GB2370545A

GB2370545A - Seat belt system with pulse width modulation control

Info

Publication number: GB2370545A
Application number: GB0211669A
Authority: GB
Inventors: Yukinori Midorikawa
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 1997-12-16
Filing date: 1998-12-16
Publication date: 2002-07-03
Anticipated expiration: 2018-12-16
Also published as: GB2370544B; GB0211669D0; GB0211665D0; GB2370544A; GB2370545B

Abstract

An automotive passenger restraint and protection apparatus for an automotive vehicle has a seatbelt and operates to restrain an occupant of the automotive vehicle by the seatbelt to protect the occupant. An electric retractor 100 has a DC motor 10 for retracting and protracting the seatbelt. A PWM signal generated by a PWM signal generating means controls the DC motor. A determining means detects at least one of current flowing to the motor and terminal voltage across the motor and thus determining a state of operation of the motor. The determining means includes a low-pass filter means having a pre-determined cut off frequency lower than a frequency of the PWM signal, thereby reducing higher frequency components of the at least one of the current and the terminal voltage.

Description

AUTOMOTIVE PASSENGER RESTRAINT AND PROTECTION APPARATUS

AND SEATBELT PROTRACTION AND RETRACTION

AMOUNT-DETECTING DEVICE

This invention relates to an automotive passenger restraint and protection apparatus for automotive vehicles such as automobiles, which uses an electric 10 retractor for retracting and protracting a seatbelt for protection of an occupant (driver or passenger), and -also relates to a seatbelt retraction and protraction amount-detecting device 15 Conventional automotive passenger restraint and protection apparatuses are operable upon a large deceleration of the automotive vehicle such as a collision to restrain an occupant by means of a seatbelt to prevent him from being thrown out of his seat and hence protect him from danger.

À The conventional automotive restraint and protection apparatuses include a type provided with a seatbelt retractor for retracting or winding a seatbelt.

The seatbelt retractor is generally provided with bias force-imparting means such as a spiral spring which 25 always biases a reel shaft (takeup shaft) on which the seatbelt is wound, in a retracting or winding direction.

The seatbelt is wound up on the reel shaft due to the bias force given by the bias force-imparting means when it is not mounted on the occupant, and it is protracted 30 or withdrawn against the bias force to fasten or restrain the occupant when it is mounted on the

occupant. An example of the automotive passenger restraint and protection apparatus provided with such an electric retractor is disclosed by Japanese Laid-Open Patent Publication (Kokai) No. 59-45240, which is adapted to control the driving of the electric motor based upon an output from a displacement detecting device which detects displacement of the seatbelt in retracting and protracting directions as well as an output from an 10 attaching detecting device which detects attaching of the seatbelt to the occupant's body.

The electric retractor, however, requires the displacement detecting device which is expensive, and therefore has an increased manufacturing cost and a 15 complicated construction.

Further, the rotation control of the electric motor of the electric retractor is carried out by applying constant voltage of negative and positive signs to the motor to cause normal rotation and reverse 20 rotation of the motor, as disclosed by Japanese Laid Open Utility Model. Publication (Kokai) No. 61-134464.

According to the known electric retractor, however, since the motor is rotated in the normal

direction or in the reverse direction depending upon the application of the constant voltage, there is a possibility that in retracting the seatbelt, the seatbelt is suddenly wound up by the motor so that a 5 tongue of the seatbelt hits against a side window pane.

In the known electric retractor, the reel shaft is driven by the motor to protract or retract the seatbelt. The motor is controlled by an MPU (Micro Processing Unit) provided in the automotive passenger 10 restraint and protection apparatus.

More specifically, the MPU controls the operative state of the motor by changing the duty factor of a PWM (Pulse Width Modulation) signal for use in the control, for example. The duty factor of the PWM signal is 15 determined based upon detected current flowing to the motor or detected terminal voltage across the motor.

