Abstract:
A method and apparatus for providing an obstacle detection system for a vehicle having an automated door or moveable panel, the detection system having a sensing system including a plurality of emitters and detectors disposed proximate to the automated moveable panel or door of the vehicle and a detection circuit in communication with the sensing system, the detecting detection circuit generating an output signal when an object is detected by the sensing system, the output signal is received by a motor control unit of the moveable panel or door and movement of the moveable panel or door is prevented when the output signal is received.

Description:
BACKGROUND  
         [0001]    The present disclosure relates generally to proximity detecting systems and, more particularly, to a non-contact obstacle detection system (for example, a human obstacle) that may be implemented in conjunction with a motor vehicle power lift-gate.  
           [0002]    Various systems have been devised for detecting obstacles (e.g., humans) in the path of a moveable panel such as an automotive power window, power sliding door or power hinged door. When an obstacle is detected, forward movement (e.g., closing) of the panel is interrupted and, optionally, the movement of the panel may be thereafter reversed (e.g., opened). These detection systems may generally be characterized as either “contacting” or “non-contacting”. In a contacting system, an obstacle is detected only after some form of physical contact occurs between the panel and the obstacle, and may include devices such as pneumatic/pressure sensitive strips, or possibly sensors responsive to changes in mechanical or electrical loading in the apparatus that moves the panel.  
           [0003]    On the other hand, in a non-contacting system, an obstacle is detected before actual contact occurs. One specific type of non-contacting obstacle detection system employs the use of a capacitive element(s) as a proximity sensor(s). Capacitive proximity sensors may include one or more electrical conductors formed along the leading edge of a moveable panel, as well as a capacitance sensitive circuit (e.g., a bridge circuit or an oscillator) coupled to the conductor(s). An obstacle (e.g., a human hand) in proximity to the conductor(s) changes the capacitance of the sensor, which change is thereafter detected by the capacitive sensitive circuit.  
         SUMMARY  
         [0004]    A method and apparatus for providing an obstacle detection system for a vehicle having an automated door or moveable panel, the detection system having a sensing system including a plurality of emitters and detectors disposed proximate to the automated moveable panel or door of the vehicle and a detection circuit in communication with the sensing system, the detecting detection circuit generating an output signal when an object is detected by the sensing system, the output signal is received by a motor control unit of the moveable panel or door and movement of the moveable panel or door is prevented when the output signal is received.  
           [0005]    In an exemplary embodiment, the system includes a sensing element disposed in proximity to a moveable panel and a proximity detection circuit in communication with the sensing element. The proximity detection circuit generates a differential output signal reflective of whether a foreign object is in proximity to the sensing element. In addition, a central control module is in communication with the sensing element. The central control module determines whether the differential output signal is reflective of a foreign object in proximity to the sensing element. If the central control module determines that the differential output signal is reflective of a foreign object in proximity to the sensing element, and the moveable panel is moving toward a closed position, then the central control module generates a control output signal to stop the moveable panel from moving toward the closed position. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIGS. 1A and 1B are perspective views of a vehicle having non-contact obstacle detection system;  
         [0007]    [0007]FIGS. 2A and 2B are side elevational views of non-contact obstacle detection systems;  
         [0008]    [0008]FIG. 3 is a schematic drawing of a control circuit for the non-contact obstacle detection system of the present disclosure;  
         [0009]    [0009]FIG. 4 is a cross-sectional view of a component of the non-contact obstacle detection system of the present disclosure; and  
         [0010]    [0010]FIG. 5 is a schematic drawing of a portion of the non-contact obstacle detection system of the present disclosure.  
     
    
     DETAILED DESCRIPTION  
       [0011]    Disclosed herein is a non-contact obstacle detection system that utilizes sensor techniques to control the movement of an electrically powered system such as power lift-gates, power sliding doors, power deck lids, or a moving door of a vehicle.  
         [0012]    Referring initially to FIGS. 1A and 1B, there is shown a non-contact obstacle detection system  10 , in accordance with an embodiment of the present disclosure. Non-contact system  10  is configured to be used on a vehicle  12  having a liftgate or door  14  having an automatic power closure feature. The non-contact obstacle detection system of the present disclosure is contemplated for use on any closing element and is not specifically limited to vehicular applications. The primary goal of the non-contact obstacle detection system is to detect the presence of an obstacle before, during and after a closing or opening sequence has been initiated.  
