Tire Pressure Monitor Wheel Position Estimation
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Solution Overview
Problem
Existing tire pressure monitoring devices face challenges in accurately determining the wheel position of a transmitter due to differences in rotation speeds among wheels during vehicle operation, leading to potential deterioration in detection accuracy when rotational position information is input discretely.
Innovation Solution
A tire pressure monitoring device that estimates the rotational position of the transmitter based on information received from the transmitter and wheel speed sensors, using a mechanism that includes a rotational position calculation unit to determine the wheel position by analyzing the dispersion characteristic value of rotational positions across multiple frames transmitted at different intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If rotational position information is input discretely at predetermined time intervals, then the device complexity is reduced, but the measurement precision of the transmitter's rotational position deteriorates
Solution Approach 1:
The patent introduces an intermediary estimation mechanism that uses received signal information as a mediator between the discrete rotational position inputs and the final position determination. The system estimates the transmitter's rotational position by combining discrete wheel rotational position information with received signal characteristics, rather than directly measuring the transmitter position continuously.
Solution Approach 2:
The system creates a computational model (copy) of the transmitter's rotational position based on discrete wheel position data and received signal information. Instead of directly measuring the transmitter position, the system generates an estimated position copy that is sufficiently accurate for wheel position determination while maintaining low device complexity.
2Device complexity
If the rotational position of the transmitter is not accurately detected, then the device complexity remains low, but the reliability of wheel position determination deteriorates
Solution Approach 1:
The system employs feedback by using the received signal information (which contains implicit positional data) to refine the estimation of the transmitter's rotational position. This feedback loop allows the system to improve position determination reliability without adding complex direct measurement devices, as the received signals themselves provide corrective information.
Solution Approach 2:
The received signal serves multiple functions: it provides both the pressure/identification data and implicit rotational position information. By extracting position information from the received signal's characteristics (timing, phase, or amplitude variations), the system achieves reliable position determination without dedicated position sensing hardware on the transmitter.
Data Source
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Figure 3(a)~3(b)
AI summary
The purpose of the present invention is to provide a tire air pressure monitoring device capable for accurately determining the wheel position of a transmitter. In order to achieve this object, the tire air pressure monitoring device comprises: a transmitter (2d) installed on each wheel (1) for transmitting detected air pressure information in a wireless signal; a rotational position detection mechanism (wheel speed sensor (8), ABSCU (6)) disposed on the vehicle body side corresponding to each wheel (1), and which detects the rotational position (wheel speed pulse) of each wheel (1) and also outputs rotational position information (count value of wheel speed pulse) to a communications line (CAN communications line (7)) at prescribed time intervals (ΔT0) (cycle 20 msec); and a vehicle body side rotation position estimation mechanism (rotation position calculation unit (4a)) that estimates the rotational position (number of teeth (zt2)) at the time of transmission (transmission command time (t2)) by the transmitters (2d), on the basis of the reception information (reception completion time (t4)) for the wireless signal from the transmitters (2d) and the rotation position information (input times (t1, t5), number of teeth (zt1, zt5)) for the wheels (1) input via the communications line (CAN communications line (7)).