DE102021000741A1 - Process for operating a machine and system for carrying out the process - Google Patents

Abstract

Method for operating a machine and system for carrying out the method, wherein an object picked up on a recording unit can be moved along a trajectory by drives of the machine, a setpoint position profile and a setpoint speed profile being determined in a first method step prior to executing the movement of the object along the trajectory in a second method step following the first method step, the object is moved in that the drives regulate the actual position of the object, which is recorded recurrently, to the associated respective setpoint position of the setpoint position curve, the deviation between the respective actual position and the setpoint position on Exceeding a permissible first dimension is monitored and, depending on the result of the monitoring, a signal to indicate a collision is generated.

Description

The invention relates to a method for operating a machine and a system for carrying out the method.

From the WO 2017/097664 A1 a method for detecting a collision of a robot arm with an object is known, the jerk, that is to say the third time derivative, being determined and evaluated.

From the DE 10 2013 016 019 B3 A method for operating a multi-unit manipulator is known as the closest prior art.

From the EP 1 477 284 B1 a drive control is known.

From the DE 10 2014 019 187 A1 a method for controlling a drive arrangement for moving a tool is known.

From the EP 0 188 109 B1 a robot controller is known.

From the DE 10 2008 024 950 A1 a method for controlling a manipulator is known.

From the DE 10 2004 026 185 A1 a device for operating a machine is known.

From the DE 603 13 006 T2 a method for detecting a malfunction during the movement of a part by a drive system is known.

From the DE 694 10 190 T2 a method for recognizing and regulating a load on a servomotor is known.

From the DE 689 19 801 T2 a method for the collision detection of movable objects driven by means of servomotors is known.

From the GB 2 106 279 A automated machine safety is known.

From the DE 10 2008 054 312 A1 a method for the reliable detection of a kinematic variable of a manipulator is known.

A method for collision detection in an industrial robot is known from JP H08-229 864 A.

The invention is therefore based on the object of developing the safety of an installation.

According to the invention, the object is achieved in the method according to the features specified in claim 1 or 4 and in the system according to the features specified in claim 12.

Important features of the invention in the method for operating a machine, in particular a robot, are that an object, in particular an end effector, received, in particular mounted, on a receiving unit, in particular on a robot arm, can be moved along a trajectory by drives of the machine ,
wherein, in a first method step, before executing the movement of the object along the trajectory, a target position profile of the respective drive and a target speed profile of the respective drive are determined,
whereby a respective set speed curve is determined from the set position curve of the respective drive,
wherein in a second process step that follows the first process step in time, the object is moved by operating the drives in such a way that their respective actual position, which is recorded recurring over time, is adjusted to the associated respective setpoint position of their respective setpoint position curve,
whereby a respective actual speed is determined from the actual positions recorded on the respective drive,
wherein the deviation between the actual speed and the target speed of the respective drive is monitored for exceeding a permissible first level and, depending on the result of the monitoring, a signal for indicating a collision is generated.

The advantage here is that a collision can be detected if the permissible level is exceeded. Since the formation of the actual speed and the comparison with the target speed can be carried out without any special effort, the detection is made possible in a simple manner and the security is increased. After a collision has been detected, either an STO signal can be carried out, i.e. all drives can be placed in a safe state, for example in the deactivated state, or a retraction movement can be carried out along the trajectory. This is because the part of the trajectory traveled through until the collision was detected was collision-free. This enables a section of the trajectory to be traversed backwards in a safe manner. In any case, the monitoring of the control deviation of the speed corresponds to the monitoring of the first derivative of the position profile with respect to time.

Alternatively, however, the collision detection can also be used to detect the presence of a transport item that is to be picked up afterwards.

