DE102016101748B4 - Holding device based on counter-EMF monitoring and method for controlling the same - Google Patents

Abstract

Holding device based on counter-EMF monitoring, comprising: - a holding device (10); - a stepping motor (20) which is connected to the holding device (10) and drives it so that it is accordingly tensioned or relaxed; - a Control device (30) which is electrically connected to the stepper motor (20), the control device (30) having a drive unit (31), a control unit (32), a receiving unit (33) and an access unit (34) which are electrically connected to one another are connected, wherein - the drive unit (31) is electrically connected to the stepper motor (20), so that it drives the stepper motor (20) and feeds back actual EMF values of the stepper motor (20); - the control unit (32) electrically with the Drive unit (31) is connected; - The receiving unit (33) is electrically connected to the control unit (32) and ensures appropriate control commands relating to a clamping state, a clamping speed and a clamping force of the holding device to receive (10); and wherein- the access unit (34) and the control unit (32) are electrically connected, a control parameter matrix being stored in the access unit (34), a counter-emf threshold being assigned to each position in the control parameter matrix, so that the control unit (32 ) can control the operation of the stepper motor (20) according to the control commands detected by the receiving unit (33), the control device (30) after the control command the corresponding counter-EMF threshold values of the control parameter matrix with the counter-EMF actual values recorded in real time compares and controls the stepper motor (20) based on a comparison result obtained.

Description

The invention provides a holding device based on counter-EMF monitoring and its control method, which u. a. be used in the technical field of industrial manipulators.

The electro-operated manipulators (also called robotic arms) are widely used in automated production in all areas, whereby the electro-robotic arms play an increasingly important role thanks to their excellent properties such as smaller size, lighter weight, human shape and greater flexibility. In order to ensure safe operation of an electrically operated robot arm, the electrically operated robot arm must be monitored or controlled in real time when it grips or handles a workpiece with its holding device.

There are currently numerous control methods for monitoring or controlling the electro-operated robot arm. A known control method of this is that the clamping force of a robot arm driven by a stepper motor is controlled by a speed changeover of the stepper motor, whereby one of the important properties of the stepper motor, namely the stepper motor, outputs a torque that is inversely proportional to its speed, the basis of this control method forms. However, the control method has an undesirable disadvantage, namely the stepper motor can with a rapid speed change such. For example: a rapid acceleration due to its reduced torque cannot withstand an external load, because the torque output by the stepper motor is inversely proportional to the speed of the stepper motor, which leads to a small slip and therefore to a step loss of the stepper motor. The control method can thus be further improved because the step loss of the stepping motor interferes with the safe operation of the holding device.

Another known control method is to attach an additional sensor, which is used to detect the step loss and ensures that the stepper motor is switched off when a step loss is detected, the desired clamping force being held up by an additional holding mechanism. This control method cannot avoid the step loss of the step motor and is therefore only a countermeasure to withstand the clamping force in the event of a step loss of the step motor, whereby the clamping force cannot be kept stable at all. In addition, the control process requires a separate holding mechanism to withstand the clamping force, so that the robot arm as a whole has an even more complicated structure and therefore requires even higher production costs. Therefore, the control process can also be further improved in order to save the manufacturing costs.

From the publication of the international patent application WO 2015/048 156 A1, a device for monitoring the fill level of a container and a method for monitoring the operating state of an engine are known. Here, by comparing the duration of a back emf with a predetermined threshold value, it is determined whether the rotation of a paddle wheel counteracts a certain resistance due to the presence of a medium and whether the rotation is blocked.

The invention is based on the object of providing a holding device based on the counter-EMF monitoring and its control method in order to remedy the disadvantages that the conventional robotic arms still have an unstable clamping force and a complicated structure in the control methods mentioned.

• - eine Haltevorrichtung;
• - einen Schrittmotor, der mit der Haltevorrichtung 10 verbunden ist und diese so antreibt, dass sie sich dementsprechend spannen bzw. entspannen lässt;
• - ein Steuergerät, das elektrisch mit dem Schrittmotor verbunden ist, wobei das Steuergerät eine Antriebseinheit, eine Steuereinheit, eine Empfangseinheit und eine Zugriffseinheit aufweist, die elektrisch miteinander verbunden sind.

