Steer-by-Wire Rollover Prevention for Harvesters
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Solution Overview
Problem
Combine harvesters with rear wheel steering systems are unstable at higher speeds due to oversteering and high center of gravity, leading to rollover risks, especially in electronically controlled steer-by-wire systems without additional stabilization measures.
Innovation Solution
A rollover risk reduction system using a steer-by-wire system with human-machine-interface (HMI) force feedback, sensors, and controllers to actively return the machine to a straight path, limit steering angles, and dynamically stabilize the machine through electronic counter-steering, eliminating the need for additional overlaid devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a steer-by-wire system is used for electronic steering control, then the reaction time is faster and steering precision is improved, but the risk of over-steering and rollover increases due to lack of natural mechanical feedback
Solution Approach 1:
The patent implements artificial feedback mechanisms including force feedback through the HMI to simulate natural steering resistance, and electronic feedback loops that continuously monitor steering angle, machine speed, and lateral acceleration to dynamically adjust steering commands and prevent over-steering conditions
Solution Approach 2:
The controller acts as an intermediary between the operator's steering input and the actual wheel positioning, inserting computational logic that considers machine dynamics, speed, and stability parameters to mediate the steering response and prevent dangerous over-steering situations
2Adaptability or versatility
If rear wheel steering is used to achieve compact turning radius, then the machine's maneuverability is improved, but the machine becomes naturally unstable at higher speeds due to oversteering characteristics
Solution Approach 1:
The patent implements dynamic steering control where the relationship between steering input and wheel angle is continuously adjusted based on machine speed, lateral acceleration, and operating conditions. The system transitions from fixed geometric steering ratios to variable dynamic steering ratios that maintain stability across different speed ranges
Solution Approach 2:
The system dynamically changes steering parameters including maximum steering angle limits, steering ratio, and response characteristics based on machine speed and operational context, allowing aggressive steering at low speeds for maneuverability while restricting steering authority at high speeds to maintain stability
3Ease of operation
If the steering system allows full steering angle range for evasive maneuvers, then the operator's ability to respond to emergencies is improved, but the likelihood of rollover during high-speed evasive maneuvers increases
Solution Approach 1:
The system applies preliminary counter-steering actions detected through lateral acceleration sensors and stability algorithms that anticipate rollover conditions before they occur, automatically applying opposing steering torque to counteract the operator's aggressive steering input and prevent the machine from entering a rollover trajectory
Data Source
AI summary
In one embodiment, a steering system for a machine, the steering system comprising: a steer-by-wire system configured to provide rear wheel based steering, the steer-by-wire system comprising: a human-machine-interface (HMI) configured to provide a force feedback to the HMI that influences the HMI to a center position; plural sensors; and one or more controllers configured by executable code to receive input from one or more of the plural sensors and reduce a risk of rollover by: causing the rear wheels to maintain or return to straight forward travel in conjunction with the force feedback; and limiting a steering angle of the machine, beyond which a rollover condition occurs, based on computation of a rollover equation with parameters corresponding to the input and machine geometry.