Excavator Arm Control via Hydraulic Pressure Feedback
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Solution Overview
Problem
Material handling machines, such as excavators, require skilled operators to simultaneously manage multiple hydraulic actuators for efficient excavation, with suboptimal penetration of the bucket into the ground affecting cycle times, and less skilled operators perform poorly due to difficulty in setting appropriate arm heights.
Innovation Solution
A control system that uses pressure in a hydraulic actuator's pressure chamber to adjust the force of engagement between the ground engaging implement and the ground by controlling the arm's position, automatically overriding operator inputs to ensure optimal penetration and filling of the bucket.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the operator sets the arm height manually, then the operator has control over the excavation process, but the penetration depth is inconsistent leading to variable cycle times
Solution Approach 1:
The control system continuously monitors the pressure in the second hydraulic actuator, which indicates the force of engagement between the bucket and ground. This feedback is used to automatically adjust the arm height via the first hydraulic actuator, ensuring optimal penetration depth without operator intervention. The system compares actual pressure with target pressure and automatically corrects arm position to maintain ideal excavation conditions.
Solution Approach 2:
The system performs self-adjustment of the arm height based on real-time pressure feedback from the bucket engagement. The control system automatically overrides operator inputs when necessary to maintain optimal penetration, allowing the machine to regulate its own operation without continuous human intervention, thereby standardizing cycle times.
2Force
If the bucket penetrates too far into the ground, then the operator achieves deeper penetration, but the bucket cannot be drawn through the ground to be filled
Solution Approach 1:
The control system monitors pressure in the second hydraulic actuator that moves the bucket relative to the arm. When pressure exceeds the target pressure, indicating excessive penetration force, the system automatically raises the arm via the first hydraulic actuator to reduce penetration depth, allowing the bucket to be drawn through the ground for filling.
Solution Approach 2:
The system preemptively reduces arm height when pressure indicates approaching excessive penetration, preventing the bucket from becoming stuck before it happens. By detecting pressure trends and automatically adjusting arm position in advance, the system avoids the harmful state of over-penetration that would prevent bucket extraction.
3Ease of operation
If the bucket does not penetrate far enough into the ground, then the bucket can be easily extracted, but the bucket only half fills
Solution Approach 1:
The control system monitors pressure in the second hydraulic actuator and compares it with the target pressure. When pressure is below target, indicating insufficient penetration, the system automatically lowers the arm via the first hydraulic actuator to increase penetration depth, ensuring the bucket fills completely while maintaining extractability.
4Ease of operation
If the operator simultaneously operates all three hydraulic actuators, then the excavation process can be controlled, but the operation requires skill and increases cycle time for less skilled operators
Solution Approach 1:
The control system automatically manages the coordination between the first hydraulic actuator (arm height) and the second hydraulic actuator (bucket position) by monitoring pressure feedback. This self-regulating mechanism eliminates the need for operators to skillfully coordinate multiple actuators simultaneously, reducing training requirements and standardizing performance across all operators.
Solution Approach 2:
The system uses pressure feedback from the second hydraulic actuator to automatically adjust the first hydraulic actuator, creating a closed-loop control system that manages actuator coordination. This feedback mechanism handles the complex coordination task automatically, reducing the skill requirement for operators while maintaining optimal excavation performance.
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
Improves excavation cycle times by automatically adjusting the arm's position based on pressure feedback, ensuring efficient filling of the bucket regardless of operator skill, preventing over or under-penetration and enhancing overall machine performance.
Implementation Method 1
a second hydraulic actuator operable to move the ground engaging implement relative to the arm, the second hydraulic actuator having a pressured chamber, pressure within the pressure chamber being indicative of a force of engagement between the ground engaging implement and the ground
Implementation Method 2
a first hydraulic actuator operable to lift and lower the arm relative to the chassis
Implementation Method 3
a second hydraulic actuator operable to move the ground engaging implement relative to the arm
Data Source
AI summary
A material handling machine includes an arm moveable relative to a chassis of the machine, a first hydraulic actuator operable to lift and lower the arm relative to the chassis, a ground engaging implement mounted on the arm and moveable relative to the arm, a second hydraulic actuator operable to move the ground engaging implement relative to the arm, the second hydraulic actuator having a pressured chamber, pressure within the pressure chamber being indicative of a force of engagement between the ground engaging implement and the ground, and a control system. The control system defines a target pressure for the pressure chamber, the control system being arranged such that when a pressure within the pressured chamber exceeds the target pressure the control system operates the first hydraulic actuator to lift the arm to reduce the force of engagement between the ground engaging implement and the ground.