Activation control apparatus for passive vehicle occupant restraint and method of controlling activation of passive vehicle occupant restraint

• US 6,347,268 B1
• Filed: 03/31/2000
• Issued: 02/12/2002
• Est. Priority Date: 11/20/1996
• Status: Expired due to Term

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Fujishima, Hiromichi, Sakaguchi, Tomokazu, Akatsuka, Takao, Iyoda, Motomi, Sugiyama, Koichi, Fujita, Koichi
• Primary Examiner(s): ARTHUR JEANGLAUDE, GERTRUDE
• Application Number:
  US09/540,546
• Time in Patent Office: 683 Days
• Field of Search: 701/45, 701/46, 701/47, 208/734, 208/735, 180/232, 180/268, 180/271, 180/282, 340/436, 340/439
• US Class Current: 701/45
• CPC Class Codes: B60R 2021/01006 Mounting of electrical components in vehicles
• CPC Class Codes: B60R 2021/0104 Communication circuits for data transmission
• CPC Class Codes: B60R 2021/01068 between different sensors and airbag control unit
• CPC Class Codes: B60R 2021/01075 between the airbag control unit and pyrotechnic fuses or equivalent actuators
• CPC Class Codes: B60R 2021/01322 comprising variable thresholds, e.g. depending from other collision parameters
• CPC Class Codes: B60R 21/013 including means for detecting collisions, impending collisions or roll-over
• CPC Class Codes: B60R 21/0133 by integrating the amplitude of the input signal
• CPC Class Codes: B60R 21/01558 monitoring crash strength

Abstract

A structure and method for enabling a passive vehicle occupant restraint to be activated at the earliest possible timing, irrespective of a type of a collision. A floor sensor measures a deceleration G applied to the length of a vehicle and outputs the deceleration as the measurement G. An arithmetic unit carries out a predetermined arithmetic operation on the measurement G output from the floor sensor, so as to determine a function f(G). A conditional activation unit has a variation pattern of a threshold value T that varies with a variation in velocity v of a non-stationary object. The conditional activation unit reads a threshold value T corresponding to an input velocity v from the variation pattern and compares the threshold value T with the value of the function f(G). In case that the value of the function f(G) exceeds the threshold value T, an activation signal A is input to a driving circuit. A satellite sensor outputs an ON signal when a deceleration of not less than a predetermined reference value is applied to the vehicle. A threshold variation pattern selection unit changes the variation pattern of the threshold value T against the velocity v used in the conditional activation unit to another variation pattern, in response to the ON signal output from the satellite sensor.

Claims

1. An activation control apparatus for controlling activation of a passive vehicle occupant restraint mounted on a vehicle, said activation control apparatus comprising:

an impact measurement unit that is disposed at a predetermined position in said vehicle and measures an impact applied to said vehicle,

an impact detection unit that is disposed at a position ahead of said impact measurement unit in said vehicle and outputs a signal based on the observed impact applied to said vehicle at least by a collision,

a threshold variation pattern selection unit that selects a working threshold variation pattern, which is used to control activation of said passive vehicle occupant restraint, among a plurality of available threshold variation patterns, based on the output of said impact detection unit; and

an activation control unit that compares a specific value calculated from the observed impact by said impact measurement unit with a working threshold value, which varies according to the working threshold variation pattern selected by said threshold variation pattern selection unit, and controls activation of said passive vehicle occupant restraint based on a result of the comparison.

2. An activation control apparatus in accordance with claim 1, wherein said impact detection unit is located at a specific part in said vehicle, which is readily deformed by a collision of said vehicle.

3. An activation control apparatus in accordance with claim 1, herein a plurality of said impact detection units are disposed in said vehicle.

4. An activation control apparatus in accordance with claim 3, wherein said impact detection units are disposed at least at positions that are off to a right front and a left front of said impact measurement unit.

5. An activation control apparatus in accordance with claim 1, wherein said impact detection unit determines whether or not the impact applied to said vehicle is not less than a predetermined reference value.

