Excavator Hydraulic Speed Control to Prevent Bucket Tip Drop
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Solution Overview
Problem
During the early stages of excavation, the tip of the working equipment in excavators may drop due to high-speed operation, leading to reduced accuracy as the tip can move beyond the target excavation landform.
Innovation Solution
A control system for excavators that calculates and outputs a control signal for the hydraulic actuators based on the smaller of two target speeds, ensuring the working equipment operates within safe limits to prevent tip drop and maintain excavation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the working equipment operates at high speed at the early stage of excavation, then productivity is improved, but the tip of the working equipment drops and moves beyond the target excavation landform, reducing manufacturing precision
Solution Approach 1:
The control system dynamically adjusts the target speed of the working equipment based on real-time conditions. It calculates a first target speed based on operation amount and distance to target landform, and a second target speed based on pump maximum flow rate, then selects the smaller value to control the hydraulic actuators. This dynamic speed adjustment prevents tip drop while maintaining efficient excavation operations.
Solution Approach 2:
The control system continuously monitors the distance between the bucket and target excavation landform, the operation amount of the operation device, and the pump maximum flow rate. Based on this feedback information, it calculates appropriate target speeds and controls the hydraulic actuators to maintain excavation accuracy while optimizing productivity.
2Manufacturing precision
If the target speed is limited by pump maximum flow rate, then manufacturing precision is improved, but productivity may be reduced due to speed constraints
Solution Approach 1:
The system dynamically determines the target speed by comparing two calculated speeds: one based on operation amount and distance (first target speed), and another based on pump maximum flow rate (second target speed). The smaller of the two is selected, allowing the system to operate at maximum speed when hydraulic capacity permits, while preventing tip drop when approaching the target landform.
Solution Approach 2:
The control system changes the target speed parameter based on the relationship between pump maximum flow rate and hydraulic actuator requirements. When the pump can supply sufficient flow, higher speeds are permitted; when flow is limited, speeds are reduced to prevent tip drop, thus optimizing both precision and productivity.
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
Prevents reduction in excavation accuracy by controlling the working equipment's speed to maintain alignment with the target landform, thereby enhancing operational precision.
Implementation Method 1
a hydraulic pump 42 that discharges hydraulic oil; a plurality of hydraulic actuators 20 that are driven by the hydraulic oil discharged from the hydraulic pump 42
Data Source
AI summary
A control method of a work machine includes: calculating a maximum flow rate of hydraulic oil discharged from a hydraulic pump; calculating a first target speed of working equipment including a bucket based on an operation amount of an operation device operated for driving a plurality of hydraulic actuators to which the hydraulic oil discharged from the hydraulic pump is supplied to drive the working equipment and a distance between the bucket and a target excavation landform; calculating a second target speed of the working equipment based on the maximum flow rate, and the operation amount of the operation device and the distance between the bucket and the target excavation landform; and outputting a control signal for controlling the hydraulic actuators based on a smaller one of the first target speed and the second target speed.