According to the invention, there is provided a holding device based on back EMF monitoring, comprising:

• - a holding device;
• - A stepper motor with the holding device 10th is connected and drives it in such a way that it can be tensioned or relaxed accordingly;
• - A control device which is electrically connected to the stepper motor, the control device having a drive unit, a control unit, a receiving unit and an access unit, which are electrically connected to one another.

The drive unit is electrically connected to the stepper motor, so that it drives the stepper motor and feeds back actual EMF values of the stepper motor. The control unit is electrically connected to the drive unit. The receiving unit is electrically connected to the control unit and ensures that corresponding control commands relating to a clamping state, a clamping speed and a clamping force of the holding device are received. The access unit and the control unit are electrically connected, a control parameter matrix being stored in the access unit, each position in the control parameter matrix being assigned a counter-EMF threshold value, so that the control unit can control the operation of the stepper motor according to the control commands detected by the receiving unit. the control device after the control command the corresponding counter-EMF threshold values of the control parameter matrix with the compares actual EMF values recorded in real time and controls the stepper motor based on the comparison result obtained.

• Antreiben eines Schrittmotors, wobei ein Steuergerät nach einem Steuerbefehl durch eine Antriebseinheit den Schrittmotor antreibt und wobei der Schrittmotor während seines Betriebes entsprechende Gegen-EMK-Istwerte erzeugt;
• Vergleichen einer Steuerparametermatrix, wobei das Steuergerät Parameter im Steuerbefehl mit Gegen-EMK-Schwellenwerten vergleicht, von denen jeder einer Position in der in einer Zugriffseinheit eingespeicherten Steuerparametermatrix zugeordnet ist;
• Ermitteln der entsprechenden Gegen-EMK-Schwellenwerte, wobei durch das Steuergerät ermittelt wird, welcher Position in der Steuerparametermatrix die Gegen-EMK-Istwerte entsprechen, um die entsprechenden Gegen-EMK-Schwellenwerte zu ermitteln;
• Überwachen der Gegen-EMK-Istwerte, wobei das Steuergerät ständig die Gegen-EMK-Istwerte überwacht; und
• Vergleichen und Ansteuern, wobei das Steuergerät die durch die Überwachung erfassten Gegen-EMK-Istwerte mit den ermittelten Gegen-EMK-Schwellenwerten vergleicht, und wobei, wenn die erfassten Gegen-EMK-Istwerte kleiner als die Gegen-EMK-Schwellenwerte sind, das Antreiben des Schrittmotors fortgesetzt wird, und wobei, wenn die erfassten Gegen-EMK-Istwerte die ermittelten Gegen-EMK-Schwellenwerte erreichen, das Antreiben des Schrittmotors gestoppt wird, um einen Spannzustand der Haltevorrichtung zu behalten.

According to the invention, a method for controlling the holding device based on the back-EMF monitoring is provided, which has the following steps:

• Driving a stepper motor, wherein a control unit drives the stepper motor after a control command by a drive unit, and wherein the stepper motor generates corresponding counter-emf actual values during its operation;
• Comparing a control parameter matrix, the control device comparing parameters in the control command with counter-EMF threshold values, each of which is assigned to a position in the control parameter matrix stored in an access unit;
• Determining the corresponding counter-emf threshold values, the control device determining which position in the control parameter matrix the actual counter-emf values correspond to in order to determine the corresponding counter-emf threshold values;
• Monitoring the actual counter-emf values, the control unit continuously monitoring the actual counter-emf values; and
• Comparing and actuating, wherein the control device compares the counter-emf actual values detected by the monitoring with the determined counter-emf threshold values, and, if the acquired counter-emf actual values are smaller than the counter-emf threshold values, the driving of the stepping motor is continued, and when the detected actual back emf values reach the determined back emf threshold values, the driving of the stepping motor is stopped in order to maintain a tensioned state of the holding device.

According to the invention, a control parameter matrix consisting of a plurality of control parameters, which are previously recorded in normal operation, and a plurality of actual counter-emf values are monitored in real time, so that the holding device is protected against abnormal operation, which means that it can be gripped or secured Handling of the robot arms is ensured in normal operation, as a result of which a stable clamping force is achieved.

