Target position detecting apparatus and method utilizing radar

• US 5,629,704 A
• Filed: 09/12/1995
• Issued: 05/13/1997
• Est. Priority Date: 09/12/1994
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Fukuhara, Hiroshige, Throngnumchai, Kraisorn, Hirota, Yukitsugu, Mihara, Teruyoshi
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US08/527,677
• Time in Patent Office: 609 Days
• Field of Search: 342/53, 342/54, 342/56, 342/126, 342/133, 342/139, 342/146, 342/157, 342/158
• US Class Current: 342/54
• CPC Class Codes: G01S 13/46 Indirect determination of position data
• CPC Class Codes: G01S 15/46 Indirect determination of position data
• CPC Class Codes: G01S 17/46 Indirect determination of position data
• CPC Class Codes: G01S 7/4914 of detector arrays, e.g. charge-transfer gates

Abstract

In a radar target position detecting apparatus, beams (, for example, light beams) irradiated from a transmitter(, for example, LED) have a predetermined divergence angle, a plurality of light (beam) receiving elements such as photodiode arrays each having a different receiving angle (directivity) are arranged in an array form, and a direction of a reflected wave (beam) is identified according to a position of the arrayed beam (wave) receiving elements in the array at which the reflected wave (beam) is captured.

Claims

1. An apparatus comprising:

a) beam transmitting means for generating and transmitting beams of at least one of either electromagnetic waves or ultrasonic waves, said beams being provided with a fixed predetermined divergence angle with said beam transmitting means as a vertex;

b) beam receiving means for receiving at least one reflected beam of the transmitted beams, said beam receiving means including a plurality of individually operable beam receiving elements arranged in an array form and each one of the beam receiving elements having a mutually different directivity from those of any other beam receiving elements;

c) first measuring means for determining which one of the beam receiving elements receives the reflected beam and determining a direction of the reflected beam with respect to the reflected beam receiving element on the basis of a position of the reflected beam receiving element in said array formed plurality of beam receiving elements; and

d) second measuring means for measuring a time duration from a time at which said beams are transmitted from said beam transmitting means to a time at which said reflected beam receiving element has received the reflected beam and calculating a distance from a beam reflected point of the transmitted beams to the reflected beam receiving element on the basis of the measured time duration.

2. An apparatus as claimed in claim 1, wherein the reflected beam is a wave reflected from at least one target located on the point falling within the fixed predetermined divergence angle and the direction of the reflected beam is a direction of the target with respect to the position of the reflected beam receiving element, the target having reflected at least one of the transmitted beams.

3. An apparatus as claimed in claim 1, wherein said first measuring means further comprises:

f) a plurality of drive switches connected to the respective beam receiving elements and so arranged and constructed as to be switched when the corresponding one of the connected beam receiving elements receives the reflected beam; and

g) scanning means for scanning the beam receiving elements in the array form to determine which one of the beam receiving elements has received the reflected beam according to the positions of the switched condition of the plurality of drive switches.

4. An apparatus as claimed in claim 1, wherein said beam receiving elements are constituted by a photo sensing device and at least two amplifiers connected between both output ends of each adjoining beam receiving element, a detection signal being output via one of the the amplifiers from both ends of the photo sensing device so that the second measuring means determines the position of the one beam receiving element which receives the reflected beam according to a magnitude of the detection signal.

5. An apparatus as claimed in claim 1, wherein said beam receiving elements are constituted by a photo sensing device and a resistor connected between both output ends of each adjoining beam receiving element, a detection signal being output via one of the resistors from both ends of the photo sensing device chip so that the second measuring means determines the position of the one beam receiving element which received the reflected beam according to a magnitude of the detection signal.

6. An apparatus as claimed in claim 1, wherein said beam transmitting means transmits the beams of either a visible light or ultra-red light and the receiving means comprises array formed plurality of photodiodes.

7. An apparatus as claimed in claim 1, wherein said beam receiving means comprises a plurality of photodiodes arranged in the array form, each output end of the photo diodes being connected to one end of each corresponding one of a plurality of resistors, each resistor having a resistance value which is so large that a resistance of a diffusion region providing an output terminal of the corresponding one of the photo diodes is negligibly small, and the other end of each resistor being connected to an output end of its adjacent one of the photo diodes.

