Electric Power Steering Banked Road Control
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Solution Overview
Problem
Existing electric power steering systems fail to provide a suitable steering feeling on banked roads, as the steering wheel returns to a neutral position unless the driver continuously applies steering torque, disrupting the intended turning angle.
Innovation Solution
An electric power steering apparatus with a steering force provider, a first control device for assist torque, a second control device to determine and maintain a target turning angle, a traveling road detection device to detect road inclination, and a changing device for banked road correspondence control, which adjusts the target turning angle based on road inclination, ensuring the steering wheel remains aligned without driver input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If turning angle feedback control is executed to make actual turning angle follow target turning angle according to input torque, then optimal steering torque can be maintained, but on banked roads the steering wheel returns to neutral position requiring continuous driver torque application
Solution Approach 1:
The patent changes the parameter of target turning angle based on detected road inclination. When a banked road is detected, the target turning angle is adjusted to account for the road slope, allowing the steering system to maintain the appropriate steered angular position without requiring continuous driver input torque.
Solution Approach 2:
The patent uses a traveling road detection device to detect road inclination and creates a corrected target turning angle that copies or replicates the appropriate steering position for banked roads, enabling the feedback control to anticipate and compensate for road conditions rather than merely reacting to driver input.
2Measurement precision
If the steering system maintains target turning angle according to input torque, then steering precision is improved, but on banked roads the system requires continuous driver torque to prevent wheel return to neutral
Solution Approach 1:
The patent performs preliminary detection of road inclination using the traveling road detection device and adjusts the target turning angle in advance before the driver needs to correct the steering position. This preliminary action allows the steering system to proactively maintain the correct angle on banked roads without waiting for driver torque input or continuous corrections.
3Force
If assist torque is increased with steering torque to improve steering assist, then steering effort is reduced, but on banked roads without road detection the assist does not compensate for the neutral return tendency
Solution Approach 1:
The patent extends the function of the control system to handle multiple road conditions universally. By incorporating the traveling road detection device and adjusting the target turning angle based on detected inclination, the steering system becomes adaptable to both flat and banked roads, providing appropriate assist torque and maintaining stable steering position across different operating conditions.
Data Source
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AI summary
A zero point change model 71 executes banked road correspondence control when a vehicle travels on a banked road. By this control, a target turning angle θp when the total torque is zero can be changed from a neutral turning angle to a lower side of an inclined road surface. Thus, a steering angle of a steering wheel according to a banked road can be realized even if the driver does not apply steering torque Th during traveling on a banked road. Accordingly, the driver can obtain a suitable steering feeling when traveling on a banked road while achieving the target turning angle θp according to the total torque.