• - unter Berücksichtigung des Sollpositionsverlaufs ein positionsabhängiger Momentenverlauf bestimmt wird,
• - unter Berücksichtigung des Sollgeschwindigkeitsverlaufs ein Reibmomentenverlauf und
• - unter Berücksichtigung des Sollbeschleunigungsverlaufs oder Sollgeschwindigkeitsverlaufs ein weiterer Momentenverlauf bestimmt wird,

und indem der Sollmomentverlauf, insbesondere durch Summation, aus dem positionsabhängigen Momentenverlauf und aus dem Reibmomentenverlauf und aus dem weiteren Momentenverlauf bestimmt wird. Von Vorteil ist dabei, dass zusätzlich überwachbar ist, ob das jeweils aktuell bestimmte Istmoment des jeweiligen Antriebs ein zulässiges Maß an Abweichung überschreitet oder nicht. Davon abhängig wird auch hierfür ein Warnsignal abgegeben.In an advantageous embodiment, a desired torque curve over time is determined in the first method step by

• - A position-dependent torque curve is determined taking into account the target position curve,
• - taking into account the target speed profile, a friction torque profile and
• - A further torque curve is determined taking into account the set acceleration curve or set speed curve,

and in that the setpoint torque curve is determined, in particular by summation, from the position-dependent torque curve and from the friction torque curve and from the further torque curve. The advantage here is that it can also be monitored whether the currently determined actual torque of the respective drive exceeds a permissible amount of deviation or not. Depending on this, a warning signal is also given for this.

In an advantageous embodiment, the deviation between the respective actual torque and the respective setpoint torque is monitored for exceeding a permissible second dimension, and a signal to indicate a collision is generated as a function of the result of the monitoring. The advantage here is that the collision can be identified easily and reliably. In particular, when using the mentioned speed monitoring of each individual drive and the mentioned torque monitoring of each individual drive, the collision detection can be carried out with a high level of security.

• - unter Berücksichtigung des Sollpositionsverlaufs ein positionsabhängiger Momentenverlauf bestimmt wird,
• - unter Berücksichtigung des Sollgeschwindigkeitsverlaufs ein Reibmomentenverlauf und
• - unter Berücksichtigung des Sollbeschleunigungsverlaufs oder Sollgeschwindigkeitsverlaufs ein weiterer Momentenverlauf bestimmt wird,

und indem der Sollmomentverlauf, insbesondere durch Summation, aus dem positionsabhängigen Momentenverlauf und aus dem Reibmomentenverlauf und aus dem weiteren Momentenverlauf bestimmt wird,
wobei die Abweichung zwischen dem jeweiligen Istmoment und dem jeweiligen Sollmoment auf Überschreiten eines zulässigen zweiten Maßes überwacht wird und abhängig vom Ergebnis der Überwachung ein Signal zum Anzeigen einer Kollision erzeugt wird.Important features in the method for operating a machine, in particular a robot, are that an object, in particular an end effector, which is received, in particular mounted, on a receiving unit, in particular on a robot arm, can be moved along a path by drives of the machine,
wherein, in a first method step, before executing the movement of the object along the trajectory, a target position profile of the respective drive and a target speed profile of the respective drive are determined,
whereby a respective set speed curve is determined from the set position curve of the respective drive,
wherein in a second process step that follows the first process step in time, the object is moved by operating the drives in such a way that their respective actual position, which is recorded recurring over time, is adjusted to the associated respective setpoint position of their respective setpoint position curve,
whereby a respective actual speed is determined from the actual positions recorded on the respective drive,
wherein in the first method step a temporal setpoint torque curve is determined by

• - A position-dependent torque curve is determined taking into account the target position curve,
• - taking into account the target speed profile, a friction torque profile and
• - A further torque curve is determined taking into account the set acceleration curve or set speed curve,

and in that the target torque curve is determined, in particular by summation, from the position-dependent torque curve and from the friction torque curve and from the further torque curve,
wherein the deviation between the respective actual torque and the respective setpoint torque is monitored for exceeding a permissible second dimension and, depending on the result of the monitoring, a signal for indicating a collision is generated.

