Dual-Motor Vehicle Wheel Off-Ground Detection via Angular Acceleration
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Solution Overview
Problem
Existing control devices for vehicles with electric motors lack accurate determination methods for wheel slippage and off-ground states, particularly due to uncertainty in threshold values for slippage and wheel off-ground determination.
Innovation Solution
A control device for vehicles with two electric motors that calculates required torque values, equivalent moments of inertia, and estimated angular accelerations to accurately determine the off-ground state of wheels by comparing actual angular accelerations with these estimates, utilizing a power distribution mechanism to amplify torque differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed threshold value is used for slippage determination, then the control device is simple to operate, but the determination accuracy is insufficient under varying driving conditions
Solution Approach 1:
The patent implements dynamic threshold adjustment by calculating the angular acceleration threshold in real-time based on current driving conditions (vehicle speed, acceleration, wheel rotation speed). This allows the threshold to adapt to varying operating conditions rather than using a fixed value, thereby improving determination accuracy without requiring complex additional hardware
Solution Approach 2:
The patent changes the parameter used for threshold determination from a fixed constant to a dynamically calculated value based on multiple measured parameters (vehicle speed, acceleration, wheel rotation speed). This parameter transformation enables the system to maintain high accuracy across different driving conditions while keeping the control algorithm computationally manageable
2Measurement precision
If the determination threshold is adjusted to improve accuracy, then the off-ground state detection becomes more precise, but the control system complexity increases
Solution Approach 1:
The patent performs preliminary calculations of the angular acceleration threshold based on pre-established relationships between vehicle parameters and off-ground conditions. By pre-defining the calculation methodology and required parameters, the system achieves accurate real-time determination without requiring complex adaptive algorithms during operation
Solution Approach 2:
The patent introduces angular acceleration as an intermediary parameter that mediates between directly measurable quantities (wheel rotation speed, vehicle speed) and the target determination (off-ground state). This intermediary enables accurate detection through a physically meaningful intermediate step that simplifies the overall determination logic
3Reliability
If conventional slippage control is applied without accurate off-ground detection, then the control response is fast, but the slippage suppression effectiveness is reduced
Solution Approach 1:
The patent implements feedback-based off-ground detection by continuously monitoring wheel angular acceleration and comparing it against dynamically calculated thresholds. This feedback mechanism provides reliable detection of off-ground conditions, enabling the control system to adjust its response appropriately while maintaining timely reaction to actual wheel states
Data Source
AI summary
A control device (10) for a vehicle (1) equipped with two electric motors (2) includes: a first calculation unit (11) that calculates a required torque value of each of left and right axles (4L, 4R); a second calculation unit (12) that calculates an equivalent moment of inertia of each of the left and right axles (4L, 4R); a third calculation unit (13) that calculates an estimated angular acceleration of each of left and right wheels (5) based on the two required torque values calculated by the first calculation unit (11) and the two equivalent moments of inertia calculated by the second calculation unit (12); and a determination unit (14) that compares actual angular accelerations of the left and right wheels (5) with the estimated angular accelerations calculated by the third calculation unit (13) to perform off-ground determination for each of the left and right wheels (5).