Actuator Load State Detection via Motor Current Analysis
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Solution Overview
Problem
Existing actuators for building elements like roller blinds and garage doors face challenges in accurately determining whether the load is driving or driven due to the partial irreversibility of the reduction gear, leading to inefficiencies in torque measurement and obstacle detection, especially when using differential brakes.
Innovation Solution
A method and system that analyze the operating state of the actuator by measuring and calculating the variation of electrical parameters such as motor torque, speed, or current, and using software logic to differentiate between driving-load and driven-load modes, with adaptive threshold settings and a learning process to account for efficiency changes and brake characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a differential brake is used to replace electro-brakes or hysteresis brakes, then the brake action masking of torque measurement is reduced, but the partial irreversibility of the reduction gear causes different motor torque variations for the same load torque variation depending on operating mode
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring motor current and comparing it against reference values obtained during a learning phase. The control unit adjusts its interpretation of motor torque based on feedback about the actual operating mode (driven-load or driving-load), allowing accurate torque measurement despite the reduction gear's partial irreversibility. This feedback loop enables the system to compensate for efficiency variations dynamically.
Solution Approach 2:
The patent performs preliminary action by conducting a learning phase during installation or initial operation to establish reference current values for different operating modes. These pre-established references are stored and used during normal operation to quickly and accurately determine the operating state without real-time complex calculations, simplifying the ongoing operational complexity.
2Measurement precision
If the reduction gear has low efficiency (less than 80%), then losses in the reduction gear prevent fine detection of driving-load situations by current direction reversal, but high efficiency is not always achievable
Solution Approach 1:
The patent replaces the mechanical detection method (relying on current direction reversal) with an electrical/electronic detection method. Instead of waiting for current direction to reverse, the system monitors motor current magnitude and compares it against reference values processed by a control unit. This substitution allows accurate detection of driving-load situations even when energy losses prevent current direction reversal, decoupling detection sensitivity from reduction gear efficiency.
3Adaptability or versatility
If manual adjustment is required for torque thresholds, then adaptation to different conditions is possible, but installation time increases and optimal adjustment is not guaranteed
Solution Approach 1:
The patent implements self-service by enabling the actuator to automatically perform a learning phase during installation or initial operation. The system autonomously measures current values under known conditions, processes this data through the control unit, and establishes appropriate reference values and thresholds without requiring manual intervention. This self-configuration capability provides both adaptability to specific installations and time savings, eliminating the need for manual torque threshold adjustment.
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 precise detection of the load state, improving obstacle detection accuracy and reducing the need for manual adjustments, while facilitating automatic operation and maintenance by distinguishing between driving and driven loads effectively.
Implementation Method 1
an electromechanical actuator (40) comprising an electric motor (10)
Implementation Method 2
an immobilization brake (20) ensuring the disabling of the actuator when the motor is not powered
Data Source
AI summary
Method of operating an actuator (1) for maneuvering a movable element (52), comprising a motor of asynchronous type or of brushless type or comprising a motor associated with a differential brake, and comprising a partially irreversible reduction gear, which comprises a step of establishing a measurement of an operating parameter of the actuator and a step of using this measurement to determine whether the actuator is driving the movable element or whether the actuator is being driven by the movable element, and then a step of implementing first logic for determining an end of travel or an obstacle, or a step of implementing second logic for determining an end of travel or an obstacle, depending on whether the actuator drives the movable element or the actuator is driven by the movable element.