DE102017009816A1 - Determining a drive reference position of a pliers drive - Google Patents

Abstract

An inventive method for determining a drive reference position (x ₀ ) of a drive (11) of a pair of pliers (10) comprises the steps:
- Applying the closed pliers by means of the drive with a first driving force;
- detecting a thereby achieved first drive position of the drive;
- applying the closed pliers by means of the drive with a larger second driving force;
- detecting a thereby achieved second drive position of the drive; and
- Determining the drive reference position for closing the pliers based on the first and second driving force and the detected first and second drive position.

Description

The present invention relates to a method and system for determining a drive reference position of a drive of a pair of pliers or a thickness of a component, in particular a force sensor, using the pliers and a computer program product for carrying out the method.

From the DE 10 2011 003 539 A1 is a method for referencing a drive position of an electric drive at least one pliers half of a production tool in a closed position of two pliers halves known, in which the actual position of the drive is determined as the closed position corresponding to a time zero crossing a straight line of a time lag error function.

Object of the present invention is to improve a determination of a drive reference position of a drive of a pair of pliers for closing the pliers or a thickness of a component using the pliers.

This object is achieved by a method having the features of claims 1 and 9, respectively. Claims 12, 13 protect a system or computer program product for carrying out a method described herein. The subclaims relate to advantageous developments.

• - Beaufschlagen der geschlossenen Zange mithilfe des Antriebs mit einer ersten Antriebskraft;
• - Erfassen einer dabei erreichten ersten Antriebsstellung des Antriebs;
• - Beaufschlagen der geschlossenen Zange mithilfe des Antriebs mit einer größeren zweiten Antriebskraft;
• - Erfassen einer dabei erreichten zweiten Antriebsstellung des Antriebs; und
• - Ermitteln der Antriebsreferenzstellung für das Schließen der Zange auf Basis der ersten und zweiten Antriebskraft und der erfassten ersten und zweiten Antriebsstellung.

According to one embodiment of the present invention, a method for determining a drive reference position of a drive of a pair of pliers comprises the steps, in particular successive steps:

• - Applying the closed pliers by means of the drive with a first driving force;
• - detecting a thereby achieved first drive position of the drive;
• - applying the closed pliers by means of the drive with a larger second driving force;
• - detecting a thereby achieved second drive position of the drive; and
• - Determining the drive reference position for closing the pliers based on the first and second driving force and the detected first and second drive position.

This is based in particular on the idea that the pliers form an elastic system with their drive, which deforms more when increasing the force applied to the closed pliers driving force, and this deformation is equal to zero with the pliers still open, so that the zero point of a driving force drive position Function characterized by closing the pliers. Accordingly, in one embodiment, the drive reference position for closing the pliers indicates the position in which the pliers are closing.

As a result, in one embodiment, the drive reference position for closing the pliers can be determined reliably (er), precisely (er) and / or with low (re) m, in particular sensory, effort, in particular in comparison to one of the aforementioned DE 10 2011 003 539 A1 known trailing error-based determination.

The forceps is in one embodiment a manufacturing, in particular welding, clinching or crimping pliers, in particular a pair of pliers, in particular X-forceps, with two movably mounted arms or pliers, in particular C-forceps, with a fixed and a movable arm. Equally, the pliers may also be a handling pliers, in particular a gripper for frictional and / or positive lifting and / or holding loads.

In one embodiment, the pliers are arranged on a robot, in particular non-destructively releasably coupled thereto, wherein the method is then performed in an embodiment at least partially by a controller of the robot. In one embodiment, the robot has at least six, in particular at least seven, actuated (moving) axes, in particular rotary joints.

This represents particularly advantageous applications of the present invention, since in such applications adjustment of the drive is particularly important and / or frequently performed. In one embodiment, the present invention is (also) used at or during an initial or initial adjustment of the forceps or the robot, since advantageously no prior knowledge is required.

In one embodiment, the drive is an electric, in particular electromotive, drive. Hereby, the present invention can be realized particularly advantageous, since in particular driving forces and / or positions reliably (he), precise (he) and / or with low (re) m, especially sensory, effort can be specified or determined. However, the drive may equally be a hydraulic or pneumatic drive.

