Automotive Motor Speed Control for Accurate Seat Positioning

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Solution Overview

Problem

Existing automotive seat control systems face challenges in accurately determining the true positioning of seats after power cut-off and motor rebound, leading to potential inaccuracies in seat positioning due to unmonitored current ripples and rotations.

Innovation Solution

A monitoring system that includes a bidirectional current sensor, band pass filter, and ripple detector to track current peaks and direction, allowing the controller to accurately determine the angular positioning of the seat by monitoring both primary and secondary current directions, even after power cut-off.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If power is cut-off to the motor after reaching desired position, then energy consumption is reduced, but motor rebound and unmonitored current ripples cause positioning inaccuracies

Engineering Contradiction:

Improveenergy consumptionVSAvoidseat positioning accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical monitoring methods with electrical signal analysis. By monitoring current ripple patterns and frequency characteristics after power cut-off, the system detects motor rebound and secondary movements without requiring additional mechanical sensors or continuous power supply, thus maintaining positioning accuracy while reducing energy consumption.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system implements feedback by continuously analyzing current ripple signals from the motor even after power cut-off. The controller processes these electrical signals to detect any position deviations caused by motor rebound, and can trigger corrective actions to maintain accurate seat positioning without sustained power input.

Inventive Principle:

Principle #23Feedback

2Measurement precision

If continuous power is supplied to the motor, then positioning accuracy is maintained, but energy consumption increases

Engineering Contradiction:

Improveseat positioning accuracyVSAvoidenergy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

Instead of continuous power supply, the system uses periodic current ripple analysis to monitor motor position. The controller periodically samples and analyzes the electrical characteristics of the motor current to detect position changes, enabling accurate monitoring with intermittent rather than continuous energy input.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The motor's own electrical characteristics (current ripples and frequency patterns) are used as the monitoring signal. The system leverages the natural electrical behavior of the motor during operation and idle states to detect position deviations, eliminating the need for separate sensing systems or continuous power supply for monitoring purposes.

Inventive Principle:

Principle #25Self-service

3Device complexity

If traditional pulse counting method is used to determine position, then device complexity is reduced, but positioning accuracy deteriorates due to unmonitored rebound after power cut-off

Engineering Contradiction:

Improvecontrol system complexityVSAvoidseat positioning accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical position sensing with electrical signal analysis. By analyzing the frequency and pattern of current ripples in the motor circuit, the system determines motor position and detects rebound movements without requiring complex mechanical sensors, encoders, or additional position feedback hardware.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The existing motor and current sensing circuitry serve dual functions: both driving the motor and monitoring its position. The same electrical signals used for motor control are also analyzed to detect position and rebound, eliminating the need for separate monitoring systems and maintaining simplicity while improving accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables precise tracking of seat positioning and direction, reducing inaccuracies and ensuring accurate determination of seat location by accounting for current ripples and rebound activities.

Implementation Method 1

a bidirectional current sensor, band pass filter, and ripple detector to track current peaks and direction

Methodology Applied

Scientific EffectElectrical current detection: Conduction (electrical)

Implementation Method 2

a bidirectional current sensor, band pass filter, and ripple detector to track current peaks and direction

Methodology Applied

Scientific EffectSignal filtering: Filter (electronic)

Data Source

PatentUS8193746B2Automotive electric motor speed control system

Publication Date: 2012.06.05 LEAR CORP

AI summary

An automotive electric motor speed control system may include at least one electric motor adapted to cause a moveable element to move, a DC/DC power converter configured to output a voltage to the at least one electric motor that increases to a desired value and subsequently decreases to control the movement of the moveable element, and a controller configured to control the rate of voltage increase and voltage decrease output by the converter.