ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

EXTRACTION OF PHALANGEAL JOINT PARAMETERS FROM
IMAGE SEQUENCES DURING PALMER GRASP
1. ABSTRACT
Avik Chatterjee 1 , A. Mahapatra 2 , S. Majumder 3 and I. Basak 4
Measurement of phalangeal joint parameters like joint angle, length of phalanges etc
during dynamic hand articulation is a challenging area and it’s implication in
behavioural biometrics is still under study. Finger goniometry is extensively used for
direct measurement of finger joint angles over many decades and still widely used in
practice. It is contact based and measure static poses of hand articulation. In certain
articulation like palmer grasp, where thumb flexion occludes the curled fingers,
goniometric measurement is extremely difficult. Use of other methods using wearable
glove based devices are restrictive as they restrict natural articulation due to bulkiness,
high degree of skin stretch and cross occlusion. In this study we have proposed a non
contact and non invasive methodology with no special camera setups and calibration
using planar homography. The extracted data has been reported compared with the
measured data of two individuals performing palmer grasp along with measurement
uncertainty.
2. INTRODUCTION
The past decade has seen considerable advances in the application of principles from
projective geometry to the problems in computer vision particularly 3D reconstruction
and metrology [1,2]. Joint range of motion data (ROM) of hand articulation consists of
various joint angles and length of phalanges that determines its kinematics.
Traditionally measurements are performed via mechanical goniometers, which must be
placed on each hand joint to measure flexion and extension angles with manual data
recording. However traditional goniometric measurements can be affected by several
sources of errors [3]. The method can not acquire ROM information simultaneously
from all hand joints even in static poses. In contrast, hands are mostly used in complex,
articulated and dynamic tasks where goniometry can not be applied. In certain
articulation like palmer grasp, where thumb flexion occludes the curled fingers,
goniometric measurement is extremely difficult.
With the miniaturization of sensor technology, other methods using wearable glove
based devices and optical tracking using multiple surface markers, were introduced later
[3]. It allows analysis of hand performance while executing dynamic tasks and
capturing the entire joint range of motion but puts restriction on natural articulation due
to its wearable nature. Optical tracking is non contact based and use multiple active or
1,2,3
Scientist, CSIR-Central Mechanical Engineering Research Institute, Mahatma Gandhi Avenue,
Durgapur - 713209, India.
4
Professor, Department of Mechanical Engineering, National Institute of Technology, Mahatma Gandhi
Avenue, Durgapur 713209, India