Robot Gear Encoder Cross-Validation for Rotation Error Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing encoders may erroneously detect the number of rotations of a main shaft gear, leading to incorrect derivation of the multiple rotation quantity, which can cause robot malfunctions due to undetected abnormalities in the gears.
Innovation Solution
A robot system with a main shaft gear and multiple countershaft gears, where the number of teeth of each gear is an integer with no greatest common divisor other than 1, performs processing to derive multiple rotation quantities based on phase detection, stopping the drive unit when discrepancies are found, thereby determining gear abnormalities and preventing malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an encoder with two countershaft gears is used to detect main shaft gear rotations, then the number of rotations can be derived, but measurement precision deteriorates when gear abnormalities occur causing erroneous detection
Solution Approach 1:
The encoder is divided into multiple independent detection paths by adding a third countershaft gear. Each path (first countershaft gear + second countershaft gear, second countershaft gear + third countershaft gear) can independently derive the main shaft gear rotations. This segmentation allows cross-validation to detect erroneous readings from single-path abnormalities.
Solution Approach 2:
The system implements feedback by comparing the number of rotations derived from different gear combinations. When the values from different paths do not match, the system identifies an abnormality and can correct or flag the erroneous measurement, improving reliability under abnormal conditions.
2Reliability
If multiple countershaft gears are added to improve detection reliability, then gear abnormalities can be detected, but device complexity increases
Solution Approach 1:
Instead of using one complex gear train, the system segments the detection function across multiple simpler gear paths. Each path uses standard gear meshing principles, but the combination of paths provides redundancy for abnormality detection without requiring complex individual components.
Solution Approach 2:
The multiple countershaft gears serve dual purposes: they each independently contribute to rotation detection while simultaneously providing cross-validation capability. The same gear structure performs both measurement and self-diagnosis functions, avoiding the need for separate monitoring systems.
Data Source
AI summary
A robot system includes: a robot having a main shaft gear attached to a rotary shaft of a drive unit, a first countershaft gear meshing with the main shaft gear, a second countershaft gear meshing with the main shaft gear, and a third countershaft gear meshing with the main shaft gear. A number of teeth of the main shaft gear, a number of teeth of the first countershaft gear, a number of teeth of the second countershaft gear, and a number of teeth of the third countershaft gear are integers having no greatest common divisor other than 1. As first processing, a first number of rotations, which is a number of rotations of the main shaft gear, is derived based on a phase of the first countershaft gear and a phase of the second countershaft gear, and a second number of rotations, which is a number of rotations of the main shaft gear, is derived based on the phase of the second countershaft gear and a phase of the third countershaft gear, and the drive unit is stopped when the first number of rotations and the second number of rotations do not coincide with each other.