Encoder Index Track Encoding for Robotic Positioning
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Solution Overview
Problem
Relative encoders in robotic systems face issues with accurate position determination due to potential errors from dirty or damaged tracks, high-speed movements, and external forces, leading to safety concerns and increased energy consumption during the homing process.
Innovation Solution
Incorporating additional information on the index track of relative encoders, allowing for shorter shaft movement to determine actual positions and increasing error detection speed, without altering the A and B tracks or associated hardware, thus enabling quicker and more accurate position determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If relative encoders use traditional homing process to determine shaft position, then position determination is achieved, but the shaft must move long distances and consume excessive energy
Solution Approach 1:
The index track encodes absolute position information in advance at multiple locations around the shaft circumference. During operation, the sensor reads this pre-encoded position data directly from the index track without needing to move the shaft through a long homing sequence, thereby determining position with minimal shaft movement and energy consumption.
2Measurement precision
If relative encoders use traditional homing process, then position determination is achieved, but it takes excessive time
Solution Approach 1:
Position information is pre-encoded on the index track at multiple angular positions. The sensor can immediately read the current position from the index track without waiting for a time-consuming homing sequence, thereby eliminating homing time while maintaining accurate position determination.
3Reliability
If additional information is added to the index track, then error detection speed increases, but the device complexity increases
Solution Approach 1:
The index track integrates multiple functions into a single component: it provides absolute position encoding, enables error detection through redundant position information, and serves as a reference for the sensor. By combining these functions in one track rather than using separate components, the solution enhances reliability without proportionally increasing device complexity.
4Measurement precision
If the shaft moves longer distances for position determination, then position accuracy is improved, but the distance required increases
Solution Approach 1:
Multiple absolute position markers are pre-encoded around the shaft circumference on the index track. The sensor can read position information from any angular position without needing to move the shaft through a long reference sequence, thereby achieving accurate position determination with minimal shaft movement distance.
Data Source
AI summary
A shaft may be rotated, where the shaft includes an encoder with a first, second, and third logical track, where the first and second logical tracks include bit patterns that are readable to be 90 degrees out of phase with one another, and where the third logical track includes a sequence of n numbers, each number being represented by m bits, where n is greater than 1. While moving the shaft, a number of the sequence from the third logical track and an extent of bits from the first or second logical track may be read. An orientation of the shaft may then be determined based on the number and the extent of bits. The orientation may be a linear position of a linear encoder or an angular position of a rotary encoder.