METHOD AND APPARATUS FOR NON-LINE-OF-SIGHT DETECTION AND CODED RADAR SIGNALS
1. A method for object detection, comprising:
- transmitting a sounding signal;
determining a clutter signature based on the sounding signal;
transmitting an object detection signal;
receiving a return object detection signal;
determining a return time of the object detection signal;
determining a location of a detected object by using the return time;
filtering out the clutter signature from the return object detection signal;
producing a filtered return object detection signal based on the filtering; and
extracting motion of the detected object by using the filtered return object detection signal.
Radar systems are disclosed to detect objects in non-line-of-sight (“NLOS”) areas. A clutter signature is used to determine a location and motion of an object.
- 1. A method for object detection, comprising:
transmitting a sounding signal; determining a clutter signature based on the sounding signal; transmitting an object detection signal; receiving a return object detection signal; determining a return time of the object detection signal; determining a location of a detected object by using the return time; filtering out the clutter signature from the return object detection signal; producing a filtered return object detection signal based on the filtering; and extracting motion of the detected object by using the filtered return object detection signal.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- 15. A radar sensing unit, comprising:
a sounding signal module for transmitting a sounding signal to determine a clutter signature; a memory unit storing the clutter signature; a radar controller generating, controlling, and interpreting an object detection signal; a transmit antenna unit coupled to the radar controller, adapted to transmit the object detection signal; a receive antenna unit coupled to the radar controller, adapted to receive a return object detection signal; and a non-line of sight module coupled to the transmit antenna unit and the receive antenna unit adapted to; determine a location of a detected object by using a return time of the object detection signal; filter out the clutter signature from the return object detection signal to produce a filtered return object detection signal; and extract motion of the detected object by using the filtered return object detection signal.
- View Dependent Claims (16, 17, 18, 19)
- 20. A system for object detection, comprising:
a transmit antenna to transmit a sounding signal and an object detection signal; a receive antenna to receive a return sounding signal and a return object detection signal; a sounding signal module to determine a clutter signature based on the return sounding signal; and a non-line of sight module to; determine a return time of the object detection signal; determine a location of a detected object by using the return time; extract motion of the detected object by using the filtered return object detection signal.
The present application claims priority to U.S. Provisional Patent Application Ser. No. 62/751,005, filed on Oct. 26, 2018, which is incorporated by reference in its entirety.
Autonomous vehicles and Automated Driver Assist Systems (“ADASs”) are the next phase of transportation around the world. While the main goal of such systems is to improve safety both for the individual and for the roadways and cities, these systems rely on accurate, reliable systems in a variety of situations, as well as the control decisions thereof.
The present application may be more fully appreciated in connection with the following detailed description taken in conjunction with the accompanying drawings, which may not be drawn to scale and in which like reference characters refer to like parts throughout, and in which:
Methods and apparatuses to enable reliable, accurate, and flexible object detection in a radar system, where such systems enable non-line-of-sight (“NLOS”) detection capabilities, are disclosed. In communications and object detection applications, a signal is transmitted to communicate information or identify a location of an object. The transmission path from a transmitter to a receiver in a communication system, or from an object detection sensor to an object, has a field of view within which the transmissions are uninterrupted. This field of view, which comprises the total area that can be captured by a movable (e.g., scanning) radar system, is referred to as the line-of-sight (“LOS”); and the area outside of the LOS is referred to as the NLOS. Within the LOS, transmission signals travel directly to a receiver or to an object. For electromagnetic millimeter wavelength transmissions, an antenna transmits signals as a beamform that defines the LOS. In real world systems, there are often obstacles that obstruct the direct transmission, such as buildings, trees, and so forth. These obstructions may act as reflection or deflection points that change the direction of all or some of the transmission signal. A reflection or deflection may also be referred to as an “echo”. Note that throughout this description, the term “reflection” (or “reflect”) is used to refer to the change in direction of energy transmitted from an antenna or transmission source, and includes both reflections and deflections. The energy is reflected, or redirected, on interaction with an obstacle. The processes and examples are described herein with respect to an object detection sensor employing a radar sensor. However, these processes, methods, and apparatuses are applicable to other systems using transmissions for communication or object detection.
An object detection system in a vehicle includes a sensor that moves with the vehicle and, therefore, the sensor position and sensor field of view are in motion. Such sensors are tasked with understanding the environment within which they operate. There are a variety of sensors (and often a design incorporates multiple sensors) that may be employed including, but not limited to, a camera, radar, lidar, ultrasound, and others.
In object detection systems, when incorporating a radar modulation scheme, such as a frequency-modulated carrier-wave (“FMCW”) scheme (e.g., using a sawtooth waveform), the difference between the transmit and receive signals provides range information and velocity. The velocity is deduced from the phase difference between the transmit and receive signals. The distance to an object, or the range, and the velocity are collated as range-Doppler information, or a mapping, to interpret the environment. The use of a FMCW scheme has many advantages in range-Doppler detection.
The disclosed systems and methods may be applied in a transportation system, such as in environment 100 of
In the implementations and examples provided herein, there is an assumption made that there exists a mathematical relationship between the gain of an antenna and the specific dimensions of the focused beam. This assumption results in an approximation that all radiated energy of an antenna is uniformly distributed across a beam with some solid angle Ωbeam, and that no energy is radiated elsewhere. In this case, the directivity of the antenna is equal to the ratio of the beam'"'"'s solid angle Ωbeam to the total area of the unit sphere (4π), and the solid angle Ωbeam is inversely proportional to the directivity (e.g., refer to the insets, INSET 1 and 2, of
INSET 2 of
The RSU 112 of vehicle 102 may transmit radiation beamforms in a variety of directions. In some examples, the RSU 112 steers the beam, thereby changing the directivity of the beamform. When a beam is directed toward an object or obstruction, there is a reflection or redirection of the energy of the beamform, which sends energy in directions and in areas that may be NLOS areas.