• 1 ein Systemblockdiagramm einer erfindungsgemäßen Haltevorrichtung,
• 2 ein Flussdiagramm eines erfindungsgemäßen Verfahrens zur Steuerung der auf die Gegen-EMK-Überwachung basierenden Haltevorrichtung und
• 3 eine schematische Darstellung einer erfindungsgemäßen Steuerparametermatrix.

The invention and its configurations are explained in more detail below with reference to the drawing. The drawings show in:

• 1 2 shows a system block diagram of a holding device according to the invention,
• 2nd a flowchart of a method according to the invention for controlling the holding device based on the counter-EMF monitoring and
• 3rd is a schematic representation of a control parameter matrix according to the invention.

In 1 to 3rd A holding device according to the invention is shown, which is controlled on the basis of the back emf monitoring, the present invention being a holding device 10th , a stepper motor 20 and a control unit 30th includes.

The stepper motor 20 is with the holding device 10th connected and drives it in such a way that it is tensioned or relaxed accordingly.

• - die Antriebseinheit 31 elektrisch mit dem Schrittmotor 20 verbunden ist, sodass sie den Schrittmotor 20 antreibt und die erfassten Gegen-EMK-Istwerte des Schrittmotors 20 zurückspeisen kann;
• - die Steuereinheit 32 elektrisch mit der Antriebseinheit 31 verbunden ist;
• - die Empfangseinheit 33 elektrisch mit der Steuereinheit 32 verbunden ist und dafür sorgt, entsprechende Steuerbefehle bezüglich eines Spannzustandes, einer Spanngeschwindigkeit und einer Spannkraft der Haltevorrichtung 10 zu empfangen;
• - die Zugriffseinheit 34 elektrisch mit der Steuereinheit 32 verbunden ist. In der Zugriffseinheit 34 wird eine 3-dimensionale Steuerparametermatrix eingespeichert, wobei die einzelnen Steuerparameter je eine Steuergröße wie einen Spannzustand (Spannen/Entspannen), eine Spanngeschwindigkeit, eine Spannkraft bezeichnen und wobei alle Positionen der genannten Steuerparametermatrix je einem Gegen-EMK-Schwellenwert entsprechen. Weil alle oben genannten Steuerparameter bei einem normalen Betriebszustand ohne Schrittverlust des Schrittmotors 20 erfasst werden, kann die Steuereinheit 32 je nach einem durch die Empfangseinheit 33 empfangenen Steuerbefehl den Schrittmotor 20 antreiben, wobei das Steuergerät 30 nach dem Steuerbefehl die entsprechenden Gegen-EMK-Schwellenwerte aus der Steuerparametermatrix mit den in der Echtzeit erfassten Gegen-EMK-Istwerten vergleicht und nach einem erhaltenen Vergleichsergebnis den Schrittmotor 20 ansteuert.

The control unit 30th which is a drive unit 31 , a control unit 32 , a receiving unit 33 and an access unit 34 which are electrically connected to each other is electrically connected to the stepper motor 20 connected, being

• - the drive unit 31 electrically with the stepper motor 20 connected so that it is the stepper motor 20 drives and the recorded counter-EMF actual values of the stepper motor 20 can feed back;
• - the control unit 32 electrically with the drive unit 31 connected is;
• - the receiving unit 33 electrically with the control unit 32 is connected and ensures appropriate control commands with regard to a clamping state, a clamping speed and a clamping force of the holding device 10th to recieve;
• - the access unit 34 electrically with the control unit 32 connected is. In the access unit 34 A 3-dimensional control parameter matrix is stored, whereby the individual control parameters each designate a control variable such as a tensioning state (tensioning / relaxation), a tensioning speed, a tensioning force, and all positions of the control parameter matrix mentioned correspond to a back emf threshold. Because all of the above control parameters in a normal operating state without step loss of the stepper motor 20 the control unit can be detected 32 depending on one by the receiving unit 33 received control command the stepper motor 20 drive, the control unit 30th after the control command, the corresponding back EMF threshold values from the control parameter matrix compares with the actual counter-EMF values recorded in real time and the stepper motor after a comparison result has been obtained 20 controls.

