Vehicle Steering-Based Speed Control for Tractor Sideslip Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Operators of agricultural tractors face challenges in slowing down vehicles during turns to avoid high sideslip, especially in field conditions, due to rapid transmission response and the need for manual control, which can result in jerky behavior.
Innovation Solution
A control system that includes a main ECU connected to speed, wheel angle, and vehicle position sensors, which determines speed limits based on yaw-rate error, lateral acceleration, and wheel angle to automatically control front wheel drive and differential lock engagement, ensuring the vehicle speed does not exceed the lowest set limit, thereby maintaining control and reducing sideslip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the transmission response is made fast to improve vehicle control responsiveness, then the vehicle speed control becomes more responsive, but the vehicle exhibits jerky behavior during speed changes
Solution Approach 1:
The system dynamically adjusts the rate of speed change based on current vehicle conditions. The ECU calculates a target speed and implements it with controlled ramping, adjusting the speed change rate based on factors like current speed, steering angle, and lateral acceleration, thereby maintaining smooth transitions while preserving responsiveness
Solution Approach 2:
The system continuously monitors actual vehicle speed via speed sensors and compares it to the target speed calculated from steering input. This feedback loop allows the ECU to modulate the transmission control signals to achieve smooth speed changes, preventing jerky behavior while maintaining responsive control
2Ease of operation
If manual control is used to slow down the vehicle during turns, then the operator can adjust speed, but the operator's attention is occupied and other tasks cannot be performed
Solution Approach 1:
The system performs speed control automatically without requiring operator intervention. The ECU receives steering wheel angle input and autonomously calculates and implements the appropriate speed reduction during turns, freeing the operator to perform other tasks while maintaining safe vehicle operation
Solution Approach 2:
The patent replaces manual mechanical speed control (operator using pedals or levers) with an electronic control system that uses sensors, processors, and actuators to automatically adjust vehicle speed based on steering input and vehicle conditions
3Reliability
If differential lock is engaged during turns to improve traction, then wheel slip is reduced, but the vehicle experiences high sideslip in field conditions
Solution Approach 1:
The system dynamically controls the differential lock engagement based on real-time vehicle conditions. Rather than fixed engagement, the ECU modulates the differential lock state during turns, disengaging or reducing lock intensity when sideslip is detected, thereby maintaining traction when needed while preventing excessive sideslip in field conditions
Solution Approach 2:
The system changes the operational parameters of the differential lock during turns. The ECU adjusts the lock engagement level, timing, and duration based on steering angle, vehicle speed, and lateral acceleration, optimizing the balance between traction and sideslip prevention for different turn conditions
4Reliability
If front wheel drive is engaged to improve turn performance, then vehicle control is enhanced, but the system complexity increases
Solution Approach 1:
The ECU serves multiple functions: it processes steering wheel angle input, calculates target speed, monitors vehicle speed and position, controls transmission shifting, and manages differential lock and front wheel drive engagement. By making the control unit multi-functional, the system achieves enhanced turn performance without proportionally increasing overall system complexity
Data Source
AI summary
A control system and method is provided for a vehicle. The control system includes a speed sensor, a wheel angle sensor, and a vehicle position sensor. An electronic control unit (ECU) determines a yaw-rate error as a function of at least the vehicle position signal, determines a first speed limit as a function of the yaw-rate error, determines a second speed limit as a function of a vehicle lateral acceleration, and determines a third speed limit as a function of the wheel angle signal. The ECU selects the lowest of the first, second and third speed limits, generates a front wheel drive command and a diff lock command as a function of the wheel angle signal. The ECU also limits the vehicle speed to not greater than the selected lowest wheel speed limit.