Vehicle Transmission Controller Reset Detection and Mitigation
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Solution Overview
Problem
Vehicle controllers face challenges in identifying the root cause of frequent resets, which can indicate component degradation, due to interruptions in diagnostic routines and loss of shift drum position, making it difficult for service technicians to diagnose and potentially leading to component failures.
Innovation Solution
A system and method that controls a manual transmission by limiting available gear ratios and storing diagnostic codes in response to threshold resets, allowing shift actuators to recover based on stored positions, and delaying movement until a calculated gear ratio matches or a watchdog timer expires, facilitating early identification of component issues and preventing further degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the controller resets after encountering operating anomalies, then the controller can resume operation, but diagnostic routines are interrupted and diagnostic codes cannot be stored
Solution Approach 1:
The controller detects resets by monitoring the watchdog timer and incrementing a reset counter before diagnostic routines can execute, allowing it to proactively identify reset conditions and store diagnostic codes in non-volatile memory before the reset occurs, preventing loss of diagnostic information
Solution Approach 2:
The controller implements a feedback mechanism where the watchdog timer continuously monitors system operation, and when a reset is detected, the reset counter provides feedback information that triggers diagnostic code storage and limits further shift actuator movements to prevent additional errors
2Productivity
If shift actuators continue moving after reset, then gear changes can be executed, but shift drum position may be lost leading to frequent resets
Solution Approach 1:
The controller applies preliminary anti-action by detecting resets and immediately limiting shift actuator movements through the reset counter mechanism, preventing the shift drums from moving to positions that would cause loss of synchronization and subsequent frequent resets, while still allowing limited gear changes based on stored positions
Solution Approach 2:
The controller stores shift actuator positions in non-volatile memory before resets occur and uses these stored positions to control shift actuator movement after reset, enabling gear changes to be executed safely without losing shift drum position synchronization
3Difficulty of detecting and measuring
If diagnostic routines execute normally, then comprehensive diagnostics can be performed, but system complexity increases
Solution Approach 1:
The diagnostic functionality is extracted as a separate monitoring layer that continuously checks for reset conditions through the watchdog timer and reset counter, independent of the main transmission control routines, allowing comprehensive diagnostics to be performed without significantly increasing the complexity of the core control system
Data Source
AI summary
A system and method for controlling a vehicle include a manual transmission operated by a controller in communication with shift actuators and programmed to, in response to each controller reset less than a threshold number of resets, control each shift actuator that was not moving at the time of the reset based on respective shift actuator positions stored prior to the reset, and to control the shift actuators to limit available gear ratios in response to the reset exceeding the threshold number of resets.