Actuator Control for Lateral Force Reduction in Railroad Vehicles

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Solution Overview

Problem

Existing methods for reducing lateral forces on railroad vehicles do not effectively address fluctuating lateral forces caused by track irregularities, and lack specific methods for estimating lateral forces from track data or determining actuator thrust.

Innovation Solution

Installation of sensors in railroad vehicles to measure state quantities correlated with track irregularities, allowing for real-time control of an actuator thrust to separate and reduce both steady and fluctuating lateral forces without relying on pre-stored track data, by converting measured state quantities into control parameters using pre-set transfer functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If an actuator is operated based on radius of curvature to reduce steady lateral force, then steady lateral force is reduced, but fluctuating lateral force caused by track irregularities is not addressed

Engineering Contradiction:

Improvesteady lateral forceVSAvoidsafety against derailment

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The invention segments the lateral force into two distinct components: steady lateral force (related to curve radius) and fluctuating lateral force (caused by track irregularities). By separating these components, the control system can apply different control strategies to each, using radius of curvature for steady force reduction and state quantity measurements for fluctuating force reduction, thereby comprehensively addressing both aspects of lateral force management.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention implements feedback control by measuring state quantities (acceleration, speed, position) and using these measurements to determine actuator thrust. The control system continuously monitors the actual lateral force through sensors and adjusts the actuator output accordingly, creating a closed-loop control system that adapts to real-time conditions rather than relying solely on pre-stored track data.

Inventive Principle:

Principle #23Feedback

2Productivity

If track data is stored in advance for feed forward control, then lateral force estimation is possible, but erroneous control occurs due to measurement errors in travel location data

Engineering Contradiction:

Improvelateral force control responsivenessVSAvoidcontrol accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention replaces open-loop feed forward control based on pre-stored track data with closed-loop feedback control using real-time sensor measurements. By continuously measuring state quantities (acceleration, speed, position) and using these actual measurements to determine actuator thrust, the system eliminates errors associated with pre-stored track data and travel location measurement inaccuracies.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control system uses the railroad vehicle's own onboard sensors to measure state quantities and generate control commands, making the system self-sufficient rather than dependent on externally stored track data. The vehicle measures its own acceleration, speed, and position to determine the required actuator thrust, eliminating the need for pre-stored track irregularity data.

Inventive Principle:

Principle #25Self-service

3Force

If actuator thrust is increased to reduce lateral force, then lateral force reduction is achieved, but energy consumption increases

Engineering Contradiction:

Improvelateral force reductionVSAvoidactuator energy consumption

Core Design Contradiction:

ForceVSUse of energy by moving object

Solution Approach 1:

The invention applies partial action by determining actuator thrust based on the actual measured state quantities rather than applying maximum or excessive thrust continuously. The control system calculates the minimum necessary thrust required to reduce lateral force to an acceptable level, avoiding unnecessary energy consumption while still achieving the safety objective.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The invention dynamically changes the actuator thrust parameter based on real-time measurements of state quantities (acceleration, speed, position). Rather than maintaining constant high thrust, the system adjusts the thrust parameter according to actual operating conditions, reducing energy consumption when high lateral force reduction is not immediately necessary while maintaining safety when conditions require it.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3040251B1Method of decreasing lateral pressure in railroad vehicle

Publication Date: 2018.10.17 NIPPON STEEL CORPORATION

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Figure 3(a)~3(b)
Figure 4(a)~4(c)

AI summary

An actuator is installed between a vehicle body and a bogie frame of a railroad vehicle mounted with a bolsterless bogie, for example. Sensors are installed in at least one of the vehicle body, the bogie, and the wheelset. One or more parameters having a correlation with a steady lateral force are computed on the basis of state quantities obtained by using the sensors while traveling, to determine a thrust command value to be output to the actuator, by applying a predetermined transfer function to the computed value. Concurrently with determining the thrust command value, one or more parameters having a correlation with a fluctuating lateral force are computed to determine a thrust command value to be output to the actuator, by applying a predetermined transfer function to the computed value. These two thrust command values are combined to determine the thrust output to the actuator. It is possible to effectively reduce the maximum lateral force generated while traveling, thus making it possible to increase the maximum traveling speed.