The advantage here is that a collision can also be detected in the area of the second derivative of the position profile with respect to time. A calculation of the jerk, i.e. the third derivative, can therefore be avoided. In order to generate the difference to be monitored, however, the torque caused by friction must be modeled and the position-dependent component of the torque must also be determined, i.e. the torque component caused by the lever action of the articulated arms of the machine designed as a robot or the torque component otherwise caused by the position in accordance with the lever law . In addition, the second derivative of the position curve according to time must also be determined.

In an advantageous embodiment, the deviation between the actual speed and the setpoint speed of the respective drive is monitored for exceeding a permissible first level, and a signal to indicate a collision is generated as a function of the result of the monitoring. The advantage here is that monitoring is made possible in a simple manner.

• - unter Berücksichtigung des Sollpositionsverlaufs ein positionsabhängiger Momentenverlauf bestimmt wird,
• - unter Berücksichtigung des Sollgeschwindigkeitsverlaufs ein Reibmomentenverlauf und
• - unter Berücksichtigung des Sollbeschleunigungsverlaufs oder Sollgeschwindigkeitsverlaufs ein weiterer Momentenverlauf bestimmt wird,

und indem der Sollmomentverlauf insbesondere durch Summation, aus dem positionsabhängigen Momentenverlauf und aus dem Reibmomentenverlauf und aus dem weiteren Momentenverlauf bestimmt wird. Von Vorteil ist dabei, dass auch im Bereich der zweiten Ableitung des Positionsverlaufs nach der Zeit eine Kollision detektierbar ist. Eine Berechnung des Rucks, also der dritten Ableitung ist somit vermeidbar. Zur Bildung der zu überwachenden Differenz muss allerdings eine Modellierung des durch Reibung bedingten Moments ausgeführt werden und zusätzlich der positionsabhängige Anteil des Moments bestimmt werden, also der durch die Hebelwirkung der Knickarme der als Roboter ausgeführten Maschine oder der anderweitig durch die Position entsprechend dem Hebelgesetz bewirkte Drehmomentanteil. Zusätzlich ist auch die zweite Ableitung des Positionsverlaufs nach der Zeit zu bestimmen.In an advantageous embodiment, a desired torque curve over time is determined in the first method step by

• - a position-dependent torque curve is determined taking into account the target position curve,
• - taking into account the target speed profile, a friction torque profile and
• - A further torque curve is determined taking into account the set acceleration curve or set speed curve,

and in that the setpoint torque curve is determined in particular by summation, from the position-dependent torque curve and from the friction torque curve and from the further torque curve. The advantage here is that a collision can also be detected in the area of the second derivative of the position profile with respect to time. A calculation of the jerk, i.e. the third derivative, can therefore be avoided. In order to generate the difference to be monitored, however, the torque caused by friction must be modeled and the position-dependent component of the torque must also be determined, i.e. the torque component caused by the lever action of the articulated arms of the machine designed as a robot or the torque component otherwise caused by the position in accordance with the lever law . In addition, the second derivative of the position curve according to time must also be determined.

In an advantageous embodiment, the deviation between the respective actual torque and the respective setpoint torque is monitored for exceeding a permissible second dimension, and a signal to indicate a collision is generated as a function of the result of the monitoring. The advantage here is that monitoring is made possible in a simple manner.

In an advantageous embodiment, the first and / or second dimension depends on the radius of curvature of the trajectory assigned to the respective target position, so in particular it is not constant. The advantage here is that, depending on the increasing demands on the control system, larger control deviations are permitted, since these are not due to collisions in these trajectory curve sections, but rather due to the shape of the trajectory curve.

In an advantageous embodiment, the first and / or second dimension in a time segment after the start of the movement of the object is greater than at a point in time arranged after the time segment,
wherein the time segment contains the point in time of the start of the movement of the object. The advantage here is that a high acceleration of the object is required at the beginning of the movement and therefore larger control deviations are present, in particular necessary, and thus higher control deviations are to be permitted without a collision.

In an advantageous embodiment, the first and / or second dimension depends on the target position of the trajectory in such a way that
that the first and / or second dimension at a first target position of the trajectory is greater than at a second target position of the trajectory. The advantage here is that the different control deviations caused by the trajectory curve shape can be taken into account and thus collision-related excesses can be clearly separated from trajectory curve shape control deviations, for example, acceleration-related control deviations.

