Wheel-Rail Friction Measurement Using Torque Feedback Control
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Solution Overview
Problem
Current methods for determining wheel-rail frictional engagement in rail vehicle technology lack precision, leading to inaccuracies in driving behavior and efficiency.
Innovation Solution
A method using a control loop to calculate rotational acceleration and speed by combining vehicle-side torque and frictional engagement torque, with a PID controller to adjust and recalculate torque values, providing a precise measurement of frictional engagement between the wheel and rail.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to determine wheel-rail frictional engagement, then the measurement process is simple, but the measurement precision is insufficient
Solution Approach 1:
The patent implements a control loop that continuously compares the measured rotational speed with the calculated expected rotational speed and adjusts the frictional engagement torque value accordingly. This feedback mechanism minimizes measurement deviations and maintains high measurement precision throughout the measurement process.
Solution Approach 2:
The system performs preliminary calculations of the expected rotational speed based on vehicle-side torque and moment of inertia before comparing it with actual measurements. This allows the system to anticipate the correct value and adjust measurements in real-time, improving precision before errors accumulate.
2Measurement precision
If a control loop with PID controller is implemented to improve measurement precision, then measurement accuracy improves, but the ease of operation decreases
Solution Approach 1:
The control loop operates autonomously, automatically adjusting the frictional engagement torque value based on the difference between measured and expected rotational speeds. The system serves itself by continuously self-correcting without requiring manual intervention, maintaining high precision while simplifying operation through automation.
3Measurement precision
If multiple torque values and calculations are used to determine frictional engagement, then measurement precision improves, but the loss of time increases
Solution Approach 1:
The control loop operates continuously during the measurement process, constantly updating the frictional engagement torque value and comparing it with expected values. This continuous operation eliminates the need for separate measurement phases, reducing total measurement time while maintaining high precision through ongoing adjustments.
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 method enables precise determination of wheel-rail frictional engagement, minimizing measurement deviations and improving driving behavior by accurately adjusting driving and braking parameters.
Implementation Method 1
the difference between the rotational estimated value and the rotational measurement value is supplied to a control facility which outputs a controller output value at the output side, the frictional engagement torque value is recalculated with the controller output value and is coupled back into the calculation module to close the control loop
Implementation Method 2
by means of a calculation module and using the vehicle-side torque value and a frictional engagement torque value which describes a frictional engagement torque acting on the rotational part on the rail side, a rotational acceleration of the rotational part and thereby the expected rotational speed of the rotational part is calculated
Data Source
AI summary
A method for measuring a parameter relevant to a journey of a rail vehicle. A parameter measurement value is determined using a control loop. A vehicle-side torque acting on a rotational part on the vehicle side is ascertained. A calculation module uses the vehicle-side torque value and a frictional engagement torque acting between the rotational part and a rail, to calculate a rotational acceleration of the rotational part and an expected rotational speed. A difference between the rotational estimated value and an actual rotational speed is supplied to a control device which outputs a controller output value at the output side. A frictional engagement torque value is recalculated with the controller output value and is coupled back into the computer module to close the control loop. The controller output and/or the recalculated frictional engagement torque value is considered the parameter measurement value, which is stored or output.