Patent Publication Number: US-9836966-B2

Title: Accelerometer integrated with display device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Application claims priority of U.S. Provisional Application No. 62/028,549, filed on Jul. 24, 2014, and the entirety of which is incorporated by reference herein. 
    
    
     TECHNOLOGICAL FIELD 
     The disclosure relates to an imager system for a vehicle. 
     BRIEF SUMMARY 
     In some embodiments, a driver assist system incorporated in a display device is disclosed. The system comprises an accelerometer and a controller in communication with the accelerometer. The controller is configured to receive at least one acceleration signal from the accelerometer and calculate a direction of rotation of the display device. The direction of rotation is utilized by the controller to calculate a drive side of the vehicle. 
     In another embodiment, a display device configured to detect an object approaching a vehicle is disclosed. The display device comprises an accelerometer and a controller in communication with the accelerometer. The controller is configured to receive at least one acceleration signal from the accelerometer and calculate a direction of rotation of the display device. The direction of rotation is utilized by the controller to assist in detecting at least one of a leading vehicle and an oncoming vehicle. 
     In yet another embodiment, a method of detecting an object on a roadway with a driver assist system of a vehicle is disclosed. The method comprises measuring an angle of rotation between a vehicle display device and a forward direction of the vehicle and identifying a drive-side of the vehicle based on the angle of rotation. The method further comprises capturing image data of a forward directed field of view relative to the vehicle. Based on the angle of rotation, the method continues to identify a characteristic of a target vehicle in the image data. 
     These and other features, advantages, and objects of the present disclosure will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a vehicle demonstrating a display angle of a display device; 
         FIG. 2  is a diagram of a vehicle interior demonstrating a display device; 
         FIG. 3  is a top view of a vehicle demonstrating a display angle of a display device; 
         FIG. 4A  is a diagram of a field of view of an image sensor corresponding to a right drive configuration; 
         FIG. 4B  is a diagram of a field of view of an image sensor corresponding to a left drive configuration; and 
         FIG. 5  is a block diagram of a controller configured to adjust a compass heading in accordance with the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     For purposes of description herein the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the device as oriented in  FIG. 1 . However, it is to be understood that the device may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     Referring to  FIG. 1 , a display device  10  for a vehicle  12  is shown. The display device  10  comprises an accelerometer, a compass, and an image sensor  13  in communication with a controller  14 . The accelerometer is operable to measure a forward acceleration of the vehicle  12  in the direction of a forward vector  16  and communicate corresponding acceleration data to the controller  14 . The forward vector  16  refers to the forward direction of travel of the vehicle  12  as significantly projected along a centerline C of the vehicle  12 . Based on the acceleration data, the controller is operable to determine a display angle δ of a display vector  18  of the display device  10  relative to the forward vector  16  of the vehicle  12 . 
     With the display angle δ, the controller  14  is operable to offset a compass heading measured by the compass to correct for the display angle δ of the display device  10 . In this way, the controller  14  is operable to correct the heading direction measured by the compass to generate an offset compass heading. The offset compass heading is adjusted based on the display angle δ to accurately display the heading of the vehicle  12  independent of the display angle δ of the display device  10 . The disclosure provides for the display device  10  to utilize the accelerometer to adjust heading measured by the compass to accurately reflect a vehicle heading  20  by adjusting the compass heading by the angular offset of the display angle δ. 
     In some implementations, the display device  10  may comprise a rearview mirror and/or display having disposed in a housing. The compass or related circuitry may be disposed in the housing such that the compass heading may change relative to a position of the housing of the display device  10 . The housing may further comprise a processor in communication with compass such that the display device  10  is operable to accurately determine the vehicle heading by adjusting the compass heading based on the display angle δ. 
     Referring now to  FIGS. 1 and 2 , the display device  10  may comprise a rearview display device and/or mirror. The rearview display device may be implemented as an interior rearview mirror  32 , a side mirror  34 , or any form of display configured to provide a view from the vehicle  12 . In some implementations, the display device  10  may comprise a video display device operable to display a view of an exterior environment outside the vehicle via a display screen  36 . The display screen  36  may comprise any form of video screen, for example a light emitting diode (LED) display, organic LED display, liquid crystal display (LCD), etc. 
     The display device  10  and/or at least one additional display of the vehicle  12  may be configured to receive the offset compass heading from the controller  14  and display the vehicle heading  20  as offset by the display angle δ. The controller  14  may be configured to communicate the vehicle heading  20  to the at least one additional display to assist an operator of the vehicle  12  in navigation. The controller  14  may further be in communication with one or more navigational or driver assist systems and provide the offset compass heading to such systems. The at least one additional display may include a radio and/or infotainment system  38 , a gauge cluster display  40 , a window  42  of the display device  10 , or any other form of display operable to display alphanumeric characters corresponding to a compass heading. 
