Motor Unit Encoder Coupling for Asymmetric Load Accuracy

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Solution Overview

Problem

Modular construction system motor units face challenges in maintaining precise rotation sensing when asymmetric loads are applied, leading to incorrect encoder measurements and compromised control of rotation.

Innovation Solution

A modular construction system motor unit with a rotation sensing mechanism that includes a disc element connected to the power outtake element via a first rotation transfer part, allowing for backlash between the power outtake element and the rotation transfer part, ensuring precise rotation sensing even under asymmetric loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a motor unit with encoder is used for precise rotation control, then rotation control precision is improved, but measurement accuracy deteriorates when asymmetric loads are applied

Engineering Contradiction:
Improverotation control precisionVSAvoidencoder measurement accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

A rotation transfer element is introduced as an intermediary between the power outtake element and the encoder. This rotation transfer element has a rotationally symmetric shape that decouples the asymmetric load on the power outtake element from the encoder, allowing the encoder to measure rotation accurately without being affected by the asymmetric load on the power outtake element.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the power outtake element is directly connected to the encoder, then device complexity is reduced, but measurement precision deteriorates under asymmetric loads

Engineering Contradiction:
Improveconnection structure simplicityVSAvoidrotational position measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The rotation transfer element serves as a simple intermediary component with a rotationally symmetric connection interface. This adds minimal complexity to the overall structure while effectively solving the measurement accuracy problem by isolating the encoder from asymmetric loads on the power outtake element.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If a rotation transfer part with backlash is used, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improverotational position sensing accuracyVSAvoidrotation sensing mechanism complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The rotation transfer element is a simple rotationally symmetric component that acts as a mediator between the power outtake element and the encoder. The backlash in the connection is intentionally designed to allow the rotation transfer element to float freely, ensuring that only pure rotational motion is transmitted to the encoder without asymmetric load interference, thereby improving measurement precision with minimal added complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4313341B1Modular construction system motor unit
Publication Date: 2024.12.18 LEGO AS
  • EP4313341B1 patent drawingFigure 1A
  • EP4313341B1 patent drawingFigure 1B~1C
  • EP4313341B1 patent drawingFigure 2

AI summary

A modular construction system motor unit (1) for a modular construction system (500), the motor unit comprising - a casing (10) - an electrical motor (150) mounted in the casing (10) - a power outtake element (20) having at least one connector (600) for connecting to a construction element (501, 502, 503), and being rotationally connected relative to said casing (10) about a rotational axis, - a gearing mechanism (200) provided between the electrical motor (150) and the power outtake element (20); and - a rotation sensing mechanism configured for sensing the rotational position of the power outtake element relative to the casing (10), wherein the rotation sensing mechanism comprises a disc element (99) rotating with the power outtake element (20) and a sensor device (399) being fixed relative to the casing, wherein the disc element (99) is connected to the power outtake element (20) or to a gear of the gear mechanism (200) via a first rotation transfer part (50) being fixedly connected to the disc element (99) and a receptacle (60) for receiving the first rotation transfer part (50), which receptacle (60) is formed in the power outtake element (20) or in said gear of the gear mechanism (200), and wherein the receptacle (60) and the first rotation transfer part (50) have cooperating shapes and sizes configured to allow a backlash between the power outtake element (20) and the first rotation transfer part (50).