Servo Control Smoothing for Transport Carriage Stability

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Solution Overview

Problem

Existing transport carriage systems experience sudden changes in instructions input to the servo system, leading to inefficiencies and potential interference between multiple cranes sharing a common track, and require complex error reduction methods.

Innovation Solution

A transport carriage system with a servo system and a traveling control unit that includes an acceleration/deceleration control unit generating intermediate instructions and a smoothing unit to smooth these instructions over multiple cycles, ensuring stable operation and efficient travel by removing high-frequency components and adjusting constraints based on track conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple transport carriages travel on a common track with communication-based interference avoidance, then transport performance is improved, but sudden changes in destination or velocity instructions cause negative influences on the crane or transported articles

Engineering Contradiction:
Improvetransport performanceVSAvoidstability of crane operation
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-calculating velocity patterns and preparing control instructions before the transport carriage actually needs to change its motion state. The on-board controller generates velocity patterns in advance based on destination information, and the smoothing unit prepares smoothed velocity instructions before they are needed, allowing the servo system to transition smoothly without sudden changes that could affect the transported articles.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary element - the smoothing unit - that acts as a mediator between the destination/velocity change requirements and the servo system execution. This smoothing unit generates intermediate velocity instructions that gradually transition from current to target values, preventing direct abrupt changes from reaching the servo system and thereby protecting the transported articles from sudden accelerations or decelerations.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If velocity pattern data is directly input to the servo system to eliminate error between input velocity pattern and actual velocity, then positioning accuracy is improved, but sudden changes in acceleration or deceleration occur

Engineering Contradiction:
Improvepositioning accuracyVSAvoidsudden acceleration or deceleration
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The smoothing unit serves as an intermediary between the velocity pattern generator and the servo system. It takes the target velocity pattern and generates smoothed intermediate velocity instructions that gradually transition from current to target values. This intermediary processing ensures positioning accuracy is maintained while eliminating sudden acceleration or deceleration changes that would otherwise be transmitted directly to the servo system.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies parameter changes by modifying the velocity instruction parameters through gradual transition rather than direct application. The smoothing unit changes the velocity parameter from current to target values in incremental steps over multiple control cycles, transforming the abrupt parameter change into a gradual one that maintains positioning accuracy while avoiding harmful sudden accelerations or decelerations.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If complex error reduction methods are used to prevent sudden changes in instructions, then operational stability is improved, but device complexity increases

Engineering Contradiction:
Improveoperational stabilityVSAvoidcomplexity of control system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent reduces device complexity by applying preliminary action - the smoothing unit pre-calculates and stores smoothed velocity instructions in advance based on the target velocity pattern. This preliminary preparation eliminates the need for complex real-time calculation and coordination mechanisms during execution, maintaining operational stability while simplifying the overall control system architecture.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2677385B1Transport carriage system and method for controlling running of transport carriage
Publication Date: 2019.12.04 MURATA MASCH LTD
  • EP2677385B1 patent drawingFigure 1
  • EP2677385B1 patent drawingFigure 2
  • EP2677385B1 patent drawingFigure 3

AI summary

A sudden change in instruction input to a servo system is prevented. Multiple transport carriages travel along a common track. Each transport carriage includes a servo system that performs servo control with respect to traveling of the transport carriage, and intermediate instruction for the servo system is generated in a predetermined cycle by an acceleration/deceleration control unit of a traveling control unit. Smoothed instruction is generated for the predetermined cycle by smoothing the generated intermediate instruction over a plurality of cycles with a smoothing unit of the traveling control unit, and the servo system is controlled based on the smoothed instruction that was generated.