Dual Absolute Encoder With Off-Axis And On-Axis Sensors
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Solution Overview
Problem
Existing dual magnetic absolute encoders lack redundancy and improved resolution in determining the position or rotation of motor shafts, leading to potential inaccuracies and faults in robotic systems.
Innovation Solution
A dual absolute encoder assembly with two position sensors, one on-axis and one off-axis, mounted on a common substrate, detecting different or common signal types, including magnetic, capacitive, or inductive signals, to provide redundancy and enhanced position detection capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single encoder with one position sensor is used, then the device complexity is low, but the reliability and measurement precision are insufficient
Solution Approach 1:
The patent combines two encoders (first encoder with off-axis sensor and second encoder with on-axis sensor) into a single integrated encoder assembly that shares common components such as the code disk, substrate, and housing. This merging approach provides redundancy and improved reliability while controlling device complexity through component sharing.
Solution Approach 2:
The encoder assembly is segmented into two distinct sensing paths: an off-axis encoder using a first position sensor and an on-axis encoder using a second position sensor. Each sensor detects different signal types (magnetic, capacitive, or inductive signals), creating independent measurement channels that enhance reliability through diversity.
2Measurement precision
If a single position sensor is used, then the device complexity is low, but the measurement precision and resolution are limited
Solution Approach 1:
The measurement function is segmented across two position sensors detecting different signal types. The first position sensor (off-axis) and second position sensor (on-axis) provide independent measurement channels that detect magnetic, capacitive, or inductive signals, thereby improving measurement precision and resolution through multi-sensor data fusion.
Solution Approach 2:
Different regions of the code disk are optimized for different sensor types: an axial surface for on-axis sensing and a radial surface for off-axis sensing. This local quality differentiation allows each sensor to operate in its optimal detection zone, improving overall measurement precision.
3Reliability
If optical signals are used in position sensors, then the measurement precision can be high, but the reliability is reduced due to susceptibility to contamination and environmental factors
Solution Approach 1:
The patent replaces optical signal detection with magnetic, capacitive, or inductive signal detection in position sensors. These non-optical signal types are less susceptible to contamination and environmental factors, thereby improving reliability while maintaining measurement precision through alternative physical fields.
Solution Approach 2:
Magnetic fields, capacitive fields, or inductive fields serve as intermediaries between the code disk and position sensors, replacing direct optical pathways. These field-based intermediaries are less susceptible to contamination and environmental interference, improving reliability while maintaining measurement capability.
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 dual encoder configuration enhances resolution and redundancy, improving the accuracy of motor shaft position determination and fault detection, reducing the risk of inaccuracies and enhancing the reliability of robotic systems.
Implementation Method 1
each position sensor is configured to detect different or common signal types, and a signal type of the second position sensor excludes optical signals
Implementation Method 2
detecting different or common signal types, including magnetic, capacitive, or inductive signals
Implementation Method 3
detecting different or common signal types, including magnetic, capacitive, or inductive signals
Implementation Method 4
each position sensor is configured to detect different or common signal types, and a signal type of the second position sensor excludes optical signals
Implementation Method 5
detecting different or common signal types, including magnetic, capacitive, or inductive signals
Implementation Method 6
detecting different or common signal types, including magnetic, capacitive, or inductive signals
Data Source
AI summary
An exemplary encoder assembly includes a substrate, a first encoder, and a second encoder. The substrate has two or more position sensors, each position sensor being configured for detecting a rotary position of a shaft or other rotating element of a machine. The first encoder includes at least one first position sensor of the two or more position sensors. The at least one first position sensor is disposed on the substrate for off-axis alignment with the shaft or other rotating element of the machine. The second encoder includes a second position sensor of the two or more position sensors, the second position sensor being disposed on the substrate for on-axis or off-axis alignment with the shaft or other rotating element of the machine. Each position sensor is configured to detect different or common signal types, and a signal type of the second position sensor excludes optical signals.