8. An apparatus as claimed in claim 7, wherein said beam receiving means further comprises a plurality of blocking diodes having anodes and cathodes which are reversed to those of the respective photo diodes and which are connected to the respective output ends of the photo diodes and wherein said resistors are connected to the respective output ends of the photo diodes via said corresponding blocking diodes.

9. An apparatus as claimed in claim 8, wherein said beam receiving means further comprises a plurality of buffer circuits, output ends of the respective buffer circuits being connected to one ends of said respective resistors and the other ends of said respective resistors being connected to the corresponding output ends of their adjacent buffer circuits.

10. An apparatus as claimed 1, wherein said beam transmitting means is a single beam transmitter disposed separate and apart from said beam receiving means.

11. A radar apparatus for at least one wave reflective object, comprising:

a) wave beam irradiating means for operatively irradiating wave beams toward a spatial region which is wide enough to include said wave beam reflective object therein;

b) wave beam responding means arranged for receiving at least one wave beam irradiated toward the statial region from said wave beam irradiating means and reflected on said reflective object, said wave beam responding means having an array of a plurality of wave beam responding elements arranged at a position of the radar apparatus, each one of said wave beam responding elements having a directivity with respect to the spatial region which is different from those of the other wave beam responding elements;

c) first measuring means for identifying one of said wave beam responding elements which receives the reflected wave beam and measuring a direction of the reflective object with respect to the wave beam responding element on the basis of a position of the identified wave beam responding element; and

d) second measuring means for measuring a time duration from a time at which the wave beams are irradiated by said wave beam irradiating means to a time at which said reflective wave beam is received by said wave beam responding element and for deriving a distance from the radar apparatus and said wave beam reflected object on the basis of the measured time duration.

12. A radar apparatus for at least one wave reflective object as claimed in claim 11, which further comprises:

e) command signal generating means for outputting a command signal to said wave beam irradiating means so that the wave beam irradiating means irradiates the wave beams in response to the command signal.

13. A radar apparatus as claimed in claim 12, wherein said wave beam irradiating means comprises a light emitting diode which emits light pulses toward the spatial region with a fixed predetermined divergence angle so as to include the wave beam reflective object therein.

14. A radar apparatus as claimed in claim 13, wherein said wave beam responding means comprises the array of a plurality of photodiodes, each of the photodiodes being so arranged and constructed as to generate and cause to flow a photocurrent I when the reflected light pulse is received thereat.

15. A radar apparatus as claimed in claim 14, wherein said first measuring means comprises an array of a plurality of analog switches, each analog switch being connected in series with the corresponding one of the photodiodes and being closed when a drive signal is received by its drive end.

16. A radar apparatus as claimed in claim 15, wherein said first measuring means further comprises scanning means for outputting said drive signal sequentially to each of said analog switches so as to receive the photocurrent I from any one of the photodiodes via the corresponding one of the analog switches serially connected to the wave beam received photodiode, thus identifying one of the photodiodes which generates and outputs the photocurrent I.

17. A radar apparatus as claimed in claim 16, which further comprises a lens located in front of the array of the photodiodes and wherein said first measuring means derives the direction θ

of the wave beam reflective object with respect to the reflected light pulse received photodiode as a function of x and y, wherein x denotes a distance from an optical axis of the lens to the light pulse received photodiode and y denotes a distance from the array of the photodiodes to the lens.

18. A radar apparatus as claimed in claim 11, wherein said wave beam irradiating means comprises an ultra sonic wave speaker irradiating ultrasonic waves having a predetermined divergence angle so as to include the wave beam reflective object in the spatial region and said wave beam responding means comprises an array of microphones.

19. A radar apparatus as claimed in claim 12, wherein said wave beams are light pulses and wherein said wave beam responding means comprises a PSD chip having two output terminals A and B, said PSD chip constituting said second measuring means for identifying a position of the PSD chip surface at which the reflected light pulse is received and said second measuring means derives the direction of the light pulse reflective object on the basis of the following;

X is a function of I1, I2, and L, wherein X denotes a distance from a center position of the PSD chip to the position at which the light pulse reflected by the light pulse reflective object is received, I1 denotes a current flowing from a photocurrent through one of the output terminal of the PSD chip, I2 denotes a current flowing from the photocurrent through the other output terminal, and L denotes a distance between both output terminals.