In one embodiment, a drive force may depend on or be indicative of a drive torque, in particular an engine torque of an especially electric gun motor, in particular such a drive torque. As a result, in one embodiment advantageously a torque control, in particular regulation or limitation can be used. Accordingly, in one embodiment, a drive limit can be a (drive) Force, in particular (drive) torque limitation, include, in particular, be in a development in an electric drive include a voltage and / or current limiting, in particular, may be.

An elastic behavior of the system pliers + drive can be approximated in a linear approximation. Then advantageously already two pairs of values enough to determine the driving force drive position function and hereby the drive reference position for the closing, which can advantageously shorten the process duration.

• - Beaufschlagen der geschlossenen Zange mithilfe des Antriebs mit einer weiteren Antriebskraft oder mehreren weiteren, unterschiedlich(groß)en Antriebskräften, die (jeweils) größer als die zweite Antriebskraft ist bzw. sind; und
• - (jeweils) Erfassen einer dabei erreichten weiteren Antriebsstellung des Antriebs; wobei die Antriebsreferenzstellung auf Basis der ersten, zweiten und einer oder mehreren weiteren Antriebskraft bzw. -kräfte und der erfassten ersten, zweiten und einer oder mehreren weiteren Antriebsstellung(en) ermittelt wird.

On the other hand, the elasticity behavior can be determined more precisely by more than two pairs of values of the drive force-drive position function, in particular a linear approximation of the elastic behavior using a, in particular linear, compensation calculation with more than two value pairs. Accordingly, in one embodiment, the method comprises the steps of:

• - Applying the closed pliers by means of the drive with a further driving force or a plurality of other, different (large) en driving forces, which is or are greater than the second driving force; and
• - (each) detecting a thereby reached further drive position of the drive; wherein the drive reference position is determined on the basis of the first, second and one or more further drive forces or forces and the detected first, second and one or more further drive position (s).

In one embodiment, the forceps is first opened to apply the first drive force, to apply the second drive force, and / or to apply the at least one further drive force (respectively) using the drive, then closed, and then the closed forceps the driving force applied.

Thereby, in one embodiment, the influence of stick-slip effects and the like can be at least partially reduced and thus the precision (further) improved.

• - Ermitteln einer, insbesondere vorläufigen, Schließposition durch Schließen der Zange; und
• - Bestimmen einer dabei, insbesondere in dieser Schließposition, wirkenden Betätigungskraft des Antriebs; wobei die erste, zweite und/oder wenigstens eine weitere Antriebskraft auf Basis dieser Betätigungskraft vorgegeben wird.

In one embodiment, the method comprises the steps preceding the application of the closed pliers with the first, second and / or at least one further drive force:

• - Determining a, in particular provisional, closing position by closing the pliers; and
• - Determining a case, in particular in this closed position, acting actuating force of the drive; wherein the first, second and / or at least one further driving force is predetermined on the basis of this actuating force.

In one embodiment, the first driving force is at least 1.1 times, in particular at least 1.2 times, and / or at most three times, in particular at most twice, the actuating force. Additionally or alternatively, in one embodiment, the second driving force is predetermined on the basis of the first driving force and thus indirectly on the basis of the actuating force. Additionally or alternatively, in one embodiment, the second drive force is at least 1.1 times, in particular at least 1.2 times, and / or at most three times, in particular at most twice, the first drive force.

As a result, in one embodiment, the risk of excessive loading by applying the closed pliers to the first, second or at least one further driving force can be reduced.

In one embodiment, the first drive force, the second drive force and / or the at least one further drive force (in each case) are predetermined by means of a drive limit. Additionally or alternatively, in one embodiment, the actuation force is determined by means of a drive limit.

Additionally or alternatively, in one embodiment, the drive for closing the pliers and / or for applying the pliers on the basis of a predetermined Sollzustellung, in particular approached target position, operated, which is selected in a development so or is that they are greater than one, in particular assumed, clear width of the forceps is or so that a closing of the forceps before reaching the desired position or position is expected.