If the current flowing to the motor or the terminal voltage across the motor is directly detected, however, the following operative state of the motor 20 cannot be accurately determined based upon such detected current or voltage, because the detected current or voltage contains fluctuations or pulsations due to high À frequency components contained in the PWM signal.

Therefore, the MPU conducts averaging filtering or the 25 like on the detected current or voltage by means of software, to remove fluctuations or pulsations attributed to the PWM signal.

The averaging filtering or the like by software imposes a large burden upon the MPU such that it takes 30 time to control the motor. To avoid this, an expensive MPU which has a high processing speed has to be used.

( An object of the invention is to provide an automotive passenger restraint and protection apparatus which is capable of quickly and accurately controlling an electric motor for driving the seatbelt.

To attain this object, there is provided an automotive passenger restraint and protection apparatus for an automotive vehicle, having a seatbelt, for restraining an occupant of the automotive vehicle by the seatbelt to protect the occupant, comprising PWM

signal generating means for generating a PWM signal, a motor for retracting and protracting the seatbelt, the motor having operation thereof controlled by the PWM signal generated by the PWM signal generating means, and 5 determining means for detecting at least one of current flowing to the motor and terminal voltage across the motor and for determining a state of the operation of the motor, based upon the detected at least one of the current and thi terminal voltage, the determining means 10 having low-pass filter means having a predetermined cutoff frequency lower than a frequency of the PWM signal, wherein the determining means causes the filter means to reduce higher frequency components than the predetermined cutoff frequency, contained in the at 15 least one.of the current and the terminal voltage, and determines the state of the operation of the motor, based upon the at least one of the current and the terminal voltage having the higher frequency components reduced. 20 With this arrangement' the low-pass filter means having a À predetermined cutoff frequency lower than a frequency of - the PWM signal reduces higher frequency components than the predetermined cutoff frequency, contained in the at 25 least one of current flowing to the motor and terminal voltage across the motor, and the state of the operation of the motor is determined, based upon the at least one of the current and the terminal voltage having the higher frequency components reduced. As a result, the 30 burden on the determining means (MPU) is greatly reduced as compared with the conventional apparatus, making it possible to quickly control the motor by the use of an inexpensive MPU. --

c' The above and other objects, features, and advantages of the invention will become more apparent 25 from the following detailed description taken in

conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a block diagram schematically showing the arrangement of an automotive passenger restraint and 30 protection apparatus according to a first embodiment of the invention; Fig. 2 is a circuit diagram showing the configuration of a DC motor driver 11 appearing in Fig.

1; Fig. 3A is a graph showing an example of the waveform of a PAM signal input through a terminal PI or P2; 5 Fig. 3B is a graph showing an example of the waveform of a voltage signal output through a terminal P5; Fig. 3C is a graph showing another example of the waveform of the voltage signal) 10 Fig. 4 is a flowchart showing a control program executed by an MPU 14 appearing in Fig. l; Fig. 5 is a flowchart showing seatbelt protraction control executed at a step S401 in Fig. 4; Fig. 6 is a flowchart showing buckle attaching 15 control executed at a step S402 in Fig. 4; Fig. 7 is a flowchart showing collision warning, collision unavoidableness and doze warning control executed at a step S403 in Fig. 4; Fig. 8 is a flowchart showing movement control 20 executed at a step S404 in Fig. 4; Fig. 9 is a flowchart showing a continued part of the Fig. 8 control; Fig. 10 is a flowchart showing a mode selecting control executed at a step S405 in Fig. 4; 25 Fig. 11 is a flowchart showing retraction stopping control executed at a step S406 in Fig. 4; Fig. 12 is a flowchart showing seatbelt storing control executed at a step S408 in Fig. 4; Fig. 13 is a flowchart showing seatbelt 30 retraction failure detecting control executed at a step S409 in Fig. 4; Fig. 14 is a flowchart showing a block diagram showing the arrangement of an automotive passenger restraint and protection apparatus according to a second 35 embodiment of the invention;

f- - Fig. 15 is a flowchart showing buckle attaching control executed at a step S1702 in Fig. 7; Fig. 16 is a flowchart showing control of warning of collision and determination of unavoidableness of 5 collision, and warning of doze executed at a step S1703 in Fig. 7; Fig. 17 is a flowchart showing movement control executed at a step S1704 in Fig. 7; Fig. 18'is a flowchart showing a continued part 10 of the Fig. 17 control; Fig. 19 is a flowchart showing a mode selecting control executed at a step S1705 in Fig. 7; and Fig 20 is a flowchart showing seatbelt storing control executed at a step S1707 in Fig. 7.

