Radar system for a vehicle as well as vehicles with such a system

Abstract

Radar system for a vehicle (100), comprising: a radar arrangement with a plurality of radar nodes (108a, 108b, 108c) arranged along a surface of the vehicle (100), each radar node (108a, 108b, 108c) comprising a first transmitter (212a) at one end of the node (108a, 108b, 108c) and a second transmitter (212b) at a second end of the node (108a, 108b, 108c) with a plurality of receivers (214a, 214b, 214c, 214d) aligned between the first transmitter (212a) and the second transmitter (212b), wherein an aperture length (Di) of the radar node (108a, 108b, 108c) and / or a distance (di) between the nodes (108a, 108b, 108c) is a variable parameter, and a processor (102) configured to: activate a transmitter (212a, 212b) of the radar arrangement to generate a test pulse; receive a reflection of the test pulse from the object (120) at a receiver (214a, 214b, 214c, 214d) of the radar arrangement;and for determining an angular position of the object (120) from the reflection of the test pulse; characterized in that the aperture length (Di) of a radar node (108a, 108b, 108c) increases with the distance (di) from a central point of the arrangement and the distance (di) between adjacent radar nodes (108a, 108b, 108c) is either constant or increases with the distance from the central point of the arrangement; or that the aperture length (Di) of each radar node (108a, 108b, 108c) is the same and a distance (di) between the radar nodes (108a, 108b, 108c) increases with the distance (di) from a central point of the arrangement.;

Description

INITIATIONThe present invention relates generally to a radar system according to the preamble of claim 1 for autonomous operation of a vehicle, as is known in the art substantially from US 2008 / 0 303 711 A1, but this document is silent about the existence of a plurality of radar nodes along a surface of the vehicle. However, this is known from the publications DE 601 07 692 T2 and DE 10 2014 014 307 A1.An autonomous vehicle includes one or more sensing systems that may sense the presence of an object in the path of the vehicle to steer the vehicle with respect to the object. The ability of the autonomous vehicle to avoid the object depends on the quality of various radar parameters obtained from the sensing system. One such detection system is a radar system that transmits an electromagnetic signal into an area surrounding the vehicle and receives a reflection of the electromagnetic signal from the object or obstacle. The need for high angular resolution with a reasonable number of radar nodes results in a large antenna distance. However, the large distance between antenna elements, such as receivers, may lead to an ambiguity in the measurement of an angle of the object, which leads to confusion with respect to an actual angular position of the object. Accordingly, it is desirable to provide an arrangement that reduces the ambiguity of an angle of incidence of reflected radar signals.SUMMARYAccording to the invention, a radar system for a vehicle is presented, which is distinguished by the features of claim 1.In embodiments, the distance between adjacent receivers of a radar node is the same or random. The radar array is disposed on a surface of the vehicle, and a direction of alignment of the transmitter and the receiver of the radar node is aligned with a direction of alignment of the plurality of radar nodes. The processor changes a trajectory of the vehicle with respect to the object using the determined angular position of the object.Furthermore, according to the invention, a vehicle is presented which is distinguished by the features of claim 4.In embodiments, the distance between adjacent receivers of a radar node is the same or random. The processor changes a trajectory of the vehicle with respect to the object using the determined angular position of the object.Further, a method of driving a vehicle will be described. The method includes transmitting a test pulse from at least one of a first transmitter at one end of a node of a radar array and a second transmitter at another end of the node, the node having a plurality of receivers aligned between the first transmitter and the second transmitter and defining an aperture length, the radar array including a plurality of radar nodes, at least one of an aperture length of the radar nodes and a distance between nodes being varied, receiving a reflection of the test pulse from an object at a receiver of one of the plurality of nodes, determining an angular position of the object from the reflection of the test pulse from the object; and changing a trajectory of the vehicle with respect to the object using the determined angular position of the object.In one embodiment, an aperture length of a radar node increases with the distance of the radar node from a central point of the array. The distance between adjacent radar nodes in this embodiment is either a constant