Numerical Controller Dynamic Time Constant for Multi-Axis Jerk Control

Solution Overview

Problem

Conventional numerical controllers fail to dynamically adjust the time constant for acceleration and deceleration filters during multi-axis operations, leading to increased cycle times and inadequate jerk control, as they maintain a constant time constant across all axes regardless of varying jerk and acceleration ratios, resulting in suboptimal performance and increased computational costs.

Innovation Solution

A numerical controller that dynamically adjusts the time constant based on the travel direction of a control target by using a command analysis unit to identify travel directions, a time constant calculation unit to calculate optimal time constants, and a time constant setting unit to set and gradually change the time constant for filter processing, ensuring the minimal time constant required is used for each axis, thereby reducing cycle times and preventing shocks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If a large time constant is used to suppress jerk, then the jerk is reduced, but the cycle time increases

Engineering Contradiction:

ImprovejerkVSAvoidcycle time

Core Design Contradiction:

Object-generated harmful factorsVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the time constant adjustable and switchable based on operational conditions. The controller dynamically changes the time constant value according to the current axis and operational state, transitioning from a fixed time constant to a dynamic one that adapts to different scenarios, thereby resolving the contradiction between jerk suppression and cycle time optimization

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements local quality by assigning different time constant values to different axes based on their specific characteristics. Each axis can have its own optimized time constant, allowing the system to apply appropriate jerk suppression locally to each axis rather than using a uniform time constant globally, thus optimizing both jerk control and cycle time

Inventive Principle:

Principle #3Local quality

2Reliability

If the maximum time constant is used for all axes, then jerk control is adequate for all axes, but the cycle time increases for axes that require smaller time constants

Engineering Contradiction:

Improvejerk controlVSAvoidcycle time

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by assigning different time constant values to different axes based on their specific characteristics. Each axis can have its own optimized time constant, allowing the system to apply appropriate jerk suppression locally to each axis rather than using a uniform time constant globally, thus optimizing both jerk control and cycle time

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements parameter changes by varying the time constant value based on the current axis and operational state. The controller switches between different time constant parameters (first time constant for normal operation, second time constant for specific conditions), allowing optimization of both jerk control and cycle time by selecting the appropriate parameter for each situation

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a time constant filter is applied to prevent shocks, then the servo control system is protected, but the acceleration response becomes slower

Engineering Contradiction:

Improveshock preventionVSAvoidacceleration response

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent applies dynamics by making the time constant adjustable and switchable based on operational conditions. The controller dynamically changes the time constant value according to the current axis and operational state, transitioning from a fixed time constant to a dynamic one that adapts to different scenarios, thereby resolving the contradiction between jerk suppression and cycle time optimization

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by varying the time constant value based on the current axis and operational state. The controller switches between different time constant parameters (first time constant for normal operation, second time constant for specific conditions), allowing optimization of both jerk control and cycle time

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10248103B2Numerical controller dynamically switching time constant for acceleration and deceleration filter

Publication Date: 2019.04.02 FANUC LTD

AI summary

A numerical controller looks ahead and analyzes commands indicated by a block contained in a program, and identifies a travel direction of a control target for each of the commands to calculate a time constant based on the identified travel direction. The numerical controller then sets a time constant for filter processing based on the time constant for each of the commands, and performs filter processing on command data subjected to a linear acceleration and deceleration process, based on the set time constant. The numerical controller then calculates movement of each axis for each interpolation period, based on the command data subjected to the filter processing.