SMA Wire Driving Device Using Sampling Resistor for Displacement Detection
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Solution Overview
Problem
Conventional SMA wire driving devices face challenges in achieving rapid and accurate control due to complex computation requirements for displacement detection, which affects the response speed and quality of optical anti-shaking.
Innovation Solution
The proposed SMA wire driving device uses a sampling resistor connected in series with the SMA wire to detect voltage changes, allowing for simple conversion to strain measurements, reducing computational complexity and enabling rapid adjustment of driving signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistance of the SMA wire is measured and converted into strain to calculate displacement, then displacement detection is achieved, but computation complexity increases and processing speed decreases
Solution Approach 1:
The patent introduces a sampling resistor as an intermediary component connected in series with the SMA wire. This resistor converts the complex electrical characteristic measurements into simple voltage measurements that are directly proportional to wire strain, eliminating the need for complex computation while maintaining measurement precision
Solution Approach 2:
The patent replaces the complex electrical measurement and computation system with a simpler voltage measurement system. By measuring voltage across the sampling resistor instead of complex electrical characteristics of the SMA wire, the system achieves the same displacement detection function with significantly reduced computational requirements
2Measurement precision
If a position sensor is arranged to detect displacement, then displacement detection is achieved, but device space requirements increase
Solution Approach 1:
The sampling resistor serves multiple functions: it acts as both a current limiting resistor in the SMA wire circuit and a measurement element for displacement detection. This multi-functionality eliminates the need for separate position sensors, saving device space while maintaining detection capability
Solution Approach 2:
The SMA wire system itself provides the measurement function through the sampling resistor. The voltage across the sampling resistor naturally reflects the wire strain and thus the displacement, eliminating the need for external position sensing components
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
This approach significantly reduces computational overhead, allowing for faster and more accurate control of the SMA wire, thereby improving movement speed and accuracy of the movable part, and enhancing the quality of optical anti-shaking.
Implementation Method 1
a voltage of a power supply connected at two ends of the SMA wire is unchanged. Since the voltage of the power supply is unchanged and the sampling resistor is connected in series with the SMA wire, a strain of the SMA wire is related to a voltage of the sampling resistor
Implementation Method 2
The shape memory alloy (SMA) has a characteristic of thermal shrink when being applied with a current
Implementation Method 3
the SMA has a characteristic of thermal shrink when being applied with a current. Due to the advantages of a large shrink force, a small volume and a good durability, the SMA is widely used as driving components
Data Source
AI summary
An SMA wire driving device, a closed-loop control method thereof and an electronic device are provided, which relates to the technical field of actuators. The SMA wire driving device includes a stationary part, a movable part being movable relative to the stationary part, and an SMA wire configured to drive the movable part to move relative to the stationary part, where a sampling resistor is connected in series with the SMA wire. By the SMA wire driving device, a displacement of the movable part relative to the stationary part can be detected by acquiring a voltage of the sampling resistor connected in series with the SMA wire. Based on the SMA wire driving device, a closed-loop control method is further provided, which has a small computation amount, so that the SMA wire can be rapidly controlled, improving driving effect of the SMA wire driving device.