Motor Unit Rotation Sensing With Backlash-Isolated Encoder Disc

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Solution Overview

Problem

Modular construction system motor units face issues with precise rotation sensing when asymmetric loads are applied, leading to incorrect encoder measurements due to encoder asymmetry.

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 a slight backlash between the receptacle and the first rotation transfer part to ensure accurate rotational position sensing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an encoder is used to sense rotational position with high precision, then measurement precision is improved, but the encoder becomes sensitive to asymmetric loads causing incorrect measurements

Engineering Contradiction:

Improverotational position sensing precisionVSAvoidencoder measurement reliability under asymmetric load

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

A disc element is introduced as an intermediary between the power outtake element and the encoder. The disc element rotates with the power outtake element and is detected by the encoder, serving as a mediator that isolates the encoder from direct exposure to asymmetric loads while still enabling precise rotational position sensing.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The rotation sensing system is segmented into separate functional components: the power outtake element, the disc element, and the encoder. This segmentation allows the encoder to sense rotation of the disc element without directly bearing the asymmetric loads applied to the power outtake element, thereby maintaining measurement reliability.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If the disc element is rigidly connected to the power outtake element, then rotational position sensing is direct, but asymmetric loads cause encoder measurement errors

Engineering Contradiction:

Improverotational position sensing precisionVSAvoidasymmetric load impact on encoder

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The disc element acts as a mediator that receives rotational motion from the power outtake element while isolating the encoder from harmful asymmetric loads. This intermediary approach allows the encoder to accurately sense rotation without being directly affected by load asymmetries.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful asymmetric loads are effectively extracted or separated from the encoder sensing path by introducing the disc element. The encoder only senses the rotational position of the disc element, while the asymmetric loads remain on the power outtake element, preventing measurement errors.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If a backlash is introduced between the receptacle and first rotation transfer part, then encoder accuracy under asymmetric load is improved, but mechanical connection precision is reduced

Engineering Contradiction:

Improveencoder measurement reliabilityVSAvoidmechanical connection precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The backlash is locally introduced only at the connection between the receptacle and the first rotation transfer part, while maintaining precise mechanical connections elsewhere in the system. This localized approach allows the encoder to accurately sense rotation without being affected by asymmetric loads, without compromising overall mechanical connection precision.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The clearance parameter between the receptacle and first rotation transfer part is specifically optimized to provide enough backlash to prevent asymmetric load transmission to the encoder, while maintaining sufficient mechanical connection precision for reliable rotational position sensing.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12494694B2Modular construction system motor unit

Publication Date: 2025.12.09 LEGO AS

AI summary

A construction system motor unit comprising a casing, an electrical motor mounted therein, a power outtake element having a connector, and being rotationally connected relative to said casing, a gearing mechanism provided between the electrical motor and the power outtake element, and a sensor to sense the position of the power outtake element relative to the casing, the sensor having a disc element and a sensor device, the disc element is connected to the power outtake element or to a gear of the gearing mechanism via a first rotation transfer part and a receptacle for receiving the first rotation transfer part, which receptacle is formed in the power outtake element or in said gear of the gear mechanism, and wherein the receptacle and the first rotation transfer part have cooperating shapes and sizes configured to allow a backlash between the power outtake element and the first rotation transfer part.