Dual-Motor Drive Assembly Sensor Fault Detection Under Backlash
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Solution Overview
Problem
Dual motor drive assemblies in vehicle handwheel actuators face challenges in determining faulty motor position sensors, which can lead to incorrect motor control and potential vehicle steering impairments, due to the redundancy of having two sensors that may both fail.
Innovation Solution
A processor-based system that estimates the position of one motor using the signal from the other motor's position sensor, accounting for backlash and compliance, and cross-checks the motor position signals to detect faults, ensuring continued operation even if one sensor fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two motor position sensors are used in a dual motor drive assembly, then redundancy is provided to maintain operation if one motor fails, but the probability of sensor faults increases and fault detection becomes more difficult
Solution Approach 1:
The system uses feedback from both motor position sensors to continuously monitor and compare their readings. The control unit receives position signals from both sensors and uses this feedback to detect discrepancies that indicate faults, allowing the system to identify sensor failures while maintaining redundancy.
Solution Approach 2:
The system performs preliminary fault detection by continuously comparing position readings from both sensors before critical failures occur. The control unit proactively monitors sensor signals and can identify faults early, enabling safe operation or graceful degradation before the fault impacts system performance.
2Productivity
If motor position sensor faults are not detected, then the system may continue operating with incorrect motor control, but vehicle steering safety is compromised
Solution Approach 1:
The control unit performs preliminary detection of sensor faults by comparing position readings before incorrect motor control can compromise steering safety. This proactive monitoring allows the system to identify faults early and take appropriate action while maintaining safe operation.
Solution Approach 2:
The system uses feedback from both motor position sensors to continuously monitor motor positions and detect faults. By comparing the feedback from both sensors, the control unit can identify discrepancies that indicate sensor failures and prevent incorrect motor control that would compromise steering safety.
3Difficulty of detecting and measuring
If backlash and compliance effects are not accounted for in position estimation, then fault detection accuracy improves, but position estimation precision deteriorates
Solution Approach 1:
The control unit changes the parameters used in position estimation by accounting for backlash and compliance effects. By incorporating these mechanical characteristics into the estimation algorithm, the system achieves more accurate position estimates while maintaining the ability to detect sensor faults through comparative analysis.
Solution Approach 2:
The control unit acts as an intermediary that processes position readings from both sensors and incorporates knowledge of backlash and compliance effects. This intermediary processing layer reconciles the mechanical imperfections with the sensor readings to produce accurate position estimates while enabling fault detection.
Data Source
AI summary
A dual-motor drive assembly comprising a housing, a shaft mounted to the housing, a first gear connected to the shaft, a first motor lane comprising motor an output, a motor drive-stage driving the first motor in response to a torque demand and applying a torque to the first gear, and a first position sensor generating a first motor position signal, a second motor lane comprising a motor having an output, a motor drive-stage driving the second motor in response to a torque demand, and applying a torque to the first gear, and a second position sensor generating a second motor signal, the two motor outputs engaging with the first gear such that both motors' torque output is applied to the shaft. A processor generates an estimate of the first motor position using the signal from the second sensor and the effect of any backlash in the assembly, and cross-checks first signal against the estimate to determine if one of the motor position sensors is faulty.