Vehicle Path-Following Control Using a Forward Control Point
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Solution Overview
Problem
Conventional automatic carrier vehicle systems using magnetic tapes for navigation suffer from delays in steering, which can cause the vehicle to deviate from its target path, necessitating reduced speed to prevent path deviation.
Innovation Solution
A control method and system that measures lateral deviation using a magnetic unit and calculates a designated steered angle to correct the vehicle's path, allowing the vehicle to follow a target path more accurately by setting a control point at a different longitudinal position from the magnetic unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the vehicle speed is reduced to prevent path deviation, then the vehicle can maintain better path following accuracy, but the productivity and efficiency of the vehicle is reduced
Solution Approach 1:
The control point is positioned forward of the magnetic unit in the longitudinal direction, allowing the system to anticipate and correct path deviations before they occur. This predictive approach enables the vehicle to maintain higher speeds while still achieving accurate path following, as the steering corrections are applied proactively rather than reactively
Solution Approach 2:
The patent introduces a control point as an intermediary element between the magnetic unit and the actual vehicle position. This control point serves as a virtual reference that accounts for the vehicle's dynamics and steering response time, allowing the control system to optimize both path following accuracy and vehicle speed independently
2Productivity
If the vehicle speed is increased to improve productivity, then the efficiency is improved, but the vehicle may deviate from the target path due to steering delay
Solution Approach 1:
By positioning the control point forward of the magnetic unit, the system performs preliminary steering corrections before the vehicle actually deviates from the path. This allows higher operating speeds while maintaining path accuracy, as the control system anticipates deviations based on the vehicle's current trajectory and dynamics
Solution Approach 2:
The system continuously measures the deviation between the control point and the target path, and uses this feedback to dynamically adjust the steering angle. This closed-loop control enables the vehicle to maintain accurate path following even at higher speeds by constantly correcting for steering delays and lateral deviations
3Device complexity
If the magnetic unit is positioned at the rear of the vehicle, then the vehicle structure is simplified, but the controllability and path following performance is reduced
Solution Approach 1:
The control point acts as a virtual intermediary that decouples the physical position of the magnetic unit from the effective control position. Even when the magnetic unit is positioned at the rear for structural simplicity, the control point can be positioned forward to maintain optimal controllability and path following performance
Solution Approach 2:
The patent resolves the positioning conflict by moving from a single-point control model to a distributed control model where the control point exists in a different longitudinal position than the magnetic unit. This dimensional separation allows the system to optimize structural simplicity and controllability independently
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 approach enhances the vehicle's followability to the target path by accurately identifying and correcting lateral deviations, improving controllability and stability regardless of the magnetic unit's position, thus preventing path deviations without the need for reduced speed.
Implementation Method 1
a magnetic unit that measures a deviation in a lateral direction with respect to a magnetic marker disposed on a traveling road
Data Source
AI summary
A control method for causing a vehicle to travel along a target path with high followability includes: a process of measuring deviation in a lateral direction with respect to a magnetic marker; a process of obtaining vehicle azimuth; a process of calculating, for a control point set at a position different from a position of a magnetic unit in a longitudinal direction of the vehicle, deviation of a control point in the lateral direction with respect to the target path, based on the deviation in the lateral direction with respect to the magnetic marker and the vehicle azimuth; a process of calculating a designated steered angle as a control target of the steered angle for bringing the deviation of the control point in the lateral direction closer to zero; and a process of controlling the steered angle of a steered wheel by taking the designated steered angle as the control target.