Drivetrain Test System Independent Tire Vehicle Speed Control
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Solution Overview
Problem
Existing drive-train test systems fail to accurately simulate tire slipping behavior on slippery road surfaces due to treating tire and vehicle speeds as dependent parameters, leading to insufficient accuracy in replicating real-world slipping conditions.
Innovation Solution
A drive-train test system that treats tire and vehicle speeds as independent parameters, using a dynamometer, inverter, shaft torque detector, velocity sensor, tire speed calculation unit, vehicle speed calculation unit, and speed control device to calculate and control tire and vehicle speeds, allowing for precise simulation of slipping and gripping states through simultaneous equations and control maps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If vehicle speed is calculated by multiplying tire rotational speed by a constant (tire radius), then the calculation is simple, but tire slipping behavior cannot be simulated with sufficient accuracy
Solution Approach 1:
The patent segments the previously unified speed calculation into two independent calculations: tire speed (from rotational speed) and vehicle speed (from dynamic model). This allows each parameter to be controlled independently, enabling accurate simulation of slipping behavior where tire speed and vehicle speed diverge.
Solution Approach 2:
The patent transitions from a static relationship (vehicle speed = tire speed × radius) to a dynamic model where vehicle speed is calculated independently based on driving torque, resistance forces, and vehicle mass. This dynamic approach allows the system to accurately represent real-world slipping conditions.
2Device complexity
If tire speed and vehicle speed are treated as dependent parameters, then the control system is simple, but slipping behavior on slippery road surfaces cannot be reproduced
Solution Approach 1:
The control system is segmented into independent tire speed control and vehicle speed control modules. The tire speed calculation unit and vehicle speed calculation unit operate independently, allowing the system to reproduce slipping conditions while maintaining manageable control complexity through modular design.
Solution Approach 2:
The patent introduces a dynamic model as an intermediary that calculates vehicle speed based on physical parameters (mass, resistance coefficients, driving torque) rather than directly from tire speed. This intermediary layer enables accurate slipping simulation while keeping the control architecture organized and manageable.
3Reliability
If a single inertia amount is set corresponding to vehicle moment of inertia, then the test system can simulate gripping conditions, but slipping conditions on snowy or icy surfaces cannot be reproduced
Solution Approach 1:
The patent creates a universal control framework that can simulate multiple road surface conditions (gripping, slipping, snowy, icy) through a single dynamic model. By calculating vehicle speed independently from tire speed, the system becomes adaptable to various friction conditions without requiring separate inertia settings for each scenario.
Data Source
AI summary
Provided is a testing system for a drivetrain, the testing system capable of simulating the slip behavior of a tire. A testing system is provided with: tire speed calculation units; a vehicle speed calculation unit; vehicle driving torque calculation units which calculate vehicle driving torque values; and speed control devices which output command signals such that the deviations between command values and output values from encoders are eliminated, respectively. The tire speed calculation units calculate the tire speed values on the basis of tire driving torque values obtained by subtracting the vehicle driving torque values from output values from shaft torque meters, respectively, and the vehicle speed calculation unit calculates the vehicle speed value on the basis of the vehicle driving torque values.