In this way, in one embodiment in each case, but in particular in combination, applying the closed pliers, closing the pliers or determining the actuating force is easy (he), reliable (he), precise (he) and / or with low (re) m, in particular sensory, effort can be realized.

mit der Antriebsreferenzstellung x₀, der ersten Antriebskraft T₁, der zweiten Antriebskraft T₂, der ersten Antriebsstellung x₁ und der zweiten Antriebsstellung x₂.In one embodiment, the drive reference position is determined by means of a linear extrapolation with the first and second drive force and drive position, in particular according to the equation: $${\text{x}}_0={\text{x}}_1-\left[\left({\text{x}}_2-{\text{x}}_1\right)/\left({\text{T}}_2-{\text{T}}_1\right)\cdot {\text{T}}_1\right]$$

with the drive reference position x ₀ , the first drive force T ₁ , the second drive force T ₂ , the first drive position x ₁ and the second drive position x ₂ .

mit der bzw. den weiteren Antriebskräften bzw. -stellungen T_j, x_j, j = 3, ....In one embodiment, the drive reference position is determined by means of a, in particular linear, compensation calculation with the first, second and at least one further drive force and drive position, in particular according to the equation $$\begin{array}{c}{\displaystyle \underset{i}{\Sigma }\left[x_i-\left(m\cdot T_i+x_0\right)\right]\cdot T_i=0}\\ {\displaystyle \underset{i}{\Sigma }\left[x_i-\left(m\cdot T_i+x_0\right)\right]=0}\end{array}\}\Rightarrow x_0$$

with the other driving forces or positions T _j , x _j , j = 3, ....

By the present invention, in particular a drive reference position for the obstacle-free closing of the empty pliers can be determined and used for adjustment or control, in particular control, of the drive. Accordingly, in one embodiment, the drive, which is especially adjusted in this manner, is controlled, in particular regulated, on the basis of the determined drive reference position for closing the clamp.

In one embodiment, a thickness of a component can also be determined using the pliers. As a result, it is particularly advantageous to determine a thickness of a force sensor with which a force-drive position function can be calibrated, wherein the thickness of the force sensor used for calibration must be taken into account as an offset of the drive position, since in addition the drive is not used in later operation without the force sensor must be delivered by the thickness.

• - Ermitteln einer ersten Antriebsreferenzstellung für das Schließen der leeren Zange mittels eines hier beschriebenen Verfahrens bzw. Systems;
• - Ermitteln einer zweiten Antriebsreferenzstellung für das Fassen des Bauteils mit der Zange mittels eines, insbesondere desgleichen, hier beschriebenen Verfahrens bzw. Systems; und
• - Ermitteln der Dicke des Bauteils auf Basis einer, insbesondere als, Differenz der ersten und zweiten Antriebsreferenzstellung.

Accordingly, according to an embodiment of the present invention, a method for determining a thickness of a component by means of the forceps, in particular for determining a thickness of a force sensor, in particular for calibrating the drive by means of the force sensor, the, in particular successive, steps:

• - Determining a first drive reference position for closing the empty pliers by means of a method or system described herein;
• - Determining a second drive reference position for grasping the component with the pliers by means of a, in particular the same, described here method or system; and
• Determining the thickness of the component on the basis of, in particular as, difference of the first and second drive reference position.

• Mittel zum Beaufschlagen der geschlossenen Zange mithilfe des Antriebs mit einer ersten Antriebskraft;
• Mittel zum Erfassen einer dabei erreichten ersten Antriebsstellung des Antriebs;
• Mittel zum Beaufschlagen der geschlossenen Zange mithilfe des Antriebs mit einer größeren zweiten Antriebskraft;
• Mittel zum Erfassen einer dabei erreichten zweiten Antriebsstellung des Antriebs; und Mittel zum Ermitteln der Antriebsreferenzstellung für das Schließen der Zange auf Basis der ersten und zweiten Antriebskraft und der erfassten ersten und zweiten Antriebsstellung.

According to one embodiment of the present invention, a system, in particular hardware and / or software, in particular program technology, is set up to carry out a method described here and / or has:

• Means for applying the closed pliers by means of the drive with a first driving force;
• Means for detecting a first drive position of the drive achieved thereby;
• Means for applying the closed pliers by means of the drive with a larger second driving force;
• Means for detecting a second drive position of the drive achieved thereby; and means for determining the drive reference position for closing the pliers based on the first and second drive forces and the detected first and second drive positions.