     In some implementations, the controller  14  is operable to calculate the display angle δ and the offset compass heading when the vehicle  12  is accelerating significantly parallel to the forward vector  16 . The controller may utilize the compass to determine if the vehicle  12  is accelerating consistently along the forward vector  16  or if the vehicle  12  is turning and accelerating along a curve (e.g. turning the vehicle  12 ). In order to determine if the vehicle  12  is accelerating consistently along the forward vector  16 , the controller  14  may compare a plurality of measurements from the compass over a temporal period to ensure that a compass heading of the vehicle is within a predetermined range. The predetermined range may correspond to a change in the compass heading being less than at least one predetermined value. 
     If the change in compass heading is sufficiently small or within the predetermined range, the controller  14  is operable to utilize the acceleration data for the same temporal period to update and/or calculate the display angle δ and the corresponding offset compass heading. If the compass heading during the temporal period varies sufficiently to exceed or fall below a maximum or minimum of the predetermined range, the display angle δ may not be calculated to ensure that the offset compass heading is accurate. Under such circumstances, a previously stored display angle δ may be utilized to provide the offset compass heading. 
     The offset compass heading may be calculated based on a trigonometric relationship between the forward vector  16  and the display vector  18 . The accelerometer may comprise a plurality of axial measurement directions, for example an x-axis and a y-axis. Each of the axial measurement directions may be aligned with the compass and the display device  10  such that a y-axis  46  is aligned with the display vector  18  and an x-axis  48  is aligned perpendicular to the display vector  18 . Upon a significantly forward acceleration along the forward vector  16  (within the predetermined range) as discussed above, the controller  14  is configured to receive acceleration data from the accelerometer and calculate the display angle δ. 
     A significant acceleration may vary based on the sensitivity of a particular accelerometer. In general, the significant acceleration may correspond to the forward acceleration exceeding a predetermined acceleration threshold. The predetermined acceleration threshold may vary based on a noise level detected by a particular accelerometer, and in some implementations, may correspond to a forward acceleration of at least  + / - 0.1 g. 
     Referring now to  FIG. 3 , the display angle δ of the display device  10  may result in the acceleration data along the forward vector  16  having an acceleration component along the display vector  18  corresponding to the y-axis  46  and an acceleration component perpendicular to the display vector  18  along the x-axis. The relationship of the display angle δ, to the x-axis  48  and the y-axis  46  is denoted as δ=arctan ( a     x   / a     y   ), wherein the acceleration in the x direction is a x  and the acceleration in the y direction is a y . Based on this relationship, the display angle δ is calculated and the compass direction of the display device  10  is updated to align with the forward vector  16  of the vehicle  12  as the offset compass heading. The accelerometer may further comprise another axial measurement direction corresponding to a z-axis  50  configured to calibrate the y-axis  46  and the x-axis  48  to gravity to further improve the accuracy of the offset compass heading. 
     Referring now to  FIGS. 4A and 4B , image data is demonstrated in a field of view  64  of the image sensor  13 . The image sensor  13  may correspond to any form of image or light sensor configured to capture image data  62  corresponding to the field of view  64  of the image sensor  13 . The image sensor  13  may correspond to the imager disclosed in the SMART BEAM lighting control system manufactured by Gentex Corporation described in commonly assigned U.S. Provisional Patent Application Nos. 60/900,588, 60/902,728 and 61/008,762; U.S. Patent Nos. 8,289,430, 8,305,471, 8,587,706, and 8,629,927, the disclosures of each of the above are incorporated in their entireties herein by reference. 
     In some implementations, the controller  14  is in communication with the image sensor  13  and is configured to identify at least one characteristic to detect a target vehicle  66 . The at least one characteristic may refer to a light source  67 , for example one or more headlamps, taillights, running lights, etc. The controller  14  is operable to detect the target vehicle  66  by identifying the at least one characteristic, and further by identifying the movement and/or behavior of the at least one characteristic over time. The motion of the at least one characteristic may be determined based on the relative location of the characteristic in a sequence of image data corresponding to a temporal period. The at least one characteristic identified by the controller  14  to detect the target vehicle  66  may comprise headlights, taillights, running lights, or any other identifying characteristic corresponding to the target vehicle  66 . 
     For example, the controller  14  is operable to identify a plurality of headlamps  68  or tail lamps  70  of the target vehicle  66  based on the relative positions of each of the headlamps  68  or tail lamps  70  in a sequence of image data. Based on the relative location of the headlamps  68  or tail lamps  70  in the field of view  64 , the controller may identify an oncoming vehicle or a vehicle traveling in a common direction. Based on the display angle δ of the display device  10 , the controller may be operable to determine a driver side of the vehicle  12  to assist in determining an oncoming portion  72  and a common portion  74  of traffic. 
     Referring to  FIG. 4A , an illustration of a right drive field of view  76  demonstrates the headlamps  68  of oncoming traffic located in a left portion and the tail lamps  70  of the traffic travelling in the common direction in a right portion. Referring to  FIG. 4B , an illustration of a left drive field of view  78  demonstrates the headlamps  68  of oncoming traffic located in a right portion and the tail lamps  70  of the traffic travelling in the common direction in a left portion. If the controller  14  determines that the display angle δ is directed toward a left portion of the interior of vehicle  12  relative to the forward vector  16 , the controller is configured to detect vehicles corresponding to the right drive field of view  76  configuration. If the controller  14  determines that the display angle δ is directed toward a right portion of the interior of the vehicle  12  relative to the forward vector  16 , the controller  14  is configured to detect vehicles corresponding to the left drive field of view  78  configuration. In this way, the controller can improve a detection of the target vehicle  66  based on a drive side which may further correspond to a geographic area of operation of the vehicle  12 . 
