Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J9/00—Programme-controlled manipulators
  • B25J9/16—Programme controls
  • B25J9/1674—Programme controls characterised by safety, monitoring, diagnostic
  • B25J9/1676—Avoiding collision or forbidden zones
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J9/00—Programme-controlled manipulators
  • B25J9/16—Programme controls
  • B25J9/1628—Programme controls characterised by the control loop
  • B25J9/1633—Programme controls characterised by the control loop compliant, force, torque control, e.g. combined with position control
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J9/00—Programme-controlled manipulators
  • B25J9/16—Programme controls
  • B25J9/1656—Programme controls characterised by programming, planning systems for manipulators
  • B25J9/1664—Programme controls characterised by programming, planning systems for manipulators characterised by motion, path, trajectory planning
  • B25J9/1666—Avoiding collision or forbidden zones
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J13/00—Controls for manipulators
  • B25J13/08—Controls for manipulators by means of sensing devices, e.g. viewing or touching devices
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/39—Robotics, robotics to robotics hand
  • G05B2219/39338—Impedance control, also mechanical
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/40—Robotics, robotics mapping to robotics vision
  • G05B2219/40198—Contact with human allowed if under pain tolerance limit
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/40—Robotics, robotics mapping to robotics vision
  • G05B2219/40201—Detect contact, collision with human
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/40—Robotics, robotics mapping to robotics vision
  • G05B2219/40587—Measure force indirectly by using deviation in position

