600 J SCI IND RES VOL 69 AUGUST 2010 Journal of Scientific & Industrial Research Vol. 69, August 2010, pp. 600-605 *Author for correspondence E-mail: neel5278@rediffmail.com Active marker based kinematic and spatio-temporal gait measurement system using LabVIEW vision Neelesh Kumar 1 , Nissan Kunju 1 , Amod Kumar 1 and B S Sohi 2 1 Central Scientific Instruments Organisation (CSIO) Chandigarh India, 2 University Institute of Engineering and Technology (UIET), Chandigarh, India Received 26 March 2010; revised 20 May 2010; accepted 02 June 2010 This study presents an automated, easy to use, cost-effective, patient-friendly, active marker based gait measurement (GM) system for 2-D tracking and extraction of spatio-temporal parameters of human gait. Active markers, consisting of visible light-emitting diodes (LEDs), were positioned at anatomical landmarks to measure coordinated kinematics of human joints. Acquired image data were processed and analyzed using LabVIEW vision for determination of spatio-temporal parameters. Keywords: Active markers, GM system, Kinematics, Spatio-temporal parameters Introduction Visual observation method, used for assessing gait by measuring spatio-temporal parameters of human gait, had several limitation and inaccuracies 1-3 . Gait measurement (GM) system incorporates timed measurement of data for calculating mean values of gait speed, stride length and cadence 4,5 . Footstep measurement systems are cumbersome and time consuming 6- Accurate estimation of human kinematics requires interdisciplinary domain knowledge of biomedical engineering, biomechanics, mechatronics, and human anatomy sciences 10 . In kinematics, instrumentation is required to estimate positions, angles, velocities and accelerations of body segments and joints during motion 11 . Gait analysis provides a scientific basis in monitoring anomalies in walking pattern 12 . Movement parameters are synchronized with kinetic parameters (body forces) to generate quantitative description of gait or human dynamics in the form of time-distance parameters and variations in joint angles, joint moments and joint powers 13 . Kinematic gait analysis 14,15 may be subdivided into direct measurement (contact) techniques [goniometers (mechanical and electronic), accelerometers, footswitches etc.] and imaging (noncontact) based measurement techniques. New imaging techniques using markers (active or passive) were developed to perform real time kinematic gait analysis 16 . Active markers use light-emitting diodes (LEDs) to generate image information. Passive markers are spheres covered with reflective Scotchlite tape, specifically designed to reflect incident light directly back along its line of incidence 17 . Manual analysis of marker images is error prone, labor intensive and a tiresome process. This study presents development of a simple, cost effective and easier detection novel automated software algorithm to analyze spatio-temporal features of human gait kinematics using LabVIEW vision. Experimental Section Experiments were conducted on 9 healthy males (age group, 21-30 y; height, 1.56-1.77 m; wt, 48-71 kg). Image acquisition (total captured volume, 1.57 m 3 ) was done in partial dark (minimum light) environment for better image contrast ratio. Each marker was made up of an array of 4 red LEDs (peak wavelength, 660 nm; luminous intensity, 380.25 mcd; viewing angle, 120°) connected in series and attached to a battery. Power dis- sipated (450 mW), ensured that marker set can be used for a lot many number of trials. Cost for one marker was estimated to be around $ 4.5 only. LEDs were arranged to appear as a single big bright circle from distance. Marker set for full body kinematic analysis (Fig. 1a) were pasted on landmarks (hip, knee and ankle) using