6. An activation control apparatus in accordance with claim 5, wherein said impact detection unit has a plurality of the predetermined reference values and determines whether or not the impact applied to said vehicle is not less than each of the predetermined reference values.

7. An activation control apparatus in accordance with claim 5, wherein the predetermined reference value is set to be smaller than an estimated value of impact that is expected to be detected at the disposed position of said impact detection unit in the case where an impact applied to said vehicle by a predetermined type of collision other than a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

8. An activation control apparatus in accordance with claim 5, wherein said impact detection unit has n reference values from a first reference value to an n-th reference value in a descending order, where n is an integer of not less than 2, and determines whether or not the impact applied to said vehicle is not less than each of then reference values, and

said threshold variation pattern selection unit has (n+1) available threshold variation patterns, said threshold variation pattern selection unit selecting a first threshold variation pattern as the working threshold variation pattern, which is used to control activation of said passive vehicle occupant restraint, when the output of said impact detection unit represents application of an impact of not less than the first reference value, said threshold variation pattern selection unit selecting an i-th threshold variation pattern as the working threshold variation pattern when the output of said impact detection unit represents application of an impact of not less than an i-th reference value but less than an (i− 1)-th reference value, where 2<

i<

n, and selecting an (n+1)-th threshold variation pattern as the working threshold variation pattern when the output of said impact detection unit represents application of an impact of less than n-th reference value.

9. An activation control apparatus in accordance with claim 5, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of said impact detection unit in the case where an impact applied to said vehicle by a predetermined type of collision has such a degree that does not require activation of said passive vehicle occupant restraint.

10. An activation control apparatus in accordance with claim 5, wherein the working threshold value varies against a preset physical quantity according to the working threshold variation pattern, and

the working threshold variation pattern, which is used after the determination by said impact detection unit that the impact applied to said vehicle is not less than the predetermined reference value, comprises a specific curve having greater values than those of at least one curve,

the at least one curve representing a variation in specific value calculated from the observed impact by said impact measurement unit against the physical quantity in the case where an impact applied to said vehicle by a predetermined type of collision other than a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

11. An activation control apparatus in accordance with claim 10, wherein the specific curve is an envelope of the at least one curve.

12. An activation control apparatus in accordance with claim 5, wherein the working threshold value varies against a preset physical quantity according to the working threshold variation pattern, and

the working threshold variation pattern, which is used before the determination by said impact detection unit that the impact applied to said vehicle is not less than the predetermined reference value, comprises a specific curve having greater values than those of at least either one of at least one first curve and at least one second curve,

the at least one first curve representing a variation in specific value calculated from the observed impact by said impact measurement unit against the physical quantity in the case where an impact applied to said vehicle by a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint,

the at least one second curve representing a variation in specific value calculated from the observed impact by said impact measurement unit against the physical quantity in the case where said vehicle runs on a rough road.

13. An activation control apparatus in accordance with claim 12, wherein the specific curve is an envelope of at least either one of the at least one first curve and the at least one second curve.

14. An activation control apparatus in accordance with claim 12, wherein the preset physical quantity is a speed of a non-stationary object in said vehicle.

16. An activation control apparatus in accordance with claim 5, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of said impact detection unit in the case where an impact applied to said vehicle by a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

17. An activation control apparatus in accordance with claim 5, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of said impact detection unit in the case where said vehicle runs on a rough road.

18. An activation control apparatus in accordance with claim 1, wherein said vehicle has at least two pathways as part of a transmission path, through which a result of the detection by said impact detection unit is transmitted from said impact detection unit to said threshold variation pattern selection unit.

19. An activation control apparatus in accordance with claim 1, wherein said impact measurement unit measures a deceleration as an index of the impact applied to said vehicle, and

said activation control unit uses an integral value of the observed deceleration over time as the specific value calculated from the observed impact by said impact measurement unit.

