Header Float Load Sensor Assembly for Precise Ground Pressure Feedback
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Solution Overview
Problem
Existing header floatation systems in agricultural vehicles suffer from variations in floatation force due to factors like hydraulic oil temperature changes, hysteresis, and weight fluctuations, leading to inaccurate position control of headers over undulating terrain.
Innovation Solution
A load sensor assembly is integrated between a frame and a skid shoe, utilizing a spring to generate a preload force that biases the skid shoe towards an extended position, with an adjustable preload spacer and linkage to measure ground reaction loads, providing accurate feedback for actuator control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydraulic pressure sensing is used to control header position, then header height control is achieved, but measurement precision deteriorates due to stiction and friction reactions in hydraulic cylinders
Solution Approach 1:
The patent introduces an intermediary mechanical linkage system between the header and ground that translates ground reaction forces into measurable displacements. This linkage acts as a mediator that converts the difficult-to-measure hydraulic pressure effects into direct mechanical position signals, eliminating the stiction and friction problems inherent in direct hydraulic pressure sensing.
Solution Approach 2:
The patent replaces the hydraulic pressure sensing system with a mechanical linkage and displacement sensing system. Instead of measuring hydraulic pressure indirectly, the system uses pure mechanical elements (linkages, pivots, gauge wheels) to directly measure header position and ground reaction forces, substituting mechanical measurement for hydraulic pressure measurement.
2Ease of operation
If PRV current setting is used to control floatation force, then floatation control is achieved, but reliability deteriorates due to variations in hydraulic oil temperature, hysteresis, and friction
Solution Approach 1:
The patent implements a feedback control system where ground reaction force measurements from the linkage system are continuously monitored and used to adjust the header position. This closed-loop feedback compensates for variations in floatation force caused by temperature, hysteresis, and friction, maintaining reliable and consistent floatation control despite changing operating conditions.
3Productivity
If header weight changes during operation, then crop processing continues, but measurement precision deteriorates as calibration becomes inaccurate
Solution Approach 1:
The patent transitions from a static calibration approach to a dynamic measurement approach. The mechanical linkage system continuously adapts to changing header weights by measuring actual ground reaction forces in real-time during operation. This dynamic system automatically compensates for weight changes from accumulated crop material or soil, maintaining measurement precision without requiring recalibration.
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
The system provides reliable and precise control of header position by accurately measuring ground reaction forces, compensating for variations in floatation force and maintaining consistent operation over uneven terrain.
Implementation Method 1
a spring connecting the load sensor to one of the frame and the skid shoe, with the spring being configured to generate a preload force that biases the skid shoe towards the extended position
Implementation Method 2
A typical accumulator is a reservoir that is fluidly connected to the hydraulic circuit, and contains a volume of pressurized gas. In use, as the header moves over undulating terrain, the gas can expand and contract to provide a spring-like resilience to the hydraulic circuit
Data Source
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AI summary
A method for dynamically operating a header float system of an agricultural vehicle having a header movably mounted to a frame of the agricultural vehicle by an actuator. The method includes: determining a target ground reaction force between the header and a ground surface located below the header, determining an actual ground reaction force between the header and the ground surface, comparing the actual ground reaction force to the target ground reaction force, and upon determining that the actual ground reaction force differs from the target ground reaction force by a predetermined amount, operating the actuator to reduce a difference in value between the actual ground reaction force and the target ground reaction force. An agricultural vehicle having a header operated as described above is also provided.