• Mittel zum Beaufschlagen der geschlossenen Zange mithilfe des Antriebs mit wenigstens einer weiteren Antriebskraft, die größer als die zweite Antriebskraft ist;
• Mittel zum Erfassen einer dabei erreichten weiteren Antriebsstellung des Antriebs; und
• Mittel zum Ermitteln der Antriebsreferenzstellung auf Basis der ersten, zweiten und wenigstens einen weiteren Antriebskraft und der erfassten ersten, zweiten und wenigstens einen weiteren Antriebsstellung.

In one embodiment, the system or its agent has:

• Means for applying the closed pliers by means of the drive with at least one further driving force which is greater than the second driving force;
• Means for detecting a further drive position of the drive achieved thereby; and
• Means for determining the drive reference position based on the first, second and at least one further driving force and the detected first, second and at least one further drive position.

Additionally or alternatively, in one embodiment, the system or its means comprises: means for closing the opened forceps to apply the first, second, and / or at least one further driving force by means of the drive;
Means for determining a closing position by closing the pliers, determining an actuating force of the drive acting thereon, and specifying the first, second and / or at least one further driving force on the basis of this actuating force;
Means for setting the first, second and / or at least one further driving force and / or determining the actuating force by means of a drive limit;
Means for actuating the drive to close and / or energize the pliers based on a predetermined desired delivery; and or
Means for determining the drive reference position by means of a linear extrapolation with the first and second drive force and drive position or a compensation calculation with the first, second and at least one further drive force and drive position.

• Mittel zum Ermitteln einer ersten Antriebsreferenzstellung für das Schließen der leeren Zange mittels eines hier beschriebenen Verfahrens bzw. Systems;
• Mittel zum Ermitteln einer zweiten Antriebsreferenzstellung für das Fassen des Bauteils mit der Zange mittels eines hier beschriebenen Verfahrens bzw. Systems; und
• Mittel zum Ermitteln der Dicke des Bauteils auf Basis einer Differenz der ersten und zweiten Antriebsreferenzstellung.

According to one embodiment of the present invention, the system or its agent comprises:

• Means for determining a first drive reference position for closing the empty clamp by a method or system described herein;
• Means for determining a second drive reference position for grasping the component with the pliers by means of a method or system described herein; and
• Means for determining the thickness of the component based on a difference of the first and second drive reference positions.

A means in the sense of the present invention may be designed in terms of hardware and / or software, in particular a data or signal-connected, preferably digital, processing, in particular microprocessor unit (CPU) and / or a memory and / or bus system or multiple programs or program modules. The CPU may be configured to execute instructions implemented as a program stored in a memory system, to capture input signals from a data bus, and / or to output signals to a data bus. A storage system may comprise one or more, in particular different, storage media, in particular optical, magnetic, solid state and / or other non-volatile media. The program may be such that it is capable of embodying or executing the methods described herein, so that the CPU may perform the steps of such methods and, in particular, control, particularly control, the drive and / or robot. In one embodiment, a computer program product may include, in particular, a non-volatile storage medium for storing a program or a program stored thereon, wherein execution of this program causes a system or a controller, in particular a computer, to do so method described herein or one or more of its steps.

In one embodiment, one or more, in particular all, steps of the method are completely or partially automated, in particular by the system or its (e) means.

In one embodiment, the system includes the forceps and / or the robot.

• 1: ein System nach einer Ausführung der vorliegenden Erfindung; und
• 2: ein Verfahren nach einer Ausführung der vorliegenden Erfindung.

Further advantages and features emerge from the subclaims and the exemplary embodiments. This shows, partially schematized:

• 1 a system according to an embodiment of the present invention; and
• 2 A method according to an embodiment of the present invention.

1 shows a system according to an embodiment of the present invention with a robot 20 , on the flange of a pair of pliers 10 attached, which is a drive 11 having a pliers arm 12 in different drive positions x emotional.

tong drive 11 and robots 20 be through a robot controller 30 controlled or -regelt, in a modification both can be controlled or -regelt also by separate controls.

