Roll Stabilizer Actuator Control for Torque Safety
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Solution Overview
Problem
Existing motor vehicle roll stabilizers face challenges in ensuring safe operation during dynamic driving conditions, particularly in avoiding inverted torque outputs and excessive torque deliveries that can lead to uncontrollable vehicle behavior, necessitating high-level safety classifications for sensors and actuators.
Innovation Solution
The actuator's setting options are limited by threshold values based on vehicle parameters like steering angle, driving speed, and lateral acceleration, and a torque sensor's signals are checked for plausibility within permissible tolerances to reduce the safety classification requirements, allowing for continuous controllable driving even in fault scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-level safety classification sensors (ASIL-B) are used to detect inverted torque output, then safety and reliability are improved, but device complexity and cost increase
Solution Approach 1:
The safety monitoring function is segmented into multiple independent monitoring channels: rotation angle monitoring, torque direction monitoring, and plausibility checking. Each channel uses simple sensors and evaluation logic, collectively achieving ASIL-B safety without requiring a single complex high-rated sensor
Solution Approach 2:
The control unit acts as an intermediary that coordinates multiple simple sensors (rotation angle sensor, torque sensor) and applies evaluation rules to achieve the safety function. The control unit synthesizes information from multiple sources to detect dangerous situations, replacing the need for a single complex ASIL-B sensor
2Productivity
If the actuator is allowed full adjustment range, then roll stabilization performance is improved, but risk of inverted torque output and uncontrollable vehicle behavior increases
Solution Approach 1:
The control unit performs preliminary evaluation of the actuator's adjustment commands before execution. It checks whether the desired adjustment would result in inverted torque output based on current vehicle state (lateral acceleration, steering angle, roll angle) and prevents such commands, allowing full performance within safe boundaries
Solution Approach 2:
The system continuously monitors rotation angle, torque, and vehicle dynamics parameters, using this feedback to dynamically adjust actuator commands. The control unit compares desired adjustments with actual vehicle response and prevents adjustments that would lead to inverted torque, maintaining both performance and safety
3Ease of manufacture
If torque sensor tolerance is set high for cost-effectiveness, then sensor cost decreases, but detection precision of dangerous situations worsens
Solution Approach 1:
The system uses a torque sensor with moderate precision (ASIL-A level) and applies plausibility checks that compare torque readings with expected values based on vehicle dynamics. The evaluation rules provide an additional layer of verification, compensating for the lower sensor precision and achieving the required safety level without needing expensive high-precision sensors
Data Source
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AI summary
The invention relates to a method for operating an electrically adjustable roll stabilizer (9) for a chassis (2) of a motor vehicle (1) having an actuator (13), which is arranged between two part-portions (9, 10) of the roll stabilizer (9) and can adjust the part-portions with respect to one another. At least one sensor is provided for detecting the twisting angle and/or the torque, wherein signals relating to the twisting angle and/or torque of at least one control device (16) are processed for controlling the actuator (13). During the operation of the roll stabilizer, within the at least one control device, the signals are compared with maximum and minimum characteristic values, wherein the maximum adjustment path and/or the maximum torque output of the actuator is determined as a function of vehicle characteristic values, preferably of vehicle speed and/or steering angle and/or transverse acceleration.