Vehicular Turning Control Torque Limiting
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Solution Overview
Problem
Existing vehicular turning control systems face instability and inaccurate yaw moment control due to delayed estimation of road surface frictional coefficients and deviations between estimated and actual coefficients, leading to potential vehicle instability and suboptimal turning performance.
Innovation Solution
A vehicular turning control system that includes a yaw moment control device and a vehicle attitude stabilization control device, which calculate and adjust braking/driving torques for each wheel based on vehicle speed, steering angle, slip rates, and angular acceleration to stabilize vehicle attitude and optimize turning performance, using torque limiters to prevent tire slip and adjust torques according to predetermined threshold conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If road surface frictional coefficient is estimated using acceleration sensor, then vehicle stability control can be implemented, but estimation is delayed causing vehicle instability
Solution Approach 1:
The system calculates wheel slip rates and angular accelerations continuously in advance, so that when yaw rate deviation exceeds the threshold, the torque limitation is immediately applied without waiting for delayed friction coefficient estimation. This preliminary calculation of wheel parameters enables immediate control response.
Solution Approach 2:
The patent introduces wheel slip rate and angular acceleration as intermediary parameters that directly indicate tire grip status. These intermediaries provide real-time feedback about actual tire-road interaction, replacing the delayed friction coefficient estimation and enabling immediate torque adjustment.
2Reliability
If yaw moment control is applied based on delayed friction coefficient estimation, then vehicle attitude control can be achieved, but control accuracy deteriorates
Solution Approach 1:
The system continuously monitors actual yaw rate and compares it with target yaw rate. When the deviation exceeds the threshold, this feedback triggers immediate torque limitation based on pre-calculated wheel slip rates and angular accelerations, eliminating the need for accurate friction coefficient estimation.
Solution Approach 2:
The patent replaces the mechanical estimation system (acceleration sensors estimating friction coefficient) with a direct wheel parameter monitoring system that calculates slip rates and angular accelerations from wheel speed sensors, providing more accurate and immediate control signals.
3Speed
If braking/driving torque is applied without torque limitation, then turning response is improved, but tire slip occurs reducing control effectiveness
Solution Approach 1:
The torque limitation thresholds are dynamically adjusted based on real-time wheel slip rates and angular accelerations. The system calculates maximum permissible torques that adapt to current tire grip conditions, enabling optimal turning response without exceeding tire adhesion limits.
Solution Approach 2:
The patent changes the control parameter from fixed torque values to dynamic torque limitations based on wheel slip rate and angular acceleration. This parameter adaptation allows the system to maintain tire grip while achieving rapid turning response by adjusting torque limits according to actual wheel behavior.
Data Source
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AI summary
Provided is a vehicular turning control system that enables immediate stabilization of the vehicle attitude and optimum control for the vehicle turning performance. This vehicular turning control system includes a yaw moment control device (14), a vehicle attitude stabilization control device (15), and a torque limiting device (32). A first torque limiter (32a) of the torque limiting device (32) limits a braking/driving torque calculated by a yaw moment controller (28), in accordance with the slip rate of the wheel (2) and the angular acceleration of the wheel (2). A second torque limiter (32b) of the torque limiting device (32) limits a braking/driving torque calculated by a vehicle attitude stabilization controller (31), in accordance with the slip rate of the wheel (2) and the angular acceleration of the wheel (2). The vehicle turning performance is optimally controlled by limiting each braking/driving torque in accordance with the slip rate of the wheel (2) and the angular acceleration of the wheel (2) as described above.