Robot Encoder Fault Detection Using Command-Feedback Position Comparison
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting encoder abnormalities in general-purpose motors, such as those used in robots, require additional sensors or modifications to the servo driver, increasing costs and complexity, and are not applicable to systems without existing abnormality detection functions.
Innovation Solution
An abnormality detection method and device that uses a robot control unit with a controller, driver, and safety unit to compare command position information with detection position information from the encoder, determining abnormalities based on a predetermined threshold, without requiring new configurations or functions in the servo driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional sensors or modifications to the servo driver are used to detect encoder abnormalities, then encoder abnormality detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The system uses its own existing command position information and encoder output signals to perform self-diagnosis of encoder abnormalities. The safety unit leverages data already present in the control system (command position from controller and feedback position from encoder) to detect inconsistencies indicating encoder failure, without requiring external sensors or modifications to the servo driver.
Solution Approach 2:
The safety unit performs multiple functions: it monitors motor control commands, processes encoder feedback signals, and detects encoder abnormalities all within a single component. This multi-functional approach eliminates the need for separate dedicated abnormality detection hardware, reducing overall system complexity while maintaining detection capability.
2Reliability
If additional sensors or modifications to the servo driver are used to detect encoder abnormalities, then encoder abnormality detection capability is improved, but cost increases
Solution Approach 1:
The system uses its own existing command position information and encoder output signals to perform self-diagnosis of encoder abnormalities. The safety unit leverages data already present in the control system (command position from controller and feedback position from encoder) to detect inconsistencies indicating encoder failure, without requiring external sensors or modifications to the servo driver.
Solution Approach 2:
The safety unit creates a virtual model of the expected system behavior by comparing command position information with actual encoder feedback. By analyzing the relationship between commanded movements and reported positions, the system can infer encoder status without physical duplication of sensing components.
3Reliability
If new configurations or functions are added to the servo driver for abnormality detection, then encoder abnormality detection capability is improved, but influence on existing systems increases
Solution Approach 1:
The safety unit acts as an intermediary component that interfaces with both the controller and encoder without requiring modifications to either. It receives command position information from the controller and feedback signals from the encoder, performing abnormality detection in between these existing system components, thus maintaining compatibility with general-purpose motors and controllers.
Solution Approach 2:
The abnormality detection function is separated into a distinct safety unit rather than being integrated into the servo driver or controller. This segmentation allows the detection functionality to be added independently without modifying existing components, preserving system compatibility while enabling encoder monitoring.
Data Source
AI summary
An abnormality detection method of an encoder includes an output step, a control step, an information acquisition step, and an abnormality determination step. The abnormality determination step compares command position information with detection position information of a motor calculated based on an output signal, and determines that the encoder is abnormal in a case where a difference between the command position information and the detection position information of the motor is equal to or more than a predetermined value.