         [0013]    The non-contact obstacle detection system of the present disclosure uses a plurality of infrared light emitting diodes  16 (LEDs) and a plurality of photo detectors  18 , which are configured to detect the signals emitted by the LEDs  16 . Contemplated LEDs  16  and detectors  18  are similar to those used in remote control applications for example, remote controls for televisions, radios, etc. In addition, LEDs  16  and detectors  18  maybe similar to those used in wireless devices used for data transfer in other electronic devices such as computers, personal display assistants (PDAs), and cell phones etc.  
         [0014]    The non-contact obstacle detection system of the present disclosure detects the presence of an obstacle when a signal path  20  between an LED and its complementary detector is broken or obstructed. Path  20  is broken when the obstacle enters an area occupied by path  20  and accordingly, the detector is no longer able to detect the infrared light being admitted by its complementary LED  16 . When this occurs a control circuit  22  will provide a signal to a motor controller  24  for liftgate  14 . The signal will instruct the closing or opening sequence of liftgate  14  to stop. In addition, and as an alternative when motor controller  24  receives such a signal the controller can also be configured to reverse the closing sequence.  
         [0015]    In the illustrated embodiment, four pairs of emitters  18  and detectors  18  are used. Of course, the number of detectors and emitters may vary depending on the amount of coverage required and the curvature of the surface on which they are disposed. As illustrated in the Figures the area surrounding liftgate  14  is monitored by disposing detectors and emitter along the sides of the opening for the liftgate. For example, the emitter and detectors are disposed from a hinge line  26  down to an area  28  above a taillight  30  of the vehicle. Thus, the two pairs of emitters and detectors define a path from above the taillight to the height of the hinge line. Of course, it is contemplated that the emitters and detectors are capable of being positioned to define path  20  along other lines and areas of the vehicle.  
         [0016]    In the present disclosure a first side of the liftgate is monitored by a first emitter  16  disposed proximate to the hinge line. The first LED emitter provides a beam of infrared light, which is received by a first detector disposed between the hinge line and the taillight, preferably at a point of curvature  32  representing the largest difference (identified as x) between the emitter and detector. A second emitter is also disposed at the point of curvature to provide a beam of infrared light, which is received by a second detector disposed proximate to the taillight. As will be discussed herein the beams of infrared light are modulated to improve detection of the same.  
         [0017]    Of course, the positioning, number and angular configuration of the emitters and detectors may vary and the positioning and angular configurations illustrated in the Figures are intended to provide examples, and the present disclosure is not intended to be limited to the same. For example, if the area of the vehicle being monitored is sufficiently flat a single pair of emitters and detectors may suffice.  
         [0018]    [0018]FIG. 2A illustrates the potential for an object  34  of a certain size, which may not be large enough to obstruct the path of light or signal between a single emitter and detector located along an edge of the liftgate opening having angle of curvature illustrated the Figure. Of course, the angle of curvature and size of object  34  may vary, FIG. 2B illustrates that two pairs of emitters and detectors are able to be positioned to locate the path of light or signal closer to the surface of the area being monitored as opposed to a single emitter and detector positioned along an area of a similar curvature. In addition, the pair of emitters and detectors on the same side of the vehicle are sequenced to prevent the system from being tricked into a false reading.  
         [0019]    [0019]FIG. 3 illustrates an exemplary control circuit  22  for use in the four pair (emitter/detector) arrangement illustrated in FIGS. 1 and 2. Of course, the number of pairs may vary. As illustrated each detector (identified as  1 - 4 , representing four detectors in total) is adapted to provide a signal to an inverter gate or NOT gate  36  (corresponding to each of the detectors), which inverts the signal of the detector. The outputted or inverted signal of the gates  36  is then inputted into a corresponding input of a three input AND gate  38  (corresponding to each of the detectors).  
         [0020]    Also shown in FIG. 3 is a first oscillator  40 , a second oscillator  42  and a 4 state sequencer or clock  44 . In the illustrated embodiment first oscillator  40  is a 38 Kilohertz (KHZ) oscillator and second oscillator  42  is a 1 Kilohertz (KHZ) oscillator. Of course, and as applications may require the values of the oscillators may be greater or less than the aforementioned values.  