) The invention will now be described in detail 15 with reference to drawings showing embodiments thereof, which are given by way of example only.

rst F:m octlment Referring first to Fig. 1, there is shown the arrangement of an automotive passenger restraint and protection apparatus according to a first embodiment of the invention. The apparatus according to the first embodiment is provided with a seatbelt retractor 100.

The seatbelt retractor 100 has a frame 1 in which is rotatably mounted a reel shaft (takeup shaft) 3 for retracting and protracting a seatbelt. Secured to an 25 end of the reel shaft 3 is a known sea/belt-locking mechanism 2 which is adapted to lock or stop the seatbelt from being protracted when a predetermined or higher degree of deceleration is applied to an automotive vehicle in which the present apparatus is 30 installed or when the seatbelt is protracted at a predetermined or higher degree of acceleration.

The reel shaft 3 has a central shaft 3a coupled

to a central shaft of a reel shaft pulley 5, which is in turn coupled to a DC motor pulley 6 via a power transmission belt 7. Provided inside the reel shaft pulley 5 is bias force-imparting means formed e.g. of a 5 spiral spring, not shown, which always applies a bias force to the pulley 5 in a direction of retraction of the seatbelt.

The reel shaft pulley 5 and the DC motor pulley 6 each have an outer periphery thereof formed with a 10 predetermined number of outer teeth, while the power transmission belt 7 has an inner periphery thereof formed with a predetermined number of inner teeth which are in mesh with the outer teeth of the reel shaft pulley 5 and the DC motor pulley 6.

15 The DC motor pulley 6 has a central shaft thereof coupled to a DC motor 10 such that the rotation of the DC motor 10 is transmitted to the reel shaft 3 via the DC motor pulley 6.

The DC motor 10 is fixed to the frame 1 at at 20 least two points thereof, and is connected to an MPU (Micro Processing Unit) 14 via a DC motor driver 11.

Fig. 2 is a circuit diagram showing the construction of the DC motor driver 11. In Fig. 2, reference numerals PI and P2 designate input terminals 25 for a PWM (Pulse Width Modulation) signal output from the MPU 14, which has a frequency of 20 kHz, for example. Reference numerals P3 and P4 designate output terminals for detecting current, and P5 and P6 output terminals for detecting voltage, the terminals PI to P6 30 being connected to the MPU 14. Supply voltage from a battery Vb shown in Fig. 2 is supplied to the DC motor 10. A plurality of transistors and FETs appearing in Fig. 2 are for selectively causing She DC motor 10 to be normally rotated or reversely rotated in response to the 35 PWM signal from the MPU 14. More specifically, the DC

motor driver 11 is constructed such that if a high-level control signal is delivered through the terminal PI from the MPU 14, the DC motor 10 is rotated in the normal direction, whereby the seatbelt is retracted by the reel 5 shaft 3, while if a high-level control signal delivered through the terminal P2 from the MPU 14, the DC motor 10 is rotated in the reverse direction, whereby the seatbelt is protracted by the reel shaft 3. The MPU 14 controls such that the high-level control signal is not 10 applied to the terminals PI and P2 at the same time.