• Schritt I: Empfangen von Steuerbefehlen. Die Steuerbefehle werden durch die Empfangseinheit 33 gegeben, wobei die Empfangseinheit 33 dafür sorgt, die momentanen Steuerbefehle bezüglich des Spannzustandes, der Spanngeschwindigkeit, der Spannkraft der Haltevorrichtung 10 zu empfangen;
• Schritt II: Antreiben eines Schrittmotors. Nachdem die Empfangseinheit 33 des Steuergerätes 30 die momentanen Steuerbefehle empfangen hat, greift die Steuereinheit 32 die eingespeicherte Steuerparametermatrix zu, während die Steuereinheit 32 den Schrittmotor 30 nach den durch die Empfangseinheit 33 erhaltenen Steuerbefehlen weiter ansteuert, wobei der Schrittmotor 20 während seines Betriebes entsprechende Gegen-EMK-Istwerte erzeugt;
• Schritt III: Vergleich der erhaltenen Steuerbefehle mit den in der Steuerparametermatrix enthaltenen Steuerparametern. Die Steuereinheit 32 des Steuergerätes 30 vergleicht die in den durch die Empfangseinheit 32 empfangenen Steuerbefehlen enthaltenen Steuerparameter mit den in der Speichereinheit 34 eingespeicherten Steuerparametermatrix enthaltenen Steuerparametern, wobei die Steuerparametermatrix an ihren jeweiligen Positionen je einen entsprechenden Gegen-EMK-Schwellenwert besitzt;
• Schritt IV: Ermitteln der entsprechenden Gegen-EMK-Schwellenwerte. Das Steuergerät 30 vergleicht die erfassten Gegen-EMK-Istwerte mit den an den jeweiligen Positionen der Steuerparametermatrix enthaltenen Steuerparametern, um die entsprechenden Gegen-EMK-Schwellenwerte zu ermitteln. In 3 ist die erfindungsgemäße Steuerparametermatrix schematisch dargestellt, wobei die Steuerparametermatrix dreidimensional ausgebildet ist, die jeweils aus den Steuerparametern von den Spannzuständen, Spanngeschwindigkeiten und die Spannkräften der Haltevorrichtung 10 ausgebildet sind. Selbstverständlich lassen sich verschiedene Elemente in den einzelnen Dimensionen der Steuerparametermatrix je nach einem gewünschten Steuerbedarf variieren. Hierunter wird die in der 3 dargestellte Steuerparametermatrix als Beispiel angeführt, wobei die erste Dimension die Spannzustände ausdrückt und zwei Elemente besitzt, die jeweils einen Spannzustand, nämlich das Spannen (1) und das Entspannen (2) bezeichnen, während die zweite Dimension die Spanngeschwindigkeit bezeichnet und über 20 Elemente verfügt, die jeweils eine Spanngeschwindigkeit von 1mm/3 bis 20mm/s repräsentieren. Die dritte Dimension repräsentiert die Spannkraft und verfügt über 11 Elemente, die jeweils eine Spannkraft von 50% bis 100% bezeichnen. Nachdem das Steuergerät 30 einen externen Steuerbefehl von seiner Empfangseinheit 33 bekommen hat, beginnt die Steuereinheit 32 sofort, die Steuerparameter in der in der Zugriffseinheit 34 eingespeicherten Steuerparametermatrix zuzugreifen, um die entsprechenden Gegen-EMK-Schwellenwerte zu ermitteln. Beispielsweise, wenn der externe Steuerbefehl einen Inhalt (Entspannen, 5mm/s und 50%) ausdrückt, wird die Steuereinheit 32 nach den angegebenen Steuerparametern an einer mit (0) (4) (0) bezeichneten Matrixposition adressiert, um die darin eingespeicherten Gegen-EMK-Schwellenwerte abzulesen;
• Schritt V: Überwachung der Gegen-EMK-Istwerte. Die Steuereinheit 32 des Steuergerätes 30 überwacht kontinuierlich die von der Antriebseinheit 31 rückgespeisten Gegen-EMK-Istwerte;
• Schritt VI: Vergleichen und Ansteuern. Die Steuereinheit 32 des Steuergerätes 30 vergleicht die durch die Überwachung erfassten Gegen-EMK-Istwerte mit den ermittelten Gegen-EMK-Schwellenwerten. Wenn die erfassten Gegen-EMK-Istwerte kleiner als die Gegen-EMK-Schwellenwerte sind, wird das Antreiben des Schrittmotors fortgesetzt. Wenn die erfassten Gegen-EMK-Istwerte die ermittelten Gegen-EMK-Schwellenwerte erreichen, bedeutet es, dass die Haltevorrichtung 10 das Werkstück schon ergriffen bzw. festgehalten hat, wobei das Antreiben des Schrittmotors 20 gestoppt wird, sodass die Haltevorrichtung 10 diesen Spannzustand hält.