2 shows a method according to an embodiment of the present invention.

In a first step S10 is at empty, open pliers, for example, a drive position x = 0 (see. 1 ), a counter i is zeroed and a maximum (allowable) drive torque T _max for the drive 11 set to an initial, very small value T _{max, 0} .

Subsequently, in one step S20 a setpoint delivery Δx _soll , for example Δx _soll = 10 mm, commanded and in one step S30 checked whether the pliers moves.

Due to the initially limited to the very small value T _{max, 0} drive torque is initially not the case ( S30 : "N").

Therefore, in one step S35 increases the maximum (permissible) drive torque T _max in small steps ΔT until the clamp starts to move due to the commanded setpoint delivery Δx _soll ( S30 : "Y").

Now the pliers continue to drive torque limited to a small value, which just overcomes the static friction, and so long, either in one step S40 it is detected that the commanded desired _{delivery .DELTA.x.sub.soll has} already been reached at a predetermined percentage _.alpha. (S40: "Y"), for example at least 95%, or in one step S50 it is recorded that the Torque limit is reached and the pliers has stopped accordingly ( S50 : "Y").

If it is detected that the commanded setpoint delivery Δx _{soll has} already been reached at a predetermined percentage α ( S40 : "Y") without first being stopped due to the torque limit, the gun was originally opened too wide.

Accordingly, then the pliers in one step S45 by a certain amount β, for example, 5mm, ascended, and the procedure, starting with step S10 , carried out again.

If it detects that the torque limit has been reached and the clamp has stopped ( S50 : "Y"), without having reached the setpoint delivery to the predetermined percentage α, the clamp is closed, wherein an actuation torque in the amount of the maximum (permissible) drive torque T _max acts. In a modification, this can also be detected by checking whether the forceps or the drive is still moving ( S50 : "Dx / dt = 0?").

The actuating torque in the amount of the currently maximum (permissible) driving torque T _max is combined with the detected provisional closed position x _{0 of} the drive in one step S60 saved.

Since a predetermined minimum number of repetitions of n ≥ 2 in this first pass (i = 0) has not yet been reached, in one step S60 the tongs are opened again by a small predetermined amount γ, the counter i is incremented by 1 and the maximum permissible drive torque compared to the actuation torque or current maximum permissible drive torque is increased by a factor δ, for example by 50% (δ = 1 , 5).

Now the process returns to step S20 back, in which again the target delivery Δx _{soll is} commanded.

Due to the increased maximum (permissible) en drive torque while the static friction is overcome (S30: "Y") and due to the opening of the pliers by the small predetermined amount γ compared to the already reached closed position the commanded target delivery .DELTA.x _should not reach the predetermined percentage α ( S40 : "N") before the clamp closes again. In a modification, the tests of the steps S30 . S40 in the subsequent to the above-described initial determination of the provisional closed position with i = 0 following passes also omitted.

Due to the increased maximum (permissible) en drive torque but the drive still continues to apply and represses the re-closed pliers under low elastic deformation with a first drive torque T ₁ amounting to the current (predetermined) maximum (permissible) drive torque T _max .

This is done together with the detected first drive position x _{1 of} the drive in step S60 saved. In the above-described rough determination of the closed position and the actuating torque acting therewith (i = 0) as a starting point for this application to the first drive torque T ₁ (i = 1), this storage can be dispensed with.

Then the procedure, starting with step S75 the tongs are again opened by γ, the counter i is incremented to 2, and the maximum (permissible) drive torque is increased by a factor δ compared to the first drive torque T ₁ or current maximum drive torque.

In this case, the drive continues to increase due to the again increased maximum (permissible) drive torque and energizes the re-closed pliers under elastic deformation now with a second drive torque T ₂ in the amount of the now currently (predetermined) maximum (permissible) drive torque T _max ,

This is done together with the detected first drive position x _{2 of} the drive in step S60 saved.

If the number of predetermined passes n for detecting drive positions when subjected to drive torques is reached, for example, the above-described passes i = 1, 2, in one step S80 the drive reference position x ₀ for closing the pliers on the basis of these drive positions and torques x ₁ , T ₁ , x ₂ , T ₂ , ... determined, for example in the above-described 2 runs by linear extrapolation according to the above equation (1).

