Traction Control Apparatus for Construction Vehicles
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Solution Overview
Problem
Existing traction control systems for all-wheel-drive vehicles, particularly construction vehicles like dump trucks, face challenges in accurately estimating vehicle speed on irregular ground, leading to errors in driving force control due to changing road conditions and wheel states, resulting in inappropriate braking and driving force adjustments.
Innovation Solution
A traction control apparatus that includes a vehicle speed estimator, a driving-force controller, and a state determiner to balance estimated vehicle speed with actual speed, using rotation speed detectors and articulate angle sensors to adjust thresholds and elapsed times for determining slip ratios and braking control amounts, thereby correcting driving-force control and preventing accumulation of errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If acceleration integration is used to estimate vehicle speed, then vehicle speed can be estimated without additional sensors, but acceleration errors accumulate over time causing large estimation errors
Solution Approach 1:
The patent implements a feedback mechanism where the estimated vehicle speed is continuously monitored against actual wheel rotation data. When the vehicle maintains a substantially constant speed, the system uses wheel rotation information to correct accumulated acceleration integration errors, thereby maintaining estimation accuracy without requiring additional sensors.
Solution Approach 2:
The system dynamically changes estimation parameters based on vehicle operating conditions. When constant speed conditions are detected, the system switches from pure acceleration integration to a hybrid method incorporating wheel rotation data, effectively adjusting the estimation approach to minimize errors under different conditions.
2Productivity
If the estimated vehicle speed is used for driving-force control, then traction can be controlled, but errors in estimation lead to inappropriate braking and driving force adjustments
Solution Approach 1:
The patent uses feedback by continuously comparing the estimated vehicle speed with actual wheel rotation speeds. When discrepancies indicate estimation errors, the system adjusts the driving-force control accordingly, ensuring reliable traction control even when initial speed estimates are inaccurate.
Solution Approach 2:
The control system dynamically adjusts driving-force control parameters based on the detected balance state between estimated speed and actual wheel rotation. The system transitions between different control modes depending on whether the vehicle is accelerating, decelerating, or maintaining constant speed, thereby maintaining control accuracy under varying conditions.
3Ease of operation
If a predetermined deviation threshold is used to determine slip convergence, then control decisions can be made, but it cannot accommodate changing road conditions and wheel states
Solution Approach 1:
The patent makes the slip convergence determination dynamic by considering both the predetermined deviation threshold and the current vehicle operating state. The system adjusts its sensitivity to slip conditions based on whether the vehicle is accelerating, decelerating, or maintaining constant speed, allowing it to adapt to changing road conditions while maintaining straightforward control logic.
Solution Approach 2:
The system changes the effective threshold parameters based on vehicle conditions. When constant speed conditions are detected, the system uses different convergence criteria compared to accelerating or decelerating conditions, allowing adaptable response to changing road and wheel states while maintaining simple control decision-making.
Data Source
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AI summary
An object of the invention is to provide a traction control apparatus capable of suitably controlling an error, if it occurs, between an estimation of a vehicle speed and an actual vehicle speed. A traction control apparatus according to the invention includes a vehicle speed estimator and a driving-force controller (84). The traction control apparatus includes a vehicle state determiner (815) that determines whether the vehicle speed of the construction vehicle estimated by the vehicle speed estimator and the driving-force control by the driving-force controller (84) are balanced, and a driving-force control changer (816) that changes a driving-force control by the driving-force controller (84) when the vehicle state determiner (815) determines the vehicle speed and the driving-force control to be unbalanced.