Int J Soc Robot (2010) 2: 3–18 DOI 10.1007/s12369-009-0039-x People Tracking with UWB Radar Using a Multiple-Hypothesis Tracking of Clusters (MHTC) Method SangHyun Chang · Rangoli Sharan · Michael Wolf · Naoki Mitsumoto · Joel W. Burdick Accepted: 16 December 2009 / Published online: 9 January 2010 © Springer Science & Business Media BV 2010 Abstract This paper presents a method to track multiple moving humans using Ultra-Wideband (UWB) radar. UWB radar can complement other human tracking technologies, as it works well in poor visibility conditions. Our track- ing approach is based on a point process interpretation of the multi-path UWB radar scattering model for moving hu- mans. Based on this model, we present a multiple hypothe- sis tracking (MHT) framework for tracking the ranges and velocities of a variable number of moving human targets. The multi-target tracking (MTT) problem for UWB radar differs from traditional applications because of the complex multipath scattering observations per target. We develop an MHT framework for UWB radar-based multiple human tar- get tracking, which can simultaneously solve the complex observation clustering and data association problems us- ing Bayesian inference. We present experimental results in The authors greatly appreciate the financial support of this work provided by the DENSO CORP., Aichi, Japan, the LIG Nex1 Corporation, Yongin, Korea, and the Agency for Defense Development (ADD), Seoul, Korea. S. Chang ( ) · R. Sharan · J.W. Burdick California Institute of Technology, Pasadena, CA, USA e-mail: sanghyun@caltech.edu R. Sharan e-mail: rsharan@caltech.edu J.W. Burdick e-mail: jwb@robotics.caltech.edu M. Wolf Jet Propulsion Laboratory, Pasadena, CA, USA e-mail: michael.wolf-131531@jpl.nasa.gov N. Mitsumoto DENSO CORPORATION, Aichi, Japan e-mail: naoki_mitsumoto@denso.co.jp which a monostatic UWB radar tracks both individual and multiple human targets to estimate target ranges and veloc- ities, even with changing numbers of targets across radar scans. Keywords UWB radar · Human tracking · Tracking · Filtering · Multi-target tracking · Multiple hypothesis tracking 1 Introduction This paper explores the use of Ultra-Wideband (UWB) radar for tracking multiple moving humans. Because the ability to track human movement is useful for the wide range of security and safety applications, a number of technologies have been pursued for human tracking. Computer vision has limited performance in poor visibility conditions, while the performance of infrared imagers can be temperature depen- dent. Human LADAR signatures may not highly discrim- inable from other moving clutter, and LADAR performance degrades in dusty and foggy conditions. UWB radar can pro- vide a complementary technology for detecting and tracking humans, particularly in poor visibility or through-wall con- ditions, as it is little affected by dust and moisture. While this paper considers the problem of tracking humans based solely on UWB radar signals, UWB radar technology can profitably joined with other human tracking modalities to provide more robust tracking and detection in a wider vari- ety of operating conditions. Compared with RF, microwave, and mm-wave radar [1, 2], UWB radar provides high-resolution ranging and lo- calization due to the fine temporal resolution afforded by its wide signal bandwidth [3–5]. However, the complex scattering behavior of UWB waveforms poses additional