         [0021]    The 38 Kilohertz frequency of the first oscillator is used to make the emitter and detector of the present disclosure more tolerant to ambient light. Infrared LEDs and infrared photo detectors are used in the present disclosure. In order to improve the detection or make the system more tolerant to ambient light the infrared (IR) signal is modulated and when the signal is detected the system will verify that the detected signal is also modulated. The modulation of the signals and confirmation of receipt of the modulated signal will be conducted in accordance with known technologies. This signal modulation will prevent the detectors from being tricked by detecting ambient light instead of infrared light.  
         [0022]    The 1 Kilohertz frequency of the second oscillator is used to drive the clock of the sequencer as well as being inputted to the same gate ( 46 ) as the first oscillator. Accordingly, the sequencer will advance every millisecond. The combined input of the first and second oscillators will advance the sequencer and will instruct each of the emitters to sequentially emit a modulated signal.  
         [0023]    The outputs of the oscillators  40  and  42  are inputted into a two input AND gate  46 , which is configured to provide a corresponding output or signal to an input of each of a plurality of two input AND gates  48  (one of each corresponding to one of the plurality of LEDs  16 ). In addition, each of the AND gates  48  receives an input from the four state sequencer  44 .  
         [0024]    In addition, each of the AND gates  38  also receives an input from the four state sequencer  44 . AND gates  38  also receive a signal from oscillator  42  as well as the emitters. The four state sequencer  44  is used to drive the circuit through a sampling sequence wherein the emitter  1  is driven and the circuit looks to see if the modulated light of emitter  1  is received by detector  1 , then, the circuit drives and checks emitter  2  and detector  2 , etc. until it returns back to emitter  1  and detector  1 . This circuit will operate continuously. The circuit is also configured to operate in a manner wherein the specific signals of each emitter are looked for receipt by a specific detector. If an obstacle is detected a fault signal is sent to the motor controller of the liftgate. The system can be configured to operate continuously or alternatively be configured to operate only when the motor control system of the motorized liftgate has been activated (e.g., closing or opening).  
         [0025]    The sequence of the system is also used to prevent the system from obtaining a false reading through a reflection of the IR signal. Referring now to FIG. 5, if a first emitter  16  emits a modulated signal that is detected by a first photo detector  18 , the circuit will determine that the path between the first two devices has not been broken and no obstacle has been detected. The circuit through the operation of the clock sequencer will then determine whether the signal of the second emitter  16  is now being received by the second photo detector  18 . As illustrated, in FIG. 5 it may be possible that a reflective object  58  is positioned to receive the signal of first emitter  16  and reflect it towards second detector  18 . In addition, an obstruction  34  can also be positioned to block the signal from the second emitter  16 . However, since the non-contact obstacle detection system of the present disclosure sequences through each pair of emitters and detectors, the circuit will not be tricked by the reflective object illustrated in FIG. 5, as it will determine that the signal of the second emitter has not been received by the second detector. Accordingly, the sequencing of the system of the present disclosure prevents a detector from receiving a signal from an incorrect emitter.  
         [0026]    Referring back now to FIG. 3, the output of the second oscillator is also received by each of the AND gates  38 . Accordingly, each of the outputs of AND gates  38  are inputted in an OR gate  50 , which will provide a signal or output indicative of whether one of the detectors is not receiving a signal from one of the emitters (e.g., an obstacle has been detected).  
         [0027]    The output signal of OR gate  50  is then inputted or received into motor control unit  24 , which will provide a signal to a motor  52  instructing the same to stop operating if an obstruction is detected by the system. If a broken light path is detected, a microprocessor within the motor control unit  24 , will then send a signal to the power door control module through a data line which will cause the power door control module stop the closing or alternatively opening motion of the door. In an exemplary embodiment the microprocessor of the motor control and door control module are one in the same. Alternatively, the controllers for the power door and motor control are located in two separate microprocessors.  
         [0028]    Accordingly, non-contact obstacle detection system  10  includes one or more sensing elements ( 16 ,  18 ), each configured to provide a beam of light, which when broken by an obstacle will produce a signal to prevent actuation of the door when an obstacle is detected. The control circuit  22  of non-contact obstacle detection system  10  is capable of being written into the memory of a microprocessor of the vehicle, preferably the same microprocessor that operates the motorized liftgate.  
