DE102009048272B3 - Method for positioning magnetic sensor attached to industrial robot, involves detecting measurement signal indicating space between sensor and magnet during movement along sliding path to calculate sensor regulation position - Google Patents

Abstract

The method involves sliding a sensor (10) relative to an output magnet (12) along a sliding path. A measurement signal indicating space between the sensor and magnet is detected during movement of the sensor and magnet. The sensor regulation position is calculated based on the measurement signal and displayed. The sensor is fixed to the regulation position. An independent claim is included for magnetic sensor.

Description

The invention relates to a method for positioning a magnetic sensor.

From the DE 10 2006 008 157 A1 a magnetic sensor is known in the teaching about a two methods of a donor magnet bearing piston of a cylinder, for. B. a gripper or arm of an industrial robot, and can be stored as desired signals. In regular operation following the teach-in mode, signals are then available at two digital outputs which signal the reaching of the learned switching points. Although it is an advantage of these sensors that an exact positioning of the sensor on the cylinder for determining the switching points is not necessary because the switching points are so electronically taught, but there are still positions that are more suitable than others. The best turn-on accuracy, Ausschaltthystere and temperature stability is achieved when the sensor is optimally positioned to the position of the encoder magnet of the piston. In most cases, it is not obvious to the user which is the optimal position, in particular because it is not possible to see from the outside where the piston stroke lies, that is, in which region the sensor magnet lies. This is especially true for grippers with their extremely short piston strokes and thus extremely short strokes of the encoder magnet. Especially in these applications, the sensors are used with teachable switching points, so that an improvement is desired here.

To solve this positioning problem mechanical auxiliary elements, eg. As mechanical and fixable in the cylinder groove stops known that predetermine the position on the cylinder or define the original position when replacing a sensor. Such mechanical auxiliary elements are expensive to assemble with additional tools. In addition, the necessary auxiliary parts are lost.

From the DE 197 12 829 A1 It is known that the position for which a position detection signal is to be generated when a moving object is reached can be set by displacing the sensors parallel to the direction of movement of the moving object. For this purpose, the movable object is moved to the position to be detected before commissioning of the inventive device and the sensors are displaced parallel to the direction of movement of the movable object until a vertical magnetic field component is zero or falls below a predetermined threshold.

The invention has for its object to provide an improved method for positioning a magnetic sensor, with which the aforementioned disadvantages can be avoided.

• a) Verschieben von Sensor und Gebermagnet relativ zueinander entlang des Verschiebeweges,
• b) Erfassen eines vom Abstand Sensor-Gebermagnet abhängigen Messsignals während der Verschiebens und Speichern des Messsignals (22, 28, 30) während der Relativverschiebung,
• c) Ermitteln der Sensor-Sollposition aus den in Schritt b) erfassten Messsignaldaten, und Anzeigen, in welche Verschieberichtung die Sensor-Sollposition liegt,
• d) Anzeigen der Sensor-Sollposition,
• e) Festlegen des Sensors an der Sensor-Sollposition.

The method according to the invention for positioning a magnetic sensor to a desired sensor position along a displacement path of a transmitter magnet, in particular along a pneumatic cylinder whose piston carries the transmitter magnet, comprises the steps:

• a) displacement of sensor and transmitter magnet relative to one another along the displacement path,
• b) detecting a measurement signal dependent on the distance between the sensor and the sensor during the movement and storage of the measurement signal ( 22 . 28 . 30 ) during the relative displacement,
• c) determining the desired sensor position from the measured signal data acquired in step b), and indicating in which displacement direction the sensor target position lies,
• d) displaying the sensor target position,
• e) Defining the sensor at the sensor setpoint position.

This inventive method can be carried out with a magnetic sensor having at least one sensor element and an evaluation unit, wherein the evaluation unit comprises means for determining a sensor target position along a displacement path of the piston on the basis of the displacement detected measurement signals of the sensor element and wherein a display means provided is for displaying the sensor target position.

