Commutation Angle Control for Drive Motor Speed Monitoring
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Solution Overview
Problem
Current monitoring systems in motion-controlled machines, such as robots, suffer from cumulative reaction times that lead to undesired overrun due to delays in reacting to speed limit exceedances, necessitating larger protective spaces.
Innovation Solution
Implementing a method where the commutation angle of an electronically commutated drive motor is controlled to limit the rate of change, allowing for immediate reduction or reversal of drive force when limits are exceeded, reducing reaction delays and overrun distances by enabling faster braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If speed monitoring is implemented in the higher-level robot controller, then speed limits are enforced, but cumulative reaction times cause overrun and require larger protective spaces
Solution Approach 1:
The patent introduces an intermediary monitoring device between the robot controller and the drive motor. This intermediary device directly monitors the actual speed from the drive motor's actual position data and compares it with speed limits, triggering immediate error reactions without the cumulative delays of higher-level controller monitoring. The intermediary acts as a dedicated speed monitoring layer that bridges the gap between control commands and motor execution.
Solution Approach 2:
The speed monitoring function is extracted from the higher-level robot controller and placed into a separate, dedicated monitoring device at the drive level. This extraction allows speed monitoring to operate independently and immediately, without being constrained by the processing cycles and reaction times of the main robot controller, thereby eliminating cumulative delays.
2Object-affected harmful factors
If the robot controller monitors speed and triggers error reactions, then safety is improved, but overrun distance increases due to cumulative reaction times
Solution Approach 1:
The dedicated intermediary monitoring device provides immediate detection and reaction to speed limit exceedances, eliminating the time delays inherent in higher-level controller monitoring. This immediate reaction significantly reduces the overrun distance when speed limits are exceeded, thereby reducing the protective space required while maintaining safety.
Solution Approach 2:
The monitoring device continuously compares actual speed with speed limits in advance, ready to trigger error reactions immediately when limits are approached or exceeded. This preliminary monitoring ensures that safety reactions occur at the earliest possible moment, minimizing overrun distance before the robot needs to stop.
3Speed
If commutation angle is controlled to limit rate of change, then drive force is automatically reduced when limits are exceeded, but control complexity increases
Solution Approach 1:
The system implements feedback by continuously determining the rate of change of the commutation angle from the drive motor's actual position and comparing it with a predetermined limit value. When the rate of change exceeds the limit, the system automatically adjusts the commutation angle to reduce the rate of change back within permissible values, creating a closed-loop control that manages speed without additional hardware.
Solution Approach 2:
The patent changes the commutation angle parameter dynamically based on the rate of change limit. When the rate of change of the commutation angle exceeds the limit, the commutation angle is adjusted (reduced or reversed) to bring the rate of change back within acceptable ranges. This parameter adjustment automatically modulates the drive force without requiring separate control mechanisms.
Data Source
Figure 1~2
AI summary
The method involves determining a limit value for a rate of change i.e. time derivative, of an actual position of electronically commutated drive motors (1.1-1.6) i.e. permanently activated synchronous motors. Commutation angle of the drive motors is set based on the actual position and a predetermined target position. The commutation angle is predetermined such that the rate of change of the commutation angle does not exceed the limit value. The actual position of the drive motors is detected by sensors associated with the drive motors. Independent claims are also included for the following: (1) a device for monitoring operation of a movement-controlled machine (2) a computer program product comprising a set of instructions for performing a method for monitoring operation of a movement-controlled machine.