Real-time tracking of a moving target in an indoor corridor of the hospital building using RSSI signals received from two reference nodes

Abstract

In this paper, implementation and validation of a target tracking system based on the received signal strength indicator (RSSI) for an indoor corridor environment of the hospital is presented. Six tracking methods of a moving target (i.e., equipment, robot, or human) using RSSI signals measured from two stationary reference nodes located at the different sides of the corridor are proposed. A filter with its optimal weight value is also applied to smoothen and increase the accuracy of estimated position results (i.e., the x-position in the corridor). Additionally, a determination approach for finding the optimal parameters assigned for the proposed tracking methods and the filter are also introduced. The proposed methods are implemented in MATLAB/Simulink, and experiments using a 2.4 GHz, IEEE 802.15.4/ZigBee wireless network have been carried out in the indoor corridor of the hospital building. Experimental results obtained from the corridor size of 22 m demonstrate that our proposed methods can automatically and efficiently track the moving target in real time. The average distance errors, in the case of varying and manual tuning the optimal parameters of the proposed methods and the filter, reduce from 5.14 to 1.01 m and 4.55 to 0.86 m (i.e., two test cases; slow moving speed and double moving speed). Here, the errors decrease by 80.35% and 81.10%, respectively. For the case using the optimal parameters determined by the optimization approach, the average errors can reduce to 0.97 m for the first test case and 0.78 m for the second test case, respectively.

Development of an indoor corridor localization system based on a WCL method with corridor area selection and distance compensation

“…Experiments have been performed in the corridor of the hospital building, the 10th floor, Hat-Yai, Thailand. [33][34][35] This test field with the lower corridor area, the upper corridor area, and the empty area of the building is shown in Figure 5.…”

“…Such factors can affect radio signal propagation and RSSI measurement. [33][34][35] Zolertia Z1 motes as low-power wireless sensor nodes 36,37 are used to operate the wireless network. The Z1 mote is equipped with a MSP430F2617 microcontroller and a CC2420RF module.…”

“…The test field; the corridor scenario. [33][34][35] the output power of Z1 are set to 250 kbps and 0 dBm, and a carrier-sense multiple-access with collision-avoidance (CSMA/CA) protocol is available for medium access. As illustrated in Figure 5, we attach Z1 with a tripod, and it is placed 1 m above the ground level.…”

“…In this test field, there are moving people and obstacles, including big concrete walls, big concrete pillars, ceilings, mirrors, tables, and furniture. Such factors can affect radio signal propagation and RSSI measurement 33–35 …”

Determining design criteria for indoor positioning system projects in hospitals: A design science approach

“…They aimed to solve the problem of high noise in RSSI measures by using a probabilistic-based method and a neural network method. Second, we consider the study of Booranawong et al, 24 who also developed a Wi-Fi-based IPS. They investigated this using two reference nodes in order to track in real time a moving target in an indoor corridor of a hospital building.…”