The above-described description explains the holding device of the present invention based on the counter-EMF monitoring, as well as its design and properties, and it still has to be explained that a control method according to the invention comprises the following steps in sequence:

• step I. : Receive control commands. The control commands are sent through the receiving unit 33 given, the receiving unit 33 ensures the current control commands with regard to the clamping state, the clamping speed, the clamping force of the holding device 10th to recieve;
• step II : Driving a stepper motor. After the receiving unit 33 of the control unit 30th has received the current control commands, the control unit intervenes 32 the stored control parameter matrix while the control unit 32 the stepper motor 30th after that by the receiving unit 33 Control commands received further drives, the stepper motor 20 generated corresponding counter-EMF actual values during its operation;
• step III : Comparison of the control commands received with the control parameters contained in the control parameter matrix. The control unit 32 of the control unit 30th compares those in the through the receiving unit 32 received control commands contained control parameters with those in the memory unit 34 control parameters stored in the stored control parameter matrix, the control parameter matrix each having a corresponding counter-EMF threshold value at its respective positions;
• step IV : Determine the corresponding back EMF threshold values. The control unit 30th compares the detected actual counter EMF values with the control parameters contained at the respective positions of the control parameter matrix in order to determine the corresponding counter EMF threshold values. In 3rd The control parameter matrix according to the invention is shown schematically, the control parameter matrix being three-dimensional, each consisting of the control parameters of the clamping states, clamping speeds and the clamping forces of the holding device 10th are trained. Of course, different elements in the individual dimensions of the tax parameter matrix can be varied depending on a desired tax requirement. This is the one in the 3rd Control parameter matrix shown as an example, the first dimension expressing the clamping states and having two elements, each of which has a clamping state, namely the clamping ( 1 ) and relaxing ( 2nd ) designate, while the second dimension denotes the clamping speed and has 20 elements, each representing a clamping speed of 1mm / 3 to 20mm / s. The third dimension represents the clamping force and has 11 elements, each of which denotes a clamping force from 50% to 100%. After the control unit 30th an external control command from its receiving unit 33 control unit starts 32 immediately, the control parameters in the in the access unit 34 to access the stored control parameter matrix in order to determine the corresponding counter-EMF threshold values. For example, if the external control command expresses content (relax, 5mm / s and 50%), the control unit 32 addressed according to the specified control parameters at a matrix position designated (0) (4) (0) in order to read the back emf threshold values stored therein;
• step V : Monitoring of the actual counter-EMF values. The control unit 32 of the control unit 30th continuously monitors the drive unit 31 regenerated counter-EMF actual values;
• step VI : Compare and control. The control unit 32 of the control unit 30th compares the actual back EMF values recorded by the monitoring with the back EMF threshold values determined. If the detected actual back EMF values are less than the back EMF threshold values, the stepping motor continues to be driven. If the detected actual counter-emf values reach the determined counter-emf threshold values, it means that the holding device 10th has already gripped or held the workpiece, driving the stepper motor 20 is stopped, so that the holding device 10th maintains this tension state.

In summary, a control parameter matrix used for control, which is previously recorded in a normal operating state without any step loss, is used, inter alia, in the present invention, the holding device to be controlled being used 10th feeds back their current counter-EMF actual values in real time, which are compared in real time with the control parameters stored in the control parameter matrix, so that the holding device 10th is monitored or controlled according to a result obtained by the comparison, whereby real-time monitoring is implemented in order to keep the control parameters in a stable state.

