| With the development of wireless network technology,mobile Internet users account for an increasing proportion of the total Internet users,and mobile devices such as mobile phones have gradually replaced traditional PCs as the main entrance to the Internet.However,mobile devices have sacrificed screen size for their portability.The current control method is mainly a touch screen solution.Although it has better control accuracy,the touch operation on the touch screen will cause the line of sight to be blocked,reducing the visible range and affecting the user experience.The technology adopted by the current virtual touchpad[1]/keyboard[2]is mainly based on the principle of optical occlusion.They require external special equipment,which affects the portability of mobile devices.With the development of 5G technology,60 GHz millimeter wave modules will be more and more integrated into mobile devices.This thesis proposes a high-precision passive tracking method based on millimeter wave sensing.Tracking of small objects such as pens or fingers is achieved by using phase changes to achieve touch interaction outside the touch screen.Due to the high spatial resolution of millimeter waves,tiny movements of objects can also be sensed by millimeter waves and reflected as changes in millimeter wave signals.With this advantage,this thesis achieves high-precision tracking effect.The key challenge is that in passive positioning and tracking,because the target object cannot actively transmit signals,and the target object is small,an effective mechanism is needed to distinguish the target object's reflection and sudden noise.This thesis proposes a method based on the closest distance update and sliding window to deal with the above-mentioned challenges,and implements the method in this thesis on the PC and mobile phones to achieve good tracking results.Experimental results show that the method in this thesis can track the movement trajectory of a pen with an average error of sub-centimeter level. |
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