Rotary Encoder Calibration Using Onboard Orientation Sensing
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Solution Overview
Problem
Existing sensor calibration methods are time-consuming and costly, and sensor measurement errors, such as scale factor and bias errors, can change over time, leading to inaccuracies in orientation sensing.
Innovation Solution
A rotary joint device with a first platform rotating relative to a second platform, equipped with an actuator, encoder, and orientation sensor, uses a controller to modulate the actuator to correct sensor measurements and calibrate encoder outputs, reducing errors by aligning measurements to a target value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sensor calibration methods are used, then measurement accuracy can be improved, but calibration time and cost increase significantly
Solution Approach 1:
The system performs self-calibration by using the encoder itself as the reference standard. The encoder measures the rotation angle of the actuator, and this measurement is used to automatically determine and apply calibration parameters for the orientation sensor, eliminating the need for external calibration equipment and manual procedures.
Solution Approach 2:
The encoder serves multiple functions: it acts as both the measurement device for the actuator's rotation angle and the reference standard for calibrating the orientation sensor. This multi-functionality eliminates the need for separate calibration equipment and reduces calibration time.
2Measurement precision
If traditional sensor calibration methods are used, then measurement accuracy can be improved, but device complexity and cost increase
Solution Approach 1:
The system uses its own encoder as the reference standard for calibration, eliminating the need for external calibration equipment. This self-service approach reduces device complexity and cost while maintaining calibration accuracy.
Solution Approach 2:
The encoder acts as an intermediary between the actuator and the orientation sensor, providing a reference measurement that mediates the calibration process. This intermediary approach simplifies the overall system by using an existing component rather than adding specialized calibration equipment.
3Measurement precision
If sensor calibration is performed frequently to maintain accuracy, then measurement precision is maintained, but productivity decreases
Solution Approach 1:
The system performs calibration periodically based on operational criteria such as elapsed time, number of actuator operations, or detection of drift conditions. This periodic self-calibration maintains measurement precision while minimizing interruptions to productivity compared to frequent manual calibration.
Solution Approach 2:
The system automatically performs calibration without requiring external intervention or system shutdown, maintaining precision while minimizing impact on productivity through seamless self-service operation.
Data Source
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AI summary
One example method involves generating a calibration control signal for controlling an actuator configured to rotate a first platform about an axis. The calibration control signal causes the actuator to rotate the first platform at least one complete rotation about the axis. The method also involves receiving encoder output signals. The encoder output signals are indicative of angular positions of the first platform about the axis. The method also involves receiving sensor output signals from an orientation sensor mounted on the first platform. The sensor output signals are indicative of a rate of change to an orientation of the orientation sensor. The method also involves determining calibration data based on given sensor output signals received from the orientation sensor during the at least one complete rotation. The calibration data is for mapping the encoder output signals to calibrated measurements of the angular positions of the first platform about the axis.