Because corresponding back emf values are used in the present invention as a basis for real time monitoring, with the control parameter matrix used in the present invention cooperating as reference values, the step loss of the stepper motor is really avoided in the present invention, so that the holding device is always in an optimum Clamping state can work if it grips and holds a workpiece, which not only enables a stable clamping force, prevents the workpiece from separating or failing, but also increases production yield.

In addition, because only the back EMF values, which occur during operation of the stepper motor 30th generated, are monitored in the present invention, no separate torque sensor is required during the monitoring, which not only enables a simple design and a higher degree of freedom in assembly, but also increases the economic added value of the product.

Because the control parameter matrix according to the invention is a 3-dimensional matrix which comprises different elements of the clamping state, the clamping speed and the clamping force, the corresponding back emf threshold values can be obtained under different circumstances such as different clamping state, different clamping speed and different clamping force. For this reason, the holding device according to the invention has high dynamic adaptability and therefore high economic efficiency. For the same reason, a further conclusion can be drawn that the control parameters stored in the control parameter matrix can be added, subtracted and changed as required if the holding device requires the different control parameters, whereby it should be mentioned that the control parameter matrix in no way corresponds to that shown in of the 3rd shown parameters is limited.

Reference list

10th

Holding device

20

Stepper motor

30th

Control unit

31

Drive unit

32

Control unit

33

Receiving unit

34

Access unit

Step I

Receive control commands

Step II

Driving a stepper motor

Step III

Compare a tax parameter matrix

Step IV

Determine the corresponding back EMF thresholds

Step V

Monitoring the actual counter-EMF values

Step VI

Compare and control

Claims (4)

Holding device based on counter-EMF monitoring, comprising: - A holding device (10); - A stepper motor (20) which is connected to the holding device (10) and drives it so that it is accordingly tensioned or relaxed; - A control device (30) which is electrically connected to the stepper motor (20), the control device (30) having a drive unit (31), a control unit (32), a receiving unit (33) and an access unit (34) are electrically connected, wherein - The drive unit (31) is electrically connected to the stepper motor (20) so that it drives the stepper motor (20) and feeds back actual EMF values of the stepper motor (20); - The control unit (32) is electrically connected to the drive unit (31); - The receiving unit (33) is electrically connected to the control unit (32) and ensures that corresponding control commands relating to a clamping state, a clamping speed and a clamping force of the holding device (10) are received; and where - The access unit (34) and the control unit (32) are electrically connected, a control parameter matrix being stored in the access unit (34), a counter-emf threshold value being assigned to each position in the control parameter matrix, so that the control unit (32) follows the control commands detected by the receiving unit (33) can control the operation of the stepper motor (20), the control unit (30) after the control command comparing the corresponding counter-EMF threshold values of the control parameter matrix with the counter-EMF actual values recorded in real time and controls the stepper motor (20) after a comparison result has been obtained. Holding device after Claim 1 , characterized in that the control parameter matrix is designed as a three-dimensional matrix that includes various parameters of the clamping states, clamping speeds and clamping forces. Method for controlling the holding device based on counter-EMF monitoring, comprising the following steps: driving a stepper motor, a control unit (30) driving the stepper motor (20) after a control command by a drive unit (31) and the stepper motor ( 20) generates corresponding counter EMF actual values during its operation; Comparing a control parameter matrix, the control device (30) comparing parameters in the control command with counter-emf threshold values, each of which is assigned to a position in the control parameter matrix stored in an access unit (34); Determining the corresponding counter-emf threshold values, the control unit (30) determining which position in the control parameter matrix the actual counter-emf values correspond to in order to determine the corresponding counter-emf threshold values; Monitoring the actual counter-emf values, the control unit (30) constantly monitoring the actual counter-emf values; and comparing and actuating, wherein the control device (30) compares the counter-emf actual values detected by the monitoring with the determined counter-emf threshold values, and wherein if the detected counter-emf actual values are smaller than the counter-emf threshold values , the stepping motor is continued to drive, and when the detected actual back emf values reach the determined back emf threshold values, the driving of the stepping motor is stopped to keep the holding device in a tensioned state. Procedure according to Claim 3 , characterized in that the control parameter matrix is designed as a three-dimensional matrix that includes various parameters of the clamping states, clamping speeds and clamping forces.

Images