In an advantageous embodiment, the first and / or second dimension depends on the mass of the end effector assigned to a respective target position; in particular, it becomes smaller with a larger mass. The advantage here is that after a transport item has been picked up by the end effector, the dimension can be reduced, because the greater inertia makes control deviations more difficult for movement sections with high speed and low acceleration.

Important features of the system for carrying out the aforementioned method, the system has the machine and an object, in particular an end effector,
wherein the machine has the drives and a receiving unit, in particular a robot arm, for receiving, in particular for mounting, the object, in particular an end effector,
each of the drives each having an electric motor fed by an inverter and having a respective means for detecting the angular position of a rotor shaft of the respective electric motor and a motor current sensor,
each drive being connected to a control of the machine by means of a signal line.

The advantage here is that the monitoring for collisions can be influenced by the control by specifying the first and / or second measure of the control of the drives. Monitoring for exceeding the first and / or second dimension can be carried out by the converter itself or, alternatively, also by the controller. Carrying out the monitoring in the converter has the advantage that fast and direct monitoring is possible. The implementation of the monitoring in the control has the advantage that the speed of the object can be determined from the actual speeds of the individual drives, taking into account the kinematics of the machine, and accordingly also the setpoint torque acting on the object. The difference in amount between the setpoint torque and the actual torque can thus be monitored and / or in a simple manner the difference between the actual speed and the target speed.

In an advantageous embodiment, the machine is a robot, in particular an articulated arm robot. The advantage here is that the drives drive the individual links of the robot and the actual position and actual speed of the object picked up by the robot on the pickup unit can be determined from the individual actual positions and actual speeds.

Further advantages result from the subclaims. The invention is not restricted to the combination of features of the claims. For the person skilled in the art, there are further sensible possible combinations of claims and / or individual claim features and / or features of the description and / or the figures, in particular from the task and / or the task posed by comparison with the prior art.

• In der 1 ist ein erfindungsgemäßes Verfahren zum Betreiben einer Maschine schematisch dargestellt.

The invention will now be explained in more detail with reference to schematic figures:

• In the 1 a method according to the invention for operating a machine is shown schematically.

The machine has electric drives fed by respective inverters, including electric motors or gearboxes driven by electric motors.

The machine is preferably designed as a robot, in particular a robot arm or articulated arm robot, or as serial and / or parallel kinematics.

An object can be picked up by a pick-up device of the machine driven by the electric drives and can be moved on a trajectory by means of corresponding control of the drives. An end effector that is mounted on a robot arm as a receiving unit can also be understood as an object.

Before the movement of the object is carried out, the trajectory is determined as a target position profile in a controller connected to the drives, with a target speed profile also being specified; because the target position profile includes the specification of the position of the object to be reached at the respective point in time. The setpoint position curve and thus also the setpoint speed curve is preferably determined in such a way that it has little jerk, in particular that the jerk remains below a jerk threshold value. The jerk is determined, in particular, as the third derivative of the desired position curve with respect to time.

During the movement of the object along the trajectory that is then carried out, the actual position of each drive is recorded repeatedly, in particular quasi-continuously, so that the respective drive regulates the recorded actual position to the associated setpoint position. However, the actual speed of each drive, i.e. each machine axis, is also determined, in particular from the temporal course of the actual positions, and compared with the associated setpoint speed and warning information is displayed or a safe state is sought if a permissible degree of deviation is exceeded.

During the movement of the object along the trajectory that is then carried out, the actual position and the actual speed of the object are determined, taking into account the kinematics of the machine from the positions of the respective drives recorded at the respective point in time, in particular the respective drive axes, and the temporal progression of the positions the actual position and the actual speed of the object can be determined.

