accompanying drawings, in which:

Figure 1 shows an exemplary first robot system for human-robot collaboration and Figure 2 shows an exemplary second robot system for human-robot collaboration.

Fig. 1 shows an exemplary first robot system 10 for human-robot collaboration. A robot 12 comprises two separate arms which are similar to human arms. Each arm might be considered to be an individual robot, whereas a single robot controller 14 is foreseen for the control of both arms of the robot 12. The robot controller 14 comprises a data storage media 16 which is connected therewith by a connection line 36. The robot 12 is foreseen to perform an assembly task of a not shown workpiece, wherein one arm of the robot 12 is holding the workpiece and the other arm is doing the assembly. A workspace 26 is foreseen for the robot 12 which is collaborating with a human person 18 having a workspace 24.

To enable collaboration of the human person 18 with the robot 12 a shared workspace 28 is provided, which is accessible for both. Thus, it is possible, for example, to exchange a not shown workpiece therein. The collaborating human 18 moves a workpiece after a first step of assembly along the arrow 40 into the shared workspace and afterwards the collaborating robot 12 picks the workpiece up and moves it along the arrow 42 into its own workspace 26 for further assembly.

Within the workspace 24 of the collaborating human 18, interaction means 44 are foreseen, in this case an adjusting knob, which enables the change of the motion parameter movement speed of the collaborating robot 12 by a rotary movement. The collaborating robot 12 performs its movements for assembly according to data of a motion program stored on the data storage media 16 of the robot controller 14. In case of discomfort of human collaborator 18, he has the easy possibility to reduce the overall movement speed of the collaborating robot 12 by a certain factor, for example by 50%. The interaction means 44 are connected with the robot controller 14 by a connection line 34. An adaptation task running on the robot controller 14 receives the desired new motion parameter effective immediately by multiplying all default speed data of the motion program with the associated factor. Temporarily it might also be useful to reduce the movement speed of the robot to zero, so that it is possible for the collaborating human 18 to leave his working place for some time.

A camera 20 is provided that observes the shared workspace 28. By use of a connection line 30, the data of the camera 20 are provided to a data processing device 22 with a data processing program running thereon. The data processing device 22 analyses the position of a workpiece which might be placed in the shared workspace 28. Thus, it is possible to automatically adapt the motion path of a grasping motion of the robot 12 according to the individual position of the workpiece.

Fig. 2 shows an exemplary second robot system 50 for human-robot collaboration. A robot 52 with six degrees of freedom in movement is connected with a robot controller 54 by a connection line 88 wherein a data storage device 56 is connected thereto by a connection line 86. A collaborating human 64 is performing a common assembly task together with the robot 52 which is foreseen to move a not shown workpiece from a start coordinate 68 to an end coordinate 70 of a movement path which is variable in between. At the end coordinate 70 the collaborating human 64 takes over the workpiece from the robot 52.

One movement parameter that influences the motion behaviour of the robot 52 is the angle 80, 82 of movement towards the collaborating human 64 to the end coordinate 70. This angle 80, 82 can be assumed to be relevant for the subjective comfort level of the collaborating human 64. At one time he might prefer to be approached from the side as shown with the motion path with the reference number 76. At another time, he might prefer an approach of the robot 52 towards him according to the motion path with the reference number 74, which is directly directed towards him along the dotted line 78, which indicates an associated reference direction. Other persons might experience the highest comfort level when the robot 52 moves the tip of its arm along the path 72 from the other side.

To adapt the motion behaviour of the robot 52 to the current individual needs of the collaborating human 64, several interaction means 58, 60, 62 are foreseen within the workspace 66. Thus, it is possible for the collaborating human 64 to manually adjust the motion parameters of the robot 52 during runtime of the robot program, wherein one of the adjustable parameters is the angle of the movement towards the end coordinate 70. The parameters are provided to the robot controller 54 by a connection line 84, wherein the robot controller 54 gets the changed parameter effective immediately.

List of reference signs exemplary first robot system for human-robot collaboration first robot

robot controller of first robot

data storage media of first robot

collaborating human

camera

data processing device

workspace of collaborating human

workspace of first robot

shared workspace

first connection line

second connection line

third connection line

fourth connection line

fifth connection line

first movement path of object

second movement path of object

interaction means of first robot system

exemplary second robot system for human-robot collaboration second robot

robot controller of second robot

data storage media of second robot

first interaction means of second robot system

second interaction means of second robot system

third interaction means of second robot system

collaborating human

workspace of collaborating human

start coordinate of movement path

end coordinate of movement path

first example for movement path

second example for movement path third example for movement path

reference direction towards collaborating human first angle of direction

second angle of direction

sixth connection line

seventh connection line

eighth connection line

Claims

1. Robot system (10, 50) for human-robot collaboration-n, comprising a robot (12, 52) and a robot controller (14, 54) with data storage media (16, 56) which controls movements (72, 74, 76) of the robot (12, 52) according to data of a motion program stored thereon, wherein variable motion parameters are provided to influence the motion characteristics of the robot (12, 54) when executing the robot program, characterized in that

interaction means (44, 58, 60, 62) are provided for changing at least one of the variable motion parameters within predefined limits during the execution of the program and in that the robot controller (14, 54) is prepared to receive and get effective a changed motion parameter during and without interrupting the execution of the robot program.

2. Robot system according to claim 1 , characterized in that the limits for the variable motion parameters are predefined in such a way that each changeable variant of motion parameters ensures a safe human-robot collaboration.

3. Robot system according to claim 1 or 2, characterized in that at least a high and a low level access mode are provided for configuration or programming the robot system, wherein an adaptation of the limits for variable motion parameters is restricted to the high level access mode.

4. Robot system according to any of the preceding claims characterized in that the motion parameters influence at least one of the following motion characteristics of the robot:

• movement speed

• acceleration behaviour

5. Robot system according to any of the preceding claims, characterized in that the motion parameters influence the motion characteristic movement path (72, 74, 76) according to, for example, one of the following criteria:

• closest distance of approach to a collaborating human (18, 64)

• angular direction (80, 82) of approach towards a collaborating human (18, 64)

6. Robot system according to claim 5, characterized in that the robot system comprises means (20) for detecting the actual position of a collaborating human (18, 64).

7. Robot system according to any of the preceding claims, characterized in that the interaction means (44, 58, 60, 62) are suitable for manual interaction with a collaborating human (18, 64).

8. Robot system according to claim 7, characterized in that the interaction means (44, 58, 60, 62) comprise physical control elements such as a slider, a potentiometer, a button, a foot pedal or a touch screen.

9. Robot system according to any of the preceding claims, characterized in that the interaction means (44, 58, 60, 62) comprise means for voice recognition and/or means for image recognition.

10. Robot system according to claim 9, characterized in that it is provided to permanently observe a human collaborator and in that in case of a detection of an abnormal state of the human collaborator at least one motion parameter is changed automatically towards its lower limit.

11. Robot system according to any of the preceding claims, characterized in that a set of initial individual motion parameters is loadable from a data storage media (16, 56) before starting the execution of the robot program.

12. Robot system according to any of the preceding claims, characterized in that the robot controller is foreseen to save the current set of motion parameters to a data storage media (16, 56).

13. Robot system according to any of the preceding claims, characterized in that it comprises at least two robots (12, 52) respectively robot controllers with variable motion parameters.

14. Robot system according to claim 13, characterized in that it is possible to change the motion parameters of the at least two robots (12, 52) synchronously by use of the same interaction means.