Path Generator End Condition Control

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Solution Overview

Problem

Discrete time controllers struggle to accurately meet end conditions in continuous time path planning due to limitations in outputting data within predetermined sampling periods, leading to undesirable paths and computational inefficiencies.

Innovation Solution

A path generator that continuously tracks the total time expired in a path plan and substitutes remaining time for the length of a full sample period when it is less than the sampling period, allowing for precise control of end conditions without introducing discontinuities or significant computational loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a discrete time controller is used with continuous time path planning, then the controller can operate with predetermined sampling periods, but the end conditions of the path plan cannot be accurately met due to sampling period limitations

Engineering Contradiction:
Improveend condition accuracyVSAvoidsampling period constraint
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent applies dynamics by making the final sample period length variable rather than fixed. The path generator dynamically adjusts the length of the final sample period based on the remaining time to satisfy end conditions, allowing the controller to adapt its sampling behavior at critical moments while maintaining predetermined sampling periods during normal operation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the parameter of sample period length from a constant predetermined value to a variable that can be adjusted. Specifically, the final sample period's length is modified based on the time remaining in the path plan, enabling accurate meeting of end conditions while maintaining the discrete time controller's operational framework.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If compensation schemes alter initial conditions to reach end conditions on even sample periods, then computational simplicity is achieved, but discontinuities are introduced in the planned path

Engineering Contradiction:
Improvecomputational simplicityVSAvoidpath continuity
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by calculating and preparing the adjusted final sample period length in advance, before executing the path plan. The path generator determines the appropriate final sample period length based on remaining time calculations, ensuring that end conditions can be met without introducing discontinuities during path execution.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If traditional compensation schemes are used to meet end conditions, then the controller can operate with fixed sampling periods, but significant increases in computational load occur

Engineering Contradiction:
Improvefixed sampling period operationVSAvoidcomputational load
Core Design Contradiction:
ProductivityVSPower

Solution Approach 1:

The patent applies local quality by making a targeted, localized adjustment only to the final sample period rather than modifying the entire sampling schedule. This localized approach maintains fixed sampling periods for the majority of the path plan while applying a specific adjustment only where needed to satisfy end conditions, thereby minimizing computational overhead.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2217979B1Method and system for meeting end conditions in a motion control system
Publication Date: 2012.05.30 GE INTELLIGENT PLATFORMS LTD
  • EP2217979B1 patent drawingFigure 1
  • EP2217979B1 patent drawingFigure 2
  • EP2217979B1 patent drawingFigure 3

AI summary

One embodiment of a system and method for meeting end conditions of a path plan utilizing a path generator (4) that continuously generates commands for a path plan ( 21) while tracking the total time expired in the path plan (22). The path generator computes the time remaining in the path plan and substitutes the remaining time for the length of the final sample period in the path plan. (24) when the length of the remaining time is less than the length of a full sample period (23).