Excavator Swing Boom Angle Sensing via IMU Velocity Ratio
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Solution Overview
Problem
Existing systems for determining the swing boom angle of excavators rely on integrating gyroscopes, which drift due to uncorrected bias and sensor noise, and cannot stabilize measurements using gravity, while wire sensors are not universally applicable.
Innovation Solution
A system utilizing multiple inertial measurement units (IMUs) mounted on the swing boom, cylinder, and vehicle frame, along with a processing unit to determine the swing boom angle based on the ratio of angular velocities, stabilized by sensor fusion algorithms like complementary filters or Kalman filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gyroscope integration is used to measure swing boom angle, then continuous position measurement is achieved, but measurement drift occurs due to uncorrected bias and sensor noise
Solution Approach 1:
The system uses feedback by continuously monitoring the angular velocity ratio between the swing boom and cylinder through IMUs and using sensor fusion algorithms (complementary filters or Kalman filters) to stabilize the integrated gyroscope measurements. The processing unit constantly adjusts the angle determination based on the ratio of angular velocities from multiple IMUs, creating a closed-loop feedback system that corrects drift in real-time.
Solution Approach 2:
The patent introduces an intermediary approach by using the angular velocity ratio between the swing boom and cylinder as a mediating parameter. Instead of relying solely on direct gyroscope integration, the system uses the proportional relationship between the angular velocities of two components (swing boom and cylinder) as an intermediate reference to stabilize the measurement and reduce drift effects.
2Reliability
If accelerometer gravity measurement is used to stabilize gyroscope integrations, then long-time orientation stability is improved, but it cannot stabilize swing boom rotation as the rotational axis is aligned with gravity
Solution Approach 1:
The patent uses the cylinder as an intermediary element to achieve stabilization. Instead of trying to use gravity directly (which doesn't work for vertically aligned rotations), the system uses the cylinder's angular velocity as an intermediate reference. The cylinder's rotation provides a measurable angular velocity signal that can be used to stabilize the swing boom angle measurement without relying on gravity-based acceleration measurements.
Solution Approach 2:
The system replaces the gravity-based mechanical stabilization approach with an inertial measurement approach using IMUs. Instead of relying on accelerometers measuring gravity to stabilize the system, the patent uses gyroscopes and accelerometers in an IMU to directly measure angular velocities, substituting the passive gravity-based stabilization with active inertial measurement and computational stabilization through sensor fusion.
3Measurement precision
If wire sensor with angular encoder is used to measure cylinder rotation, then swing boom angle can be determined, but the system is not universally applicable to different excavator configurations
Solution Approach 1:
The patent achieves universality by using a multi-functional IMU-based measurement system that can be applied to different excavator configurations. The system uses inertial measurement units that can measure angular velocities in multiple axes and adapts to different mechanical arrangements by determining the angular velocity ratio between the swing boom and cylinder. This approach is more universally applicable than wire sensors with encoders, which require specific mounting configurations and one-to-one correspondence between encoder rotation and swing boom angle.
Solution Approach 2:
The system changes the measurement parameter from direct angle measurement (using wire sensors and encoders) to angular velocity ratio measurement. By measuring the ratio of angular velocities between the swing boom and cylinder using IMUs, the system creates a measurement approach that is less dependent on specific mechanical configurations and more adaptable to different excavator types, as it relies on kinematic relationships rather than direct mechanical coupling.
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
Accurately determines the swing boom angle without relying on gyroscopes or wire sensors, providing stable and precise measurements through angular velocity ratios and sensor fusion techniques.
Implementation Method 1
Typical sensing algorithms rely on integrating gyroscopes to measure displacements in position
Data Source
AI summary
A system for determining a swing boom angle of an excavator including a vehicle frame including a cabin, a swing boom arranged on the vehicle frame and configured to be rotated relative to the vehicle frame about a first rotation axis and a pneumatic or hydraulic cylinder. A first end of the pneumatic or hydraulic cylinder is coupled to the vehicle frame and a second end is coupled to the swing boom, wherein the cylinder is configured to be rotated relative to the vehicle frame about a second rotation axis at the first end, wherein the cylinder is configured to rotate the swing boom. The system comprises a first inertial measurement unit (IMU), configured to be mounted on the swing boom and to generate first IMU data, a second IMU configured to be mounted on the cylinder and to generate second IMU data and a processing unit.