WO2017036520A1

WO2017036520A1 - System and method for generating a robot program with a hand-held teaching device

Info

Publication number: WO2017036520A1
Application number: PCT/EP2015/070005
Authority: WO
Inventors: Fan Dai; Arne WAHRBURG; Björn MATTHIAS; Hao Ding
Original assignee: Abb Schweiz Ag
Priority date: 2015-09-02
Filing date: 2015-09-02
Publication date: 2017-03-09

Abstract

A robot teaching system and method by applying a force on a teaching pendant (mechanical interaction tool 14,44,84), wherein the sensed force and teaching pendant's position and orientation is transmitted to the robot controller (20,68,116,158) to be stored. The teaching pendant may comprise a gripper with finger (46,48,86) operated by a spring mechanism (88). The robot arm is moved according to the applied force, position and orientation of the teaching pendant and a robot program is generated based on these data. During future execution of the a robot program, a robot gripper is foreseen to automatically apply a force on a workpiece or an object to be gripped, which is corresponding exactly to the afore mentioned manually applied force.

Description

SYSTEM AND METHOD FOR GENERATING A ROBOT PROGRAM WITH A

HAND-HELD TEACHING DEVICE

Description

The invention is related to a robot teaching system and a method for generating a robot program.

It is known that robots are widely used in industrial production, such as for handling tasks like gripping, but also for welding or painting. Dependent on their respective purposes robots have typically a robot arm with a length in the range of 0,5 to 3,5m which consists of several robot members and which are connected by respective hinged joints to a kinematic chain. A robot arm typically comprises five to seven joints, so that in total five to seven degrees of freedom in movement are gained. Usually a mechanical interaction tool is mounted at the tip of the robot arm to mechanically go into contact with a workpiece to be treated or gripped. A mechanical interaction tool might be a gripper or a welding gun for example.

In principle a robot with at least six degrees of freedom in movement has the ability to reach all coordinates within its working range in each desired orientation with the tip of its arm. Dependent on the coordinate system of the robot three degrees of freedom in movement are required to reach any x, y, z coordinate, whereas the other three degrees of freedom in movement are required to gain any orientation around the coordinate. Such flexibility is required for example for complex robot tasks like gripping a workpiece or welding or the like. Of course six degrees of freedom in movement are of also advantage for tasks with no direct mechanical contact to the workpiece to be treated such as robotic paint spraying.

The robot joints are driven by dedicated motors which usually are controlled by a common robot controller. A typical robot controller comprises a computing unit and several amplifiers for the electric supply of the motors with a respective suitable variable voltage signal. The robot controller is foreseen to execute a respective robot program on its computing unit. A robot program usually comprises data about the desired movement path of the tip of the robot arm respectively of a reference point in a fixed relation thereto, which is a so-called tool center point (TCP). Based on the robot program executed by the computing unit the motors of the respective robot joints are controlled in that way, that the tip of the robot arm respectively the TCP is moving along the desired movement path. Normally a desired movement path is described within the robot program by subsequent coordinates along its extension. A coordinate might include - besides values for desired x, y, z position - a desired orientation of the tip of the robot arm respectively the TCP, so that - dependent on the coordinate system used - three values per coordinate are required to define the coordinate as such within the three dimen- sional x, y, z coordinate system and further three values per coordinate are required to define the orientation. The robot controller interpolates the movement path in between the subsequent coordinates provided within the robot program. In order to get the coordinates within the robot program aligned with the coordinate system of the real robot, both, the coordinates in the robot program and the coordinate system of the robot itself, have to be aligned to the same reference coordinate system.

A robot movement program might additionally include some reference values for a force on a workpiece to be treated which has to be applied through the mechanical interaction tool. This might be for example a gripping force which is applied through the gripper fingers of a gripper on a gripped object in between them. But also a mechanical force which is applied by use of a tip-like mechanical interaction tool mounted on the tip of a robot arm on a workpiece in order to move it to another location might be subject to be defined in a robot program. The observance of such a force during execution of the robot program might be enabled as well by use of force sensors implemented in the mechanical interaction tool as by an indirect calculation of a force by use of the electrical currents of the motors of the robot joints for example. In case that the given maximum force is reached the respective motors are controlled in that way that the prescribed maximum force is not exceeded.

