Fingermouse: A wearable pointing device

Type: Semester thesis
Students: Marco Lüthi, Claudio Semini
Advisor: Patrick de la Hamette, Thomas von Büren

Introduction

The Fingermouse is a wearable pointing device that tracks the position of a finger/hand to control a mouse pointer. Activated by the distance sensor, the two cameras start to take pictures of the finger/hand, as soon as it is in accepted range (10 cm to 30 cm). After the transfer of the two contemporaneously captured images to the Digital Signal Processor (DSP), these data is being processed. The implemented algorithm calculates the coordinates of the the actual finger position. They are sent to the wearable system by an integrated RS232 interface or by the WearARM Bus.

Hardware

• Digital Signal Processor (TMS320VC33, 150 MHz, 136 KByte SRAM
• 2 Camera Sensors (APS256D, black/white, CMOS, low-power)
• Flash Memory (Am29LV008B)
• Distance Sensor (GP2D02)
• 32Bit WearARM Bus
• Power consumption: 250 mW (17 mW Standby)
• Input Voltage: 5-7 Volts
• Size: 6 cm * 7 cm

Experimental Setup

For debugging reasons the DSP of an evaluationboard (eZdsp-231 for TMS320VC33) has been used. With the Software Code Composer the algorithm, developed in C, could be tested and improved.

Image Processing Algorithm

1. Original pictures of both cameras (stereo setup), resolution: 256 * 256 pixel
2. Subsampling and creating the difference picture (absolute value of the difference of every corresponding pixel)
3. Creating a binary picture with a calculated threshold value
4. Removing noise by erosion (morphologic image processing operation)
5. Calculation of the centroid coordinates