Servomotor Load Diagnosis Using Torque Direction Consistency
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Solution Overview
Problem
Conventional abnormality detection devices for servomotors rely on relative load values and change rates, making it difficult to evaluate the load state absolutely, leading to ambiguous threshold settings and impractical determinations.
Innovation Solution
A load state diagnosis device and method for servomotors that detect the rotational direction of torque by measuring command current values, determining consistency with the predetermined rotational drive direction, and outputting a load index to provide an absolute evaluation of the load state, thereby avoiding unnecessary force application and potential tool deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional abnormality detection devices use relative load values and change rates to detect abnormalities, then real-time abnormality detection can be achieved, but the load state cannot be absolutely evaluated and threshold settings become ambiguous
Solution Approach 1:
The patent changes the parameter from relative load values to rotational direction of torque, which provides an absolute evaluation criterion. By detecting whether the torque rotational direction matches the predetermined drive direction, the system eliminates the need for ambiguous threshold settings while maintaining reliable abnormality detection.
2Ease of operation
If absolute evaluation of load state is implemented, then clear determination standards can be established, but conventional detection methods based on relative values and change rates cannot be used
Solution Approach 1:
The patent replaces the conventional mechanical detection approach (measuring load magnitude and change rates) with a directional detection approach. By using a detection unit to measure the rotational direction of torque through command current values, the system achieves absolute evaluation while maintaining detection reliability.
3Measurement precision
If rotational direction of torque is detected by measuring command current values, then absolute load state evaluation becomes possible, but additional detection functionality is required
Solution Approach 1:
The patent uses command current values as an intermediary to indirectly detect the rotational direction of torque. Instead of directly measuring torque direction, the system measures the command current values from the servo driver, which represent the torque direction, thereby achieving precise load state evaluation without complex direct torque measurement mechanisms.
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
Enables absolute evaluation of the load state of servomotors, reducing maintenance costs by monitoring torque direction inconsistencies and adjusting control parameters to prevent overload and deterioration, applicable across various rotary tools and processing conditions.
Implementation Method 1
a detection part that detects a rotational direction of a torque acting on the servomotor by measuring a command current value for the servomotor
Data Source
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AI summary
There are provided a load state diagnosis device and a load state diagnosis method for a servomotor that can diagnose the present load state of a servomotor with an absolute evaluation index regardless of rotary tool types, processing conditions and differences in machines. A PLC 10 diagnoses the load state of the servomotor 2 which rotationally drives a rotary tool 1 in a predetermined rotational drive direction at a constant speed. The PLC 10 includes a detection part 12 that detects the rotational direction of a torque acting on the servomotor 2, a determination part 13 that determines whether the rotational direction of the torque detected by the detection part 12 is consistent with the predetermined rotational drive direction, and a load index output part 14 that outputs a load index indicating the load state of the servomotor 2 based on a determination result of the determination part 13.