Acceleration Sensor Calibration via Rotational Offset Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Industrial machinery sensors, such as IMUs, often suffer from misalignment during manufacturing, leading to inaccurate gravity vector measurements due to rotational offsets, particularly about the z-axis, which affects the reliability of sensor data.
Innovation Solution
A method and system for calibrating acceleration sensors on machines by determining a rotational offset value using measurements from different positions of a linkage, incorporating force and acceleration data to correct the sensor alignment and provide accurate gravity vector measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an IMU is installed using pre-drilled holes and bolts during manufacturing, then the installation process is simplified and manufacturing efficiency is improved, but the IMU may have rotational misalignment (particularly about the z-axis) leading to inaccurate gravity vector measurements
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements during the manufacturing process itself. The IMU is measured in multiple predetermined positions (e.g., level, tilted at known angles) before the machine leaves the factory, allowing rotational offset values to be calculated and stored in memory. This preliminary calibration ensures measurement accuracy is established upfront, eliminating the need for post-installation adjustments while maintaining the simplicity of the bolted installation process.
2Ease of operation
If the IMU is mounted with manufacturing tolerances, then the installation is easier and more flexible, but the z-axis orientation cannot be well-controlled resulting in rotational offset
Solution Approach 1:
The system applies self-service by automatically measuring the IMU's rotational offset through software-based procedures rather than requiring precise mechanical alignment during installation. The calibration process autonomously determines the offset values by comparing sensor readings at known orientations, and the controller automatically compensates for the misalignment using stored calibration data. This eliminates the need for complex mechanical alignment fixtures or skilled manual adjustment, allowing flexible installation while achieving precise orientation compensation.
3Measurement precision
If calibration measurements are taken at multiple predetermined positions, then the rotational offset calibration is more accurate, but the calibration process requires more time and operational steps
Solution Approach 1:
The patent performs calibration measurements during manufacturing before the machine enters service, eliminating time loss during operational calibration. The predetermined positions are established once during factory calibration, and the resulting offset values are permanently stored in memory for automatic application during all subsequent operations. This preliminary action converts a potentially time-consuming operational process into a one-time manufacturing step.
Solution Approach 2:
The calibration process uses periodic action by measuring the IMU at discrete, predetermined positions (e.g., level position, then tilted at specific angles) rather than requiring continuous adjustment. These periodic measurements at key orientations are sufficient to calculate the rotational offset, avoiding the need for exhaustive measurement at every possible angle while achieving accurate calibration.
Data Source
AI summary
A method for calibrating an acceleration sensor coupled to a machine may comprise: at a first position of a linkage of the machine, obtaining a first acceleration measurement from the acceleration sensor and obtaining from an input a first force value indicative of a first force on the linkage; at a second position of the linkage of the machine, obtaining a second acceleration measurement from the acceleration sensor and obtaining from the input a second force value indicative of a second force on the linkage; determining a rotational offset calibration value of the acceleration sensor as a function of the first acceleration measurement, the first force value, the second acceleration measurement, and the second force value; and using the rotational offset calibration value to calibrate the acceleration sensor.