Disadvantageous within the state of the art is that defining a value for a force to be applied through a robot or a gripper is a very intuitive task, so that it is rather difficult to define an exact and adequate value for such a force. The height of a suitable gripping force for example strongly depends on the size, type and surface of the object to be gripped.

Objective of the invention is to provide a device and a method that facilitate the teaching of values for respective forces, which have to be applied through a robot or a robot gripper on a workpiece to be treated.

The problem is solved by a robot teaching system of the aforementioned kind. This is characterized by

• a computing device, in particular a robot controller,

• a hand-held teaching device, comprising

o a hand-held base body,

o a mechanical interaction tool mounted on the hand-held base body, o at least one force sensor for measuring a force applied in particular through the mechanical interaction tool,

o a communication interface for data exchange with the computing device, in particular with the robot controller,

• wherein the hand-held teaching device is foreseen to provide data to its communication interface which are describing the force measured by the at least one force sensor and wherein the computing device, in particular the robot controller, is foreseen to receive and store those data.

Basic idea of the invention is to use a hand-held teaching device for intuitively and manually applying a force through the mechanical interaction tool, automatically measure this force and transferring a respective determined data value describing this force into a robot program as a force reference value. During future execution of such a robot program the robot, a gripper respectively a further interaction tool mounted thereon is foreseen to automatically apply a force on a workpiece or an ob- ject to be gripped, which is corresponding exactly to the afore mentioned manually applied force. Preferably the taught force is associated with a position and an orientation of the further interaction tool.

During teaching the force the manually applied force is measured by a respective force sensor and a respective data value describing the strength of the force is transmitted to the computing device by use of the communication interface. On the computing device itself a CAD software program product can be installed, so that the implementation of the data values describing the manually applied force easily can become implemented in a robot program. Of course it is also possible that a robot program is generated by use of a simple text editor, so that in the easiest case a data value describing the force can manually become implemented into a robot program by use of a clipboard respectively copy paste functionality.

Thus an advantageous possibility is provided to feed intuitively determined values describing a desired force into a robot program to be generated.

According to another embodiment of the invention the hand-held teaching device further comprises a user interface for manual interaction to initiate providing data to the communication interface, in particular a button. Of course also a touch display or the like is a suitable interface. Thus it is facilitated to manually apply a pressure force as desired and to trigger the determination of data value describing the force afterwards by using the user interface respectively by pushing a button.

According to another embodiment of the invention, the hand-held teaching device comprises a force-sensing button which is in contact with the at least one force sensor or a further force sensor for measuring a force applied on the force sensing button and wherein the hand-held teaching device is foreseen to provide data to its communication interface which are describing this force. Thus it possible to manually apply a reference force to be taught directly on the force sensing button. Of course also other interaction means such as a pressure foil or the like can be used as a force sensing button. The user friendliness is increased therewith in an advantageous way. According to a further embodiment of the invention, the hand-held teaching device is foreseen to determine an average force measured by the at least one or the further force sensor during a time span and to provide data to its communication interface which are describing this average force. By determining an average force it is easier to define a respective reference force more precisely, since unintended variations in the manual applied force are compensated therewith.

According to another embodiment of the invention the mechanical interaction tool comprises a gripper with moveable gripper fingers. Grippers might have two or more gripper fingers which can be opened and closed. A gripper mounted on the arm of a robot might be driven by a motor or another actuator.

According to another embodiment of the invention the gripper comprises a manually usable spring mechanism so that except a manual force no drive or actuator is required for opening and closing the gripper. This enables the intuitive gripping of a workpiece in an advantageous way.

According to another embodiment of the invention the mechanical interaction tool comprises a force sensor for determining an applied force in between the gripper fingers. Thus it is possible to determine the preferably manually applied gripping force in between the gripper fingers. Also the contact force between the gripped object and other objects can be determined according to a further embodiment of the invention.