With this method, the sensor thus detects during a displacement of sensor and sensor magnet relative to each other permanently a measurement signal, ie a signal that is dependent on the distance sensor-donor magnet. From the measured signal detected and stored via the displacement, a sensor nominal position is determined from the detected and stored measurement signal data in the evaluation unit. This desired sensor position is now determined electronically, specifically from the measuring signal of the sensor element, for example a Hall sensor element. Such determination of a desired sensor position is considerably more accurate and provides a more optimal position than that obtained with mechanical aids. Because very often, the magnetic fields of the sensor magnet are strongly distorted due to surrounding disturbing materials, so that the optimal sensor target position by observing the measurement signal is significantly more accurate and thus implicitly the distortions are taken into account in the determination of the sensor target position.

In this case, it is also displayed after the step of determining the sensor target position on the display means, in which displacement direction is the sensor target position. This makes it easier to find the correct position and can make a back and forth superfluous, so that assembly time can be saved.

It is useful to provide a further development of the invention, a separate positioning in which the sensor is positioned. Then, for example, components such. B. LEDs are used both in normal operation and in the positioning mode. The positioning mode may be started and ended by a sensor positioning mode operating means.

If the sensor target position corresponds to the location at which the measurement signal has its largest gradient, ie z. B. the magnetic field strength undergoes the maximum change in displacement, the sensor target position can be determined most accurately. This is z. B. then very useful if the sensor target position should also correspond to a switching point of the sensor.

If the sensor target position corresponds to the location at which the measurement signal has its greatest value in terms of magnitude, the determination of the desired sensor position is particularly simple. Then also not the entire measurement signal waveform would have to be stored via the displacement, but only the largest amount in terms of amount, which is then used for the display of the sensor target position via a display means. Furthermore, in this case, the detected measurement signal can also be displayed simultaneously during the displacement, which possibly facilitates the positioning by displacing the sensor back and forth along the displacement path for positioning while observing the display, which is eg. B. at the sensor target position brightest lights.

• Ea) Starten des Einlernmodus,
• Eb) Anfahren des den Gebermagneten tragenden Kolbens an eine Kolbenposition, an der der Sensor schalten soll,
• Ec) Einlernen eines Schaltpunktes durch Abspeichern des Messsignals an dieser Kolbenposition, insbesondere initiiert durch ein Einlernmodusbetätigungsmittel,
• Ed) gegebenenfalls Wiederholen der Schritte b) und c) zum Einlernen weiterer Schaltpunkte,
• Ee) Beenden des Einlernmodus.

In a further development, the positioning mode is followed by a teach-in mode with the following steps:

• Ea) starting the learning mode,
• Eb) approaching the piston carrying the transmitter magnet to a piston position at which the sensor is to switch,
• Ec) teaching a switching point by storing the measuring signal at this piston position, in particular initiated by a teach-in mode actuating means,
• Ed) optionally repeating steps b) and c) for teaching in further switching points,
• Ee) Exit the teach-in mode.

Thus, the switching point or the switching points of the sensor are just as easily and advantageously entered into the sensor, so that on the one hand, the sensor is optimally positioned and on the other hand, the switching points are set very accurately. Overall, a sensor is thus created and positioned so that a much more accurate determination of the piston position is possible, as was previously the case, in addition, the handling, d. H. the mounting for positioning and the adjustment of the switching points is very simple and thus fast and reliable possible.

The corresponding modes, namely the positioning mode and the learning mode, are most easily initiated via a sensor positioning mode actuating means or a learning mode actuating means.

This makes it very easy to teach the respective switching signals for the different piston positions by a simple key press. After starting the teach-in mode, the piston is successively moved to the desired positions and z. For example, by further operating the teach-in mode actuating means at each piston position, the corresponding switching point is stored by storing the corresponding unique measurement signals in a switchpoint memory. If, in regular operation, the piston reaches the taught-in position, the evaluation unit generates the corresponding switching signal.

In a further development of the invention, a further display option can additionally be present for displaying the teach-in process. After pressing the button to start the teach-in process and a successful storage of the switching points corresponding measurement signals, for example, an optical signal can be output via the display option, eg. B. a light or flashing signal.

The Sensorpositioniermodusbetätigungsmittel and / or the Einlernmodusbetätigungsmittel may be formed in further development of the invention by input signals, so that the magnetic sensor in the positioning or Einlernmodus by the input signals over z. B. a bus system to which the sensor is connected, is offset.

Furthermore, the magnetic sensor for mounting in a groove, in particular a T or C groove of the pneumatic cylinder, in a known manner (see, for. DE 202 04 874 U1 or DE 196 43 413 A1 ) be formed.

