Page - 11 - in Integration of Advanced Driver Assistance Systems on Full-Vehicle Level - Parametrization of an Adaptive Cruise Control System Based on Test Drives

2.2. Environmental-Recognition Sensors xs ys irs iϕs FOVϕ FOVr i S Figure 2.2.: Sensor quantities for object i, including FOV of the sensor 2.2. Environmental-Recognition Sensors For ACC systems, environmental-recognition sensors measure the position of object i, described by the polar coordinates sri and sϕi and in some cases, speed sr˙i and sϕ˙i as well in the sensor coordinate system, see fig. 2.2. If speed is not measured directly, it is calculated in the data processing. In addition, fig. 2.2 depicts the Field of View (FOV) of the sensor bounded by rFOV andϕFOV , representing the area where the sensor can detect an object. The following sections describe various sensors that are available. 2.2.1. RADAR Sensor ProductionACCsystemsuseat leastoneRadio Detection and Ranging (RADAR)sensor. TheautomotiveRADARsensoremitselectromagneticbundledwaves,whicharereflected by objects. They are available at frequency bands of 24 to 24.5GHz, 76 to 77GHz and 77 to 81GHz, [Win09]. For automotive applications, different types of RADAR sensors with different measurement principles are available, which are described in the following sections. Pulsed Doppler RADAR The Pulsed Doppler RADAR is the simplest RADAR sensor for automotive application. It emits a pulse of a certain length, which is reflected by the object and received by the sensor, see fig. 2.3. The relationship r= cτ 2 (2.1) describes how the distance r can be calculated using the signal propagation time τ and the speed of light c. The Doppler Effect is used to determine the relative velocity r˙. Assuming small velocities (r˙ c), the frequency shift reads ∆fr˙=−f02r˙ c , (2.2) 11