Oversteering: System Improves Line-Holding Ability
John Deere's new 7280R tractor, which was chosen as Tractor of the Year at the Agritechnica conference in Germany in November, comes with the option of an ActiveCommand Steering system.
Many factors contribute to oversteering, including driver fatigue, obstacles in the path, and rough terrain. Of course, safety is a top concern, as is damage fields and equipment.
Tractor producer John Deere has developed a technology called ActiveCommand Steering (ACS™) to combat oversteering. According to the company, ACS "reduces steering effort, which results in reduced operator fatigue and improves operator comfort and control."
How does it work? A gyroscope senses tractor yaw and automatically makes small steering adjustments to improve line-holding abilities.
The system is "fail operational," which means manual steering is still functional in the event of any single-point failure: The operator has the ability to steer the tractor if something goes wrong.
According to John Deere, "if the primary controller fails, a second controller takes over. If power from the alternator fails, the battery resumes control. If the engine quits running and is unable to supply hydraulic oil to the system, an electric-driven backup pump is used to supply the oil. There is a backup for all ACS components."
Here are the key components of ACS:
Gyroscope: Measures the yaw rate (turn rate) of the tractor during transport speeds.
Road-wheel angle sensors:Measure the steer angle of the tractor.
Power-supply module: Distributes the power of the battery and alternator throughout the ACS system.
Hand-wheel angle sensors and tactile feedback unit: Includes the steering wheel position sensors and a brake that can increase or decrease resistance depending upon speed. (Lighter feedback for normal field use, and slightly heavier feedback during transport and while the tractor is cornering at high speeds.)
Controllers: Located in the back of the tractor, the controllers are the brains of the system.
Control values: Also called steering valves, control valves are used to steer the tractor.
Electric-drive backup pump: Supplies oil to the steering system, brakes, and park (for towing) brake if there is no longer a sufficient oil supply to the steering and brakes.
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