Electric Power Steering Torque Limiting Element
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current electric power steering systems face limitations in maintaining driving stability and error tolerance, particularly in critical situations, as they do not fully utilize the dynamic range of the servo drive and are sensitive to control oscillations, leading to inadequate support torque and sudden loss of power assistance.
Innovation Solution
A control method that includes a limiting element between the controller and motor driver unit, allowing full evaluation of sensor signals and application of maximum available output current, with upper and lower limit values for motor torque, and a damping approach to limit values to prevent oscillations and ensure continuous transition, thereby adapting to driving conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If upper and lower limit values for motor current are imposed to prevent overshooting and oscillations, then control stability is improved, but the maximum possible motor power and support torque are limited
Solution Approach 1:
The patent implements dynamic limit values that adapt to driving conditions. The control unit determines motor torque limit values based on real-time sensor data (steering wheel torque, vehicle speed, steering angle) and adjusts the allowed motor output accordingly. This enables the system to provide maximum power when needed while maintaining stability through condition-dependent limitations.
Solution Approach 2:
The patent changes the parameters of motor torque limit values dynamically. Instead of fixed limits, the system adjusts the upper and lower limit values for motor current and torque based on operating conditions. The control unit modifies these parameters in real-time to optimize both stability and power availability across different driving scenarios.
2Stability of the object's composition
If sensor signals are limited to prevent extreme values, then control stability is improved, but information about extreme torque situations is lost
Solution Approach 1:
The patent employs feedback mechanisms where the control unit continuously monitors sensor signals (torque sensor, speed sensor, steering angle sensor) and adjusts motor torque limit values based on this feedback. This allows the system to recognize extreme situations through sensor data while maintaining controlled motor output, preventing information loss about critical driving conditions.
3Reliability
If the driver limitation device shuts down the motor driver completely when an error is detected, then safety is improved, but driving comfort deteriorates due to sudden loss of power assistance
Solution Approach 1:
The patent prepares for error conditions by continuously monitoring system parameters and pre-adjusting motor torque output. When anomalies are detected (such as sensor inconsistencies or impossible steering positions), the system gradually reduces power assistance rather than shutting down abruptly. This cushioning approach maintains driving comfort while ensuring safety.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a control method for a steering system having electric power assistance, comprising a control means, for example a steering wheel, which can be controlled by a driver, an electric power-assistance motor, an electric control unit, which contains a memory for storing digital data, a motor driver unit (motor controller), which determines electrical signals for controlling the power-assistance motor in accordance with a target motor torque that was transmitted to the motor driver unit and outputs said electrical signals to the power-assistance motor, at least one sensor device for determining a control variable, for example a manual torque, introduced into the control means, wherein a specification value for a motor torque of the power-assistance motor is determined in the control unit with the aid of the control variable, wherein in addition, an upper limit for the target motor torque is stored in a limiting element, and for a case A in which the specification value exceeds the upper limit, the limiting element outputs the upper limit as a target motor torque to the motor driver unit, and for a case B in which the specification value does not exceed the upper limit, the limiting element outputs the specification value as a target motor torque to the motor driver unit.