Procedure for commissioning actuators

Abstract

Method for commissioning a pressure-medium-operated actuator, which is designed as a rotary or linear actuator and is controlled by means of a position controller, characterized in that - that the actuator (6) is supplied with a constant flow of pressure medium during commissioning, - that during operation, a drive-specific characteristic curve of the reported position is recorded over time, - that the determined characteristic curve is compared with a predetermined sample characteristic curve and - that the drive type of the actuator (6), rotary or linear drive, is determined from the degree of deviation or conformity of the drive-specific characteristic curve from the standard characteristic curve.

Description

[0001] The invention relates to a method for commissioning pressure medium-operated actuators which are controlled by means of a position controller.

[0002] In automation technology, linear actuators and rotary actuators are commonly used, which differ from one another in the way they actuate the actuator. These different actuator types require different control methods from the positioner. When commissioning the pressure-operated actuator, a parameter is manually entered to determine whether a linear actuator or a rotary actuator is connected to the positioner. This operation is error-prone and, if incorrectly entered, can lead to damage to the actuator and / or the actuator.

[0003] The invention is therefore based on the object of improving the commissioning of the known pressure medium-operated actuator in such a way that the actuator type is automatically recognized.

[0004] According to the invention, this object is achieved by the means of patent claim 1. Advantageous embodiments of the invention are specified in the dependent claims.

[0005] The invention is based on a pressure medium-operated actuator which is connected to and controlled by a position controller, whereby the position of the output of the actuator is fed back to the position controller.

[0006] According to the invention, to determine the actuator type, the actuator is subjected to a constant pressure flow during commissioning, and a drive-specific characteristic curve of the feedback position is recorded over time. The determined characteristic curve is then compared with a predefined model characteristic curve. The actuator type is determined from the degree of deviation or agreement between the drive-specific characteristic curve and the model characteristic curve.

[0007] The shape of the characteristic curve of a rotary actuator differs significantly from that of a linear actuator. By comparing it with a given sample characteristic curve, the differences are easily apparent.

[0008] According to a further feature of the invention, the predetermined model characteristic curve is determined by idealizing known characteristic curves of one of the two actuator types to be distinguished. If the observed actuator type matches the actuator type underlying the model characteristic curve, the degree of match between the characteristic curves is significantly high. If the observed actuator differs from the actuator type underlying the model characteristic curve, its characteristic curve differs significantly from the model characteristic curve.

[0009] According to a further feature of the invention, it is provided that the degree of agreement between the characteristic curve of the observed actuator and the sample characteristic curve is determined by cross-correlation.

[0010] Further details and advantages of the invention are explained in more detail below using an exemplary embodiment. The accompanying drawings show: Fig. 1 a representation of a pressure medium operated actuator on a process valve

[0011] According to the Fig.1, a process valve 2 is installed in a fragmentarily indicated pipeline 1 of a process plant not shown in detail. The process valve 2 has a closing body 4 inside it, which interacts with a valve seat 3 to control the amount of process medium 5 passing through. The closing body 4 is actuated linearly by an actuator 6 via a lifting rod 7. The actuator 6 is connected to the process valve 2 via a yoke 8. A position controller 9 is attached to the yoke 8. The stroke of the lifting rod 7 is reported to the position controller 9 via a position sensor 10. The detected stroke is compared with the setpoint supplied via a communication interface 11 in a control unit 18, and the actuator 6 is controlled depending on the determined control deviation. The control unit 18 of the position controller 9 has an I / P converter for converting an electrical control deviation into an appropriate control pressure.The I / P converter of the control unit 18 is connected to the actuator 6 via a pressure medium supply 19.

[0012] During commissioning, the actuator 6 is subjected to a constant pressure flow via the positioner 9 to determine the actuator type. As a result, the actuator rod 7 is moved, and this movement is reported to the positioner 9 by the position sensor 10. In the positioner 9, an actuator-specific characteristic curve of the reported position of the actuator rod 7 is recorded over time.

[0013] The recorded characteristic curve is compared with a predefined model characteristic curve. The drive type is determined based on the degree of deviation or agreement between the drive-specific characteristic curve and the model characteristic curve. yl=xl(l) for I=0..(n−1)

[0014] The y-values ​​are compared with an ideal function for a linear actuator. The cross-correlation is determined by the coefficients cl=∑k=0n−1ykzk+1 certainly.

[0015] Furthermore, by comparing the characteristic curve of the observed actuator with the model characteristic curve, installation errors can be detected using cross-correlation. These errors manifest themselves as a shift of the characteristic curve relative to the model characteristic curve by a fixed amount (offset). This error is advantageously detected using the same means used to detect the actuator type. This improves the result of the absolute position measurement. List of reference symbols 1 pipeline 2 process valve 3 Valve seat 4 locking bodies 5 Process medium 6 Actuator 7 Valve rod 8 yoke 9 Positioner 10 position sensors 11 Communication interface 18 Control unit 19 Pressure medium supply

Claims

[1] Method for commissioning a pressure medium-operated actuator which is designed as a rotary or linear actuator and is controlled by means of a position controller, characterized by , - that the actuator (6) is subjected to a constant pressure medium flow during commissioning, - that during the application a drive-specific characteristic curve of the reported position is recorded over time, - that the determined characteristic curve is compared with a given sample characteristic curve and - that the type of actuator (6), rotary or linear actuator, is determined from the degree of deviation or agreement of the actuator-specific characteristic curve from the sample characteristic curve. [2] Method according to claim 1 characterized by that the specified sample characteristic curve is determined by idealizing known characteristics of one of the two drive types to be distinguished. [3] Method according to one of the preceding claims characterized by that the degree of agreement of the characteristic curve of the observed actuator (6) with the sample characteristic curve is determined by cross-correlation.

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