According to another embodiment of the invention the mechanical interaction tool is exchangeable by another mechanical interaction tool. Thus the same hand-held base body can be used for teaching with different manual interaction devices making the hand-held teaching device more flexible therewith. Preferably a standardized plug and play interface is foreseen to facilitate exchange. According to another embodiment of the invention the communication interface is based on a wireless data connection. Thus a higher movability of the hand-held teaching device is gained and no restrictions by a cable are present. This facilitates its use in an advantageous way.

The problem of the invention is also solved by a method for generating a robot program using a robot teaching system according to the invention, wherein the robot program is foreseen to be executed by a robot controlled by the or by a further computing device, in particular by the or by a further robot controller, wherein the robot has a robot arm with a further mechanical interaction tool mounted thereon, comprising the following steps:

• applying a force (106, 154) in particular through the mechanical interaction tool (14, 44, 84) of a hand-held teaching device (80, 104, 152) and measuring the force with a force sensor (32, 50, 52),

· providing data about the measured force to the communication interface,

• receiving and storing those data by means of the computing device,

• generating a robot program comprising data of at least one desired pressure force which has to be applied at least temporarily through the further mechanical interaction tool, wherein the data about the measured contact force are used as robot program data describing a desired force to be applied through the further mechanical interaction tool during runtime of the robot program.

The advantages resulting from this method have already been explained before, in particular the intuitive determination of a pressure force by use of a robot teaching system.

According to a further variant of the method it is repeated for several force values to be applied through the further mechanical interaction tool during future runtime of the robot program. In case that the robot program comprises a movement path for ex- ample along that various handling tasks have to be executed by a robot gripper, it is easily to determine separately for each handling task a suitable pressure force.

According to a further variant of the method the robot program comprises data describing a desired movement path of the robot arm. It is also possible to teach posi- tion vectors describing the course of the movement path by use of the robot teaching system according to the invention in the case that it has an integrated position determination device. Thus the robot teaching device can be held at desired locations on a reference workpiece wherein a force might be applied thereon through the me- chanical interaction tool and wherein not only data values describing the applied force but also data values describing the determined position and/or orientation of the hand-held teaching device are provided by the communication interface to the computing unit. Thus according to a further embodiment of the invention the hand held teaching device further comprises means for determining its position and/or orienta- tion wherein the desired movement path of the robot arm is teached by use of the hand held teaching device. Thus force and position are subject to be taught simultaneously.

According to another variant of the method the robot program is generated by use of a software program package running on the or on a further computing device, in particular on the or on a further robot controller. There are several suitable tools such as a simple text editor or even complex CAD system software available which are suitable for generating a robot program. In a preferred variant the received data are provided in a clipboard of the computing environment or the like, so that they can be easily transferred into the robot program to be generated by use of the clipboard for example.

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 teaching system,

Figure 2 shows an exemplary second robot teaching system,

Figure 3 shows an exemplary hand-held teaching device,

Figure 4 shows an exemplary third robot teaching system,

Figure 5 shows an exemplary first robot system,

Figure 6 shows an exemplary fourth robot teaching system and Figure 7 shows an exemplary second robot system.

Figure 1 shows an exemplary first robot teaching system 10. A mechanical interaction tool 14 - in this case an elongated part with a tip - is mounted on a hand-held base body 12. A force sensor 32 is foreseen to determine any force that is applied through the mechanical interaction tool 14 on an external workpiece. The respective measurement data of a respective force are provided to a communication interface 26. A computing unit 30 is foreseen for performing smaller computing tasks such as preprocessing of measurement values for example.

The communication interface 26 is foreseen to communicate the respective determined measurement data via a data exchange 28 to an external computing unit that is not depicted in this figure. Providing of data to the communication interface 26 can be initiated by pushing a button 34.

Figure 2 shows an exemplary second robot teaching system 40. A mechanical interaction tool 44 - in this case gripper with gripper fingers 46, 48 - is mounted on a hand-held base body 42. Each gripper finger 46, 48 is provided with a respective force sensor 50, 52, so that a clamping force in between the gripper fingers 46, 48 is determinable therewith.

