Excavator Boom-Arm Control for Accurate Target Depth Dragging
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Solution Overview
Problem
Existing working machines face challenges in accurately controlling the excavation depth due to differing response characteristics of the boom and arm, often resulting in excavation deeper than the target depth during horizontal dragging operations.
Innovation Solution
A working machine with a controller that sets target angular velocities for the boom and arm based on distance and time elapsed from the start of movement, using hydraulic cylinders and control valves to maintain the bucket edge at a preset excavation depth, incorporating a memory for angular acceleration and power mode adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the boom and arm are controlled to move simultaneously during excavation, then the excavation operation can be performed efficiently, but the different response characteristics of the boom and arm cause inaccurate control of the bucket front end position at the target height
Solution Approach 1:
The controller performs preliminary determination of target angular velocities for both the boom and arm before the excavation operation begins. By calculating and setting the target angular velocities in advance based on the initial distance to the target depth, the system ensures that both components start moving with pre-coordinated speeds that account for their different response characteristics, enabling accurate depth control from the very beginning of the operation
Solution Approach 2:
The control system dynamically adjusts the angular velocities of the boom and arm during operation. The controller continuously monitors the actual positions and velocities, comparing them against the target values, and makes real-time adjustments to maintain accurate depth control while adapting to the changing mechanical responses of different components
2Speed
If the arm moves faster than the boom during horizontal dragging, then the bucket can reach the target depth quickly, but the boom's delayed upward movement causes the bucket to dig deeper than the target excavation depth
Solution Approach 1:
The controller changes the velocity parameters of the boom and arm based on their different response characteristics. By setting the arm's target angular velocity higher than the boom's target angular velocity during the initial phase, the system allows the arm to move faster to reach the target depth quickly, while the boom follows with appropriate delay and speed to maintain accurate depth control
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 effectively reduces the likelihood of excavating deeper than the target depth by precisely controlling the boom and arm movements, ensuring accurate excavation depth control.
Implementation Method 1
a hydraulic pump to deliver hydraulic fluid toward the arm cylinder and the boom cylinder
Implementation Method 2
an arm cylinder to extend and retract by receiving and discharging hydraulic fluid to rotate the arm, a boom cylinder to extend and retract by receiving and discharging hydraulic fluid to rotate the boom
Implementation Method 3
an arm control valve including a solenoid to switch supplying and discharging hydraulic fluid to and from the arm cylinder and to adjust a flow rate of hydraulic fluid based on a current value inputted thereto
Data Source
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AI summary
Embodiments of the present invention include a boom (310) rotatably coupled to a machine body (2) such that the boom (310), an arm (311) rotatably coupled to the boom (310), a bucket (312) coupled to the arm (311) and including an edge portion (312a) to function as a leading edge when the bucket (312) excavates earth, and a controller (4). The controller (4) is configured or programmed to, in performing a first process in which the controller (4) causes the arm (311) to rotate toward the boom (310) while causing the boom (310) to rotate to move up to perform excavation along a plane at a target excavation depth, set a first target angular velocity of the arm (311) and a second target angular velocity of the boom (310) based on a distance between the edge portion (312a) in a movement start position and the target excavation depth, the first target angular velocity being a target angular velocity corresponding to a period of time elapsed from a start of movement of the arm (311), the second target angular velocity being a target angular velocity corresponding to a period of time elapsed from a start of movement of the boom (310), and control rotation of the arm (311) and the boom (310) based on the set first target angular velocity and the set second target angular velocity.