Header Float Calibration Using Ground Force Sensing
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Solution Overview
Problem
Existing header floatation systems in agricultural vehicles suffer from inaccuracies due to variations in hydraulic oil temperature, hysteresis, and changes in operating friction, leading to inconsistent floatation force, and issues with hydraulic pressure sensing causing inaccuracies in header height control.
Innovation Solution
A method and system that utilizes ground-contact force measurement through load sensors to dynamically adjust the header position, involving calibration of load sensors by raising the header out of contact with the ground, comparing initial and subsequent zero value sensor signals, and adjusting actuator pressure to maintain target ground reaction force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydraulic pressure sensing is used to control header height, then header position control is achieved, but measurement accuracy deteriorates due to stiction and friction reactions
Solution Approach 1:
The patent introduces an intermediary mechanism (friction compensation system) that detects and compensates for friction forces in the hydraulic system. This intermediary layer separates the measurement function from the friction-affected pressure readings, allowing accurate header height control despite hydraulic system friction.
Solution Approach 2:
The patent replaces direct reliance on hydraulic pressure sensing (mechanical system) with an alternative control approach that uses position feedback and friction compensation algorithms. This substitution eliminates the measurement errors caused by stiction and friction in the hydraulic cylinders.
2Adaptability or versatility
If pressure reducing valve is used to control accumulator pressure, then floatation force adjustment is achieved, but reliability deteriorates due to hysteresis and temperature variations
Solution Approach 1:
The patent implements a feedback control system that continuously monitors actual header weight and floatation force, then adjusts the pressure reducing valve accordingly. This closed-loop feedback compensates for hysteresis and temperature variations, maintaining reliable and consistent floatation force despite environmental changes.
Solution Approach 2:
The patent performs preliminary calibration of the pressure reducing valve and accumulator system before operation. By pre-setting the system parameters and conducting calibration routines, the system establishes reliable baseline values that compensate for manufacturing tolerances and initial temperature conditions.
3Adaptability or versatility
If manual adjustment of PRV signal is required to maintain floatation force, then adaptability to weight changes is achieved, but ease of operation deteriorates
Solution Approach 1:
The patent enables the system to automatically detect header weight changes and adjust the pressure reducing valve signal without operator intervention. The control system continuously monitors load sensor readings and self-adjusts the floatation force, making the system adaptive to weight changes while eliminating the need for manual adjustments.
Solution Approach 2:
The patent uses feedback from load sensors to automatically adjust the pressure reducing valve signal in response to header weight changes. This closed-loop control system continuously compares actual floatation force with target values and makes real-time adjustments, providing adaptability without requiring operator involvement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accurately and automatically adjusts for changing conditions, ensuring consistent floatation force and precise header positioning by eliminating errors associated with hydraulic pressure sensing.
Implementation Method 1
a load sensor configured to generate an output signal representative of a ground force sensed by the load sensor
Implementation Method 2
The hydraulic actuators comprise piston and cylinder assemblies that use hydraulic fluid to move the piston relative to the cylinder
Implementation Method 3
as the header moves over undulating terrain, the gas can expand and contract to provide a spring-like resilience to the hydraulic circuit. Thus, the header is effectively suspended on an air spring
Data Source
AI summary
A method for dynamically operating a header float system of an agricultural vehicle having a header movably mounted to a frame by an actuator and a flotation adjustment system that relies on ground-contact force measurement. The method includes: determining an initial zero value load sensor output signal representative of an initial position of the header raised out of contact with the ground surface, calibrating the sensor with the initial zero value, operating the header to process a crop material, detecting a subsequent position of the header out of contact with the ground surface, determining a subsequent zero value representative of the subsequent position of the header, and re-calibrating the sensor with the subsequent zero value. Also, an agricultural vehicle having a header operated as described above.