Steering Control Unit Wake-Up Using Rotor Position Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for waking up a steering control unit (SCU) in steer-by-wire systems are unreliable due to the small and inaccurate back EMF voltage at low speeds, which is further compromised by environmental noise and interference, making it difficult to implement tight voltage thresholds and hysteresis.
Innovation Solution
The method uses the absolute rotational angle of the rotor shaft of a motor, monitored by a rotor position sensor, to wake up the SCU, utilizing a comparator that increments or decrements for every 90° rotation, ensuring reliable wake-up even at low speeds without additional cost, and leveraging existing rotor position sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If back EMF voltage monitoring is used to wake up the steering control unit, then the wake-up function can be implemented, but the reliability is poor at low speeds due to small and inaccurate voltage signals compromised by environmental noise
Solution Approach 1:
The patent replaces the electrical back EMF monitoring method with a mechanical position sensing method. Instead of measuring the small back EMF voltage generated by motor rotation, the system uses a rotor position sensor to directly detect the absolute rotational angle of the rotor shaft. This mechanical position detection method is independent of voltage signal strength and immune to electrical noise, providing reliable wake-up detection even at low speeds where back EMF voltage is minimal and inaccurate.
2Measurement precision
If tight voltage thresholds and hysteresis are implemented for the comparator, then wake-up detection accuracy may improve, but the system becomes disproportionately expensive and still unreliable due to noise interference
Solution Approach 1:
The patent eliminates the need for voltage threshold comparison and hysteresis configuration by replacing the electrical monitoring approach with mechanical position sensing. The rotor position sensor directly provides absolute angular position information, which is processed digitally without requiring analog voltage threshold adjustments. This avoids the complexity and cost of precision comparator circuits while providing noise-immune detection.
Solution Approach 2:
The patent uses the existing rotor position sensor, which is already part of the motor control system for normal operation, to also perform wake-up detection. This sensor copying approach leverages existing hardware infrastructure rather than adding separate voltage monitoring circuitry, reducing overall system complexity and cost while improving reliability.
3Use of energy by moving object
If the steering control unit remains in sleep state during parking, then power consumption is reduced, but the unit must reliably detect steering wheel movement to block the steering wheel when needed
Solution Approach 1:
The patent implements preliminary action by having the rotor position sensor continuously monitor the absolute rotational angle of the rotor shaft even while the steering control unit is in sleep state. The sensor data is buffered and ready for immediate processing, so that when steering wheel movement occurs, the unit can wake up instantly and block the steering wheel without delay. This preliminary monitoring setup maintains low power consumption while ensuring reliable detection capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach prevents unintended wake-ups, enhances reliability, meets standby power requirements, and is cost-effective by utilizing existing sensors, while being independent of engine BEMF levels and flexible through SPI configurability.
Implementation Method 1
The rotor position of a rotor of the motor is monitored. For example, the situation or position of a rotor shaft of the rotor of the motor is monitored.
Implementation Method 2
the so-called back EMF voltage generated by the motor due to the steering wheel torque is monitored and sensed. Back-EMF is an electromotive force (EMF) that occurs when a motor rotates, in particular a brushless motor, rotates. The engine acts as a generator that generates an electromotive resistance.
Data Source
AI summary
A method is disclosed of waking up a steering control unit including a controller and a motor in which a rotor position of a rotor of the motor is monitored and, in the event that a change in the rotor position is detected, the steering control unit is woken up.