Actuator Breakaway Force Detection via Sensor Feedback
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Solution Overview
Problem
Existing methods for determining the breakaway force in actuators, especially safety-related ones, often result in uncontrolled movement due to exceeding the holding force, leading to the slip-stick effect and making it difficult to predict the maximum holding force accurately.
Innovation Solution
A method that uses sensors to detect changes in measured variables, such as position or deformation, to determine when the drive energy required for breakaway is reached without exceeding the holding force, allowing for precise prediction of the breakaway force without moving the actuator, and employs a gradual increase in drive energy with iterative adjustments to prevent uncontrolled movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the drive force is increased to exceed the holding force to determine breakaway force, then the breakaway force can be determined, but the actuator moves in an uncontrolled manner causing the slip-stick effect
Solution Approach 1:
The patent applies partial action by increasing the drive energy only to the point where the breakaway force is reached, not exceeding it. The method detects the moment of breakaway through sensor signals and stops the energy increase at that precise moment, avoiding the excessive force that causes slip-stick movement while still achieving accurate breakaway force determination.
Solution Approach 2:
The patent employs feedback by continuously monitoring sensor signals during the drive energy increase process. When the sensor detects that breakaway force has been reached (through signal changes indicating movement onset), the system responds by stopping the energy increase, thereby preventing the harmful slip-stick effect while maintaining measurement accuracy.
2Measurement precision
If the actuator is moved to analyze the actuator status, then breakaway time can be determined, but the method cannot determine forces smaller than the predicted holding force
Solution Approach 1:
The patent applies preliminary action by performing sensor-based detection of breakaway force before actual actuator movement occurs. The method monitors sensor signals during gradual drive energy increase to detect the precise moment of breakaway, enabling determination of both breakaway time and force without requiring the actuator to move through its full range of motion.
3Object-generated harmful factors
If drive energy is increased gradually with sensor detection to prevent uncontrolled movement, then uncontrolled movement is prevented, but the device complexity increases due to additional sensors and control mechanisms
Solution Approach 1:
The patent applies self-service by utilizing the actuator's own existing sensor system to detect breakaway force and provide feedback for controlling the drive energy increase. The method repurposes sensors already present in the actuator for position or status monitoring to also detect the breakaway moment, eliminating the need for additional external sensors or complex control hardware.
Data Source
Figure 1
AI summary
The method involves successively increasing driving energy required for moving an actuator drive (12) i.e. pneumatic actuator drive, when an actuator (16) is in a rest state in an initial condition. The driving energy is converted into driving force by a driving unit. A measurement value at the actuator drive is measured by a sensor. Change of the measurement value is detected in a state, in which holding force counteracting to movement of the actuator and force generated by the driving power are balanced, such that slight increase of the driving power generates required break-away force. The sensor is designed as a position sensor (34), a strain gauge (36) and a body noise sensor (38). The driving unit is designed as pistons (26, 28) and a drive shaft (32). Independent claims are also included for the following: (1) a partial stroke test (PST) (2) a device for determining break-away force in an actuator.