In Fig. 2, reference numeral C1 designates a current detecting circuit which detects current i flowing to the DC motor 10, based upon current flowing through a resistance rl. The current detecting circuit 15 C1 is comprised of interface circuits (hereinafter abbreviated as "IFs") IF1 and IF2 which operate to remove current fluctuations or variations due to the influence of the PWM signal. The MPU 14 receives voltage signals from the IFs IF1 and IF2 and detects 20 current i flowing to the DC motor 10 from these voltage signals. In Fig. 2, reference numeral C2 designates a voltage measuring circuit 2 which measures terminal voltage across the DC motor 10, and is comprised of IFs 25 IF3 and IF4 which operate to remove fluctuations or variations in the terminal voltage due to the influence of the PAM signal. The MPU 14 receives voltage signals from the IFs IF3 and IF4 and measures the terminal voltage across the DC motor 10 from these voltage 30 signals.

The IFs IF1 to IF4 are each formed by a low-pass filter formed of a resistance r2, a resistance r3 smaller in resistance value than the resistance r2, and a capacitor c3, all the IFs having a cutoff frequency of 35 20 Hz, for example. By virtue of these IFs, the

( - \ influence of the PWM signal output from the MPU 14 upon the current detecting circuit C1 and the voltage measuring circuit C2 is reduced to 60 do, which is almost negligible for detection of current by the 5 current detecting circuit C1 and detection of terminal voltage by the voltage measuring circuit C2.

Fig. 3A shows an example of the waveform of the PWM signal input through the terminal P1 or P2, and Figs. 3B and 36 show examples of the waveform of the 10 voltage signal output through the terminal P5.

First, when the PWM signal having a duty factor of 50 % and a frequency of 20 kHz as shown in Fig. 3A is input through the terminal P1 or P2, the voltage signal output through the terminal P5 has high maximal voltage 15 v due to the influence of the PWM signal input through the terminal P1 or P2, as shown in Fig. 3B, if the low pass filter IF3 is not provided.

On the other hand, if the low-pass filter IF3 is provided as in the present embodiment, the voltage 20 signal output through the terminal P5 has low constant voltage v/2 which is free of the influence of the PWM signal input through the terminal P1 or P2, as shown in Fig. 3C.

As described above, according to the present 25 embodiment, the current i flowing to the DC motor 10 and the terminal voltage across the DC motor 10 are detected based on the voltage signals obtained by the low-pass filters. As a result, the current flowing to the DC motor and the terminal voltage across the DC motor have 30 much reduced fluctuations caused by the influence of the PWM signal. Further, the use of the low- pass filters greatly reduces the burden upon the MPU 14, making it possible to quickly and accurately control the motor using a low-cost MPU.

35 Referring back to Fig. 1, connected to the MPU 14

are a buckle connection detector 16 which detects whether a tongue of the seatbelt has been attached to or mounted on the buckle and whether the tongue of the seatbelt has been disconnected from the buckle, a mode 5 selector 18 which selects a mode of rotation control of the reel shaft 3, and a temperature sensor 19 which detects temperature in the vicinity of the DC motor 10 or the temperature of the DC motor 10 itself.

Further/connected to the MPU 14 is an MPU 15 10 provided in a traveling condition detector 20 which detects a traveling condition of the automotive during driving of the vehicle. Connected to the MPU 15 are a distance sensor 12 which detects the distance between the present vehicle (occupant's vehicle) and an object 15 lying ahead of the vehicle, and a steering angle sensor 13 which senses the steering angle of a steering arm of the vehicle. The MPU 14 has a built-in timer 21 for measuring time.

The mode selector 18 can select a default mode 20 for holding the degree of slackness or looseness of the seatbelt at a level comfortable to the occupant based upon a control signal from the traveling condition : detector 20, and further, if required, forcibly removing the slackness or forcibly imparting oppression to the 25 occupant, or alternately forcibly removing the slackness and forcibly imparting oppression to the occupant.

Further, the mode selector 18 can select a doze preventing function adding mode for additionally providing a function of imparting alternately oppression 30 and slackness at irregular time intervals, and a rough road traveling function adding mode for additionally providing a function of removing the slackness or looseness of the seatbelt so as to make the seatbelt difficult to protract in addition to the default mode.

