Multi-Motor Command Scaling for Mixed Precision Control

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Solution Overview

Problem

When multiple motors with different controlled variable units are connected via the same network, they often misunderstand the motor controlled variables, leading to operational issues due to inconsistent units, resulting in either poor precision or excessively high precision.

Innovation Solution

A multi-motor system where each motor unit receives a command with position-designating data that specifies the radix point within the control data, allowing the control circuit to extract and generate control signals tailored to the motor's specific units, ensuring appropriate precision for each motor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a unified communication rule is used for all motors on the same network, then communication simplicity is improved, but measurement precision deteriorates because different motors have different controlled variable units

Engineering Contradiction:
Improvecommunication simplicityVSAvoidcontrolled variable precision
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent applies local quality by allowing each motor to have its own specific data format configuration for controlled variables while maintaining a unified communication protocol. Each motor unit can independently set the number of bits for integer and fractional parts according to its specific control precision requirements, thus achieving both communication simplicity and appropriate measurement precision for each motor.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If the fractional part bits are increased for all motors, then measurement precision is improved, but device complexity increases due to inconsistent data formats

Engineering Contradiction:
Improvecontrolled variable precisionVSAvoiddata format complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements dynamics by making the data format configuration adjustable and adaptable for each motor unit. The system allows dynamic configuration of bit allocation for integer and fractional parts based on each motor's specific requirements, rather than using a fixed uniform format. This enables the system to adapt to different precision needs without increasing overall complexity.

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If different data formats are used for different motors, then measurement precision is improved for each motor, but ease of operation deteriorates due to communication inconsistencies

Engineering Contradiction:
Improvecontrolled variable precisionVSAvoidcommunication ease
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent applies universality by designing a communication protocol that can handle multiple data formats within a single unified framework. The protocol is multi-functional, capable of accommodating different bit allocations for integer and fractional parts while maintaining consistent communication rules. This allows each motor to use its optimal data format without creating communication inconsistencies.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3562027B1Multi-motor system
Publication Date: 2024.02.21 NIDEC CORP(JP)
  • EP3562027B1 patent drawingFigure 1A
  • EP3562027B1 patent drawingFigure 1B
  • EP3562027B1 patent drawingFigure 2

AI summary

A multi-motor system (103) includes a plurality of motor units (106A) and (106B). The motor unit (106A) includes: a motor (116A); a communication circuit (110A) to receive a command (12A) which is transmitted from outside; a control circuit (112A) to generate a control signal for rotating the motor with a controlled variable that is designated by the command (12A) ; and a motor driving circuit (114A) to flow a current in the motor based on the control signal. The command (12A) includes: control data (C1) indicating the controlled variable of the motor in fixed data length, the controlled variable being expressed at least with an integer; and position-designating data (A1) designating a position of the radix point in the control data. The position-designating data (A1) is independently determined for each motor unit.