Agricultural Header Height Sensor with Segmented Arm
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Solution Overview
Problem
Existing header height sensors for agricultural combines are prone to damage due to rough handling and collect debris, leading to inaccurate readings, especially when flexible coil springs and spherical contact points are used, causing the sensor arm to bend and lose shape.
Innovation Solution
A header height sensor with a rigid elongate sensor arm, a reversing joint, and dual springs to absorb side loads, featuring a mechanical stop to prevent excessive movement and a hardened lower end for durability, along with a rotary position sensor to provide accurate height measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible sensor arm with coil spring is used to allow the sensor to follow ground contours, then the sensor can adapt to terrain variations, but the coil spring collects plant matter and the sensor arm bends and loses its original shape
Solution Approach 1:
The sensor arm is divided into multiple segments connected by joints, allowing each segment to rotate independently. This segmentation enables the sensor to follow ground contours through articulated movement rather than continuous flexing, preventing the coil spring from collecting plant matter while maintaining adaptability to terrain variations.
Solution Approach 2:
The sensor arm transitions from a statically flexible design with coil springs to a dynamically articulated design with rotating joints. The joints allow the sensor arm to actively adapt to terrain changes through controlled rotation, eliminating the need for coil springs that deform and lose their original shape over time.
2Ease of operation
If a spherical contact point is used for ground engagement, then the sensor can roll over obstacles, but the spherical shape gathers dirt and plant matter and allows lateral deflection
Solution Approach 1:
The contact point is changed from a symmetric spherical shape to an asymmetric design with a laterally extending protrusion. This asymmetric feature prevents rotation about the vertical axis by engaging the ground in a way that resists lateral movement, while still allowing the sensor to roll over obstacles. The protrusion acts as a steering function that eliminates lateral deflection and prevents plant matter accumulation.
3Strength
If the sensor arm is made large and strong to resist damage from rough handling, then the sensor can withstand harsh conditions, but the increased size and strength requirements complicate the sensor design
Solution Approach 1:
The sensor arm employs dynamic joints that allow controlled movement and rotation, enabling the structure to absorb and distribute forces from rough handling. This dynamic design provides durability through motion rather than requiring excessive structural strength, thereby reducing overall device complexity while maintaining robustness against harsh conditions.
4Strength
If the sensor arm is made flexible to avoid damage when dropped, then the sensor can withstand impact, but the flexible shaft bends easily when deflected left and right by the soil
Solution Approach 1:
The flexible sensor arm is segmented into rigid sections connected by rotational joints. Each segment maintains structural integrity to resist impact, while the joints between segments allow controlled rotation to absorb lateral forces from soil deflection. This segmentation prevents the continuous flexing that would cause a monolithic flexible arm to bend and provide erroneous readings.
Solution Approach 2:
The asymmetric protrusion on the contact point creates a lateral constraint that prevents excessive side-to-side deflection of the sensor arm. By engaging the ground with this protrusion, the design limits lateral movement of the flexible shaft, reducing bending and maintaining measurement accuracy while preserving impact resistance through the segmented flexible structure.
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 solution provides an accurate and durable header height sensor that resists damage and maintains precise readings even under harsh conditions, ensuring effective control of the harvesting head's height above the ground.
Implementation Method 1
The sensor arm is made flexible by providing a coil spring (42) as part of its length
Implementation Method 2
The lower end of the sensor arm is hardened to provide a durable contact point
Data Source
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AI summary
A header height sensor (102) for an agricultural harvester has an elongate sensor arm (112), a reversing joint (114) and a rotary sensor (116) mounted to a bracket (106) that is fixed to a point (100) of a harvesting head. The reversing joint includes a housing (152) that limits the deflection of the sensor in a lateral direction.