Motion Sensor Power Control for Accurate Step Counting

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Solution Overview

Problem

Portable electronic devices with integrated motion sensors, such as pedometers, inaccurately count steps when the user is riding in a vehicle due to vehicle motion, leading to false activity detection.

Innovation Solution

The motion sensor is disabled by disconnecting power or commanding algorithms to ignore sensor output when the device is connected to an external power source, preventing false step counting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the motion sensor is continuously enabled to track user activity, then activity monitoring capability is improved, but false step detection occurs when the device is carried in a moving vehicle

Engineering Contradiction:

Improveaccuracy of step countingVSAvoidfalse step detection

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system preemptively disables the motion sensor when it detects the device is placed in a pocket or bag, preventing false step detection before it occurs. This is achieved by monitoring acceleration patterns that indicate the device is not being worn on the body, and automatically suspending step counting during these periods

Inventive Principle:

Principle #9Preliminary anti-action

2Object-affected harmful factors

If the motion sensor is disabled to prevent false step detection, then false activity detection is reduced, but activity monitoring capability is lost

Engineering Contradiction:

Improvefalse step detectionVSAvoidactivity monitoring capability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The motion sensor's operational state is dynamically adjusted based on real-time detection of device location and usage context. The system transitions between enabled and disabled states according to whether the device is detected in a wearable position or stored in a pocket/bag, optimizing both accuracy and functionality

Inventive Principle:

Principle #15Dynamics

3Ease of operation

If the motion sensor operates in all conditions, then convenience is improved, but measurement precision deteriorates due to vehicle motion interference

Engineering Contradiction:

Improvecontinuous activity trackingVSAvoidstep counting accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system uses feedback from acceleration sensor data to determine whether the device is being worn or stored, and automatically adjusts motion sensor operation accordingly. This closed-loop control ensures accurate step counting only when the device is in a wearable position while maintaining user convenience

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS7608050B2Motion detector for a mobile device

Publication Date: 2009.10.27 SONY GROUP CORP

AI summary

A portable electronic device comprises a motion sensor to detect motion and to generate motion data, and an activity monitor to detect user activity based on said motion data. A power detection circuit detects connection of said portable electronic device to an external supply power. A control circuit monitors the output signal from the detection circuit and prevents activity detection by said activity monitor while said portable electronic device is connected to said power supply.