Autonomous Excavator ZMP Stability Control
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Solution Overview
Problem
Conventional autonomous excavators risk tipping over or overturning when operating on uneven or inclined terrain due to the lack of consideration for posture, excavation amount, and topography in generating work trajectories.
Innovation Solution
An autonomous excavator system that includes a front work device with sensors and a processor to calculate a zero-moment point (ZMP) and generate work trajectories based on this calculation, ensuring stable operation by maintaining the ZMP within the supporting polygon, thus preventing tipping or overturning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the excavator limits the speed and acceleration of each joint and generates a work trajectory that minimizes moving time in a limited situation, then the productivity is improved, but the excavator may tip over or overturn when working on uneven terrain or inclined terrain
Solution Approach 1:
The system dynamically changes operating parameters (speed and acceleration limits) based on real-time stability assessment. The processor calculates maximum allowable speed and acceleration values by considering the excavator's current posture, center of gravity position, and terrain conditions, then generates work trajectories that respect these dynamically adjusted parameters to prevent tipping while maintaining efficient operation
Solution Approach 2:
The work trajectory generation transitions from static speed/acceleration limits to dynamic adjustment based on real-time excavator state. The system continuously monitors joint positions, calculates center of gravity, assesses stability margins, and adapts the trajectory parameters accordingly, enabling the excavator to operate efficiently on both flat and uneven terrain without compromising stability
2Device complexity
If the excavator does not consider posture, excavation amount, and topography in generating the work trajectory, then the device complexity is reduced, but the excavator may tip over or overturn
Solution Approach 1:
The processor performs preliminary stability assessment and center of gravity calculation before generating the work trajectory. By pre-calculating the maximum allowable speed and acceleration values based on the current excavator state and terrain conditions, the system ensures stability constraints are built into the trajectory generation process, preventing tipping without requiring complex real-time adjustments during execution
Solution Approach 2:
The system incorporates feedback loops where the processor continuously monitors joint positions, calculates the current center of gravity, assesses stability margins, and uses this information to adjust work trajectory parameters. This closed-loop control ensures the excavator maintains stable operation while performing autonomous work
Data Source
AI summary
Embodiments disclosed herein relate to an autonomous work excavator and an operation method therefor. According to an embodiment, an excavator comprises a front work device including an arm, a boom, and a bucket; a sensor device configured to collect state information of the excavator and information related to the surrounding environment; and a processor electrically connected to the front work device and the sensor device. The processor is configured to perform a digging operation based on a work instruction such that soil is loaded in the bucket; calculate a zero-moment point of a force acting on the excavator based on mass information on at least a portion of the front work device after the digging operation has been performed; and obtain a work trajectory for processing the soil loaded in the bucket by using the ZMP and the information related to surrounding environment.