Skid Detection via Wheel Acceleration Ratio
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Solution Overview
Problem
Existing skid detection systems for four-wheel drive vehicles fail to accurately detect simultaneous skids of both front and rear wheels, as they rely on differences in wheel speeds which are not generated when both sets of wheels skid simultaneously.
Innovation Solution
A skid detection apparatus that calculates the acceleration ratio of one set of wheels over time, comparing it to a predetermined value to determine if a skid has occurred, and considers driving force and change in driving force to prevent false detection, allowing for accurate detection of skids in both individual and simultaneous wheel scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wheel speed difference method is used to detect skid, then detection is simple for single wheel skid, but simultaneous skid of front and rear wheels cannot be detected
Solution Approach 1:
The patent changes the detection parameter from wheel speed difference to wheel acceleration ratio. By calculating the ratio of acceleration between current and previous time periods, the system can detect skids in all scenarios including simultaneous front and rear wheel skids, where speed difference methods fail. This parameter transformation enables universal skid detection across different driving conditions.
2Adaptability or versatility
If acceleration ratio calculation is added to detect simultaneous skids, then detection coverage improves, but calculation complexity increases
Solution Approach 1:
The system performs preliminary calculation of wheel acceleration by comparing current rotational speed with previous speed data before making skid determination. This preliminary acceleration calculation is reused in the ratio computation, avoiding redundant calculations and reducing overall system complexity while enabling comprehensive skid detection.
Solution Approach 2:
The wheel acceleration ratio calculation serves multiple functions: it detects single wheel skids, simultaneous front and rear wheel skids, and provides a unified detection mechanism for all skid scenarios. This multi-functional approach eliminates the need for separate detection systems for different skid types, reducing overall system complexity.
3Speed
If acceleration ratio threshold is used for skid determination, then detection speed improves, but false detection may occur without additional conditions
Solution Approach 1:
The system uses feedback by comparing wheel acceleration ratio against a predetermined threshold value to determine skid occurrence. This threshold-based feedback mechanism enables rapid skid detection while maintaining reliability. The threshold is set based on normal driving conditions, allowing the system to distinguish between normal acceleration variations and actual skid events.
Data Source
AI summary
In a skid detecting apparatus for a vehicle having an engine and a CVT changing an output of the engine in speed to drive front wheels and rear wheels, it is configured to detect rotational speeds of one of the front and rear wheels, sequentially calculate accelerations (wheel accelerations var1, var2) of the one of the wheels based on the detected rotational speeds, calculate a ratio (var1/var2) between two accelerations of the same wheel calculated at different time points among the sequentially-calculated accelerations (S10), compare the ratio between the two accelerations with a predetermined value (S16) and determine that the one of the wheels has skidded or some or all of the wheels including the one have skidded when the calculated ratio between the two accelerations exceeds the predetermined value (S18).