distance or a distance which increases with the distance from the radar nodes from a central point of the array. In another embodiment, a distance between adjacent receivers of a radar node is the same or random. The radar assembly is disposed on a surface of the vehicle such that a direction of alignment of the transmitter and receiver of the radar node is aligned with a direction of alignment of the plurality of radar nodes.The above features and advantages, as well as other features and functions of the present invention, will be readily apparent from the following detailed description taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGSOther features, advantages, and details appear, by way of example only, in the following detailed description of the embodiments, wherein the detailed description refers to the drawings, in which: FIG. 1 shows a top view of an example vehicle configured to navigate an environment with respect to an object within the environment; FIG. 2A shows an illustrative radar node of a radar array in an embodiment; FIG. 2B shows an illustrative radar node of a radar array in another embodiment; FIG. 3 shows an illustrative radar array showing a selected array of a plurality of radar nodes in one embodiment; FIG. 4 shows an illustrative radar arrangement showing a different arrangement of a plurality of radar nodes than shown in FIG. 3 ; FIG. 5 illustrates a beamforming simulation of a reflected signal received at a radar array with one of the embodiments disclosed herein; and FIG. 6 shows an expanded portion of the beamforming simulation of FIG. 5.DETAILED DESCRIPTIONThe following description is merely exemplary in nature.According to an exemplary embodiment, FIG. 1 illustrates a top view of an exemplary vehicle 100 configured to navigate an environment with respect to an object 120 in the environment. The vehicle 100 includes a radar system having a radar array of radar nodes 108 a, 108 b, and 108 cto obtain information about one or more objects 120 in the environment. In one embodiment, the radar nodes 108 a, 108 b, 108 crespectively include transmitters that transmit electromagnetic test pulses to the environment of the vehicle 100 (such as the example test pulse 112 transmitted by the radar node 108 a) and receivers that receive one or more reflections (such as the illustrative reflections 114 a, 114 b, and 114 c) of the test pulse 112 from one or more objects 120 in the environment. The electromagnetic test pulses may be in a radio frequency range of frequencies.The vehicle 100 includes a central processor 102 for performing the various methods disclosed herein for data collection, data processing, and vehicle navigation. The central processor 102 controls operation of the array of radar nodes (e.g., the radar node 108 a) to generate a test pulse 112 at a radar node (e.g., the radar node 108 a) and process reflections (e.g., reflection 114 a) of the test pulse from the one or more objects 120 received at the radar node 108 a. It should be understood that test pulse 112 also results in reflected signals 114 band 114 cdetected at radar nodes 108 band 108 c. The processor 102 processes signals in which the reflected signal at any selected radar node (e.g., radar node 108 a) corresponds to a test pulse transmitted from the selected sensor. However, processor 102 may also process signals in which the transmitted test pulse is output by one radar node (e.g., radar node 108 a) and its corresponding reflected pulse is received at another radar node (e.g., radar node 108 b, 108 c). The processor 102 performs various methods for determining radar parameters of the one or more objects 120, such as its distance, relative speed, angular position, etc.The processor 102 is further in communication with various internal state sensors 110 of the vehicle 100. The internal state sensors 110 measure various parameters of the vehicle 100, including, but not limited to, a speed of the vehicle 100, a position of the vehicle, a braking parameter indicative of a state of the braking system of the vehicle 100, an acceleration parameter indicative of a driving state of the vehicle 100, a steering parameter of the vehicle 100, etc. The processor 102 is further in communication with various actuator devices 111 of the vehicle 100, and may provide a control signal to one or more of the actuator devices 111 to control operation of the vehicle 100 in response to various computations related to the environment and / or the object 120. The various actuator devices 111 include, but are not limited to, a steering actuator for steering the vehicle 100 in response to a steering signal from the processor 102, an accelerator for providing acceleration to the vehicle 100 in response to an acceleration signal from the processor 102, and a brake device for decelerating the vehicle 100 in response to a brake signal from the processor 102. In another embodiment, the processor 102 may provide information about the environment