Three-Wheel Vehicle Electronic Stability System Control
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Solution Overview
Problem
Three-wheeled vehicles with two wheels in the front and one wheel in the rear face unique stability challenges due to differences in tire grip and wheel lift thresholds compared to four-wheeled vehicles, which existing electronic stability systems (ESS) do not adequately address, as they were primarily designed to simulate four-wheel behavior without considering these specific characteristics.
Innovation Solution
An ESS for three-wheeled vehicles that uses sensors to monitor longitudinal and lateral acceleration, determining if a precursory condition for wheel lift exists and if the tire grip threshold has been exceeded, and reduces longitudinal acceleration by a controlled amount to prevent wheel lift while maintaining traction, employing engine torque reduction and braking strategies to manage acceleration and stabilize the vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an existing electronic stability system (ESS) designed for four-wheeled vehicles is used on three-wheeled vehicles, then the vehicle stability is improved to some extent, but the system cannot adequately address the unique stability challenges of three-wheeled vehicles due to differences in tire grip and wheel lift thresholds
Solution Approach 1:
The patent modifies the ESS to specifically address three-wheeled vehicle characteristics by implementing different control strategies for the single rear wheel versus the two front wheels. The system calculates unique tire grip thresholds and wheel lift thresholds specific to each wheel position, allowing localized optimization of stability control rather than applying a uniform four-wheeled vehicle approach to all wheels.
Solution Approach 2:
The system changes key parameters including the calculation of tire grip thresholds (μ_max) and wheel lift thresholds specific to three-wheeled vehicle geometry. The control strategy adjusts brake force distribution and engine torque reduction based on these modified parameters, fundamentally altering how the ESS operates compared to four-wheeled vehicle systems.
2Reliability
If the ESS reduces longitudinal acceleration to prevent wheel lift, then vehicle stability is improved, but the acceleration capability of the vehicle is reduced
Solution Approach 1:
The system applies partial brake force to the rear wheel only when precursory conditions for wheel lift are detected, rather than continuously applying full brake force. The control strategy modulates brake force and engine torque reduction to the minimum necessary amount to prevent wheel lift, preserving acceleration capability while maintaining stability.
Solution Approach 2:
The ESS continuously monitors vehicle dynamics and detects precursory conditions for wheel lift before they occur. By identifying trends in lateral and longitudinal acceleration that precede wheel lift, the system can take preventive action through engine torque reduction and selective braking, allowing the vehicle to maintain higher acceleration levels without actually experiencing wheel lift.
3Reliability
If the ESS continuously monitors vehicle dynamics to detect precursory conditions for wheel lift, then stability control is improved, but the system complexity increases
Solution Approach 1:
The system implements continuous feedback monitoring of lateral acceleration and longitudinal acceleration to detect precursory conditions for wheel lift. The ESS processes this feedback in real-time and adjusts engine torque and brake force accordingly, creating a closed-loop control system that improves stability without requiring complex mechanical modifications.
Solution Approach 2:
The patent replaces complex mechanical stability control mechanisms with an electronic control system that uses sensors and processors to monitor vehicle dynamics and adjust engine torque and brake force. This electronic substitution simplifies the physical system while enabling more sophisticated and adaptive stability control compared to purely mechanical approaches.
Data Source
AI summary
A method for enhancing stability of a three wheel vehicle having a pair of front wheels and a single rear wheel, each of the wheels having a tire with a tire grip threshold. The method including deploying an electronic stability system (ESS) on the vehicle, providing the ESS with input from various vehicle sensors related to the longitudinal and lateral acceleration of the vehicle, causing the ESS to determine whether (i) a precursory condition indicative of a wheel lift exists and (ii) the tire grip threshold of any of the tires has been exceeded; and when a precursory condition indicative of a wheel lift exists and the tire grip threshold of none of the tires has been exceeded, causing the ESS to reduce the longitudinal acceleration of the vehicle by a first amount less than that which would cause the tire grip threshold of any of the tires to be exceeded.