20. An activation control apparatus in accordance with claim 1, wherein said impact detection unit comprises:

a signal output terminal that outputs a result of the detection;

a diode that has one end connected to said signal output terminal;

a first resistor that has one end connected to the other end of said diode;

an inner switch that has one end connected to the other end of said diode, is arranged in parallel to said first resistor, and is turned on under application of an impact of not less than the predetermined reference value to said vehicle; and

a second resistor that has one end connected to the other ends of said first resistor and said inner switch and the other end connected to earth.

21. An activation control apparatus in accordance with claim 20, wherein said impact detection unit comprises at least two signal output terminals and at least two diodes,

one end of each of said at least two diodes is connected to each of said at least two signal output terminals,

a transmission path, through which a result of the detection by said impact detection unit is transmitted from said impact detection unit to said threshold variation pattern selection unit, has at least two signal lines respectively connected to said at least two signal output terminals.

22. An activation control apparatus in accordance with claim 20, said impact detection unit comprises at least two signal output terminals, at least two diodes, and at least one earth output terminal,

one end of each of said at least two diodes is connected to each of said at least two signal output terminals,

a transmission path, through which a result of the detection by said impact detection unit is transmitted from said impact detection unit to said threshold variation pattern selection unit, has at least two signal lines respectively connected to said at least two signal output terminals and at least one earth line connected to said at least one earth output terminal.

15. An activation control apparatus in accordance with 12, wherein the preset physical quantity is time.

23. An activation control apparatus for controlling activation of a passive vehicle occupant restraint mounted on a vehicle, said activation control apparatus comprising:

an impact measurement unit that is disposed at a predetermined position in said vehicle and measures an impact applied to said vehicle;

an impact detection unit that is disposed at a position ahead of said impact measurement unit in said vehicle and outputs a signal based on the observed impact applied to said vehicle at least by a collision;

a threshold value selection unit that selects a working threshold value, which is used to control activation of said passive vehicle occupant restraint, among a plurality of available threshold values, based on the output of said impact detection unit; and

an activation control unit that compares a specific value calculated from the observed impact by said impact measurement unit with the working threshold value selected by said threshold value selection unit, and controls activation of said passive vehicle occupant restraint based on a result of the comparison.

24. An activation control apparatus in accordance with claim 23, wherein said impact detection unit is located at a specific part in said vehicle, which is readily deformed by a collision of said vehicle.

25. An activation control apparatus in accordance with claim 23, wherein a plurality of said impact detection units are disposed in said vehicle.

26. An activation control apparatus in accordance with claim 25, wherein said impact detection units are disposed at least at positions that are off to a right front and a left front of said impact measurement unit.

27. An activation control apparatus in accordance with claim 23, wherein said impact detection unit determines whether or not the impact applied to said vehicle is not less than a predetermined reference value.

28. An activation control apparatus in accordance with claim 27, wherein said impact detection unit has a plurality of the predetermined reference value and determines whether or not the impact applied to said vehicle is not less than each of the predetermined reference values.

29. An activation control apparatus in accordance with claim 27, wherein the working threshold value, which is used before the determination by said impact detection unit that the impact applied to said vehicle is not less than the predetermined reference value, is greater than at least either one of a first value and a second value,

the first value being calculated from the observed impact by said impact measurement unit at a certain time point in the case where an impact applied to said vehicle by a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint,

the second value being calculated from the observed impact by said impact measurement unit at a certain time point in the case where said vehicle runs on a rough road.

30. An activation control apparatus in accordance with claim 29, wherein the working threshold value is greater than at least either one of the first value an the second value by a predetermined quantity.

31. An activation control apparatus in accordance with claim 27, wherein the working threshold value, which is used after the determination by said impact detection unit that the impact applied to said vehicle is not less than the predetermined reference value, is greater than a specific value,

the specific value being calculated from the observed impact by said impact measurement unit at a certain time point in the case where an impact applied to said vehicle by a predetermined type of collision other than a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

32. An activation control apparatus in accordance with claim 31, wherein the working threshold value is greater than the specific value by a predetermined quantity.

