Object detection system

Details Object detection system Object detection system

2001-04-02

2003-06-17

Tarcza, Thomas H. (Department: 3662)

Communications: directive radio wave systems and devices (e.g.,

Return signal controls external device

Radar mounted on and controls land vehicle

C180S169000, C356S004040

Reexamination Certificate

active

06580385

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an object detection system. Such a system may be used, for example, as part of an adaptive cruise control in a motor vehicle. Such a control can regulate a previously set driving speed and/or a previously set distance from a vehicle in front or from objects in the direction of travel without intervention by the driver. This is done with appropriate regard for the environment around the motor vehicle and optionally additional parameters such as visibility and weather conditions. Such a control is known as an adaptive cruise control system (ACC system). The ACC system must be flexible enough to react appropriately to all driving situations, especially in view of today's growing traffic density. This in turn requires an appropriate object detection sensor system to supply the measured data required for control purposes in all driving situations.
BACKGROUND INFORMATION
A plurality of different technical concepts/systems are available for object detection; some of these are described in greater detail below.
German Published Patent Application No. 43 30 476 discloses an optical radar system for a motor vehicle. This radar system contains essentially a light emitting unit for emitting light in the direction of a target object and a light receiving unit for receiving the light reflected by the target object. The light receiving unit contains a condenser lens, which is arranged to capture the reflected light, and a light-sensitive element arranged in an offset position relative to a focal point of the condenser lens by a preselected distance in an imaging space so it is exposed to light propagating from the condenser lens to ensure a narrower detection zone for a remote target object and a wider detection zone for a nearby target object. In other words, in order to ensure a narrower detection zone for a remote target object and a wider detection zone for a nearby target object, a first and second light-sensitive element are arranged in appropriate positions in an imaging space of a first and second condenser lens. Such an optical radar system based on light emission and light reception is also referred to below as a LIDAR (light detection and ranging) sensor.
German Published Patent Application No. 197 13 826 describes a radar device and a vehicle safety distance control system using this radar device. This radar device has a rotating polygonal mirror having a plurality of mirror surfaces inclined at different angles. A semiconductor laser diode and a collimator lens are arranged above the polygonal mirror. An infrared pulsed beam emitted by the laser diode is reflected by a reflective mirror arranged at an upper location in front of the polygonal mirror to reflect the pulsed beam downward obliquely toward the rotating polygonal mirror in such a way that the pulsed beam is reflected as a transmitted beam traveling toward a measurement zone in a forward direction. A light receiving device receives the transmitted beam returning from an object inside the measurement zone. Due to the use of a rotating polygonal mirror, two-dimensional scanning in the forward direction is possible, so that the pulsed beam can be swiveled horizontally due to the rotation of the polygonal mirror, and the pulsed beam can be swiveled vertically due to the faces of the polygonal mirror inclined at different angles. On the basis of the time between transmission of the pulsed beam and reception of the reflected beam, a calculation circuit determines a distance, an angle and a speed relative to a vehicle traveling in front that has been detected.
Such a radar device based on light is also referred to below as a LIDAR sensor.
German Published Patent Application No. 195 30 065 describes a monostatic FMCW radar sensor for a motor vehicle for detecting objects. In the case of this radar sensor, high frequency microwave beams (in the range of approx. 76 to 77 GHz) are sent out over antenna feeds designed for both sending and receiving a corresponding echo signal. The beams are concentrated by upright dielectric emitters located in the path of the beam and focused by a dielectric lens. Millimeter waves are generated by a Gunn oscillator driven by a stabilization network which contains a linearization network having a frequency regulator. Millimeter waves generated in this way are sent over conductors to parallel rat-race rings and from there are beamed over antenna feeds. Millimeter waves reflected by a possible target object are sent through the antenna feeds, the rat-race rings and ring mixers, for further signal processing. A portion of the energy of the Gunn oscillator is branched off by the ring mixer and mixed down. For further signal processing, each reception channel has a separate analyzer containing an amplifier, a low-pass filter, a downstream weighting filter and an A/D converter. The signals obtained after A/D conversion are analyzed using fast Fourier transform. An FMCW radar sensor designed accordingly has a range of approx. 150 meters and is preferably used in a vehicle for detection of one or more objects in a vehicle.
Such an FMCW radar sensor is also referred to below as an ACC (adaptive cruise control) radar sensor or simply an ACC sensor.
German Published Patent Application No. 197 24 496 discloses an obstacle detection device and a passenger safety device which utilizing the obstacle detection device. The obstacle detection device determines the distance between an obstacle and a vehicle by means of two distance measuring sensors, and it includes an impact angle calculating device, which calculates a plurality of positions of the obstacle by triangulation on the basis of the distance information provided by the two distance measuring sensors. Furthermore, the location of the obstacle, which is calculated by means of the plurality of calculated positions of the obstacle, is used to determine the impact angle formed by the obstacle and the vehicle. The two distance measuring sensors used are designed as radar sensors mounted on the right and left of the front part of a motor vehicle. The relevant distance measuring range of the sensors is in the range of less than a meter.
Such an obstacle detecting device is also referred to below as a precrash sensor or as a short-range radar.
U.S. Pat. No. 5,872,536 describes a multi-sensor object detection system which determines the instantaneous distance, relative velocity, collision angle and point of impact of a colliding object. This system has a plurality of signal transmitters which monitor a predetermined area within a certain angle range. Each signal transmitter emits a modulated carrier wave and receives the corresponding modulated carrier wave reflected by an object. The distance of the object from each individual signal transmitter is determined from the reflected signals on the basis of the amplitudes of the harmonic components of the reflected signal by using the Doppler effect. The instantaneous relative velocity relative to the object is determined on the basis of the frequencies of the harmonic components of the reflected signal. An impact detecting unit determines on the basis of the distance and relative velocity data whether there will be a collision, and if so, where the point of impact will be and at which angle the collision will occur.
A preferred embodiment provides for the use of two signal transmitters operating in a frequency range of 5.8 GHz. The maximum range of the sensor system is 3 meters, an especially sensitive range being up to approx. 1.5 meters. Such a sensor system is also referred to below as a precrash sensor or short-range radar.
German Published Patent 42 36 619 describes a distance determining device for automobiles which is equipped with an imaging and image recording system for imaging objects at a predetermined zone outside the automobile. This distance determining system is provided with a stereoscopic optical system and has a stereoscopic image processing device for processing the images produced by the optical system to calculate three-dimensional dist

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