Vehicle Speed Limiting Device with Function Switching Prohibition
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Solution Overview
Problem
Existing vehicle speed limiting devices may incorrectly interpret a driver's intention when changing speed limits, leading to unintended changes in the upper-limit vehicle speed.
Innovation Solution
Incorporating a function switching mechanism that temporarily switches the upper-limit vehicle speed change operation unit from a first function for changing the speed to a second function for accepting speed limit changes, with a prohibition period to ensure accurate recognition of driver intentions, and a display system to inform the driver of the speed limit changes and acceptance methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the function switching means switches the operation unit to the second function when speed limit is changed, then the system can respond to speed limit changes, but the driver's intended speed adjustment may be misinterpreted as a reply operation
Solution Approach 1:
The system performs a preliminary check by detecting whether the operation unit is being operated when a speed limit change is detected. If an operation is detected, the system prohibits the function switch to the second function, preventing the misinterpretation of the driver's intended speed adjustment as a reply operation.
Solution Approach 2:
The operation detection mechanism acts as an intermediary between the speed limit change detection and the function switching. It mediates the decision-making process by providing information about driver operations, allowing the system to distinguish between intended speed adjustments and reply operations.
2Device complexity
If the system uses a common switch for both change operation and reply operation, then the device complexity is reduced, but the ease of operation decreases due to function switching
Solution Approach 1:
The same operation unit is designed to perform multiple functions: changing upper-limit vehicle speed and replying to speed limit change proposals. The system manages this multi-functionality by detecting operation timing and prohibiting function switching when operations are detected, ensuring the driver can intuitively understand the current function being performed.
3Speed
If the function switches immediately when speed limit changes, then the system responds quickly, but it may incorrectly interpret ongoing speed adjustment operations as reply operations
Solution Approach 1:
Before switching functions when a speed limit change is detected, the system performs a preliminary detection of whether the operation unit is being operated. This preliminary check ensures that ongoing speed adjustment operations are not interrupted or misinterpreted, maintaining measurement precision while still enabling timely response to speed limit changes.
Data Source
AI summary
An upper-limit vehicle speed should be prevented from being set to speed different from an intention of a driver. When it is detected that a speed limit is changed, an upper-limit vehicle speed setting ECU temporarily switches a control mode from a normal mode to an inquiry mode. An ASL operation unit serves a function for a change operation of upper-limit vehicle speed in the normal mode, and serves a function for a reply operation about whether the speed limit is accepted in the inquiry mode. When the ASL operation unit is operated in the normal mode, the upper-limit vehicle speed setting ECU does not switch the control mode to the inquiry mode, even if a change of a speed limit is detected, until a certain period of time (a certain period during which a mode switching prohibition period is set) has passed since the operation.