33. An activation control apparatus in accordance with claim 27, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of said impact detection unit in the case where an impact applied to said vehicle by a predetermined type of collision has such a degree that does not require activation of said passive vehicle occupant restraint.

34. An activation control apparatus for controlling activation of a passive vehicle occupant restraint mounted on a vehicle, said activation control apparatus comprising:

an impact measurement unit that is disposed at a predetermined position in said vehicle and measures an impact applied to said vehicle;

an impact detection unit disposed in a specific part that is positioned ahead of said impact measurement unit in said vehicle and is readily deformed by a collision of said vehicle, said impact detection unit outputting a signal based on the observed impact applied to said vehicle at least by a collision; and

an activation control unit that controls activation of said passive vehicle occupant restraint, based on a specific value calculated from the observed impact by said impact measurement unit and the output of said impact detection unit.

35. An activation control apparatus in accordance with claim 34, wherein a plurality of said impact detection units are disposed in said vehicle.

36. An activation control apparatus in accordance with claim 35, wherein said impact detection units are disposed at least at positions that are off to a right front and a left front of said impact measurement unit.

37. An activation control apparatus in accordance with claim 36, wherein each of said impact detection units determines whether or not an impact applied to said vehicle is not less than a predetermined reference value.

38. An activation control apparatus in accordance with claim 37, in the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of each of said impact detection units in the case where an impact applied to said vehicle by a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

39. An activation control apparatus in accordance with claim 37, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of each of said impact detection units in the case where said vehicle runs on a rough road.

40. An activation control apparatus in accordance with claim 37, wherein the predetermined reference value is set to be smaller than an estimated value of impact that is expected to be detected at the disposed position of each of said impact detection units in the case where an impact applied to said vehicle by a predetermined type of collision other than a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

41. An activation control apparatus in accordance with claim 37, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of each of said impact detection units in the case where an impact applied to said vehicle by a predetermined type of collision has such a degree that does not require activation of said passive vehicle occupant restraint.

42. An activation control apparatus in accordance with claim 37, wherein each of said impact detection units has a plurality of the predetermined reference values and determines whether or not the impact applied to said vehicle is not less than each of the predetermined reference values.

43. An activation control apparatus in accordance with claim 37, wherein part of a transmission path, through which a result of the detection by each of said impact detection units is transmitted from said each impact detection unit to said activation control unit, has a rightward pathway running through a right side of said vehicle and a leftward pathway running through a left side of said vehicle.

44. An activation control apparatus for controlling activation of a passive vehicle occupant restraint mounted on a vehicle, said activation control apparatus comprising:

an impact measurement unit that is disposed at a predetermined position in said vehicle and measures an impact applied to said vehicle;

a speed detection unit that determines a speed of a non-stationary object in said vehicle relative to said vehicle, based on the observed impact by said impact measurement unit; and

an activation control unit that determines a variation in specific value, which is calculated from the observed impact by said impact measurement unit, against the speed determined by said speed detection unit, and controls activation of said passive vehicle occupant restraint, based on the variation.

45. An activation control apparatus in accordance with claim 44, said activation control apparatus further comprising:

an impact detection unit that is disposed at a position ahead of said impact measurement unit in said vehicle and outputs a signal based on the observed impact applied to said vehicle at least by a collision; and

a threshold variation pattern selection unit that selects a working threshold variation pattern, which is used to control activation of said passive vehicle occupant restraint, among a plurality of available threshold variation patterns, based on the output of said impact detection unit,

wherein each of the threshold variation patterns represents a variation in threshold value against the speed of the non-stationary object in said vehicle, and

said activation control unit compares the specific value, which is calculated from the observed impact by said impact measurement unit and varies against the speed determined by said speed detection unit, with a working threshold value, which varies against the speed determined by said speed detection unit according to the working threshold variation pattern selected by said threshold variation pattern selection unit, and controls activation of said passive vehicle occupant restraint based on a result of the comparison.

46. An activation control apparatus in accordance with claim 45, wherein said impact detection unit is located at a specific part in said vehicle, which is readily deformed by a collision of said vehicle.

