Excavator Swing Boom Angle Tracking from Centripetal Acceleration
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Solution Overview
Problem
Existing excavator grade control systems for swing boom excavators suffer from long-term drift in IMU-based measurements and require additional sensors or software to track the swing boom angle accurately without relying on gravity, as the rotational axis is aligned with gravity, leading to inaccuracies.
Innovation Solution
A system utilizing a first inertial measurement unit (IMU) mounted on the swing boom to determine the direction of centripetal acceleration, combined with a processing unit to calculate the swing boom angle, and optionally using a second IMU on the upper part to remove gravitational components, with sensor fusion algorithms for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If IMU-based measurement is used to determine swing boom angle, then the system can track motion continuously, but long-term drift occurs due to uncorrected bias and sensor noise
Solution Approach 1:
The system uses feedback by continuously monitoring the centripetal acceleration direction and comparing it with the expected direction based on upper part rotation. This feedback loop allows the system to detect and correct drift in the integrated swing boom angle measurement, maintaining long-term accuracy without requiring periodic re-initialization.
2Reliability
If gravity is used to determine swing boom position, then the measurement is stable, but it becomes ineffective because the rotational axis is aligned with gravity
Solution Approach 1:
The system introduces centripetal acceleration as an intermediary measurement approach. Instead of directly using gravity (which is ineffective due to axis alignment), the system uses the upper part's rotational motion to generate centripetal acceleration, whose direction provides indirect information about the swing boom angle while avoiding the gravity alignment problem.
3Measurement precision
If additional sensors or software initialization is added to track swing boom motion accurately, then measurement precision improves, but device complexity increases
Solution Approach 1:
The system applies self-service by utilizing data already being collected by the IMU for other purposes (motion tracking). The centripetal acceleration direction is derived from the same accelerometer data used for general motion monitoring, eliminating the need for additional dedicated sensors while improving swing boom angle measurement accuracy.
4Measurement precision
If wire sensor with angular encoder is used to measure swing boom angle, then absolute position can be determined, but the system requires additional sensors and complex installation
Solution Approach 1:
The system applies multi-functionality by making the IMU serve multiple purposes: it simultaneously performs general motion tracking, determines swing boom angle through centripetal acceleration analysis, and provides absolute position information. This eliminates the need for separate wire sensors and angular encoders, reducing overall system complexity while maintaining measurement capabilities.
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
The system provides accurate and drift-free determination of the swing boom angle by isolating centripetal acceleration, allowing for precise tracking of the swing boom motion without long-term errors and without the need for additional sensors or software initialization.
Implementation Method 1
determine a direction of a centripetal acceleration acting on the first IMU based on the received first IMU data when the upper part rotates about the first rotation axis relative to the lower part
Data Source
AI summary
A system for determining a swing boom angle of an excavator. The excavator comprises a lower part, an upper part comprising a cabin, the upper part being arranged on the lower part and configured to be rotated relative to the lower part about a first rotation axis and a swing boom arranged on the upper part and configured to be rotated relative to the upper part about a second rotation axis that an actual swing boom position defines a swing boom angle. The system comprises a first inertial measurement unit (IMU) configured to be mounted on the swing boom and to generate first IMU data, wherein the first IMU comprises at least one acceleration sensor and a processing unit. The processing unit is configured to receive the first IMU data, determine a direction of a centripetal acceleration acting on the first IMU and determine the swing boom angle.