Marine Drive Steering Sensor Fusion for Fault-Tolerant Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing marine vessel steering systems experience significant uncommanded steering changes when switching between primary and backup sensors due to sensor failures, leading to potential steering faults and loss of control.
Innovation Solution
A dual sensor system that calculates a measured steering position as an average or filtered output of two steering sensors, allowing for fault detection and seamless transition to a single sensor in case of failure, minimizing uncommanded steering changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single steering sensor is used in the marine drive system, then the system complexity is reduced, but the reliability deteriorates due to potential sensor failures causing uncommanded steering changes
Solution Approach 1:
The patent applies local quality by implementing asymmetric sensor configuration where one sensor (first steering sensor) serves as the primary sensor and the other (second steering sensor) serves as a backup sensor. This local differentiation in sensor roles allows the system to maintain high reliability through redundant sensing capability while managing complexity through structured primary-backup architecture rather than treating all sensors equally
Solution Approach 2:
The patent implements beforehand cushioning by pre-configuring a backup steering sensor that remains standby ready to take over if the primary sensor fails. This preparatory redundancy cushions against the harmful effect of sensor failures, preventing uncommanded steering changes by having a pre-positioned backup sensor that can immediately assume the sensing function without system disruption
2Reliability
If a backup steering sensor is added to the system, then the fault tolerance is improved, but the device complexity increases due to additional sensor integration and control logic
Solution Approach 1:
The patent applies preliminary action by pre-establishing the backup steering sensor and its integration into the control system before any failure occurs. The controller is pre-programmed with logic to monitor both sensors and automatically switch to the backup sensor upon detecting a failure condition, eliminating the need for complex real-time decision-making during critical failure scenarios
Solution Approach 2:
The patent implements feedback mechanisms where the controller continuously monitors the output signals from both the first and second steering sensors, comparing their readings to detect discrepancies indicating sensor failure. This feedback loop enables automatic fault detection and triggers the switching mechanism to the backup sensor, managing system complexity through intelligent control logic rather than hardware complexity
3Reliability
If sensor switching is implemented upon failure, then the resilience is improved, but uncommanded steering changes occur during the transition
Solution Approach 1:
The patent introduces the controller as an intermediary element that mediates between the dual steering sensors and the steering actuator. The controller receives signals from both sensors, processes them to detect failures, and smoothly transitions control to the backup sensor while maintaining continuous steering control. This intermediary function prevents abrupt uncommanded steering changes by managing the transition process rather than allowing direct sensor-to-actuator switching
4Difficulty of detecting and measuring
If the steering system uses redundant sensors and switching logic, then the fault detection capability is improved, but the ease of operation deteriorates due to complex control behavior
Solution Approach 1:
The patent applies self-service by enabling the steering system to automatically detect sensor failures and switch to the backup sensor without requiring operator intervention. The controller autonomously monitors sensor health, detects faults, and manages the switching process, allowing the system to service itself during failure conditions and maintaining ease of operation by eliminating the need for operator awareness or action during the transition
Data Source
AI summary
A steering system for a marine drive includes a marine drive, wherein the marine drive is steerable about a steering axis, a steering actuator configured to steer the marine drive to a range of steering positions within a permitted steering range, a first steering sensor configured to sense the steering position of the marine drive and output a first sensed value, a second steering sensor configured to sense the steering position of the marine drive and output a second sensed value and a controller. The controller is configured to calculate a measured steering position for the marine drive based on the first sensed value and the second sensed value, and control the steering actuator based on the measured steering position.