47. An activation control apparatus in accordance with claim 45, wherein said vehicle has at least two pathways as part of a transmission path, through which a result of the detection by said impact detection unit is transmitted from said impact detection unit to said threshold variation pattern selection unit.

48. An activation control apparatus in accordance with claim 45, wherein said impact detection unit comprises:

a signal output terminal that outputs a result of the detection;

a diode that has one end connected to said signal output terminal;

a first resistor that has one end connected to the other end of said diode;

an inner switch that has one end connected to the other end of said diode, is arranged in parallel to said first resistor, and is turned on under application of an impact of not less than the predetermined reference value to said vehicle; and

a second resistor that has one end connected to the other ends of said first resistor and said inner switch and the other end connected to earth.

49. An activation control apparatus in accordance with claim 48, wherein said impact detection unit comprises at least two signal output terminals and at least two diodes,

one end of each of said at least two diodes being connected to each of said at least two signal output terminals,

a transmission path, through which a result of the detection by said impact detection unit is transmitted from said impact detection unit to said threshold variation pattern selection unit, has at least two signal lines respectively connected to said at least two signal output terminals.

50. An activation control apparatus in accordance with claim 48, wherein said impact detection unit comprises at least two signal output terminals, at least two diodes, and at least one earth output terminal,

one end of each of said at least two diodes being connected to each of said at least two signal output terminals,

a transmission path, through which a result of the detection by said impact detection unit is transmitted from said impact detection unit to said threshold variation pattern selection unit, has at least two signal lines respectively connected to said at least two signal output terminals and at least one earth line connected to said at least one earth output terminal.

51. An activation control apparatus in accordance with claim 50, wherein said impact detection units are disposed at least at positions that are off to a right front and a left front of said impact measurement unit, and

part of a transmission path, through which a result of the detection by each of said impact detection units is transmitted from said each impact detection unit to said activation control unit, has a rightward pathway running through a right side of said vehicle and a leftward pathway running through a left side of said vehicle.

52. An activation control apparatus in accordance with claim 45, wherein a plurality said impact detection units are disposed in said vehicle.

53. An activation control apparatus in accordance with claim 52, wherein said impact detection units are disposed at least at positions that are off to a right front and a left front of said impact measurement unit.

54. An activation control apparatus in accordance with claim 45, wherein said impact detection unit determines whether or not the impact applied to said vehicle is not less than a predetermined reference value.

55. An activation control apparatus in accordance with claim 54, wherein said impact detection unit has a plurality of the predetermined reference values and determines whether or not the impact applied to said vehicle is not less than each of the predetermined reference values.

56. An activation control apparatus in accordance with claim 55, wherein said impact detection unit has n reference values from a first reference value to an n-th reference value in a descending order, where n is an integer of not less than 2, and determines whether or not the impact applied to said vehicle is not less than each of the n reference values, and

said threshold variation pattern selection unit has (n+1) available threshold variation patterns, said threshold variation pattern selection unit selecting a first threshold variation pattern as the working threshold variation pattern, which is used to control activation of said passive vehicle occupant restraint, when the output of said impact detection unit represents application of an impact of not less than the first reference value, said threshold variation pattern selection unit selecting an i-th threshold variation pattern as the working threshold variation pattern when the output of said impact detection unit represents application of an impact of not less than an i-th reference value but less than an (i-1)-th reference value, where 2<

i<

n, and selecting an (n+1)-th threshold variation pattern as the working threshold variation pattern when the output of said impact detection unit represents application of an impact of less than n-th reference value.

57. An activation control apparatus in accordance with claim 54, wherein the working threshold value varies against a preset physical quantity according to the working threshold variation pattern, and

the working threshold variation pattern, which is used after the determination by said impact detection unit that the impact applied to said vehicle is not less than the predetermined reference value, comprises a specific curve having greater values than those of at least one curve,

the at least one curve representing a variation in specific value calculated from the observed impact by said impact measurement unit against the physical quantity in the case where an impact applied to said vehicle by a predetermined type of collision other than a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

58. An activation control apparatus in accordance with claim 57, wherein the specific curve is an envelope of the at least one curve.