As in 1 is shown, when executing the movement of the object, in particular therefore with the guided movement of the object, then for each drive, in particular for each machine axis, of the machine with a respective comparison means 4th The difference between the actual speed and the target speed of the respective drive is always, in particular recurring, determined and, when a first permissible amount of deviation between the actual speed and the target speed is exceeded, an output signal is in a state corresponding to the detection of a collision.

The actual torque produced by the drives is also determined. Alternatively or additionally, the difference between the actual torque and the setpoint torque is always determined, in particular recurring over time, and an output signal corresponding to the detection of a collision is brought about when a second degree of deviation between this actual torque and the setpoint torque is exceeded.

As in 1 shown, the target torque is determined by taking into account the actual position of a means 5 to determine a position-dependent torque, in particular dependent on the kinematics of the machine, a first component of the setpoint torque and a means 6th To determine a friction torque, a second component of the target torque can be determined. A third portion of the target torque is achieved by a means 2 , in particular by forming the second time derivative of the position profile. The first, second and third proportions are averaged 3 summarized, in particular added, and in this way the setpoint torque is formed, which the comparison means 4th is fed.

In a first exemplary embodiment, only the speed with regard to exceeding the first dimension is monitored.

In a second exemplary embodiment, only the moment is monitored with regard to exceeding the second dimension.

In a third exemplary embodiment, both the speed and the torque are monitored, although the two dimensions are each smaller in terms of amount than the dimensions used in the first and second exemplary embodiments. Because by monitoring two variables, reliable collision detection can still be achieved.

In a further exemplary embodiment, the first and / or second dimension is not constant, but rather depends on the position. Because the greater the radius of curvature of the trajectory in the area of the position, the greater the first and / or second dimension. In this way, when the drive controller is used to a greater extent, the greater control deviation is taken into account during operation, in particular when the trajectory is traversed quickly. But even when starting, that is to say accelerating the object that was previously at rest, a larger value is specified for the first and / or second dimension for a period of time from the starting time than after this period of time has elapsed. This also takes into account the larger control deviations that initially occur with high acceleration values.

Depending on the output signal of the comparison means 4th , i.e. depending on the collision signal K , an STO signal is generated for the drives and / or a warning is forwarded and / or displayed. However, other collision reactions can also be used; For example, when a collision is detected within a position range, instead of an STO signal, it is possible to generate a signal which signals the detection of a transport item to be subsequently picked up by the end effector.

List of reference symbols

1

Means for determining the speed

2

Means for determining the acceleration

3

Means for determining the torque

4th

Comparison means

5

Means for determining a position-dependent moment, in particular as a function of the kinematics of the machine

6th

Means for determining a frictional torque

X_set

Target position

V_Soll

Target speed

a_Soll

Target acceleration

M_Soll

Target torque

X_is

Target position

V_lst

Target speed

K

Collision signal

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2017/097664 A1 [0002]
• DE 102013016019 B3 [0003]
• EP 1477284 B1 [0004]
• DE 102014019187 A1 [0005]
• EP 0188109 B1 [0006]
• DE 102008024950 A1 [0007]
• DE 102004026185 A1 [0008]
• DE 60313006 T2 [0009]
• DE 69410190 T2 [0010]
• DE 68919801 T2 [0011]
• GB 2106279 A [0012]
• DE 102008054312 A1 [0013]

Claims (13)