         [0029]    Also, it is noted that the control circuit is activated upon receipt of signal to the motor control unit to either open or close the motorized door.  
         [0030]    In addition, the non-contact obstacle detection system of the present disclosure is contemplated for use with a control scheme configured for detecting the amount of torque or current being applied to motor  52  to open or close the liftgate. For example, motor control unit  24  will include a control system to monitor the amount of current motor  52  is drawing or alternatively how much torque a shaft of the motor is applying in order to open or close the liftgate. If the control system determines that the motor is operating outside of the prescribed range (e.g., normal amount of current or torque required to open or close the liftgate) then the control system will instruct the motor to stop operating, and as an alternative reverse its direction. It being understood to one skilled in the art that the range of operating the motor to open the liftgate will be higher than the range of operation for closing the liftgate. Alternatively, the non-contact obstacle detection system of the present disclosure is also contemplated as a stand alone obstacle system.  
         [0031]    Each of the emitters and detectors will be positioned within a nodule or housing  54  disposed on the surface of the vehicle. In one embodiment nodule  54  is secured to a trim portion of the vehicle. Alternatively, the nodule is formed as part of the trim portion. Nodule  54  will have a relatively low profile so as not to excessively protrude from the surface to which it is mounted. In addition, nodule  54  will also have an opening  56  configured to allow either the detector to receive the infrared light or alternatively, the emitter to emit the infrared light. Nodule  54  will provide a housing for the emitter or detector to protect it form debris or impacts, which may damage or adversely affect performance of the device. As yet another alternative nodule or housing  54  may be configured to provide an aesthetically pleasing piece of the trim of the vehicle.  
         [0032]    The housing in particular protects the detector from outside light sources such as sunlight. Sunlight has a significant amount of near infrared light. Such large light sources can saturate the infrared detectors. Accordingly, by limiting the field of view of the detectors the present disclosure is able to control this. Therefore, placing the detectors behind a small aperture (opening  56 ) prevents large amounts of sunlight from saturating the detector.  
         [0033]    In the event one of the emitters or detectors becomes blocked by dirt or debris or fails to operate through a mechanical failure, the system is provided with a fail-safe mode of operation. The fail-safe detection of an obstruction is a “failsafe” type of failure because the liftgate will not power close if an obstruction is detected. In order for the operator to distinguish between a situation, which causes the liftgate to not power close, that is caused by a false obstruction detection or which is caused by some other failure of the system, the following operational sequence or system is employed.  
         [0034]    When an obstruction is detected while the gate is closing or attempting to close an error signal will be generated. The error signal, which may be an audible tone, will tell the operator that an obstruction was detected. The audible tone will be provided by a noise emitting device and controller  60  that is also configured to receive the output signal of OR gate  50 . The operator will then check the area around the liftgate and if no obstruction is found, the sensors may be in need of cleaning as the signal may be blocked. Alternatively, if the liftgate does not close and no audible signal is not present, then it is not the failure of the obstruction sensing system which is causing the liftgate to not power close. In this situation the operator or service mechanic will know that there is some other type of problem associated with the device.  
         [0035]    The sensor system is able to detect and signal if it is not functioning properly or fall in a failsafe mode such that it signals an object has been detected (audible tone) if the sensor system has an internal failure. For example, if the 38 kilohertz oscillator stops oscillating (e.g., system fault) none of the detectors would receive a signal and an obstruction would be detected and an audible tone will be heard. Alternatively, and if the one kilohertz oscillator stops oscillating (e.g., system fault), one emitter would be continuously be emitting. The configuration of the system and the detectors require that the emitters are oscillating for a predetermined period for example, 500 microseconds and then off for 500 microseconds. Otherwise, the detectors signal that the beam has been broken (e.g., obstructed) and an object is detected. Thus, the system will provide a signal (audible tone) if it detects an object or the system has an internal failure. In yet another alternative, the audible tone of a detected obstruction can be a single continuous audible noise or tone, while an internal failure of the system can be associated with an intermittent tone or vice versa. It is noted that the predetermined period can be greater or less than 500 microseconds.  
         [0036]    While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.