59. An activation control apparatus in accordance with claim 54, wherein the working threshold value, which is used before the determination by said impact detection unit that the impact applied to said vehicle is not less than the predetermined reference value, is greater than at least either one of a first value and a second value,

the first value being calculated from the observed impact by said impact measurement unit at a certain time point in the case where an impact applied to said vehicle by a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint,

the second value being calculated from the observed impact by said impact measurement unit at a certain time point in the case where said vehicle runs on a rough road.

60. An activation control apparatus in accordance with claim 59, wherein the working threshold value is greater than at least either one of the first value and the second value by a predetermined quantity.

61. An activation control apparatus in accordance with claim 54, wherein the working threshold value, which is used after the determination by said impact detection unit that the impact applied to said vehicle is not less than the predetermined reference value, is greater than a specific value,

the specific value being calculated from the observed impact by said impact measurement unit at a certain time point in the case where an impact applied to said vehicle by a predetermined type of collision other than a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

62. An activation control apparatus in accordance with claim 61, wherein the working threshold value is greater than the specific value by a predetermined quantity.

63. An activation control apparatus in accordance with claim 54, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of said impact detection unit in the case where an impact applied to said vehicle by a predetermined type of collision has such a degree that does not require activation of said passive vehicle occupant restraint.

64. An activation control apparatus in accordance with claim 54, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of said impact detection unit in the case where an impact applied to said vehicle by a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

65. An activation control apparatus in accordance with claim 54, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of said impact detection unit in the case where said vehicle runs on a rough road.

66. An activation control apparatus in accordance with claim 54, wherein the predetermined reference value is set to be smaller than an estimated value of impact that is expected to be detected at the disposed position of said impact detection unit in the case where an impact applied to said vehicle by a predetermined type of collision other than a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

67. An activation control apparatus in accordance with claim 54, wherein the working threshold value varies against a preset physical quantity according to the working threshold variation pattern, and

the working threshold variation pattern, which is used before the determination by said impact detection unit that the impact applied to said vehicle is not less than the predetermined reference value, comprises a specific curve having greater values than those of at least either one of at least one first curve and at least one second curve,

the at least one first curve representing a variation in specific value calculated from the observed impact by said impact measurement unit against the physical quantity in the case where an impact applied to said vehicle by a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint,

the at least one second curve representing a variation in specific value calculated from the observed impact by said impact measurement unit against the physical quantity in the case where said vehicle runs on a rough road.

68. An activation control apparatus in accordance with claim 67, wherein the specific curve is an envelope of at least either one of the at least one first curve and the at least one second curve.

69. An activation control apparatus in accordance with claim 67, wherein the preset physical quantity is a speed of a non-stationary object in said vehicle.

70. An activation control apparatus in accordance with claim 67, wherein the preset physical quantity is time.

71. An activation control apparatus in accordance with claim 44, wherein said impact measurement unit measures a deceleration as an index of the impact applied to said vehicle, and

said activation control unit uses an integral value of the observed deceleration over time as the specific value calculated from the observed impact by said impact measurement unit.

72. An activation control apparatus in accordance with claim 44, said activation control apparatus further comprising:

a plurality of impact detection units that are disposed ahead of said impact measurement unit in said vehicle and respectively output a signal based on the observed impact applied to said vehicle at least by a collision,

wherein said activation control unit controls activation of said passive vehicle occupant restraint based on both the variation and the output of each of said impact detection units.

73. An activation control apparatus in accordance with claim 72, wherein said each impact detection unit is located at a specific part in said vehicle, which is readily deformed by a collision of said vehicle.

74. An activation control apparatus in accordance with claim 72, wherein said impact detection units are disposed at least at positions that are off to a right front and a left front of said impact measurement unit.

75. An activation control apparatus in accordance with claim 72, wherein said each impact detection unit determines whether or not the impact applied to said vehicle is not less than a predetermined reference value.

