Method for determining closed-control parameters for a hydraulic system

Patent metadata

Field	Value
Publication number	US-11149756-B2
Application number	US-201816495699-A
Country	US
Kind code	B2
Filing date	Mar 20, 2018
Priority date	Mar 20, 2017
Publication date	Oct 19, 2021
Grant date	Oct 19, 2021

Abstract

In order to carry out largely automated parameterisation of the closed-loop control parameters for closed-loop control of a hydraulic system comprising a servo drive, a method and a device for determining the closed-loop parameters of a closed-loop control unit of the hydraulic system are specified, wherein an actual system pressure of a hydraulic consumer of the hydraulic system is closed-loop controlled by means of a predefined set point rotational speed of a servo drive, wherein an actual rotational speed of the servo drive follows the predefined set point rotational speed, wherein an excitation signal is applied to the setpoint rotational speed, and the actual system pressure which is set here is measured, the dynamics of the hydraulic system are acquired from the actual rotational speed and/or the setpoint rotational speed and the actual system pressure, and the closed-loop control parameters are calculated from the acquired dynamics.

First claim

The invention claimed is:

1. A method for determining control parameters of a control unit of a hydraulic system, comprising:
controlling an actual system pressure of a hydraulic load of the hydraulic system by a predetermined target speed of a servo drive, wherein the servo drive comprises a motor and a pump, and an actual speed of the servo drive follows the predetermined target speed;
applying an excitation signal to the target speed;
measuring the resulting actual system pressure, wherein dynamics of the hydraulic system are determined from at least one of the actual speed or the target speed and the actual system pressure; and
calculating the control parameters from the determined dynamics.

2. The method according to claim 1 , wherein a constant initial speed is predetermined for the target speed before the application of the excitation signal, at which point an initial pressure results in the hydraulic system as the actual system pressure.

3. The method according to claim 1 , wherein the actual system pressure represents a pressure of a hydraulic cylinder or a hydraulic motor.

4. The method according to claim 1 , wherein a square wave signal, a harmonic signal, pulses, or a mixed signal is used as the excitation signal.

5. The method according to claim 4 , wherein the harmonic signal has an increasing frequency.

6. The method according to claim 1 , wherein the dynamics of the hydraulic system is described by a transfer function of the hydraulic system.

7. The method according to claim 6 , wherein the transfer function is determined by a Fast Fourier Transformation.

8. The method according to claim 6 , wherein the parameters of the transfer function are approximated by a method of least squares.

9. The method according to claim 1 , wherein the control parameters are calculated by a frequency characteristic method.

10. The method according to claim 9 , wherein default parameters of a step response, are predetermined for the frequency characteristic method.

11. The method according to claim 10 , wherein the default parameters of the step response are rise time and overshoot, and the frequency characteristic method comprises an overshoot and a rise time of the step response.

12. The method according to claim 1 , wherein, after determining the control parameters, control behavior of the control unit is verified by step-shaped changes in the system pressure being predetermined and a step response being determined.

13. The method according to 12 , wherein a user carries out verification of the control behavior of the control unit.

14. The method according to claim 1 , wherein a compensation filter for the control unit is additionally parameterized from the determined dynamics.

15. A hydraulic system comprising:
a servo drive with a motor and a pump, wherein the servo drive has a target speed predetermined by a control unit, and wherein an actual speed of the servo drive follows the predetermined target speed, and comprising
a hydraulic load which has an actual system pressure which is controlled by the predetermined target speed, wherein
a control unit configured to apply an excitation signal to the target speed and to measure the resulting actual system pressure of the hydraulic system, to determine dynamics of the hydraulic system from at least one of the actual speed or the target speed and the actual system pressure, and to calculate the control parameters of the control unit from the determined dynamics.

16. The hydraulic system according to claim 15 , wherein the control unit is integrated in the servo drive.

17. The hydraulic system according to claim 15 , wherein the control unit is integrated in an operating unit which is superordinate to the servo drive.

Assignees

• B & R Ind Automation Gmbh

Inventors

• Zehetleitner Kurt
• Wick Lukas
• Griessler Leopold

Classifications

• G05B13/025

  using a perturbation signal · CPC title

• F15B2211/6652

  Control of the pressure source, e.g. control of the swash plate angle · CPC title

• G05B2219/41318

  Electro hydraulic drive, electric motor drives hydraulic actuator · CPC title

• G05B13/045 Primary

  using a perturbation signal · CPC title

• F04D15/0066

  by changing the speed, e.g. of the driving engine · CPC title