and / or the object 120 to a display to alert the driver of a vehicle to the object 120.The processor 102 communicates with a storage device 104 that includes various programs 106, which when executed by the processor 102, enable the processor 102 to perform the various methods disclosed herein. In one aspect, the programs 106 enable the processor 102 to determine various parameters of an object 120, such as distance, relative speed, angular position, etc., with respect to the vehicle 100 from the reflected signals received at the radar system. The processor 102 may determine, from an internal state of the vehicle 100 (measured by internal state sensors 110) and the determined radar parameters of the object 120, a predicted trajectory of the vehicle 100 with respect to the object 120 as well as a predicted determined result along the predicted trajectory, such as a probability of a collision with the object 120. The processor may redirect the vehicle 100 to change the trajectory based on the predicted result, thereby obtaining another result, such as avoiding the predicted collision. The processor 102 activates the various actuator devices 111 of the vehicle 100 to redirect the vehicle 100.The radar assembly of the vehicle 100 includes a plurality of radar nodes 108 a, 108 b, 108 c, each node comprising at least two transmitters and a plurality of receivers, as discussed herein. The radar nodes are mounted on a surface of the vehicle 100.FIG. 2A illustrates an illustrative radar node 200 of a radar array in an embodiment. The radar node 200 includes at least two transmitters (202a, 202b) and a plurality of receivers (204a, 204b, 204c, 204d). The radar node 200 includes an aperture 206 having a length dimension D. The at least two transmitters (202a, 202b) and the plurality of receivers (204a, 204b, 204c, 204d) are aligned within the aperture 206 along the length dimension D. A first transmitter 202a is placed or arranged at a first end of the aperture 206 and a second transmitter 20b is placed or arranged at a second end of the aperture 206. The plurality of receivers 204 a, 204 b, 204 c, and 204 dare arranged between the first transmitter 202 aand the second transmitter 202 b. Only four receivers are shown in FIG. 2A for purposes of illustration. However, it should be appreciated that any number of receivers may be placed or arranged within a selected node.The receivers 204 a, 204 b, 204 c, 204 dare spaced apart from each other by a distance between the receivers. Distance S 1 is a distance between receiver 204 aand receiver 204 b. Distance S 2 is a distance between receiver 204 band receiver 204 c. Distance S 3 is a distance between receiver 204 cand receiver 204 d. In the embodiment of Figure 2A, the distance between the receivers is uniform, i.e., S 1= S 2= S 3.FIG. 2B shows an illustrative radar node 210 of a radar array in another embodiment. The radar node 210 includes an aperture 216 having a length dimension D and has at least two transmitters (212a, 212b) and a plurality of receivers (214a, 214b, 214c, 214d) within the aperture 216 aligned along the length dimension D. A first transmitter 212 ais placed or arranged at a first end of the opening 216, and a second transmitter 212 bis placed or arranged at a second end of the opening 216. The plurality of receivers 214 a, 214 b, 214 c, and 214 dare disposed between the first transmitter 212 aand the second transmitter 212 b. Receivers 214a, 214b, 214c, and 214d are spaced from each other by distances S1, S2, and S3, as discussed above with respect to FIG. 2A. In the embodiment of FIG. 2B, the inter-receiver distances S1, S2, and S3 are randomly determined, selected, or assigned. Therefore, the distances S1, S2 and S3 are generally not equal.FIG. 3 shows an illustrative radar array 300 that shows a selected array of a plurality of radar nodes ( 301, 303, 305, 307, 309, 313, 315, 317, 319) in one embodiment. The radar nodes ( 301, 303, 305, 307, 309, 313, 315, 317, 319) are arranged on a surface of the vehicle, which may be a curved surface and from which a length L of the radar arrangement 300 is measured from the outer edges of the outermost radar nodes ( 309 and 319). A direction of alignment of the transmitters and receivers of the radar nodes is generally aligned with a direction of alignment of the radar nodes of the radar array. In other words, the length dimension D of FIGS. 2A and 2B is generally aligned with the length L of FIG. 3. A central point C of the radar array is located midway along half length L. In the illustrative radar array 300, the distance between nodes varies with the distance from the central point C. In particular, the distance between the nodes increases with the distance from the central point of the radar array 300. Central node 301 is separated on its left side from node 303 by distance d 1. Node 303 and node 305 are separated by distance d 2. Node 305 and node 307 are separated by distance d 3. Node 307 and node 309 are separated