Definitions

• the invention relates to a method for operating a robot manipulator and a corresponding robot system.
• the object of the invention is to improve the safety when operating a robot manipulator.
• a first aspect of the invention relates to a method for operating a robot manipulator, comprising the steps:
• the impedance control having an artificial spring component and a current reference force of the artificial spring component based on a specified spring stiffness and based on the difference between the current position and the specified Target position of the reference point of the robot manipulator is determined
• All steps of the method according to the first aspect of the invention are preferably carried out by a control unit of the robot manipulator.
• the control unit has corresponding interfaces and at least one processing unit in order to carry out the corresponding method steps.
• the current position of the reference point of the robot manipulator is also determined in particular with the aid of position determination means, in particular position sensors.
• the position determination means preferably comprise at least one of the following: joint angle sensors of the robot manipulator; external camera unit; Sensor fusion unit for sensor data fusion of the data from the joint angle sensors Robot manipulator and the data from the external camera unit; redundant joint angle sensors of the robot manipulator.
• the object from the environment of the robot manipulator can on the one hand be a workpiece or another object, or on the other hand a living organism, in particular a human person.
• maximum permissible force which describes the maximum permissible force to be exerted by the robot manipulator on an object in the vicinity of the robot manipulator, is in principle interchangeable with the term “maximum permissible pressure” that may be exerted on the object.
• the concepts of force and pressure only differ in terms of a surface reference; While the concept of force indicates the absolute load on the object by the robot manipulator without reference to the distribution of the force on the object, the concept of pressure takes into account a corresponding contact area over which the maximum permissible force is transmitted. In this respect, pressure and force can be converted into one another at any time, the reference surface of the contact pressure being determined in particular by assuming complete contact between a structural section of the robot manipulator and the object in the surroundings.
• a conservative assumption that is used as an alternative to the previous assumption of the reference surface is the assumption of the surface of a protruding geometry of the portion of the robot manipulator, for example an edge, a shell segment, or other protruding parts of the respective structural portion of the robot manipulator.
• the robot manipulator itself has in particular a large number of links connected to one another by joints, actuators, preferably electric motors, in particular allowing the robot manipulator to be controlled and moved accordingly on the joints of the robot manipulator.
• an end effector is preferably arranged at the distal end of the robot manipulator, which end effector is used to carry out a task such as machining a workpiece.
• the term used below and above of the reference point of the robot manipulator is preferably to be understood as a predefined location on the robot manipulator, particularly preferably on the end effector of the robot manipulator.
• the reference point of the robot manipulator is therefore intended to be fixed to the body at all times on the robot manipulator and in particular on the end effector of the robot manipulator.
• the current position of the reference point of the robot manipulator specifies, in particular, where the reference point of the robot manipulator is in particular with respect to a fixed coordinate system or a coordinate system of the base or a base of the robot manipulator.
• the position of the reference point therefore designates a position in space and specifies in particular how the reference point of the robot manipulator moves in space or where it is currently located.
• the robot manipulator is controlled by means of an impedance control, in particular when performing a task.
• the result of the implementation of the impedance control is a manipulated variable which has corresponding command variables for the actuators of the robot manipulator.
• An impedance control has at least one artificial spring component.
• the impedance control can have an artificial damper component that generates a drag force opposite to a current speed.
• the artificial spring component generates a correlation between a deflection of the reference point from a predetermined target position and a restoring force associated with the deflection. This restoring force is referred to above and below as the reference force of the artificial spring component. There is thus a clear connection between deflection and force.
• the reference force is aligned in a resetting manner so that when the reference point is released after a deflection of the reference point from the target position, the reference force has a resetting effect in the direction of the target position.
• the target position can be specified statically with respect to a coordinate system, in particular fixed to the earth, that is to say fixed in space and immovable.
• the target position can be understood in terms of a momentary consideration of a sequence of a plurality of target positions.
• the reference point of the robot manipulator travels on a predetermined path, with each position on the predetermined path in the ideal case also corresponding to a position of the reference point at a respective point in time.
• a deflection from the target position in the case of a predetermined movement path can on the one hand correspond to the simple case that the deflection is viewed from a fixed target position of the predetermined path, or alternatively, preferably as a current deflection from the target position continuously carried along the path.
• the path is not only defined by a set of predetermined locations in space, but also by Time information is also assigned to predefined locations, so that the predefined path can be referred to as a predefined trajectory.
• a deflection from the predetermined trajectory accordingly includes a deflection from the setpoint present at a current point in time at its current location on the predetermined path.
• the robot manipulator is controlled with an emergency control program.
• redundant information can be used to check whether the maximum permissible force exerted by the robot manipulator on the object is exceeded using redundant information that can be easily implemented using redundant position-determining means, in particular position sensors.
• the emergency control program comprises at least one of the following control programs: stopping the robot manipulator, moving the robot manipulator back on its original path, switching to an alternative controller mode, in particular to an admittance control and / or a gravitational force-compensated mode with termination of all movement and / or force commands.
• the maximum permissible force is specified by recording an input from a user at a user interface.
• the user interface is, in particular, a touch-sensitive screen, a screen whose elements can be operated with a keyboard and / or mouse, buttons, switches, voice control, or the like.
• the maximum permissible force is specified by means of a database, a plurality of body zones of a person with a respective associated maximum permissible force with respect to one of the body zones being stored in the database.
• the database is stored in particular on a central processing unit, so that in particular a control unit of the Robot manipulator can obtain data from the database through a corresponding interface.
• the body zones are particularly defined in relation to the surface zones of a body of a human person, for example the front of the thigh, the back of the thigh, face, chest, etc. Different maximum permissible forces may also be applied to the person's body by the robot manipulator.
• This embodiment advantageously takes into account the fact that different body zones of a human person are also differently sensitive to force and pressure.
• a maximum permissible force is selected on the basis of a camera-based detection of a collision of a specific body zone of the person with the robot manipulator, the colliding body zone of the person being assigned to a body zone stored in the database and the maximum permissible force associated with the assigned body zone being selected will.
• the advantage of a camera-based detection of a collision is the simple detection of the colliding body zone of the person with the robot manipulator.
• the associated maximum permissible force can advantageously be determined from the database with simple effort.
• all of the maximum permissible forces in the database or the selected one of the maximum permissible forces are adapted as a function of an edge geometry of the robot manipulator and / or as a function of a task or task class to be carried out by the robot manipulator.
