Cam Curve Switching Control for Driven Shaft Synchronization

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Solution Overview

Problem

Existing synchronization control systems face challenges in switching cam curves without causing vibration and impact, requiring pre-generated velocity curves and complex software processing, which limits real-time calculation capabilities and restricts arbitrary timing changes.

Innovation Solution

A synchronization control apparatus that calculates position command values for a driven shaft using a weighted average of values from a first and second cam curve during switch-over periods, with weights varying from 0 to 1 over time, allowing seamless switching of cam curves without delay.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a cam curve is switched in a position control system, then the position target value becomes discontinuous, causing vibration and impact, but if a higher-order curve is generated to maintain continuity, then complicated software processing is required and real-time calculation is disabled

Engineering Contradiction:
Improvesmoothness of cam curve switchingVSAvoidsoftware processing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system pre-calculates and stores position target values, velocity command values, and acceleration command values in memory before switching occurs. By preparing these values in advance and using a weighted average transition during switching, the system avoids complex real-time calculations while ensuring smooth transitions without vibration or impact.

Inventive Principle:
Principle #10Preliminary action

2Stability of the object's composition

If a higher-order curve is generated to maintain velocity continuity, then the derivative value becomes continuous, but then complicated software processing is required

Engineering Contradiction:
Improvecontinuity of velocity curveVSAvoidsoftware processing complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

Instead of generating complex higher-order curves, the system changes the parameter blending approach by using a weighted average of position target values from different cam curves. This method maintains velocity continuity through simple linear interpolation, avoiding the need for complex higher-order mathematical operations while achieving smooth transitions.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If pre-generated velocity curves are used to avoid discontinuity, then smooth switching is achieved, but then arbitrary timing switching is not possible and real-time calculation is disabled

Engineering Contradiction:
Improvecontinuity of position and velocityVSAvoidarbitrary timing switching capability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system dynamically calculates position target values, velocity command values, and acceleration command values at each control timing based on the current cam curve and a weighted average factor. This dynamic approach allows arbitrary timing switching while maintaining continuity, as the weighted average factor can be adjusted in real-time to ensure smooth transitions regardless of when switching occurs.

Inventive Principle:
Principle #15Dynamics

4Reliability

If a weighted average is used to transition between cam curves, then smooth switching is achieved, but then calculation complexity increases

Engineering Contradiction:
Improvesmoothness of cam curve transitionVSAvoidcalculation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system pre-calculates and stores position target values, velocity command values, and acceleration command values in memory before switching occurs. By preparing these values in advance and using a weighted average transition during switching, the system avoids complex real-time calculations while ensuring smooth transitions without vibration or impact.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2555068B1Synchronization control apparatus
Publication Date: 2016.06.01 OMRON CORP
  • EP2555068B1 patent drawingFigure 1
  • EP2555068B1 patent drawingFigure 2
  • EP2555068B1 patent drawingFigure 3

AI summary

The present invention provides a synchronization control apparatus capable of switching cam curves with ease and without delay. A cam curve storing unit 64 stores a first cam curve and a second cam curve. Before switch-over of the cam curves, a control unit 66 finds a position command value to a driven shaft, based on a value on the first cam curve at each control timing, after the switch-over of the cam curves, the control unit finds the position command value, based on a value on the second cam curve at each control timing, and in a switch-over period of the cam curves, the control unit finds the position command value to the driven shaft, based on a value obtained by subjecting first data based on the first cam curve or a position of the driven shaft, and second data based on the second cam curve to weighted average at each control timing.