Excavator Control System for Dynamic Trajectory Adjustment
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Solution Overview
Problem
Automated excavators face challenges in recognizing underground obstacles, leading to excessive pressure application and potential bucket entrapment during excavation, which affects fuel economy, durability, and work efficiency.
Innovation Solution
A control method for construction machinery that calculates the digging force in real time using joint state values and cylinder pressure values, generating a new excavation trajectory based on a Momentum-based Disturbance Observer and Dynamic Movement Primitives algorithm to reduce excavation speed and depth when excessive force is detected, preventing excessive pressure and entrapment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the excavator follows a preset excavation trajectory without real-time force adjustment, then the excavation speed and depth can be maintained at optimal levels, but excessive digging force may be applied causing bucket entrapment and increased fuel consumption
Solution Approach 1:
The system continuously monitors digging force through sensors measuring joint torques and cylinder pressures, compares the measured force against threshold values, and dynamically adjusts the excavation trajectory in real-time based on the feedback signal. This closed-loop control prevents bucket entrapment by reducing excavation depth or speed when excessive force is detected, thereby optimizing fuel consumption while maintaining productivity.
Solution Approach 2:
The excavation trajectory is transformed from a static preset path to a dynamic adaptive trajectory that changes in real-time based on actual digging conditions. The system continuously recalculates the optimal trajectory parameters (speed, depth, direction) according to the measured digging force, allowing the excavator to adapt its motion dynamics to varying ground conditions and prevent energy-wasting entrapment events.
2Productivity
If the excavator increases excavation depth and force to improve work efficiency, then more material can be moved per unit time, but the risk of bucket entrapment and hydraulic system damage increases
Solution Approach 1:
The system takes preliminary protective action by continuously monitoring digging force before entrapment can occur. When the measured force approaches dangerous thresholds, the control system proactively adjusts the trajectory to reduce excavation depth or speed, preventing bucket entrapment and subsequent hydraulic system damage before they happen. This preventive approach protects the durability of hydraulic components while maintaining high work efficiency.
Solution Approach 2:
Real-time feedback from force sensors enables the system to detect approaching dangerous force levels and immediately adjust excavation parameters. The continuous monitoring and responsive trajectory adjustment create a safety mechanism that prevents excessive forces from damaging hydraulic cylinders and other components, thereby improving reliability without sacrificing productivity.
3Device complexity
If the excavator operates autonomously without real-time force monitoring, then the system complexity is reduced, but the ability to detect and respond to underground obstacles is lost
Solution Approach 1:
The system replaces complex mechanical obstacle detection methods with a smarter approach using existing sensors (joint torque sensors, pressure sensors) combined with mathematical modeling. By calculating digging force from measurements already taken for control purposes and comparing against thresholds, the system achieves obstacle detection without adding significant hardware complexity, maintaining autonomous operation capability while improving obstacle awareness.
Data Source
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AI summary
In a method of controlling construction machinery, a bucket of a working device is moved along a first excavation trajectory to perform an excavation operation on the ground of a work area. A digging force exerted on the bucket during the excavation operation is calculated. A new second excavation trajectory is generated based on the calculated digging force. The bucket is moved along the second excavation trajectory.