Excavator Load-Sensing Control for Precise Design Surface Digging
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Solution Overview
Problem
Existing excavation systems struggle to efficiently and precisely achieve a design surface, particularly during gross excavation, due to their reliance on kinematic assistance that does not account for material interaction, leading to increased material costs and operator skill requirements.
Innovation Solution
A method and system that utilize resistance data, including force and moment measurements, to transition between kinematic and load-based control rules, enabling automation over a larger operating envelope and reducing operator skill requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If kinematic assistance systems are used to control excavation operations, then precision near the design surface is improved, but the system becomes inactive during gross excavation requiring manual operation
Solution Approach 1:
The control system dynamically switches between kinematic control mode (for precision near design surface) and load-based control mode (for gross excavation). The system adapts its control strategy based on real-time resistance data, transitioning from purely position-based control to load-aware control when material interaction forces exceed thresholds, thereby extending automation coverage throughout the entire excavation process while maintaining precision where needed
Solution Approach 2:
The system changes the control parameter from purely kinematic (position/trajectory) to include dynamic load parameters (resistance forces). By monitoring resistance data during excavation and comparing it against threshold values, the system determines when to activate load-based conversion rules, effectively changing the control regime to match the excavation phase and material interaction conditions
2Ease of operation
If purely kinematic control rules are used, then control simplicity is maintained, but material interaction effects are not accounted for reducing digging efficiency
Solution Approach 1:
The system incorporates feedback from resistance sensors that continuously monitor material interaction forces during excavation. This feedback is processed by the control unit, which compares resistance values against predefined thresholds and automatically adjusts the control strategy by switching between conversion rules. The feedback mechanism enables the system to respond to actual material conditions while maintaining automated control, resolving the conflict between control simplicity and digging efficiency
Solution Approach 2:
The control unit acts as an intermediary between the operator's control commands and the end effector execution. It introduces a layer of intelligence that processes resistance data and applies appropriate conversion rules (kinematic or load-based) to translate operator inputs into optimized end effector movements. This intermediary layer maintains ease of operation while incorporating complex material interaction awareness
3Extent of automation
If load sensing is implemented to enable load-based control, then automation coverage is improved, but system complexity increases
Solution Approach 1:
The control system is segmented into distinct operational modes with dedicated conversion rules: kinematic control rules for precision work near the design surface and load-based control rules for gross excavation. Each mode has its own control logic and parameter set, allowing the system to manage complexity through modular design while achieving comprehensive automation coverage across different excavation phases
Solution Approach 2:
The control unit is designed as a universal system that can execute multiple types of conversion rules (both kinematic and load-based) depending on the excavation phase. Rather than requiring separate control systems for different excavation modes, a single multi-functional control unit handles both regimes by selecting the appropriate conversion rules based on resistance data, thereby reducing overall system complexity while maintaining broad automation capability
Data Source
AI summary
Automation and/or operator assistance in an excavation operation to obtain a design surface that makes use of resistance data indicative of a resistance exerted on an end effector of the excavator when it engages material to be moved. Control commands for maneuvering the end effector are mapped to movement commands for the end effector according to a first and a second conversion rule. Digging under the first conversion rule causes the end effector to move according to a target path derived from the design surface, whereas digging under the second conversion rule causes the end effector to move as a function of the resistance data and a digging efficiency criterion, which allows to move the end effector independently from the target path. The automation and/or operator assistance automatically transitions from the first conversion rule to the second conversion rule as a function of the resistance data.