• the adaptation is in particular a reduction of the maximum permissible force or forces with tapering and sharpening edges of the robot manipulator.
• Such pointed and sharper edges of the robot manipulator are more uncomfortable for a person when the robot manipulator collides with this person compared to blunt and round geometries of the robot manipulator, and easily damage an object as an object when the robot manipulator collides with this object.
• the first variant the less computationally intensive, a body zone affected by the collision and the associated maximum permissible force are first selected from the database and this selected force is adjusted.
• all entries in the database are continuously adjusted so that the selected one
• the value of the database of the permissible force for the person's body zone currently in question does not have to be further adjusted and can be adopted unchanged.
• the target position is specified by specifying a desired path of the reference point of the robot manipulator.
• Specifying the desired path of the reference point of the robot manipulator can be understood as specifying a large number of target positions, but more expediently than the course of a single target position over the desired path, the desired path together with predetermined time information being referred to as the desired trajectory.
• the deflection from the target position always relates to the deflection from the current target position on the desired trajectory of the reference point.
• the method for checking whether the maximum permissible force is exceeded can also be carried out while traveling a desired path through the reference point of the robot manipulator, in particular in such a way that an unintentional or unplanned stop of the robot manipulator in relation to the reference force is also detected, because then the location of the target position continues on the desired path while the robot manipulator is forced to stand still or is slowed down - which inevitably leads to an increasing deflection of the reference point from the target position until the reference force exceeds the maximum permissible force and the emergency control program is executed.
• the current position of the reference point of the robot manipulator is determined on the basis of redundant sensor signals.
• Redundant sensor signals can on the one hand be supplied by sensors of the same type, for example multiple position sensors on the joints of the robot manipulator.
• the term redundant sensor signals does not exclude different measuring principles, so that, for example, the measurements of joint angle sensors on the joints of the robot manipulator can also be merged with sensor signals from an external camera unit, with the external camera unit preferably completely encompassing the surroundings of the robot manipulator and the complete robot manipulator itself their detection area.
• the target position of the reference point of the robot manipulator is specified behind a surface of the object, so that the robot manipulator exerts a force on the surface of the object in the direction of the target position.
• This embodiment becomes appropriate used in particular for objects as an object, a force being intended to be exerted on the object by the robot manipulator.
• the strategy mentioned above and below is used with the help of impedance control in order to infer a corresponding reference force based on the deflection of the reference point of the robot manipulator from the target position of the reference point .
• the robot manipulator applies a force to the object. If this force (which corresponds to the reference force) exceeds the maximum permissible force, the emergency control program is executed.
• This embodiment advantageously offers the possibility of also exerting desired forces on an object by means of the robot manipulator.
• Another aspect of the invention relates to a robot system having a robot manipulator and a control unit connected to the robot manipulator, the control unit being designed to specify a maximum permissible force that may be exerted by the robot manipulator on an object in the vicinity of the robot manipulator, for specifying a target position of a Reference point of the robot manipulator is designed, is designed to determine a current position of the reference point of the robot manipulator, is designed to control the robot manipulator by performing an impedance control, the impedance control having an artificial spring component and a current reference force of the artificial spring component based on a predetermined spring stiffness and on Based on the difference between the current position and the specified target position of the reference point of the robot manipulator is determined, and to control the robot manipulator rs is executed to execute an emergency control program when the current reference force exceeds the specified maximum permissible force.
• Advantages and preferred developments of the proposed robot system result from an analogous and analogous transfer of the statements made above in connection with the proposed method.
• FIG. 2 shows a robot system which is used to carry out the method according to FIG. 1.
• Control S4 of the robot manipulator 1 by executing an impedance control, the impedance control having an artificial spring component and a current reference force of the artificial spring component based on a specified spring stiffness and based on the difference between the current position and the specified target position 5 of the reference point 7 of the robot manipulator 1 is determined, and
• FIG. 1 The method as described in this FIG. 1 is carried out on a robot system 100 in FIG. 2.
• FIG. 2 The above-identified reference numerals that are not shown in Fig.
• FIG. 2 shows a robot system 100 for carrying out the method of FIG. 1.
• the robot system 100 has a robot manipulator 1 and a control unit 11 connected to the robot manipulator 1.
• the control unit 11 specifies a maximum permissible force that may be exerted by the robot manipulator 1 on an object 3, here specifically the body zone of the person 3 affected by a collision with a person 3.
• a collision is initially detected by torque sensors in the joints of the robot manipulator 1.
• the affected body zone is determined based on a camera, that is to say based on an external camera system (not shown in FIG. 2). In the present example, this is the elbow of person 3.
• the control unit 11 queries a database as to which maximum force may be applied to the elbow of person 3.
• This maximum permissible force of the database is specified by the user through a user interface 9.
• the user interface 9 is a user computer that is connected to the control unit 11 of the robot manipulator 1.
• the corresponding body zone, namely the elbow of person 3, is assigned a corresponding maximum permissible force in the database. This maximum permissible force is read out.
• the control unit 11 is also designed to specify a current target position 5 of a reference point 7 of the robot manipulator 1, the collision creates an increasing deflection of the current position of the reference point 7 of the robot manipulator 1, which is intended to be arranged on the end effector of the robot manipulator 1. This continuous setpoint position 5 of the reference point 7 continues accordingly on its predetermined trajectory.
• This current position of the reference point 7 of the robot manipulator 1 is continuously determined by the control unit 11. Furthermore, the robot manipulator 1 is controlled by its control unit 11 by means of an impedance control, which has an artificial spring component and a current reference force of the artificial spring component on the basis of a predetermined spring stiffness and on the basis of this difference between the current position and the predetermined target position 5 of the reference point 7 of the robot manipulator 1 determined. If this reference force exceeds the maximum permissible force associated with the body zone affected by the collision, the emergency control program is executed.
• the emergency control program includes a short retraction of the robot manipulator on its path carried out until the collision, and then stopping the entire robot manipulator 1 in its current pose.

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• Engineering & Computer Science (AREA)
• Robotics (AREA)
• Mechanical Engineering (AREA)
• Manipulator (AREA)
• Human Computer Interaction (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=74853610

Family Applications (1)

Country Status (7)

Families Citing this family (4)

Family Cites Families (13)

• 2020
  • 2020-02-14 DE DE102020103857.7A patent/DE102020103857B4/de active Active
• 2021
  • 2021-02-10 CN CN202180011277.2A patent/CN115003462A/zh active Pending
  • 2021-02-10 WO PCT/EP2021/053129 patent/WO2021160635A1/de unknown
  • 2021-02-10 JP JP2022549098A patent/JP2023513603A/ja active Pending
  • 2021-02-10 EP EP21709343.4A patent/EP4103363A1/de active Pending
  • 2021-02-10 KR KR1020227030767A patent/KR20220137735A/ko not_active Application Discontinuation
  • 2021-02-10 US US17/794,501 patent/US20230107982A1/en active Pending

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