Tractor-Trailer Coupling Detection Using High-Impedance Voltage Measurement
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Solution Overview
Problem
Current trailer telematics systems cannot accurately determine whether a trailer is decoupled from a tractor or if the tractor's ignition is simply switched off, leading to confusion and potential false disconnect/reconnect sequences during stops or when the tractor is shut off while connected.
Innovation Solution
A trailer-mounted system that uses a high-impedance power source and a voltage-measuring device to differentiate between the trailer's electrical loads alone and those of both the trailer and tractor, with a controller transmitting connect/disconnect information via a wireless link to manage fleet operations accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tractor's ignition is switched off while connected to a trailer, then the trailer has no way of determining whether the tractor has been decoupled or merely shut off, but this leads to confusion and potential false disconnect/reconnect sequences
Solution Approach 1:
The patent introduces a test switch as an intermediary component that activates a high-impedance power source in the trailer. This test switch bridges the information gap by enabling voltage measurement on the ignition line when the tractor ignition is off, allowing the trailer to distinguish between decoupling (voltage present) and ignition switch-off (voltage absent) scenarios without interfering with normal tractor operation.
Solution Approach 2:
The patent changes the electrical impedance parameter of the power source based on the operational state. During normal operation, the power source operates at low impedance to supply power to trailer loads. During testing when the tractor ignition is off, the power source switches to high impedance to measure voltage on the ignition line without drawing significant current, thereby enabling detection while minimizing interference.
2Measurement precision
If a high-impedance power source is used to measure voltage on the ignition line, then accurate coupling detection is achieved, but the system complexity increases
Solution Approach 1:
The high-impedance power source is designed to serve multiple functions: it provides normal power supply to trailer electrical loads during operation and enables voltage measurement on the ignition line during testing when the tractor ignition is off. This multi-functionality reduces the need for separate dedicated measurement equipment, thereby limiting the increase in system complexity while achieving accurate coupling detection.
Solution Approach 2:
The system dynamically adjusts the impedance of the power source based on operational conditions. The power source switches between low-impedance mode during normal power supply and high-impedance mode during voltage measurement. This dynamic adaptation allows the same component to perform different functions optimally, reducing overall system complexity compared to having separate dedicated components for each function.
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 accurate detection of coupling states between trailers and tractors, reducing false disconnect/reconnect sequences and improving remote monitoring efficiency by distinguishing between decoupling and ignition switch-off scenarios.
Implementation Method 1
a meter measures the voltage at the line, so that one voltage denotes only the electrical load in the trailer and thus a decouple, and another voltage denotes the electrical loads in both trailer and tractor and hence a coupling
Data Source
AI summary
To test whether a trailer is coupled to a tractor when the tractor ignition switch is off, a test switch in the trailer connects a high-impedance power source in a trailer to a line carrying energy from the tractor ignition switch to the trailer's electrical load, and measures the voltage at the line. A high voltage indicates a connection only to the electrical load in the trailer and thus a decouple. A low voltage indicates a measurement of the electrical loads in both trailer and tractor and hence a coupling.