This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination. IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS 1 Surrogate Bicycle Design for Millimeter-Wave Automotive Radar Pre-Collision Testing Domenic J. Belgiovane Jr., Student Member, IEEE, Chi-Chih Chen, Fellow, IEEE , Stanley Y.-P. Chien, Senior Member, IEEE , and Rini Sherony, Member, IEEE Abstract—This paper discusses the development of a sur- rogate bicycle target for evaluating the effectiveness of vehicular autonomous emergency braking (AEB)/ pre-collision systems (PCSs) that uses 77-GHz radar systems in detecting bicyclists on the road. The design objective of the surrogate bicycle is to produce similar optical appearance and radar response in a 76–78 GHz band as a real bicycle selected based on its popularity (in 2014) in the United States. In addition, the surrogate bicyclist needs to be able to withstand the impact of the test vehicle traveling at 30 mph (or 48 kph) should it fail to detect the surrogate target. Our design approach differs from the only other surrogate bicyclist developed by a European research group in that our surrogate bicyclist produces similar radar response as a real bicyclist over the entire 360° of azimuth angles. Our design approach began with experimental characterizing the radar cross section (RCS) patterns of real bikes of different types as well as identifying RCS contributions of different parts on a bike via accurate simulations, which were also used for design optimizations. The RCS performance of the fabricated surrogate bicycle was verified via 360° azimuth pattern measurement comparison with a real bicycle. Its physical performance was tested via actual field testing on a test track with two commercial vehicles equipped with AEB and PCS systems. Index Terms— Radar cross section, pedestrian detection, auto- motive radar, bicycle radar surrogate, collision avoidance. I. I NTRODUCTION V EHICULAR radars have been used in measuring distance and relative speed of objects in front of cars, and improv- ing the driver’s ability to perceive objects under bad visibility conditions or objects in blind spots. Using radar echoes to detect pedestrians has advantages in longer detection range, better position resolution and compatibility with various road and weather conditions [10], [11]. Research and development of automotive radar technology has been actively pursued by the automotive industry. State of the art technologies have already implemented radar systems with applications such as Intelligent Brake Assist and Blind Spot Detection [15]. Vehicular radar operating at 24 GHz is currently being phased out in favor of the 79-81 GHz band in Europe [14]. The Fed- eral Communications Commission (FCC) for these vehicular Manuscript received February 17, 2016; revised September 6, 2016 and November 14, 2016; accepted December 17, 2016. The Associate Editor for this paper was J. Zhang. D. Belgiovane and C.-C. Chen are with The Ohio State University, Columbus, OH 43210 USA (e-mail: belgiovane.2@osu.edu; and Chen.118@osu.edu). S. Y.-P. Chien is with Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202 USA (e-mail: schien@iupui.edu). R. Sherony is with Toyota’s Collaborative Safety Research Center, Ann Arbor, MI 48105 USA (e-mail: rini.sherony@toyota.com). Digital Object Identifier 10.1109/TITS.2016.2642889 collision avoidance applications has allocated the 76-78 GHz frequency band. The entire 76-81 GHz band is widely referred to as the 77 GHz band, which includes both the worldwide long-range radar (LRR) band and the European ultra- wideband (UWB) band [27]. In addition to the FCC, the International Telecommunication Union (ITU) in Europe and the Ministry of Internal Affairs and Communications (MIC) in Japan for vehicular radar have also adopted this standard. Many automotive companies have begun to develop autonomous emergency braking (AEB) systems to avoid or mitigate pedestrian and bicyclist crashes [6], [8]–[10]. Auto- matic emergency braking systems are also referred to as colli- sion imminent braking system or pre-collision system (PCS). These systems also provide warning directly to the driver before braking. The effectiveness of such systems need to be accu- rately tested using standardized test procedures that have yet to be agreed upon among the international automo- bile industry and government agencies. Such standards help consumers and government regulation agencies assess the actual bicycle autonomous emergency braking (BAEB) ability of each vehicle equipped with BAEB function- ality. Furthermore, it provides the information on how the vehicle responds to the false positive bicycle colli- sion, since false warning and emergency braking can be a driving hazard. Obviously, it is neither practical nor safe to use real bicy- clists and pedestrians to conduct these tests. Therefore, the key element of these standardized tests are standard surrogate targets that are able to produce similar sensor responses as real-life cars, pedestrians, and bicycles. Furthermore, such standard targets need to be able to withstand to impacts from the vehicle under test (VUT) without damaging the VUT and easily reassemble after impact. As of now, standard 77GHz surrogate pedestrian and bicycle targets are still being devel- oped and evaluated by the international community. The main contribution of our work is to produce a high fidelity surrogate bicycle target that is suitable for evaluating the effectiveness of 77 GHz automobile radars in detecting bicyclists. A surrogate bicyclist is composed of a surrogate rider and a surrogate bicycle. The surrogate pedestrian developed by Chen et al. [1] can be readily adopted as the rider surrogate. However, there is still a need for a surrogate bicycle design, which is, therefore, the focus of this paper. Experimentally characterizing radar response at 77 GHz is not trivial, and is often inaccurate due to extremely short wave- lengths, making the radar response potentially very sensitive to 1524-9050 © 2017 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.