Likewise, further runs i = 3,... Can be carried out in the manner described above, and then the drive reference position x ₀ can be determined by means of a compensation calculation, for example according to the above equation (2).

To determine a thickness of a component, in particular a force sensor for calibrating the drive, is, as in 1 indicated by dashed lines, according to the above-described determination of the (first) drive reference position x ₀ for closing the (empty) pliers again the method described above performed, however, the pliers when closing the component or the force sensor 40 summarizes and analogously a second drive reference position x ' ₀ and the thickness as the difference x ₀ - x' _{0 is} determined.

Although exemplary embodiments have been explained in the foregoing description, it should be understood that a variety of modifications are possible. It should also be noted that the exemplary embodiments are merely examples that are not intended to limit the scope, applications and construction in any way. Rather, the expert is given by the preceding description, a guide for the implementation of at least one exemplary embodiment, with various changes, in particular with regard to the function and arrangement of the components described, can be made without departing from the scope, as it turns out according to the claims and these equivalent combinations of features.

LIST OF REFERENCE NUMBERS

10

tongs

11

drive

12

tong

20

robot

30

robot control

40

Force sensor (component)

x

drive position

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102011003539 A1 [0002, 0007]

Claims (13)

A method for determining a drive reference position (x ₀ ) of a drive (11) of a pair of pliers (10), comprising the steps of: - applying to the drive with a first drive force the closed pliers; - detecting a thereby achieved first drive position of the drive; - applying the closed pliers by means of the drive with a larger second driving force; - detecting a thereby achieved second drive position of the drive; and determining the drive reference position for closing the pliers based on the first and second drive forces and the detected first and second drive positions. Method according to Claim 1 Characterized by the steps of: - exposing the closed pliers using the drive with at least one further driving force, which is greater than the second drive force; and - detecting a thereby achieved further drive position of the drive; wherein the drive reference position is determined on the basis of the first, second and at least one further drive force and the detected first, second and at least one further drive position. Method according to one of the preceding claims, characterized in that the opened pliers for applying the first, second and / or at least one further driving force is closed by means of the drive. Method according to one of the preceding claims, characterized by the preceding steps: - determining a closing position by closing the pliers; and determining an actuation force of the drive acting thereon; wherein the first, second and / or at least one further driving force is predetermined on the basis of this actuating force. Method according to one of the preceding claims, characterized in that the first, second and / or at least one further driving force predetermined by means of a drive limit and / or the actuating force is determined by means of a drive limit. Method according to one of the preceding claims, characterized in that the drive for closing and / or acting on the pliers is actuated on the basis of a predetermined desired delivery. Method according to one of the preceding claims, characterized in that the drive reference position is determined by means of a linear extrapolation with the first and second drive force and drive position or a compensation calculation with the first, second and at least one further drive force and drive position. Method according to one of the preceding claims, characterized in that the drive is controlled on the basis of the determined drive reference position. Method for determining a thickness of a component, in particular a force sensor (40), by means of pliers, comprising the steps: - Determining a first drive reference position for closing the empty pliers according to one of the preceding claims; - Determining a second drive reference position for grasping the component with the pliers according to one of the preceding claims; and - Determining the thickness of the component based on a difference of the first and second drive reference position. Method according to the preceding claim, characterized in that the drive is calibrated on the basis of the determined thickness of the force sensor. Method according to one of the preceding claims, characterized in that the forceps on a robot (20) is arranged. System (10 - 30) for determining a drive reference position (x ₀ ) of a drive (11) of a pliers (10) and / or a thickness of a component (40), in particular force sensor, using a pair of pliers for performing a method according to any one of the preceding claims is arranged and / or comprising: - means for applying the closed pliers by means of the drive with a first driving force; - means for detecting a thereby achieved first drive position of the drive; - means for applying the closed pliers by means of the drive with a larger second driving force; - means for detecting a thereby achieved second drive position of the drive; and means for determining the drive reference position for closing the pliers based on the first and second drive forces and the detected first and second drive positions A computer program product having a program code stored on a computer-readable medium for performing a method according to any one of the preceding claims.

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