A method for operating a machine, in particular a robot, wherein an object, in particular an end effector, received, in particular mounted, on a receiving unit, in particular on a robot arm, can be moved by drives of the machine along a trajectory, in a first method step before the movement is carried out of the object along the trajectory, a setpoint position profile of the respective drive and a setpoint speed profile of the respective drive are determined, a respective setpoint speed profile being determined from the setpoint position profile of the respective drive, characterized in that in a second method step following the first method step, the object is moved in that the drives are operated in such a way that their respective chronologically recurring actual position is adjusted to the associated respective setpoint position of their respective setpoint position curve, with the respective n actual positions detected in the drive, a respective actual speed is determined, the deviation between the actual speed and the setpoint speed of the respective drive being monitored for exceeding a permissible first level and, depending on the result of the monitoring, a signal to indicate a collision is generated, in particular the first level being a Speed value is. Procedure according to Claim 1 , characterized in that in the first method step a temporal setpoint torque curve is determined by - taking into account the setpoint position curve, a position-dependent torque curve is determined, - taking into account the setpoint speed curve, a friction torque curve and - taking into account the setpoint acceleration curve or setpoint speed curve, a further torque curve is determined, and by the Setpoint torque curve, in particular by summation, is determined from the position-dependent torque curve and from the friction torque curve and from the further torque curve. Method according to one of the preceding claims, characterized in that the deviation between the respective actual torque and the respective target torque is monitored for exceeding a permissible second dimension and, depending on the result of the monitoring, a signal to indicate a collision is generated, in particular the second dimension being a Torque value is. Method for operating a machine, in particular a robot, wherein an object, in particular an end effector, received, in particular mounted, on a receiving unit, in particular on a robot arm, can be moved by drives of the machine along a path curve, wherein, in a first method step, before executing the movement of the object along the trajectory, a target position profile of the respective drive and a target speed profile of the respective drive are determined, whereby a respective set speed curve is determined from the set position curve of the respective drive, wherein in a second process step that follows the first process step in time, the object is moved by operating the drives in such a way that their respective actual position, which is recorded recurring over time, is adjusted to the associated respective setpoint position of their respective setpoint position curve, whereby a respective actual speed is determined from the actual positions recorded on the respective drive, wherein in the first method step a temporal setpoint torque curve is determined by - A position-dependent torque curve is determined taking into account the target position curve, - taking into account the target speed profile, a friction torque profile and - A further torque curve is determined taking into account the target acceleration curve or the target speed curve, and in that the target torque curve is determined, in particular by summation, from the position-dependent torque curve and from the friction torque curve and from the further torque curve, the deviation between the respective actual torque and the respective target torque being monitored for exceeding a permissible second level and depending on the result of the monitoring a signal for indicating a collision is generated, in particular wherein the second dimension is a torque value. Procedure according to Claim 4 , characterized in that the deviation between the actual speed and the target speed of the respective drive is monitored for exceeding a permissible first dimension and, depending on the result of the monitoring, a signal to indicate a collision is generated, in particular wherein the first dimension is a speed value. Method according to one of the preceding claims, characterized in that the first and / or second dimension depends on the radius of curvature of the trajectory assigned to the respective target position, in particular is therefore not constant. Method according to one of the preceding claims, characterized in that the first and / or second dimension increases with the radius of curvature increasing along the path curve and / or that the first and / or second dimension decreases with the radius of curvature decreasing along the path curve. Method according to one of the preceding claims, characterized in that the first and / or second dimension in a time segment after the start of the movement of the respective drive is greater than at a point in time arranged after the time segment, the time segment being the time at which the movement was started of the respective drive, in particular wherein the maximum acceleration of the respective drive in the time segment is at least ten times the amount of the acceleration of the respective drive present at the point in time. Method according to one of the preceding claims, characterized in that the first and / or second dimension depends on the mass of the end effector assigned to a respective target position, in particular including transported goods that have been taken up or not, and in particular become smaller with larger masses. Method according to one of the preceding claims, characterized in that the first and / or second dimension decreases with an increase in the mass of the end effector, in particular when a transport item is picked up. Method according to one of the preceding claims, characterized in that the first and / or second dimension depends on the target position of the trajectory in such a way that the first and / or second dimension is greater at a first target position of the trajectory than at a second target position of the trajectory. System for carrying out a method according to one of the preceding claims, characterized in that the system has the machine and an object, the machine the drives and a receiving unit, in particular a robot arm, for receiving, in particular for assembling, the object, in particular end effector, each of the drives each having an electric motor fed by an inverter and having a respective means for detecting the angular position of a rotor shaft of the respective electric motor, each drive being connected to a control of the machine by means of a signal line. System according to one of the preceding claims, characterized in that the machine is a robot, in particular an articulated arm robot, or serial and / or parallel kinematics.

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