Vehicle Suspension Control Using Roadhook Logic for Grip
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Solution Overview
Problem
Existing suspension control systems for motor vehicles, particularly those using Skyhook logic, fail to ensure adequate vehicle grip on the road, especially under heavy loads, and provide poor estimation of body speeds due to sensitivity to inclination and limited measurement of inertial stresses, leading to compromised comfort and reassurance for drivers.
Innovation Solution
Implementing Roadhook logic, which minimizes modal accelerations relative to the wheel plane, enhancing body handling and grip by processing body modes such as pumping, rolling, and pitching, and utilizing sensors and actuators to adjust damping laws dynamically based on real-time wheel travel and vehicle dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vertical accelerometers are used to measure body accelerations, then measurement is simplified, but measurement precision deteriorates under driver demands
Solution Approach 1:
The system uses wheel travel sensors as an intermediary measurement point. Instead of directly measuring body acceleration with accelerometers, it measures wheel travel and derives body speed information from this intermediate data, which is less affected by gravitational projection errors during driver demands.
Solution Approach 2:
The system replaces direct accelerometer-based mechanical measurement with a sensor-based measurement of wheel travel. This substitution eliminates the problem of gravitational projection affecting acceleration measurements during vehicle maneuvers.
2Reliability
If shock absorber flexibility is increased to promote comfort on bumps, then comfort is improved, but vertical force on tire decreases
Solution Approach 1:
The system dynamically adjusts shock absorber characteristics based on the selected control mode. In Roadhook mode, when grip is prioritized, the shock absorber operates to maintain vertical tire force by controlling relative motion between body and wheels, rather than allowing excessive flexibility that would reduce tire contact force.
Data Source
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AI summary
The invention relates to a device for controlling the suspension of the body shell of a motor vehicle. According to the invention, the device comprises: a means (31) for calculating a relative modal body shell speed (Vmod2) in relation to the mid-plane of the wheels, and a second means (34, 22) for calculating the set modal stress (cf2, c?2, Fz2) of the shock absorber as a function of the relative modal body shell speed (Vmod2) in relation to the mid-plane of the wheels. The control value (ER) comprises a determined shock absorption principle from among a plurality of different shock absorption principles (ER) that impose the force (FA) of the shock absorber as a function of the travel speed (VDEB) thereof.