by distance d 4. On the other side of array 300, central node 301 is separated on its right side from node 313 by distance d 1. Node 313 and node 315 are separated by distance d 2. Node 315 and node 317 are separated by distance d 3. Node 317 and node 319 are separated by distance d 4. The intranode spaces are associated with d 1< d 2< d 3< d 4. It should be appreciated that the number of radar nodes shown in the radar array 300 is selected for illustrative purposes only, and that the radar array 300 may include any number of radar nodes in alternative embodiments.Each of the radar nodes ( 301, 303, 305, 307, 309, 313, 315, 317, 319) in the radar arrangement 300 has the same aperture length D 0. The arrangement of transmitters and receivers in the aperture of the radar nodes can be as shown in FIGS. 2A and 2B. In other words, all radar nodes may have a uniform distance between the receivers, or all radar nodes may have a random distance between the receivers, or some of the radar nodes may have a uniform distance between the receivers, while the rest of the radar nodes may have a random distance between the receivers.FIG. 4 shows an illustrative radar array 400 showing a different arrangement of a plurality of radar nodes (401, 403, 405, 407, 409, 413, 415, 417, 419) than shown in FIG. 3. The radar nodes ( 401, 403, 405, 407, 409, 413, 415, 417, 419) are arranged on a surface of the vehicle, which may be a curved surface and from which a length L of the radar arrangement 400 is measured from the outer edges of the outermost radar nodes ( 409 and 419). A direction of alignment of the transmitters and receivers of the radar nodes is generally aligned with a direction of alignment of the radar nodes of the radar array. In other words, the length dimension D of FIGS. 2A and 2B is generally aligned with the length L of FIG. 4. A central point C of the radar arrangement is arranged at half the length L. In the illustrative radar array 400, the length of the aperture of each radar node varies with distance from the central point of the radar array 400. In particular, the length of the aperture of a radar node increases with distance from the central point of the radar array 400. The central node 401 has an aperture length D 0. Nodes 403 and 413 have an aperture length D 1 on each side of central node 401, nodes 405 and 415 have an aperture length D 2 nodes 407 and 417 have an aperture length D 3 and the outermost nodes 409 and 419 have an aperture length D 4 respectively. The aperture lengths are linked by D 0< D 1< D 2< D 3< D 4. It should be appreciated that the number of radar nodes shown in radar array 400 is selected for illustrative purposes only, and that radar array 400 may include any number of radar nodes in alternative embodiments. The distance between the nodes may remain constant, as shown in FIG. 4, or may vary. In some embodiments, the distance between the apertures increases with the distance from the central point C.The arrangement of transmitters and receivers in the aperture of the radar nodes can be as shown in FIGS. 2A and 2B. In other words, all radar nodes may have a uniform distance between the receivers, or all radar nodes may have a random distance between the receivers, or some of the radar nodes may have a uniform distance between the receivers, while the rest of the radar nodes may have a random distance between the receivers.It should be understood that the lengths described in FIG. 3 do not necessarily refer to the lengths described in FIG. 4. For example, the length D 0 of the aperture of the radar node 301 in FIG. 3 is not necessarily equal to the length D 0 of the aperture of the radar node 401 in FIG. 4.FIG. 5 shows a beamforming simulation 500 of a reflected signal received at a radar arrangement with one of the embodiments disclosed herein. The angle is given in degrees along the abscissa and the intensity is given in decibels along the axis of ordinates. The object reflecting the signal is at zero degree azimuth. As can be seen from Figure 5, a main lobe 502 is shown having a maximum peak that is clearly detectable along the azimuth at zero degrees. Side lobes have a significantly lower intensity, thereby allowing the processor to identify the main lobe 502 without ambiguity or with significantly reduced ambiguity.FIG. 6 shows an extended range of the beamforming simulation 500 of FIG. 5. The main lobe 502 is clearly distinguishable. The next side lobes 602 and 604 have an intensity that is about 9 decibels less than the intensity of the main lobe 502. In addition, the side lobes 602 and 604 are +-0.2 degrees of the main lobe 502. Thus, the main lobe 502 may be identified without ambiguity and may be used to identify an angular position of an object detected by the radar system with a high angular resolution. This high resolution angular position of the object may thus be used to steer or navigate the vehicle with respect to the object, as discussed above with respect to FIG. 1.