In the examples provided herein, the transmissions (i.e. transmission signals) are illustrated as individual transmission paths. However, it is understood that the transmission from vehicle 152 is a radiation beam that covers a detection area that includes the objects detected. Portions of the energy of the radiation beam reflect on interaction with an obstacle. The inset illustration of
The RSU 112, of the present examples, provides a steerable beam, as is illustrated in
The actual size of a radiation beam may be fine, referred to as a pencil beam, and may be adjusted by a radar controller (e.g., RSU 212) in response to road conditions, objects detected, and operation of the vehicle. In environment 200, the vehicle 206 is moving in a north direction, as is vehicle 210. Vehicle 208 is moving in an east direction. Vehicle 206 comprises RSU 212, which is transmitting beams 214 over a short-range area 202. The individual beams 214 are used to scan the short-range area 202 for objects, including vehicles and buildings, such as building 204. There may be any number of reflection points where these interactions with objects cause abrupt discontinuations in the radiation pattern and transmissions.
In some examples, the transmissions from RSU 212 are provided in a FMCW modulation scheme, thereby enabling detection of objects'"'"' location and movement. This information is in the form of range and velocity coordinated data, referred to as a Range-Doppler Map. This is discussed hereinbelow in more detail.
Referring back to
If no interference is detected, 316, then the RSU 212 may transmit an FMCW signal(s) at a desired frequency. However, if interference is detected, then frequency hopping is turned on for operation of the RSU 212 (i.e. the RSU 212 will transmit an FMCW signal(s) using frequency hopping), 318, to avoid the detected interference. It should be noted that some implementations, the disclosed method 300 may operate to utilize frequency-hopping without determining whether or not interference is present (e.g., omitting step 316 of method 300).
After the FMCW signal(s), with or without frequency-hopping, (i.e. object detection signal(s)) is transmitted by the RSU 212, the RSU 212 will receive a returned FMCW signal(s). Clutter is filtered out of the returned FMCW signal(s), 320, by using the calculated clutter signature to isolate the radar signals of interest. Then, the NLOS motion (e.g., motion of an NLOS object(s)) is extracted, 322, from the filtered FMCW return signal(s).
The filtered returned FMCW signal(s) is processed to determine whether a detected object(s) is located within the LOS area or within an NLOS area. When the round-trip time of the transmitted FMCW signal(s) is greater than a maximum return time delay, it is determined that the object(s) is located within an NLOS area, which is an area located outside of an area (e.g., the LOS area) generated by the radar beams of the RSU 212. And, when the round-trip time of the transmitted FMCW signal(s) is less than or equal to a maximum return time delay, it is determined that the object(s) is located within the LOS area. Once an NLOS object(s) (or an LOS object(s)) is detected, the method 300 compares the filtered returned FMCW signal(s) to the transmitted FMCW signal(s) to calculate the velocity of the object(s) as a function of the frequency difference of the filtered returned FMCW signal(s) and the transmitted FMCW signal(s) and, in some examples, a comparison of the filtered returned FMCW signal(s) to the transmitted FMCW signal(s) is used to obtain a location of the object(s).
Referring back to step 306 of
Applying the method 300 of
Continuing with RSU 400, mixer 410 is coupled to mixer 428 in the receive chain, which includes receive antenna unit 426 having power distribution and antenna network 442. The receive antenna unit 426 is used to receive a returned sounding signal(s) and a returned object detection signal(s). Received signals are provided to a low noise amplifier (“LNA”) 424 that is coupled to mixers 428, 422. The analog signals are then filtered by respective filters 430, 420, and converted by respective analog-to-digital converters (“ADCs”) back to digital signals having n bits each, which are then provided to DSP 416.
The radar controller 402 comprises a sounding signal module 450 to generate and transmit a sounding signal, and to evaluate a return sounding signal (e.g., by determining a clutter signature based on the return sounding signal). The return sounding signal is used to identify objects, such as stationary objects, within an environment. The radar controller 402 also includes an NLOS module 452 to identify objects in an NLOS area (or in a LOS area) from radar signals, such as FMCW signals. In particular, the NLOS module 452 is used to generate and transmit an object detection signal(s) (e.g., a FMCW signal(s)), to determine a location (e.g., whether a detected object(s) is located within an NLOS area or LOS area) of a detected object(s) by using a return time of the object detection signal(s), to filter out the clutter signature from a return object detection signal(s) to produce a filtered return object detection signal(s), and to extract motion (and/or obtain the location) of the detected object(s) by using the filtered return object detection signal(s).
A radar unit 500 having antenna system 564 is illustrated in
In the implementations, examples, scenarios, situations and others, a variety of transmission paths may lead to detection of a target. There are a variety of possible transmission paths, and there may be any number of interactions with obstacles. Where the transmission signal is a FMCW signal, the received signal processing indicates the location of the target by processing time delay, range, and Doppler information relating to velocity. This processing involves time of flight and reflection angles, and extends the detection capability from direct reflections (i.e. radar unit to target and back) to multi-hop transmissions for object detection.
The radar system 500 of
It is appreciated that the previous description of the disclosed examples is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these examples will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other examples without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Where methods described above indicate certain events occurring in certain order, those of ordinary skill in the art having the benefit of this disclosure would recognize that the ordering may be modified and that such modifications are in accordance with the variations of the present disclosure. Additionally, parts of methods may be performed concurrently in a parallel process when possible, as well as performed sequentially. In addition, more steps or less steps of the methods may be performed. Accordingly, examples are intended to exemplify alternatives, modifications, and equivalents that may fall within the scope of the claims.