Open-Loop Control of Voice Coil Motor With Magnetic Restoring Force Using High-Low Frequency Composite Signals

This study proposed an approach to control voice coil motors (VCMs) installed in smartphone modules as autofocus actuators. The VCM developed in this study comprises guide rods. The magnetic field attraction force between guide rods and movable parts serves as lens restoring force. This study did not use feedback elements to avoid the stick-slip phenomenon between VCM guide rods and movable parts. Instead, this study used a high-low frequency composite signal based on the findings from a mathematical model analysis and VCM dynamic attribute analysis, preventing stick-slip and offering the VCM a more favorable positioning precision.