Excavator Attachment Control With Load Feedback Near Target Surfaces
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Solution Overview
Problem
Hydraulic excavators face challenges in accurately controlling the operating velocity of hydraulic cylinders due to varying loads on the front work implement, leading to inaccurate excavation along the construction target surface and difficulty for operators to recognize load status.
Innovation Solution
A work machine equipped with a posture sensor, load sensor, and controller that calculates and adjusts operation command values based on the distance to the construction target surface and load on the actuator, allowing for accurate positioning and load recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the operating velocity of hydraulic cylinders is controlled based on a fixed operation command value, then the control system is simple, but the excavation accuracy deteriorates when the load on the front work implement varies
Solution Approach 1:
The control system incorporates feedback from load sensors that detect the load on the actuator, and uses this feedback to dynamically adjust the operation command value. The controller calculates a correction amount based on the detected load and adds it to the original operation command value, creating a closed-loop control system that adapts to varying loads while maintaining excavation accuracy.
Solution Approach 2:
The system changes the operation command value parameter dynamically based on the detected load conditions. When the load on the actuator changes, the controller modifies the operation command value by adding a correction amount calculated from the load detection, allowing the system to adapt to different working conditions without requiring a completely complex control architecture.
2Ease of operation
If the operating velocities of hydraulic cylinders remain constant irrespective of load, then the control system is simple, but the operator's ability to recognize load status deteriorates
Solution Approach 1:
The system provides feedback to the operator about load conditions through the behavior of the hydraulic cylinders. When the load increases, the correction amount increases, which affects the operating velocity in a way that the operator can perceive. This allows the operator to recognize the load status on the front work implement while the system maintains relatively simple control logic.
3Manufacturing precision
If the operation command value is adjusted based on load detection, then the excavation accuracy improves, but the response time deteriorates due to additional calculation steps
Solution Approach 1:
The controller is pre-programmed with the logic to calculate correction amounts based on load detection. When the load sensor detects a change in load, the controller immediately applies the pre-established calculation method to determine the correction amount and adjust the operation command value, eliminating the need for complex real-time decision-making and reducing response time.
Data Source
AI summary
A work machine is capable of making a working attachment operate accurately along a construction target surface in the vicinity thereof and of allowing an operator to operate the work machine while recognizing the load acting on a front work implement thereof when the working attachment is not in the vicinity of the construction target surface. To accomplish this, a controller calculates target velocitys for actuators on the basis of an operation amount from an operation input device, postures of a machine main body and the front work implement, and the distance between the working attachment and the construction target surface. The controller calculates operation command values for the actuators on the basis of the target velocities, calculates correction amounts for the operation command values on the basis of loads on the actuators sensed by a load sensor, and adds the correction amounts to the operation command values.