In the following, the invention will be explained with reference to exemplary embodiments with reference to the drawing in detail. In the drawing show:

1a to 1c schematic representations of a magnetic according to the invention Sensors on a cylinder with a donor magnet-bearing piston;

2a to 2c schematic representations like 1a to 1c ;

3a and 3b Diagrams with schematic representations of measuring signals.

The magnetic sensor according to the invention 10 is usually used to at least one piston position of a donor magnet 12 carrying the piston 14 to determine. The piston 14 is part of a cylinder 16 , z. As a pneumatic cylinder of a robot, a gripper or the like industrial machine.

The sensor 10 has at least one sensor element 18 on and in the illustrated embodiment even two sensor elements 18 and 20 , The sensor elements 18 . 20 For example, magnetic field-sensitive sensor elements, such as, for example, Hall sensor elements, can be used. Each of the sensor elements 18 . 20 delivers a measurement signal 22 , z. B. such as it is in 3a is shown schematically. With the help of the measuring signal, an evaluation unit 24 depending on the position of the encoder magnet 12 relative to the sensor 10 a signal at an output 26 give. This signal may be a switching signal, for example, which is output when the transmitter magnet 12 takes a certain position.

The measuring signal 22 a sensor element 18 . 20 may be, for example, a Hall voltage, the typical course in 3a is shown. Of course, the detailed course depends on the orientation of the magnetic field of the transmitter magnet and the orientation of the sensor elements. Other waveforms are therefore possible. On the abscissa is the relative displacement between sensor 10 and encoder magnet 12 plotted and on the ordinate the Hall voltage of a sensor element. Such courses are for example in the EP 1 847 810 A1 explained in more detail.

Lying two sensor elements 18 and 20 As in the present embodiment, two Hall voltages arise as the measurement signal 28 and 30 , as in 3b represented by a small offset, the distance between the two sensor elements 18 and 20 corresponds, are spaced. As in DE 10 2006 008 157 A1 explained, two of these measurement signals are useful if there is a clear signal for each piston position. This signal then consists of a value pair, namely the two Hall voltages 28 and 30 , at the respective position.

As in the course of the measuring signals 22 . 28 . 30 can be seen, there are areas in which a switching point can be set very precisely, namely those areas in which the measurement signal is very steep, that has a large gradient. In contrast, there are also areas in which a switching point can be set only inaccurate, namely the flat areas, for example in the area of an extremum or in the edge areas.

So you want to achieve that at a certain piston position of the sensor 10 Switches in a desired area with large gradients, the sensor must 10 be positioned accordingly. The essence of the invention relates precisely to this positioning, that is to say a method for finding a suitable position of the correspondingly equipped sensor. A first embodiment of the method is described below:
First, the piston 14 with its transmitter magnet 12 placed in the position where the sensor 10 to give a switching signal. This is, for example, as in the 1a to 1c shown, a center position. Now it is the sensor 10 correspondingly optimally positioned. The sensor 10 is in the longitudinal direction of the cylinder 16 slidably disposed along a displacement path V. The displacement is defined by a mounting groove for the sensor 10 on the cylinder 16 ,

First, a positioning mode is started by operating a sensor positioning mode operating means 34 which may be a simple button, for example. After that, the sensor becomes 10 from one edge position ( 1a ) into the other edge position ( 1c ) moved manually. While moving the sensor 10 become the measuring signals 28 and 30 the sensor elements 18 and 20 from the evaluation unit 24 captured and stored in memory 36 saved. From the data thus acquired for the measurement signal 28 and 30 the evaluation unit determines the sensor target position S under corresponding specifications. For example, this sensor target position S can correspond to the position at which the measurement signal has its greatest gradient ( 3b ). Alternatively, the desired sensor position could also correspond to the position at which the measurement signal has its greatest value in terms of magnitude. Other alternatives are conceivable. For example, the position could be taken where the sum of both Hall voltages U is equal to zero. On the one hand, this is on the one hand in the range of a large gradient and on the other hand, such a determination can be made simply by merely checking whether both Hall voltages are equal in magnitude but have different signs. Which criterion is used also depends on the type of measuring signals and their calculation in the evaluation unit.

