Rotational Speed Sensor Duty Cycle Correction

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Solution Overview

Problem

Existing rotational speed sensors face challenges in accurately measuring wheel circumferential speed due to non-uniform scanning of incremental encoder wheels, leading to systematic measurement errors.

Innovation Solution

The method involves ascertaining time intervals between measurement events, estimating duty cycle values based on these intervals, correcting the time intervals to account for deviations from ideal values, and using these corrected intervals to determine rotational speed and movement variables.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If non-uniform scanning of incremental encoder wheel is used, then device complexity is reduced, but measurement precision deteriorates due to systematic measurement errors

Engineering Contradiction:

Improveencoder wheel scanning mechanismVSAvoidrotational speed measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent changes the parameter of time intervals by introducing correction factors based on estimated duty cycles. The corrected time intervals compensate for non-uniform scanning effects, thereby improving measurement precision without modifying the physical encoder wheel or scanning mechanism.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism where measured time intervals are used to estimate duty cycle values, which then generate correction factors that are applied back to the time intervals. This closed-loop approach continuously improves measurement accuracy by compensating for systematic errors.

Inventive Principle:

Principle #23Feedback

2Measurement precision

If duty cycle correction is applied, then measurement precision is improved, but device complexity increases due to additional calculation steps

Engineering Contradiction:

Improverotational speed measurement accuracyVSAvoidsignal processing algorithm

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies partial correction by estimating duty cycle values only for specific periods and applying corrections selectively. This approach improves measurement precision while avoiding the complexity of complete real-time correction for all possible variations in the encoder wheel scanning.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20250172581A1Method for asceryaining a rotational speed and/or a movement variable derived from a rotational speed, computer program product, computer device

Publication Date: 2025.05.29 ROBERT BOSCH GMBH

AI summary

A method for ascertaining a rotational speed and/or a movement variable derived from a rotational speed, in particular wheel circumferential speed, using a rotational speed sensor having a plurality of sensor elements and an incremental encoder wheel. Time intervals between temporally adjacent measurement events of the rotational speed sensor are ascertained, in particular continuously, wherein at least one estimated value for at least one duty cycle of a period including at least two of the measurement events, in particular a or a particular signal curve of the sensor elements, is ascertained depending on the ascertained time intervals. At least two of the time intervals are corrected depending on the estimated value, and the rotational speed and/or the movement variable are ascertained depending on the corrected time intervals.