20. A radar apparatus as claimed in claim 18, wherein said PSD chip comprises an array of photodiode cells whose cathode terminals are connected to a plus bias supply (+Vcc) and a plurality of resistors, one end of each of the resistors being connected to an anode of the corresponding one of the photodiode cells and the other end of each of the resistors being connected to the anode of the corresponding adjacent one of the photodiode cells, the anode of an end positioned photodiode cell being directly connected to the one output terminal and the anode of another end positioned photodiode cell being connected to the other output terminal via one of the resistors.

21. A radar apparatus as claimed in claim 19, wherein each photodiode cell is constituted by a PIN photodiode and each one of the PIN photodiodes is separated by a separation region to another PIN photodiode and the resistors are constituted by diffusion resistors.

22. A radar apparatus as claimed in claim 20, wherein each photodiode cell is constituted by a PIN photodiode and each one of the PIN photodiodes is separated by a separation region to another PIN photodiode and the resistors are constituted by polycrystalline silicons.

23. A radar apparatus as claimed in claim 19, wherein said PSD chip comprises two aligned arrays of PIN photodiode cells, two arrays of resistors, and a plurality of switches, one of the two aligned arrays of PIN photodiode cells being selected depending on whether the position of the light received PIN photodiode is near to the center position of the PSD chip.

24. A radar apparatus as claimed in claim 21, wherein said PSD chip further comprises an array of blocking diodes, each anode of the blocking diodes is connected to the anode of the corresponding one of the PIN photodiodes and each cathode of the blocking diodes is connected to one end of the corresponding one of the resistors.

25. A radar apparatus as claimed in claim 21, wherein said PSD chip further comprises an array of blocking diodes, each anode of the blocking diodes is connected to the anode of the corresponding one of the PIN photodiodes and each cathode of the blocking diodes is connected to one end of the corresponding one of the resistors, each of said resistors being constituted by a MOSFET.

26. A radar apparatus as claimed in claim 25, wherein each anode of the PIN photodiodes is connected commonly to a minis bias voltage supply (-Vcc).

27. A radar apparatus as claimed in claim 21, wherein said PSD chip further comprises an array of buffer circuits connected between each cathode of the PIN photodiodes and a junction of the mutually adjacent resistors.

28. A radar apparatus as claimed in claim 18, which further comprises an array of amplifiers and an array of adders installed between the microphones and two output terminals and wherein said second measuring means derives two voltages (V2 and V1 ) at the two output terminals A and B so that the position X of the microphone array at which the ultrasonic wave reflected by the object is derived using the following relationship;

X is a function of V1, V2, Δ and

G, wherein X denotes a position of one of the microphones which has received the reflected ultrasonic wave, i.e., the distance from the ultrasonic wave received microphone to a center position of the microphone array, Δ

denotes a pitch between the mutually adjacent microphones in the microphone array, and G denotes an amplification factor of each amplifier.

29. An apparatus as claimed in claimed 11, wherein said beam irradiating means is a single beam irradiator disposed separate and apart from said beam responding means.

30. An apparatus as claimed 11, wherein said beams are irradiated from a single irradiator disposed separate and apart from said beam responding means.

31. A method for determining a position of at least one wave beam reflective object, comprising the steps of:

a) operatively irradiating wave beams toward a spatial region which is wide enough to include said wave beam reflective object therein in response to a command signal to command irradiation of said wave beams;

b) receiving at least one wave beam irradiated from said step a) and reflected on said reflective object, at said step b), providing wave beam responding means having an array of a plurality of wave beam responding elements arranged at a predetermined fixed position, each one of said wave beam responding elements having a directivity with respect to the spatial region different from those of the other wave beam responding elements; and

c) identifying one of said wave beam responding elements which receives the reflected wave beam and measuring a direction of the reflective object on the basis of a position of the identified wave beam responding element.