A communication interface 64 is foreseen to communicate the respective determined measurement data via a data exchange 66 to an external computing unit that is not depicted in this figure. A computing unit 68 is foreseen for performing smaller compu- ting tasks such as preprocessing of measurement values. Providing of data to the communication interface 64 can be initiated by a manual action, for example by pushing a button 70, or by detecting the contact with the work piece by galvanic contact, or by detecting a predetermined threshold force to be achieved by the contact with the work piece or other objects, or by other sensory means.

Figure 3 shows an exemplary hand-held teaching device 80. A mechanical interaction tool 84 - in this case gripper with gripper fingers 86 - is mounted on a hand-held base body 82. A user interface 90 respectively a button is foreseen to initiate providing measurement data to a communication interface. The gripper fingers 86 can be opened and closed by manually compressing a clamplike user interface 88 for manual interaction. This is a very simple and intuitive method that also provides a simple force feedback to the hand of the user. The hand-held position device 80 can easily be equipped with one or more force sensors.

Figure 4 shows an exemplary third robot teaching system 100 with a user 102. A conveyor 1 12 is foreseen to provide workpieces 1 10 to be gripped. The user 102 held in his right hand an exemplary hand-held teaching device 104. He is manually applying a force 106 on a gripped workpiece 108, wherein the force is determined by a force sensor integrated in the hand-held teaching device 104. A communication interface is foreseen for data exchange 1 14 with an external computing device 1 16, so that measurement data of the force in between the gripper fingers can be provided to the external computing device 1 1 6.

Figure 5 shows an exemplary first robot system 130. A conveyor 138 is providing workpieces to be gripped. A robot 140 is controlled by a computing device 142 - in this case a robot controller - and has a further mechanical interaction tool 132 respectively a gripper mounted on the tip of its arm. The gripper applies a force 134 on a gripped workpiece 136.

The movements of the robot 140 and of the gripper are controlled according to a movement program running on the computing device 142. The reference values for forces to be applied by the gripper have been teached by use of a hand-held teach- ing device as depicted in figure 4.

Figure 6 shows an exemplary fourth robot teaching system 150 with a user 156. The user 156 held in his right hand an exemplary hand-held teaching device 152. He is manually applying a force 154 on a workpiece, wherein the force is determined by a force sensor integrated in the hand-held teaching device 152. A communication interface is foreseen for data exchange with an external computing device 158, so that measurement data of the force in between the gripper fingers can be provided to the external computing device 158. Figure 7 shows an exemplary second robot system 1 60. A robot 166 is controlled by a computing device 1 68 - in this case a robot controller - and has a further mechanical interaction tool 1 62 mounted on the tip of its arm. The mechanical interaction tool 162 applies a force 1 64 on a workpiece.

The movements of the robot 1 66 are controlled according to a movement program running on the computing device 1 68. The reference values for forces to be applied by the mechanical interaction tool 162 have been teached by use of a hand-held teaching device as depicted in figure 6.

List of reference siqns

10 exemplary first robot teaching system

12 hand-held base body

14 mechanical interaction tool (tip)

26 communication interface

28 data exchange

30 computing unit

32 force sensor

34 user interface for manual interaction (buttons)

40 exemplary second robot teaching system

42 hand-held base body

44 mechanical interaction tool (gripper)

46 gripper finger

48 gripper finger

50 force sensor

52 force sensor

64 communication interface

66 data exchange

68 computing unit

70 user interface for manual interaction (buttons)

80 exemplary hand-held teaching device

82 hand-held base body

84 mechanical interaction tool (gripper)

86 gripper fingers

88 user interface for manual interaction (clamp)

90 user interface for manual interaction (button)

100 exemplary third robot teaching system

102 user

104 exemplary hand-held teaching device

106 manually applied force

108 gripped workpiece

1 10 further workpieces

1 12 conveyor

1 14 data exchange 1 1 6 computing device

30 exemplary first robot system

132 further mechanical interaction tool (gripper)

134 force applied by further mechanical interaction tool 136 gripped workpiece

138 conveyor belt

140 robot

142 computing device (robot controller)

150 exemplary fourth robot teaching system

152 hand-held teaching device

154 manually applied force

156 user

158 computing device

160 exemplary second robot system

162 further mechanical interaction tool (gripper)

164 force applied by further mechanical interaction tool

166 robot

168 computing device (robot controller)

