Feedforward Steering Control for Rail Vehicles Under Speed Changes
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Solution Overview
Problem
Existing moving body control systems fail to accurately calculate feedforward steering angles when the vehicle accelerates or decelerates, as they only consider kinematics and not dynamics, leading to potential steering errors.
Innovation Solution
A moving body control device that calculates feedforward steering angles by combining kinematic and dynamic components, using bogie position, vehicle mass, velocity, and track curvature, along with curvature change rate, and incorporating bank angles to account for forces acting on the vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only kinematic calculation is used for feedforward steering angle, then the calculation is simple and stable for constant velocity travel, but the accuracy deteriorates when the vehicle accelerates or decelerates
Solution Approach 1:
The patent applies dynamics by incorporating dynamic components into the steering angle calculation. The feedforward steering angle is computed as the sum of a kinematic component (based on geometrical relationships) and a dynamic component (based on equations of motion that account for acceleration and deceleration). This allows the system to maintain high accuracy during velocity changes while keeping the calculation structure systematic and manageable.
Solution Approach 2:
The patent changes the calculation parameters from purely kinematic (position-based) to include dynamic parameters (velocity, acceleration, mass, moment of inertia). By introducing these additional parameters into the equation of motion, the system adapts to varying operational conditions and maintains accuracy across different travel states.
2Reliability
If feedforward steering is performed in advance using map information, then stable traveling is achieved at constant velocity, but steering accuracy deteriorates at track change points during acceleration or deceleration
Solution Approach 1:
The patent maintains preliminary action by pre-calculating the feedforward steering angle based on track information and vehicle state. However, it enhances this preliminary calculation by including dynamic components that anticipate the effects of acceleration and deceleration, allowing the steering to remain accurate even when conditions change at track points.
Solution Approach 2:
The patent combines feedforward steering with feedback control. The feedback component compensates for deviations from the desired trajectory, particularly at track change points where dynamic effects are most pronounced. This closed-loop approach ensures both stability during constant velocity travel and accuracy during velocity transitions.
Data Source
AI summary
A moving body control device for controlling a moving body, including an information acquisition unit that acquires moving body-specific information including a bogie position and a vehicle body mass, a moving body position, a moving body velocity, and track information including a curvature for each position of the track, and a feedforward steering angle calculation unit that calculates a steering angle by using the moving body-specific information, the moving body position, the moving body velocity, and the track information. The feedforward steering angle calculation unit calculates the steering angle according to a sum of a kinematic component calculated based on a geometrical relationship between the bogie position and the curvature of a track, and a dynamic component calculated based on an equation of motion including the bogie position, the vehicle body mass, the moving body velocity, and the curvature and a curvature change rate of the track.