The thus determined sensor target position S can now via a display means 38 are displayed. This can be done by the sensor 10 is repeatedly shifted along the displacement path V and observed, at which point the display means 38 shines ( 1b ), if this is formed for example as an LED. According to the invention, the display means 38 Also be designed as a display that in addition to the sensor target position S at other positions of the sensor 10 along the displacement path can indicate the direction in which the sensor 10 is to move to reach the sensor target position S. In an alternative, during the shift could also via the display means 38 the detected measurement signal 28 . 30 be displayed, for example, in that the display means can emit light of different brightness, where it shines brightest at the sensor target position S.

If it is difficult, the sensor 10 manually to move in the mounting groove along the displacement path V for detecting the measurement signal via the displacement, in an alternative embodiment of the method and the sensor 10 be provisionally fixed at a position as indicated in the 2a to 2c is shown. The relative displacement of sensor 10 to the encoder magnet 12 is then achieved by now that the piston 14 with its transmitter magnet 12 from the one end position ( 2a ) to the other end position ( 2c ) is moved. After that, the piston can 14 be brought to the position at which the sensor 10 should switch, then what the sensor 10 can be set in the optimum position with the already described method steps. Of course, then the sensor must be 10 be at least a little displaceable in order to achieve the optimum sensor target position S.

After setting the sensor 10 in the sensor target position S, by again operating the sensor positioning mode operating means 38 the positioning mode ends.

In a further development of the invention, a teach-in mode can follow this positioning mode, as it already exists in principle from the DE 10 2006 008 157 A1 is known. This is done via a teach-in mode actuator 40 the teach-in mode started. After that, the piston 14 with its transmitter magnet 12 brought to the piston position at which the sensor 10 should switch. By, for example, repressing the teach-in mode actuating means 40 this position becomes the switching point SP1 in the sensor 10 stored by the corresponding measurement signal 28 . 30 is stored at this piston position in a switching point memory. If the sensor 10 is able to store several switching points SP1, SP2, as in DE 10 2006 008 157 A1 , the piston must be brought to the new switching point SP2 and this new switching point taught again. After the switching points have been learned, the teach-in mode is ended by repeatedly actuating the teach-in mode actuating means.

Claims (8)

Method for positioning a magnetic sensor ( 10 ) to a sensor target position (S) along a displacement path (V) of a transmitter magnet ( 12 ) with the steps: a) shifting sensor ( 10 ) and encoder magnet ( 12 ) relative to each other along the displacement path (V), b) detecting at least one of the distance sensor-donor magnet-dependent measurement signal ( 22 . 28 . 30 ) while moving and storing the measurement signal ( 22 . 28 . 30 during the relative displacement, c) determining the target sensor position (S) from the measured signal data acquired in step b), and indicating in which displacement direction the sensor target position lies, d) indicating the desired sensor position (S), e) setting of the sensor ( 10 ) at the sensor set position (S). A method according to claim 1, characterized in that in a first step, a positioning mode in the sensor ( 10 ) is started, which is terminated after step e). Method according to one of the preceding claims, characterized in that the sensor nominal position (S) corresponds to the location at which the measuring signal ( 22 . 28 . 30 ) has its largest gradient. Method according to one of the preceding claims 1 or 2, characterized in that the sensor target position corresponds to the location at which the measurement signal has its greatest value in terms of magnitude. Method according to one of the preceding claims 1 or 2, characterized in that the sensor setpoint position corresponds to the location at which the measurement signal has the value 0 in absolute value. A method according to claim 4, characterized in that after detection of the measuring signal over the entire displacement only the amount largest value is stored for the display of the sensor target position. Method according to one of the preceding claims, characterized in that during the Shift simultaneously the detected measurement signal is displayed. Method according to one of the preceding claims, characterized in that the positioning mode is followed by a teach-in mode with the steps: Ea) starting the teach-in mode, Eb) approaching the transmitter magnet ( 12 ) carrying the piston ( 14 ) to a piston position at which the sensor ( 10 ), Ec) teach in a switching point by storing the measuring signal ( 22 . 28 . 30 ) at this piston position, in particular initiated by a teach-in mode actuating means ( 40 If necessary, repeating steps b) and c) to teach in further switching points, Ee) terminating the teach-in mode.

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