4WD Vehicle Speed Reset Logic for Acceleration Slip Control
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Solution Overview
Problem
In four-wheel drive vehicles, existing techniques fail to accurately control acceleration slip, leading to potential safety issues due to excessive TRC intervention and poor acceleration, as they cannot distinguish between estimated and actual vehicle body speeds.
Innovation Solution
A vehicle control method that acquires acceleration, rotational speed, and driving force information to determine if the estimated speed should be reset to the calculated speed, with conditions including a non-dropping state and a holding period, and adjusts the estimated speed based on driving force thresholds to properly manage acceleration slip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the estimated speed is reset to the calculated speed in the acceleration slip state, then the acceleration slip amount decreases and TRC intervention is suppressed, but in four-wheel drive vehicles this may lead to excessive TRC intervention and poor acceleration
Solution Approach 1:
The patent changes the parameter of estimated speed by resetting it to the initial speed under specific conditions (when calculated speed is less than estimated speed and driving force exceeds threshold). This parameter change allows proper control of acceleration slip amount while preventing excessive TRC intervention that would degrade acceleration performance.
2Productivity
If the estimated speed is not reset to the calculated speed, then acceleration performance is maintained, but the running safety cannot be ensured due to potential actual slip states
Solution Approach 1:
The patent selectively resets the estimated speed parameter based on driving force conditions. When driving force exceeds the threshold, reset occurs to ensure safety; when below threshold, reset is suppressed to maintain acceleration performance. This conditional parameter change resolves the contradiction between safety and performance.
Solution Approach 2:
The patent applies different control strategies to different operating conditions by introducing a driving force threshold. Below the threshold, one control strategy (no reset) applies; above the threshold, another strategy (reset) applies. This local differentiation ensures both safety and performance in respective operating ranges.
3Productivity
If the TRC intervention is suppressed in the acceleration slip state, then excessive suppression of driving force is prevented, but in four-wheel drive vehicles this may lead to actual slip states where estimated speed exceeds actual vehicle body speed
Solution Approach 1:
The patent changes the estimated speed parameter based on the relationship between calculated and estimated speeds combined with driving force conditions. This parameter change ensures that TRC intervention is appropriately controlled, preventing both excessive suppression and actual slip states.
Data Source
AI summary
A vehicle control method includes: acquiring information on acceleration, information on rotational speed of a drive wheel, and information on driving force; after a dropping state where a calculated speed indicative of a vehicle body speed calculated from the rotational speed is less than an estimated speed indicative of a vehicle body speed in a front-rear direction estimated from the acceleration has transitioned to a non-dropping state and a holding period in which the non-dropping state is held has passed, determining whether or not a reset condition to reset the estimated speed is satisfied; when the reset condition is satisfied, determining whether or not the driving force is less than a threshold value; and when the driving force is less than the threshold value, resetting the estimated speed and setting a current value of the calculated speed to a vehicle body initial speed used for estimating the estimated speed.