Vehicle State Estimation Using Ground Contact Load Correction
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Solution Overview
Problem
Conventional techniques for calculating vehicle suspension stroke speed accuracy are compromised by vehicle design, particularly when the suspension angle is perpendicular to the road surface, leading to inaccuracies in determining vehicle state quantities.
Innovation Solution
A state quantity calculating device that includes a ground contact load calculating section, tire change amount calculating section, and state quantity calculating sections to accurately determine vehicle state quantities using ground contact load, tire change amounts, and vehicle models, along with input quantities from sensors like G sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the suspension angle is made perpendicular to the road surface for compact vehicle design, then the vehicle structure becomes more stable, but the accuracy of calculating suspension stroke speed decreases
Solution Approach 1:
The patent changes the calculation parameters from wheel speed-based longitudinal movement components to ground contact load-based tire deformation amounts. By using the relationship between ground contact load and tire deformation (Fz = kx), the system calculates suspension stroke speed through tire deformation rate, which remains accurate regardless of suspension angle. This parameter transformation resolves the contradiction by finding an alternative measurement approach that is insensitive to the perpendicular suspension angle condition.
2Device complexity
If conventional wheel speed-based calculation method is used, then the calculation process is simple, but the accuracy of state quantity calculation decreases when suspension angle is perpendicular
Solution Approach 1:
The patent substitutes the mechanical measurement approach (wheel speed sensors measuring longitudinal movement) with a load-based measurement approach (ground contact load sensors measuring tire deformation). This substitution replaces the mechanical system that relies on suspension angle geometry with a system based on force-deformation relationships, which are independent of suspension orientation. The ground contact load method provides accurate state quantity calculation without being affected by perpendicular suspension angles.
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
Enables highly accurate calculation of vehicle state quantities, enhancing vehicle stability control by improving the precision of suspension and braking force management.
Implementation Method 1
a ground contact load calculating section 610 that calculates a ground contact load that is a load acting in a vertical direction under a spring of the vehicle
Implementation Method 2
a tire change amount calculating section 670 that calculates a current amount of a change in a tire from the ground contact load, which is calculated by the ground contact load calculating section 610, and a spring constant gain of the tire
Data Source
AI summary
Realized is a technique of highly accurately calculating a state quantity of a vehicle. An ECU (600) of a vehicle (900) includes a ground contact load calculating section (610), an input quantity calculating section (620), a first state quantity calculating section (630), an observable calculating section (640), a second state quantity calculating section (650), and a damper ECU (660). The ECU (600) calculates a first state quantity of the vehicle (900) by inputting, into a vehicle model, a value calculated from a G sensor value and/or the like, and calculates a second state quantity of the vehicle (900) by correcting the first state quantity with use of an observable which is calculated from a ground contact load and a spring constant gain of a tire.