Work Vehicle Travel Control Device for Vibration-Resistant Speed Ratio
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Solution Overview
Problem
Work vehicles equipped with hydrostatic transmission systems face challenges in maintaining a desired speed ratio and turning radius due to short operation stroke ranges and vibrations, leading to fatigue and instability in control characteristics.
Innovation Solution
A travel control device and program that set specific relationships between operation stroke and speed ratio, including lines with decreasing, increasing, and hysteresis characteristics, to stabilize speed ratios and absorb vibrations, ensuring the desired turning radius can be maintained according to operator feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the operation stroke range is set to be short to reduce fatigue, then operator fatigue is reduced, but the fine control characteristic for speed ratio change becomes insufficient
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the speed ratio based on the operation stroke position. The control device changes the speed ratio parameter according to whether the operation stroke is increasing or decreasing, creating different control characteristics for different stroke directions. This allows fine control capability to be maintained within a short operation stroke range by optimizing the speed ratio adjustment parameters.
2Ease of operation
If vibrations from the work vehicle body are large, then it is difficult to hold the operation lever at the desired fixed operation stroke, but the speed ratio behavior should not show large variations
Solution Approach 1:
The patent implements feedback control by continuously monitoring the operation stroke position and adjusting the speed ratio accordingly. The control device uses feedback from the operation stroke sensor to dynamically modify the speed ratio, compensating for vibrations and maintaining stable speed ratio behavior even when the operation lever is difficult to hold at a fixed position due to vehicle vibrations.
3Ease of operation
If the operation lever is reclined fully to the full stroke side and then returned for fine adjustments, then the desired turning radius can be obtained, but the change in speed ratio becomes large causing operational feel mismatch
Solution Approach 1:
The patent applies dynamics by creating different control characteristics for different operation stroke directions. When the operation stroke is increasing (reclining), the speed ratio changes according to one set of characteristics, while when the operation stroke is decreasing (returning), the speed ratio changes according to another set of characteristics. This dynamic adjustment ensures that fine adjustments during the return stroke produce appropriate speed ratio changes that match the operator's operational feel, preventing large unwanted changes.
Data Source
AI summary
A traveling control device and a traveling control program for a work vehicle in which a change in a control quantity due to an effect of vehicle body vibrations is small, fixing the desired control quantity is possible, and the control quantity can be matched with the operator's feel. A travel control program in which a first line on which the speed ratio reduces corresponding to a change in the operation stroke, a second line having hysteresis with respect to the first line and on which the speed ratio increases corresponding to a change in the operation stroke, and third lines on which the speed ratio changes corresponding to the change in the operation stroke and the change in speed ratio with respect to the change in the operation stroke is smaller than that of the first and the second line are set is installed in the control device.