PROBLEM TO BE SOLVED: To enhance the accuracy of collision avoidance.SOLUTION: A figure shows the propagation characteristic of a radio wave in a collision avoidance system in which an avoidance device is installed on a power-assisted car and a detection object device is held by a pedestrian. Because a magnetic field passes through a wall without reflection, the avoidance device can communicate with a detection object device (#1) behind a wall or pillar. The strength of the magnetic field has an attenuation characteristic of 60 dB/dec when a typical loop antenna is used. Therefore, it is hardly influenced by the variation of reception circuits, and the boundary of the communication range of the magnetic field becomes clear. Thus, a detection object device (#2) out of the communication range can be prevented from receiving the magnetic field. In other words, a scheme using a magnetic field can clarify a detection area and is influenced little by the shielding and reflection by an obstacle, and thereby can accurately detect an object having a possibility of collision in comparison with conventional methods of performing intercommunication by GPS and radio wave. Furthermore, it can also recognize an object (such as an obstacle or a stereoscopic dangerous article) hung from a ceiling.SELECTED DRAWING: Figure 6COPYRIGHT: (C)2017,JPO&INPIT【課題】衝突回避の精度を高める。【解決手段】図は、電動アシストカーに回避装置を設置し、歩行者に被検知装置を保持させた衝突回避システムにおける電波の伝搬特性を示す。磁界は壁で反射せずに透過するので、回避装置は、壁や柱の陰にある被検知装置(#1)と通信できる。通常型のループアンテナを使うと磁界の強度は60dB/decの減衰特性になる。このため、受信回路のばらつきの影響を受けにくく、磁界の通信範囲の境界は明瞭になる。従って、通信範囲外の被検知装置(#2)が磁界を受信するのを防止できる。すなわち、磁界を使う方式は、検出エリアを明確化でき、且つ障害物による遮蔽・反射の影響が少ないので、GPS・電波による相互通信をする従来の方法と比べて、衝突の可能性のある対象物を精度よく検知できる。さらに、天井から吊り下がる対象物(障害物、立体的な危険物)を認識することもできる。【選択図】図6
