Laboratory of Advanced Microfluidic Systems  
  Micro Input Devices System (MIDS) based on Human Motions  

In the last decades, the evolution of human-to-computer input devices lagged far behind the technology development. For instance, computer input devices (mouse and keyboard) are much bulkier than their state-of-the-art intelligent interfacing counterpart: the handheld computers. In this project, Micro Input Devices System (MIDS) was developed by merging micro-sensors and wireless technologies into electronic devices with the multiple input functionality (Fig. 1). Ten motion sensors were applied to directly transform finger tip motions for both hands into commands, in order to enable a “novel” input style such as typing or manipulating a virtual mouse in the mid-air. The proof-of-concept of such historical “novel” concept is obvious. After years of technology advancement, the analogous motion-based input styles had emerged as the irreplaceable input methodology of electronics, e.g. mobile phones (iPhone, Apple®) and video game machines (Wii, Nintendo Co. Ltd.).

Using MIDS as the input device, human motions are directly captured from micro-sensors, instead of constrained by the position and style of input elements on the devices, e.g. buttons on keyboard and trackball in mouse for computers. The input styles of MIDS can be arbitrarily defined by users and it need not be taken off when unused. Therefore, it is flexible, wearable, adaptive, egronomical and universal – integrating all finger tip based devices into one multi-functional system. MIDS has been demonstrated as a virtual mouse, a virtual keyboard, a virtual light pen, and also its robotics applicability to control a gripper robot.


Figure 1. Wearable wireless MIDS prototype. Five motion sensory rings are connected to a wrist watch module, which processes the real-time data analysis and the wireless transmission to a computer terminal.
  A Motion Sensing System for Sport Science Applications  

Motion is a general term describing the act or continuous process of changing position and orientation of a dynamic object, as an overall or local spatial quantity. Therefore, physical sports can be viewed as the competition of athletics’ records or, in the more engineering sense, the optimization of motion efficiency under defined sport rules. To quantify the efficiency for a particular sport, acquisition, quantification and analysis of the sportive motion become the major concerns in sport science. At present, vision-based motion sensing systems are widely used for motion analysis. These techniques have remarkable performances on measuring instantaneous displacement and motion trajectories. However, these methods can only provide higher-order motion information, e.g. velocity and acceleration, to only a limited extent, which are critical factors for the sportive motion optimization. For instance, acceleration can be related to the power consumption, or the vibration levels causing sudden or chronic injuries.

An acceleration-based wireless motion sensing system has been developed for sports science applications. It provides the additional real-time measurement of higher order of movement information, other than the conventional vision-based position capture systems. This system contains multiple motion sensing modules and each contains two dual-axis accelerometers to provide local acceleration in three-dimension. It has been successfully applied to detect motion characteristics such as resonance frequency and acceleration, and motion identification. By mounting the modules (Fig. 2) at different locations of an athlete’s body, local acceleration and so the vibration level can be detected. This may help to identify what motion is potentially harmful to athletes. On top of this, this system can be further integrated with the existing vision-based system to provide more comprehensive motion information for sport science applications.


Figure 2. Circuitry in an acceleration-based wireless sensing module. The multiple modules with a data-receiving platform were integrated as the motion sensing system.



Laboratory of Advanced Microfluidic Systems | Department of Mechanical and Biomedical Engineering | City University of Hong Kong
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