Vehicle Speed Controller State Transition for Safety
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Solution Overview
Problem
Existing vehicle speed control systems are ineffective in congested traffic conditions and off-road environments due to minimum speed requirements and susceptibility to wheel slip events, which can lead to unintended system disabling.
Innovation Solution
A vehicle speed control system that includes a controller capable of transitioning between states based on door and occupant presence indicators, allowing for automatic brake application to maintain a target speed without developing drive torque when the door is open or an occupant is not present, and employing a ramp function for torque reduction during state transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a minimum speed requirement is imposed on cruise control systems to reduce the likelihood of low speed collision, then safety is improved, but the system becomes ineffective in congested traffic conditions where vehicle speed varies widely
Solution Approach 1:
The system dynamically transitions between different operational states (first state with drive torque and second state with brake application) based on real-time door state and occupant presence conditions, allowing the minimum speed requirement to be adaptively applied only when safety conditions are met, thereby maintaining effectiveness in congested traffic while preserving safety benefits
2Reliability
If cruise control systems are integrated with radar-based adaptive functionality to maintain safe following distance, then safety is improved, but the system complexity increases
Solution Approach 1:
The control system is segmented into distinct operational states (first state for drive torque application and second state for brake application only), with clear transition criteria based on door state and occupant presence. This segmentation simplifies the control logic compared to fully integrated radar-based adaptive cruise control, while still providing safety benefits through state-dependent torque and brake management
3Speed
If the system transitions from first state to second state by abruptly removing drive torque, then response time is improved, but vehicle stability deteriorates due to sudden torque changes
Solution Approach 1:
The system applies brake torque in advance during the transition from first state to second state, cushioning the effect of drive torque removal. By coordinating brake application with the state transition, the system maintains vehicle stability while achieving timely response to door state or occupant presence changes
Data Source
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AI summary
The invention provides a system comprising: a first controller operable to assume one of a plurality of respective states, in a first state the first controller being configured automatically to cause a powertrain to develop drive torque and cause a vehicle to operate in accordance with a target speed value, the first controller being configured to receive a door state indicator signal indicative of whether a door is in an open or closed state, and an occupant presence indicator signal indicative of whether an occupant is present in a given seat of a vehicle, the system being configured not to permit operation of the first controller in the first state in dependence on the door state indicator signal and the occupant presence indicator signal.