Abstract—This paper presents a real time force sensing instrument that is designed for human gait analysis purposes. This instrument mainly consists of three main elements: the force sensing mat, signal conditioning and switching circuit and data acquisition device. In order to control and to process the incoming signals from the force sensing mat, Force-Logger and Force-Reloader program are developed using Labview 8.0. This paper describes the architecture of the force sensing mat, signal conditioning and switching circuit and the real time streaming of the incoming data from the force sensing mat. Keywords—Force platform, Force sensing resistor, human gait analysis. I. INTRODUCTION S the study on biomechanics is growing, various methods and tools have been developed to collect either dynamics or kinematics parameters of the human gait. And force platform emerges as one of the most common tools used to provide information on three orthogonal forces and moments exerted by human body. It is widely used in engineering and medical research, orthopedics, rehabilitation evaluation, prosthetics and other general industrial uses. If it is mounted properly, force platform is a very reliable and accurate device. Manuscript received April 9, 2008. This work was supported under Mechatronics Project II by Monash University Sunway Campus. Darwin Gouwanda is with Monash University Sunway Campus as a Research Student leading to Master’s Degree in Engineering Science (phone: +603 - 551461852; fax: +603 - 55146249; e-mail: darwin_gouwanda@yahoo.com). Namal A. Senanayake is with the Monash University Sunway Campus, Malaysia since 2002 (phone: +603-55146249; fax: +603-55146207; e-mail: senanayake.namal@eng.monash.edu.my). M. M. Danushka Ranjana Marasinghe is currently with Monash University Sunway Campus pursuing Bachelor’s degree in Mechatronics Engineering. Mervin Chandrapal is currently with Monash University Sunway Campus pursuing Bachelor’s degree in Mechatronics Engineering. Jeya Mitra Kumar is currently with Monash University Sunway Campus pursuing Bachelor’s degree in Mechatronics Engineering. Tung Mun Hon is currently with Monash University Sunway Campus pursuing Bachelor’s degree in Mechatronics Engineering. Yulius is currently with Monash University Sunway Campus pursuing Bachelor’s degree in Mechatronics Engineering. However, despite of its capabilities and performances, force platform has several limitations. One of its limitation is that force platform does not provide either qualitative or qualitative information on how the ground reaction forces are distributed on the human foot, from toe to heel. Therefore, due to this reason, engineers and other various field researchers have designed and developed force sensing mat that is capable to visualize the force distribution of the human feet. Paradiso, et al used Polyvinylidene Fluoride polymer (PVDF) wires to develop a magic carpet that is capable of measuring human foot pressure [1]. Srinivasan, et al developed a pressure sensing floor that has one sensor per square centimeter, with sensor spaced 10 mm apart and each sensor has active area of 6 mm x 6 mm [2]. With similar functionalities as the force sensing mat mentioned earlier, a real time force sensing instrument that has different concept is introduced in this paper. This instrument contains an array of force sensing elements that is capable of monitoring and recording the movement pattern of a test subject in standing, walking, jumping and running. Additionally it is able to provide qualitative information on how the vertical ground reaction forces are exerted on each part of the human foot i.e. toe, middle foot and heel. II. FORCE SENSING MAT ARCHITECTURE There are two similar force sensing mats have been developed. Each force sensing mat contains 144 Force Sensing Resistors (FSR) that are distributed evenly on 480 mm x 540 mm acrylic board. And each force sensing platform has an effective sensing area of 480 mm x 480 mm. Fig. 1 Force Sensing Platform In addition, each force sensing mat has a total of 5 layers that serve different purposes. The first layer is 3mm thick acrylic board with 144 through holes to expose the sensing area of the sensors. The second layer is a customized Printed Circuit Board (PCB) that connects the sensing elements to four 40 ways connectors where the links between the mat and the signal conditioning circuit is established. The third layer is a rubber mat that protects the connection beneath the circuit Darwin Gouwanda, S. M. N. Arosha Senanayake, M. M. Danushka Ranjana Marasinghe, Mervin Chandrapal, Jeya Mithra Kumar, Tung Mun Hon, and Yulius Real Time Force Sensing Mat for Human Gait Analysis A World Academy of Science, Engineering and Technology International Journal of Mechanical and Mechatronics Engineering Vol:2, No:3, 2008 349 International Scholarly and Scientific Research & Innovation 2(3) 2008 ISNI:0000000091950263 Open Science Index, Mechanical and Mechatronics Engineering Vol:2, No:3, 2008 publications.waset.org/2146/pdf