     Referring to  FIG. 5 , a block diagram of the controller  14  is shown. The image sensor  13  is in electrical communication with the controller  14  which comprises a processor. The processor is configured to receive image data from the image sensor  13 . The processor is further configured to process images corresponding to the image data to detect the at least one characteristic corresponding to the target vehicle  66 . The processor may be in communication with a memory configured to store the image data during processing. The processor may be implemented using a microcontroller, a microprocessor, a digital signal processor, a programmable logic unit, a discrete circuitry, or any combination thereof. Additionally, the microcontroller may be implemented using more than one microprocessor. 
     The controller  14  is shown in communication with the accelerometer  82 , the image sensor  13 , and the compass  84 . The accelerometer  82  may comprise a 3-axis accelerometer and may be configured to measure a range of approximately +/− 4 g at a resolution of approximately 16-bits. The accelerometer  82  may further be operable to operate in a wide range of temperatures and have an effective sampling rate of approximately 25 Hz. The accelerometer signal as discussed herein may include a plurality of accelerometer signals which may correspond to each axis of the accelerometer  82 . Though specific performance characteristics corresponding to the accelerometer  82  are discussed herein, a variety of accelerometers may be utilized according to the particular precision, operating parameters of the controller  14 , and the operating conditions/environments of a particular host vehicle. 
     The image sensor  13  may correspond to any form of image or light sensor, for example a charge-coupled devices (CCD) or complementary metal-oxide-semiconductor (CMOS). Further, detailed descriptions image sensors and vehicle detection systems configured to detect a target vehicle are described in commonly assigned U.S. Pat. Nos. 5,837,994; 5,990,469; 6,008,486; 6,130,448; 6,130,421; 6,049,171; 6,465,963; 6,403,942; 6,587,573; 6,611,610; 6,621,616; 6,631,316; 6,774,988; 6,861,809; and 8,045,760; and U.S. Provisional Patent Application Nos. 60/404,879 and 60/394,583, the disclosures of which are also incorporated herein in their entireties by reference. Also, commonly assigned U.S. Provisional Application Nos. 60/780,655 and 60/804,351; U.S. Patent No. 8,339,526;and U.S. patent application Publication No. 2009/0096937 describe various displays for use with the present disclosure. The entire disclosures of each of these applications are also incorporated herein by reference. 
     The compass  84  may be implemented as any device operable to determine an absolute or relative direction or compass heading of the vehicle  12 , for example a magnetometer, etc. Further detailed descriptions of display devices configured to display a compass heading are described in commonly assigned U.S. Pat. Nos. 6,140,933; 6,968,273; 7,149,627; and 6,023,229. An ambient light sensor  86  is further in communication with the controller  14 . The ambient light sensor  86  may be utilized in combination with the image sensor  13  to provide additional data to identify the at least one characteristic corresponding to the target vehicle  66 . For example, the controller may utilize an ambient light signal from the ambient light sensor  86  to identify the lighting conditions of the operating environment to determine a lighting level contrast to detect the target vehicle  66 . 
     In order to assist in the detection of the target vehicle  66 , the controller  14  may further utilize various input signals corresponding to the operating conditions of the vehicle  12 . A speed input  88  may be utilized to provide vehicle speed information to the controller  14 . The speed input  88  may be utilized by the controller  14  in addition to the image data received from the image sensor  13  to identify and discern among non-target objects and approaching vehicles. The controller  14  may further be in communication with a vehicle bus  90  configured to send and receive operating information pertaining to the vehicle  12 . In some implementations, the vehicle bus may be utilized to communicate the adjusted compass heading to additional vehicle systems, some of which are discussed herein. 
     The disclosure provides for various benefits including reducing manufacturing time, complexity, and cost by limiting communications to the display device  10  from a vehicle communication bus. Further benefits include a reduced likelihood of a manufacturing error that may occur if a mirror configured for a right drive vehicle was installed in a left drive vehicle. By providing for the display device  10  to measure the display angle δ and update the compass heading based on an orientation of the display device  10  relative to a vehicle heading, the disclosure provides for improved accuracy and reliability in the compass heading measured by the display device  10 . 
     It will be understood that any described processes or steps within described processes may be combined with other disclosed processes or steps to form structures within the scope of the present device. The exemplary structures and processes disclosed herein are for illustrative purposes and are not to be construed as limiting. 
     It is also to be understood that variations and modifications can be made on the aforementioned structures and methods without departing from the concepts of the present device, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise. 
     The above description is considered that of the illustrated embodiments only. Modifications of the device will occur to those skilled in the art and to those who make or use the device. Therefore, it is understood that the embodiments shown in the drawings and described above is merely for illustrative purposes and not intended to limit the scope of the device, which is defined by the following claims as interpreted according to the principles of patent law, including the Doctrine of Equivalents.