Claims

1 . Robot teaching system ( 0, 40, 00, 130), comprising

• a computing device (20, 68, 1 1 6, 158), in particular a robot controller,

• a hand-held teaching device (80, 104, 152), comprising

o a hand-held base body (12, 42, 82),

o a mechanical interaction tool (14, 44, 84) mounted on the hand-held base body (12, 42, 82),

o at least one force sensor (32, 50, 52) for measuring a force (106, 154) applied in particular by the mechanical interaction tool (14, 44, 84), o a communication interface (26, 64) for data exchange (28, 66) with the computing device (20, 68, 1 16, 158), in particular with the robot controller,

• wherein the hand-held teaching device (80, 104, 152) is foreseen to provide data to its communication interface (26, 64) which are describing the force (106, 154) measured by the at least one force sensor (32, 50, 52) and wherein the computing device (80, 104, 152), in particular the robot controller, is foreseen to receive and store those data.

2. Robot teaching system according to claim 1 , characterized in that the hand-held teaching device (80, 104, 152) further comprises a user interface (34, 70, 90) for manual interaction to initiate providing data to the communication interface (26, 64), in particular a button.

3. Robot teaching system according to claim 1 or 2, characterized in that the handheld teaching device comprises a force-sensing button which is in contact with the at least one force sensor or a further force sensor for measuring a force applied on the force sensing button and wherein the hand-held teaching device (80, 104, 152) is foreseen to provide data to its communication interface (26, 64) which are describing this force.

4. Robot teaching system according to any of the previous claims, characterized in that the hand-held teaching device is foreseen to determine an average force measured by the at least one or the further force sensor during a time span and to provide data to its communication interface (26, 64) which are describing this average force.

5. Robot teaching system according to any of the previous claims, characterized in that the mechanical interaction tool (14, 44, 84) comprises a gripper with moveable gripper fingers (46, 48, 86).

6. Robot system according to claim 5, characterized in that the gripper comprises a manual usable spring mechanism, so that except a manual force no drive or actuator is required for opening and closing the gripper.

7. Robot system according to claim 6, characterized in that the mechanical interaction tool (14, 44, 84) comprises a force sensor (32, 50, 52) for determining an applied force in between the gripper fingers (46, 48, 86).

8. Robot teaching system according to any of the previous claims, characterized in that the mechanical interaction tool (14, 44, 84) is exchangeable by another mechanical interaction tool.

9. Robot teaching system according to any of the previous claims, characterized in that the communication interface (26, 64) is based on a wireless data connection.

10. Method for generating a robot program using a robot teaching system according to claim 1 to 9, wherein the robot program is foreseen to be executed by a robot (140, 1 66) controlled by the (20, 68, 1 1 6, 158) or by a further computing device, in particular by the or by a further robot controller, wherein the robot (140, 166) has a robot arm with a further mechanical interaction tool (132, 1 62) mounted thereon, comprising the following steps:

• applying a force (106, 154) in particular through the mechanical interaction tool (14, 44, 84) of a hand-held teaching device (80, 104, 152) and measuring the force with a force sensor (32, 50, 52), • providing data about the measured force to the communication interface (26, 64),

• receiving and storing those data by means of the computing device (20, 68, 1 1 6, 158),

• generating a robot program comprising data of at least one desired pressure force which has to be applied at least temporary through the further mechanical interaction tool (132, 1 62), wherein the data about the measured pressure force are used as robot program data describing a desired pressure force to be applied through the further mechanical interaction tool (132, 1 62) during runtime of the robot program.

1 1 . Method according to claim 8, characterized in that it is repeated for several pressure force values to be applied through the further mechanical interaction tool (132, 162) during runtime of the robot program.

12. Method according to claim 8 or 9, characterized in that the robot program comprises data describing a desired movement path of the robot arm.

13. Method according to claim 12, characterized in that the hand held teaching device further comprises means for determining its position and/or orientation and in that the desired movement path of the robot arm is teached by use of the hand held teaching device.

14. Method according to claim 8 to 10, characterized in that the robot program is generated by use of a software program package running on the (20, 68, 1 1 6, 158) or on the further computing device, in particular on the or on the further robot controller.