Claims

A radar system for a vehicle (100), comprising: a radar arrangement having a plurality of radar nodes (108a, 108b, 108c) arranged along a surface of the vehicle (100), each radar node (108a, 108b, 108c) including a first transmitter (212a) at an end of the node (108a, 108b, 108c) and a second transmitter (212b) at a second end of the node (108a, 108b, 108c) having a plurality of receivers (214a, 214b, 214c, 214d) aligned between the first transmitter (212a) and the second transmitter (212b), wherein an aperture length (D i) of the radar node (108a, 108b, 108c) and / or a distance (d i) between the nodes (108a, 108b, 108c) is a variable parameter, and a processor (102) configured to: activate a transmitter (212a, 212b) of the radar array to generate a test pulse; receive a reflection of the test pulse from the object (120) at a receiver (214a, 214b, 214c, 214d) of the radar array; and determine an angular position of the object (120) from the reflection of the test pulse; characterized in that the aperture length (D i) of a radar node (108a, 108b, 108c) increases with the distance (d i) from a central point of the array and the distance (d i) between adjacent radar nodes (108a, 108b, 108c) is either constant or increases with the distance from the central point of the array; or in that the aperture length (D i) of each radar node (108a, 108b, 108c) is the same and a distance (d i) between the radar nodes (108a, 108b, 108c) increases with the distance (d i) from a central point of the array.The radar system of claim 1, wherein a distance (d i) between adjacent receivers (214a, 214b, 214c, 214d) of a radar node (108a, 108b, 108c) is the same or random.The radar system of claim 1, wherein the radar array is disposed on a surface of the vehicle (100), and a direction of alignment of the transmitter (212a, 212b) and the receiver (214a, 214b, 214c, 214d) of the radar node (108a, 108b, 108c) is aligned with a direction of alignment of the plurality of radar nodes (108a, 108b, 108c).A vehicle (100) comprising: a radar array having a plurality of radar nodes (108a, 108b, 108c) disposed along a surface of the vehicle (100), each radar node (108a, 108b, 108c) including a first transmitter (212a) at an end of the node (108a, 108b, 108c) and a second transmitter (212b) at a second end of the node (108a, 108b, 108c) having a plurality of receivers (214a, 214b, 214c, 214d) aligned between the first transmitter (212a) and the second transmitter (212b), and wherein an aperture length (D i) of the radar node (108a, 108b, 108c) and / or a distance (d i) between the nodes (108a, 108b, 108c); and a processor (102) configured to: activate a transmitter (212a, 212b) of the radar array to generate a test pulse; receive a reflection of the test pulse from the object (120) at a receiver (214a, 214b, 214c, 214d) of the radar array; and determine an angular position of the object (120) from the reflection of the test pulse; characterized in that the aperture length (D i) of each radar node (108a, 108b, 108c) increases with the distance (d i) from a central point of the radar array and the distance (d i) between adjacent radar nodes (108a, 108b, 108c) is either constant or increases with the distance from the central point of the array; or in that the aperture length (D i) of each radar node (108a, 108b, 108c) is the same and a distance (d i) between radar nodes (108a, 108b, 108c) increases with the distance (d i) from a central point of the array.The vehicle (100) of claim 4, wherein a distance (d i) between adjacent receivers (214a, 214b, 214c, 214d) of a radar node (108a, 108b, 108c) is equal or random.The vehicle (100) of claim 4, wherein the processor (102) is further configured to change a trajectory of the vehicle (100) with respect to the object (120) using the determined angular position of the object (120).

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