Container Transport Servo Control for Synchronized Fault Stopping

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Solution Overview

Problem

Existing methods for transporting containers, such as those in the beverage processing industry, face issues with synchronization failures leading to potential damage when position sensors malfunction, as existing solutions like stopping servomotors with a speed command of 0 do not adequately prevent damage.

Innovation Solution

A method and device that bring servomotors to a controlled standstill by using the current or target position determined by position sensors, maintaining synchronization during the stopping process, and employing alternative position indicators like virtual position encoders or reserve sensors to reduce damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If servomotors are brought to a standstill using a speed command of 0 when a position sensor malfunction is detected, then the servomotors can be stopped quickly, but significant damage still occurs due to lack of synchronization of the movement of individual devices

Engineering Contradiction:
Improvestopping speedVSAvoidsynchronization
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The control unit is pre-programmed with target positions for all transport devices. When a position sensor malfunction is detected, the control unit immediately commands all servomotors to move to their predetermined target positions and stop, rather than simply commanding a speed of 0. This preliminary preparation of target positions enables synchronized stopping without damage.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the position of each transport device and compares it with the target position. When a position sensor malfunction is detected, the feedback mechanism triggers a controlled stopping sequence where all devices are guided to their target positions and stopped in a coordinated manner, maintaining synchronization and preventing damage.

Inventive Principle:
Principle #23Feedback

2Reliability

If mechanical brakes are used to stop servomotors in addition to speed commands, then stopping is achieved more reliably, but damage still occurs due to synchronization failures

Engineering Contradiction:
Improvestopping reliabilityVSAvoiddamage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system replaces mechanical braking with an electronic control solution. Instead of relying on mechanical brakes that cause abrupt stopping and potential damage, the control unit electronically commands all servomotors to move to their target positions and stop in a coordinated manner. This substitution of mechanical stopping with electronic position-controlled stopping eliminates synchronization failures and prevents damage while maintaining reliable stopping.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the position sensor cannot determine the current position of the transport device, then the system must use target position instead, but this reduces the precision of the stopping control

Engineering Contradiction:
Improvesystem operationVSAvoidposition determination
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

When the position sensor cannot determine the current position, the control unit uses the predetermined target position as a virtual copy of the expected position. All transport devices are commanded to move to their respective target positions and stop. This copying approach allows the system to maintain operation and achieve synchronized stopping even without accurate real-time position feedback from malfunctioning sensors.

Inventive Principle:
Principle #26Copying

Data Source

PatentEP3384351B1Method for transporting containers
Publication Date: 2022.04.13 KRONES AG
  • EP3384351B1 patent drawingFigure 1
  • EP3384351B1 patent drawingFigure 2

AI summary

The invention relates to a method for transporting containers by means of at least two transport devices (101, 102) each driven by a servo motor (110, 120), wherein the servo motors are controlled in a closed-loop manner on the basis of a comparison of the position of the servo motors determined by the position sensors (111, 121) of the servo motors (110, 120) and a target position of the servo motors and, in the event of a fault of one of the position sensors, the servo motors are brought to a standstill, characterized in that a) at least one of the servo motors is brought (205) to a standstill with closed-loop control by using the position determined by the position sensor if the position sensor can determine the current position of the transport device or b) at least one of the servo motors is brought (210) to a standstill with open-loop control if the position sensor cannot determine the current position of the transport device, wherein, instead of the current position of the transport device determined by the position sensor, a target position of the transport device is used (211) to bring the servo motor to a standstill with open-loop control.