Friction Model Torque Diagnosis for Power Transmission Mechanisms
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Solution Overview
Problem
Existing methods for diagnosing abnormalities in power transmission mechanisms, such as those used in industrial robots, are inadequate as they fail to accurately account for the influence of changing friction torque, which affects the accuracy of diagnosis.
Innovation Solution
An abnormality diagnosis apparatus that includes a friction identification unit to calculate friction parameters, a model torque calculation unit to estimate torque based on these parameters, and an abnormality determination unit to compare detected motor torque with the estimated model torque, thereby diagnosing mechanical abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vibration patterns or extracted spectrum are used for diagnosis, then diagnosis can be performed based on existing methods, but the influence of friction torque changes cannot be removed, reducing diagnosis accuracy
Solution Approach 1:
The patent extracts and separates the friction torque component from the total motor torque using a friction model. By calculating friction torque based on motor speed and pre-stored friction characteristics, the method removes this harmful factor from the diagnosis target, allowing abnormality detection to focus only on power transmission mechanism issues.
Solution Approach 2:
The patent introduces a friction model as an intermediary element between the motor and power transmission mechanism. This model acts as a mediator that accounts for friction effects, allowing the diagnosis system to compensate for friction torque changes and improve measurement precision without being affected by temperature variations.
2Reliability
If friction torque changes due to temperature are not accounted for, then the diagnosis system remains simple, but the change in characteristic reduces diagnosis reliability
Solution Approach 1:
The patent performs preliminary action by pre-storing friction characteristics and models in memory before actual diagnosis operations. This allows the system to quickly access and apply friction compensation during runtime without adding complex real-time calculation mechanisms, thereby improving reliability while maintaining system simplicity.
Solution Approach 2:
The patent utilizes parameter changes in friction characteristics with respect to motor speed and temperature. By incorporating these parameter variations into the friction model, the system accurately compensates for friction torque changes under different operating conditions, enhancing diagnosis reliability without requiring complex adaptive mechanisms.
Data Source
AI summary
An abnormality diagnosis apparatus includes: a friction identification unit that calculates a friction parameter that is a parameter used for calculation of frictional force of a power transmission mechanism connected to a motor; a model torque calculation unit that calculates model torque by performing a process of calculating an estimated value of torque of the motor by using a set value calculated in advance and the friction parameter; and an abnormality determination unit that diagnoses whether the power transmission mechanism is abnormal, on the basis of a result of comparison between the model torque and a motor torque detected by a motor torque detection unit.