Two-Wire Adapter Circuit for Mass Transit Door Presence Sensing
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Solution Overview
Problem
Existing passenger presence sensing circuits in mass transit vehicles face space limitations due to the need for multiple electrical conduits, which complicates the signaling of passenger presence at vehicle doors.
Innovation Solution
A two-wire adapter circuit with a current shunt monitor and sensing circuit is used to detect abrupt changes in current, generating a defined digital signal on a third wire, allowing for efficient passenger presence detection using a two-wire electrical conduit connected to a voltage regulator with a shunt resistor, enabling effective communication with vehicle control computers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple electrical conduits are used for power supply and signaling, then reliable passenger presence detection is achieved, but space requirements and circuit complexity increase
Solution Approach 1:
The patent combines power supply and signaling functions into a single two-wire electrical conduit. The adapter circuit monitors current draw through a shunt monitor on the two-wire conduit and generates digital signals based on detected current changes, eliminating the need for separate power and signal conduits while maintaining reliable passenger presence detection
Solution Approach 2:
The two-wire electrical conduit serves multiple functions simultaneously: it provides power supply to the remote sensor circuit and carries signaling information for passenger presence detection. The adapter circuit enables this multi-functionality by monitoring current characteristics and generating digital output signals through the same conduit used for power delivery
2Reliability
If multiple electrical conduits are used for power supply and signaling, then reliable passenger presence detection is achieved, but space constraints in door areas are violated
Solution Approach 1:
The patent merges power supply and signaling functions into a single two-wire electrical conduit that passes through the limited space along the hinged edge of the door. This consolidation reduces the physical space required for conduit installation while maintaining reliable passenger presence detection capabilities
Solution Approach 2:
The two-wire electrical conduit performs multiple functions (power delivery and signaling) simultaneously, reducing the number of separate conduits needed and thereby minimizing the space required in the constrained door area where conduits must be routed
3Area of stationary object
If a two-wire adapter circuit is used to reduce space requirements, then space constraints are satisfied, but additional circuit components are introduced
Solution Approach 1:
The adapter circuit acts as an intermediary device that receives power through the two-wire conduit, monitors current draw using a shunt monitor, and generates digital output signals. This intermediary circuit enables the two-wire configuration to perform both power delivery and signaling functions, accepting the added circuit components as necessary for achieving space efficiency
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 addresses space constraints and ensures reliable passenger presence signaling, providing a clear digital input to vehicle control systems while minimizing circuit complexity and space requirements.
Implementation Method 1
A two-wire electrical conduit connects a power supply to a load via a current shunt monitor
Implementation Method 2
A circuit is provided for sensing an abrupt change in the output of the current shunt monitor due to a change in the current drawn by the load
Implementation Method 3
A two-wire electrical conduit connects a power supply to the voltage regulator of the remote circuit via a resistor in parallel with the current shunt monitor
Implementation Method 4
The sensing circuit in the remote circuit connects the output of the voltage regulator to a shunt resistor to place an additional drain on the voltage regulator upon detection of a sensed condition
Implementation Method 5
an electric field-sensing circuit for sensing the presence of a passenger at a mass transit vehicle door, including a circuit having a voltage regulator and circuit for sensing the change in capacitance in an ac electric field
Data Source
AI summary
A two-wire adapter circuit comprises a current shunt monitor and a circuit for sensing an abrupt change in the output of the current shunt monitor, a power supply, and a two-wire electrical conduit connecting the power supply to a load via the current shunt monitor, the circuit for sensing the abrupt change in the output of the current shunt monitor configured to output a defined digital signal on a third wire upon sensing the abrupt change.