76. An activation control apparatus in accordance with claim 75, wherein said each impact detection unit has a plurality of the predetermined reference values and determines whether or not the impact applied to said vehicle is not less than each of the predetermined reference values.

77. An activation control apparatus in accordance with claim 75, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of each of said impact detection units in the case where an impact applied to said vehicle by a predetermined type of collision has such a degree that does not require activation of said passive vehicle occupant restraint.

78. An activation control apparatus in accordance with claim 75, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of each of said impact detection units in the case where said vehicle runs on a rough road.

79. An activation control apparatus in accordance with claim 75, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of each of said impact detection units in the case where an impact applied to said vehicle by a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

80. An activation control apparatus in accordance with claim 75, wherein the predetermined reference value is set to be smaller than an estimated value of impact that is expected to be detected at the disposed position of each of said impact detection units in the case where an impact applied to said vehicle by a predetermined type of collision other than a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

81. An activation control apparatus in accordance with claim 44, said activation control apparatus further comprising:

an impact detection unit disposed in a specific part that is positioned ahead of said impact measurement unit in said vehicle and is readily deformed by a collision of said vehicle, said impact detection unit outputting a signal based on the observed impact applied to said vehicle at least by a collision,

wherein said activation control unit controls activation of said passive vehicle occupant restraint based on both the variation and the output of said impact detection unit.

82. An activation control apparatus in accordance with claim 81, wherein a plurality of said impact detection units are disposed in said vehicle.

83. An activation control apparatus for controlling activation of a passive vehicle occupant restraint mounted on a vehicle, said activation control apparatus comprising:

an impact measurement unit that is disposed at a predetermined position in said vehicle and measures an impact applied to said vehicle;

a plurality of impact detection units that are disposed ahead of said impact measurement unit in said vehicle and respectively output a signal based on the observed impact applied to said vehicle at least by a collision; and

an activation control unit that controls activation of said passive vehicle occupant restraint based on a specific value calculated from the observed impact by said impact measurement unit and the output of said each impact detection unit.

84. An activation control apparatus in accordance with claim 83, wherein said each impact detection unit is located at a specific part in said vehicle, which is readily deformed by a collision of said vehicle.

85. An activation control apparatus in accordance with claim 83, wherein said impact detection units are disposed at least at positions that are off to a right front and a left front of said impact measurement unit.

86. An activation control apparatus in accordance with claim 83, wherein said each impact detection unit determines whether or not the impact applied to said vehicle is not less than a predetermined reference value.

87. An activation control apparatus in accordance with claim 86, wherein said each impact detection unit has a plurality of the predetermined reference values and determines whether or not the impact applied to said vehicle is not less than each of the predetermined reference values.

88. An activation control apparatus in accordance with claim 86, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of each of said impact detection units in the case where an impact applied to said vehicle by a predetermined type of collision has such a degree that does not require activation of said passive vehicle occupant restraint.

89. An activation control apparatus in accordance with claim 83, wherein said impact detection units are disposed at least at positions that are off to a right front and a left front of said impact measurement unit, and

part of a transmission path, through which a result of the detection by each of said impact detection units is transmitted from said each impact detection unit to said activation control unit, has a rightward pathway running through a right side of said vehicle and a leftward pathway running through a left side of said vehicle.

90. An activation control apparatus in accordance with claim 86, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of each of said impact detection units in the case where an impact applied to said vehicle by a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.

91. An activation control apparatus in accordance with claim 86, wherein the predetermined reference value is set to be greater than an estimated value of impact that is expected to be detected at the disposed position of each of said impact detection units in the case where said vehicle runs on a rough road.

92. An activation control apparatus in accordance with claim 86, wherein the predetermined reference value is set to be smaller than an estimated value impact that is expected to be detected at the disposed position of each of said impact detection units in the case where an impact applied to said vehicle by a predetermined type of collision other than a head-on collision has such a degree that does not require activation of said passive vehicle occupant restraint.