Vehicle Seat Position Detection Using Motor Current Polarity
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Solution Overview
Problem
Existing vehicle seat devices face limitations in accurately determining the rotation direction of a motor after it stops, leading to errors in positional detection based on pulse edge counting.
Innovation Solution
A vehicle seat device that includes a motor, a controller, a rotation sensor, and a motor current sensor, where the controller counts pulse edges in the forward direction during motor operation and reverse direction after motor stoppage based on motor current polarity changes, to accurately determine the rotation direction and reduce positional detection errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reverse rotation is presumed based on rotation speed comparison after motor stopping, then error reduction in positional detection is achieved, but determination accuracy is limited due to presumptive nature
Solution Approach 1:
The patent replaces the mechanical/inertial-based reverse rotation detection method (comparing rotation speeds) with an electrical field-based method (detecting motor current polarity). The motor current sensor detects the polarity of current flowing through the motor windings, which directly indicates the rotation direction without relying on presumptive calculations or inertial characteristics. This substitution provides direct, reliable detection of rotation direction.
Solution Approach 2:
The patent introduces motor current polarity as an intermediary indicator to determine rotation direction. Instead of directly measuring rotation direction through complex speed comparisons, the system uses the polarity of motor current (a readily available electrical parameter) as a mediator that directly correlates with rotation direction. This intermediary provides a simple, accurate, and reliable means of determining whether the motor is rotating forward or in reverse.
2Adaptability or versatility
If pulse edge counting is performed without accurate rotation direction detection, then seat memory function can be implemented, but positional detection errors occur
Solution Approach 1:
The patent implements feedback by continuously monitoring motor current polarity during and after motor operation. The position detection unit uses this real-time polarity information to correctly interpret the direction of pulse edges from the rotation sensor. This feedback mechanism ensures that pulse counting accurately reflects the actual movement direction of the seat, enabling reliable seat memory functionality without positional detection errors.
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 approach improves the accuracy of rotation direction determination and reduces errors in positional detection by using motor current polarity changes to differentiate between forward and reverse inertial rotations, thereby enhancing the reliability of seat position memory functions.
Implementation Method 1
a motor current sensor that detects a motor current flowing through the motor
Implementation Method 2
a rotation sensor that outputs a pulse signal in which pulse edges appear in predetermined rotation cycles in synchronization with rotation of the motor
Data Source
AI summary
This vehicle seat device is equipped with a position detection unit which detects the movement position of a vehicle seat. The position detection unit is equipped with a forward direction counting unit and a reverse direction counting unit. The forward direction counting unit counts, in a forward direction, pulse edges during the driving of a motor and pulse edges during the time interval in which the motor current changes from a first polarity to a second polarity opposite to the first polarity due to driving of the motor being stopped. The reverse direction counting unit counts, in a reverse direction opposite to the forward direction, the pulse edges during the time interval in which the motor current changes from the second polarity to the first polarity after driving of the motor is stopped.