Gyro Offset Calculation for Vehicle Movement Detection

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Solution Overview

Problem

Existing angular velocity calculating devices face challenges in accurately measuring offset values when a vehicle is stationary, especially at low speeds or when turning, leading to incorrect direction measurements and failure to detect vehicle stopping and starting, particularly in vehicles without speed sensors or those with insensible zones.

Innovation Solution

An angular velocity calculating device that determines the stationary range of gyro signals by detecting minimum and maximum values, updates this range at shorter intervals, and calculates an offset value based on average angular velocity signals stored before movement detection, preventing wrong offset values during low-speed travel or turning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a vehicle speed sensor is used to detect vehicle stopping and starting, then vehicle movement detection can be achieved, but the system cannot detect movement at low speeds due to the insensible zone of the sensor

Engineering Contradiction:

Improvevehicle movement detection accuracyVSAvoidlow-speed detection capability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent introduces an angular velocity sensor (gyro) as an intermediary device to detect vehicle movement. This sensor measures angular velocity directly without relying on wheel rotation, thereby eliminating the insensible zone problem of speed sensors at low speeds. The gyro signal serves as a mediator to detect both stopping and starting conditions across the entire speed range including very low speeds.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If offset values are calculated using average angular velocity signals during stationary periods, then offset cancellation can be performed, but wrong offset values are obtained when the vehicle starts to move with the steering wheel turned

Engineering Contradiction:

Improveoffset value accuracyVSAvoidstationary state detection reliability

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent implements a feedback mechanism where the angular velocity sensor continuously monitors vehicle state and provides feedback to the offset calculation unit. The system uses this feedback to dynamically adjust offset calculation timing, ensuring that offset values are only calculated when the vehicle is truly stationary and the steering wheel is not being turned, thereby preventing wrong offset values.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary detection of steering wheel position and vehicle motion state before initiating offset value calculation. By checking these conditions in advance, the system ensures that offset calculation is only performed under appropriate conditions (vehicle stationary, steering wheel not turning), preventing acquisition of incorrect offset values.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If the stationary range of angular velocity signals is updated at longer intervals, then system complexity is reduced, but accurate detection of vehicle stopping and starting is compromised

Engineering Contradiction:

Improvesignal processing complexityVSAvoidmovement detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements dynamic updating of the stationary range based on real-time angular velocity signal characteristics. The system continuously monitors the signals and adjusts the stationary range thresholds adaptively, allowing accurate detection of movement transitions while maintaining reasonable system complexity through event-driven updates rather than continuous recalibration.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables accurate detection of vehicle movement and offset calculation even without speed sensors, preventing measurement errors and ensuring correct direction detection by dynamically updating the stationary range and using stored average values as offset values.

Implementation Method 1

signals corresponding to an angular velocity output from a gyro installed on the vehicle

Methodology Applied

Scientific EffectGyroscope: Gyroscope

Data Source

PatentUS8131418B2Angular velocity calculating device, offset determination method for the same, and vehicle stopping detecting device

Publication Date: 2012.03.06 ALPINE ELECTRONICS INC

AI summary

Minimum and maximum values of an angular velocity signal output from a gyro while a vehicle is stationary are detected. A range of the angular velocity signal is set that is used to determine when the vehicle is stationary. When the angular velocity signal output from the gyro exceeds the range, the vehicle starts to move, offset values calculated within a set time from a movement start detection time are discarded, and an average angular velocity signal having been calculated and stored the set time before, is output as the offset value. Thus, even when the vehicle does not have a vehicle speed sensor, the stopping and starting of the movement of the vehicle can be accurately detected using the output signal from the gyro and the accurate offset value can be output.