Biased Drive Control for Work Vehicle Turn Traction
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Solution Overview
Problem
Work vehicles face traction issues during turns due to speed variations between longitudinally offset wheels, leading to potential spin-out conditions and reduced traction under certain wheels.
Innovation Solution
A drive system with wheel sensors and a computing system that determines the differential shaft ratio between front and rear differential input shafts to maintain proper wheel speeds, ensuring equal traction across all wheels by correlating the front axle reference point to the rear axle reference point and controlling the differential shafts accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mechanical differential is used to regulate rotational speeds of laterally offset wheels during turns, then the wheel speed difference is self-regulated, but speed variations between longitudinally offset wheels cause low traction conditions and potential spin-out
Solution Approach 1:
The system uses wheel speed sensors to detect actual wheel speeds and a computing system to calculate the difference between actual and ideal wheel speeds. This feedback loop enables the controller to adjust brake application on individual wheels to maintain proper speed relationships during turns, preventing spin-out conditions while maintaining self-regulation capability.
Solution Approach 2:
The patent introduces an electronic control system as an intermediary between the mechanical differential and the wheels. This intermediary uses sensors, a computing system, and a controller to mediate the speed distribution to front and rear wheels, ensuring proper speed relationships are maintained during turns without direct mechanical intervention.
2Speed
If varied speeds are allowed for longitudinally offset wheels through a turn, then the mechanical differential can self-regulate lateral speed differences, but traction is reduced under at least one wheel causing spin-out conditions
Solution Approach 1:
The system continuously monitors actual wheel speeds using sensors and compares them against ideal speeds calculated by the computing system. This feedback enables real-time detection of speed variations that could lead to spin-out, allowing the controller to apply corrective brake force to maintain safe speed relationships during turns.
Solution Approach 2:
The system proactively prevents spin-out conditions by calculating ideal wheel speeds before turns are completed and applying brake force in advance to counteract potential traction loss. The controller anticipates speed variations that could cause spin-out and takes corrective action before the harmful effect manifests.
3Measurement precision
If the vehicle follows a commanded trajectory, then the vehicle can maintain accurate path following, but differential shaft speed ratios must be precisely controlled to maintain equal traction across all wheels
Solution Approach 1:
The patent replaces complex mechanical differential shaft ratio control mechanisms with an electronic control system. The computing system calculates the required speed ratios based on the commanded trajectory, and the controller electronically adjusts brake application to achieve the desired speed relationships, eliminating the need for complex mechanical ratio changers.
Solution Approach 2:
The system dynamically adjusts the effective differential shaft ratio during operation based on the commanded trajectory and actual wheel speeds. Rather than using fixed mechanical ratios, the controller continuously modifies brake application to maintain optimal speed relationships, allowing the system to adapt to varying turn conditions and trajectory requirements.
Data Source
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AI summary
A drive system (14) for a work vehicle (10) includes a chassis (12), a first front wheel (20, 22) and a second front wheel (20, 22) operably coupled with a front axle assembly (18), and a first rear wheel (28, 30) and a second rear wheel (28, 30) operably coupled with a rear axle assembly (26). At least one wheel sensor (90) can be associated with the first front wheel (20, 22), the second front wheel (20, 22), or both. A transfer case (40) can be operably coupled with a front differential input shaft (48) and a rear differential input shaft (60). A computing system (130) can be operably coupled with the at least one wheel sensor (90) and the transfer case (40). The computing system (130) can be configured to receive an input related to a commanded vehicle trajectory, determine a correlation of a front axle reference point (168) to a rear axle reference point (170), and determine a differential shaft ratio based at least partially on the correlation.