35 These modes can be selected by the occupant. Initially'

al the mode selector 18 selects the default mode.

Next, the flow of control signals at various components of the automotive passenger restraint and protection apparatus according to the present embodiment 5 will be described The distance sensor 12 delivers an output signal indicative of results of detection of the distance between the present vehicle and an object lying ahead of the vehicle to the MPU 15. The MPU 15 calculates a 10 safety distance ds (m) between the present vehicle and an object lying ahead by the use of the following formula (1), and when the calculated safety distance ds is larger than a value indicated by the output signal from the distance sensor 12, the MPU 15 delivers a 15 control signal for collision danger warning to the MPU 14. Further, the MPU 15 calculates a collision unavoidable distance dd (m) by the use of the following formula (2), and when the calculated collision unavoidable distance dd is larger than a value indicated 20 by the output signal from the distance sensor 12, the MPU 15 delivers a signal indicative of a collision being unavoidable, to the MPU 14.

ds = Vr x (td + p) (1) dd = Vr x td (2) 25 where Vr represents relative speed (m/sec), td response delay of the driver (e.g. 0.5 to 2 see), and a value determined by the braking characteristic of the vehicle (e.g. 0.5 to 2 see).

The steering angle sensor 13 delivers an output 30 signal indicative of the sensed steering angle to the MPU 15, and when the maximum value of change amount in the detected steering angle within a prescribed time period (e.g. 2 see) is less than a predetermined value

(e.g. 8 degrees), the MPU 15 judges that the driver might be dozing and delivers a control signal for doze warning to the MPU 14.

The buckle connection detector 16 detects whether 5 the tongue of the seatbelt has been connected to the buckle, and delivers an output signal indicative of results of the detection to the MPU 14. The DC motor driver 11 controls the rotation of the DC motor 10, based upon a control signal from the MPU 14.

10 The mode selector 18 delivers an output signal indicative of the selected mode to the MPU 14, which in turn delivers a control signal corresponding to the selected mode to the DC motor driver 11 to control the seatbelt retractor 100.

15 The temperature sensor 19 delivers an output signal indicative of the temperature in the vicinity of the DC motor 10 or the temperature of the DC motor itself to the MPU 14.

Fig. 4 is a flowchart showing a control program 20 executed by the MPU 14.

First, the MPU 14 executes seatbelt protraction control for protracting the seatbelt at a step S401.

Details of the seatbelt protraction control will be described hereinafter with reference to Fig. 5, 25 Then, the MPU 14 executes buckle attaching control at a step S402. The buckle attaching control is executed when attaching of the tongue of the seatbelt to the buckle has been detected by the buckle connection detector 16, as described hereinafter with reference to 30 Fig. 6.

Then, when the MPU 15 detects that the present vehicle is about to collide against an object lying ahead, that collision of the present vehicle with an object lying ahead is unavoidable or that the driver is 35 dozing, the MPU 14 carries out collision warning,

( - collision unavoidableness and doze warning control at a step S403. Details of this control will be described hereinafter with reference to Fig. 7.

Then, the MPU 14 carries out movement control at 5 a step S404. The movement control is executed when protraction of the seatbelt has been detected while the rotation of the reel shaft 3 is in stoppage, as described hereinafter with reference to Figs. 8 and 9.

Then, the MPU 14 executes mode selecting control 0 according to the mode selected by the mode selector 18 at a step S405. Details of the mode selecting control will be described hereinafter with reference to Fig. 10.

Further, the MPU 14 executes retraction stopping control for preventing excessive retraction of the 1S seatbelt at a step S406. Details of the retraction stopping control will be described hereinafter with reference to Fig. 11.

Then, it is determined at a step S407 whether the tongue of the seatbelt has been disconnected from the 20 buckle has been detected by the buckle connection detector 16. If the disconnection has not been detected, the processing returns to the step S403, whereas if the disconnection has been detected, the MPU 14 executes seatbelt storing control at a step S408.

25 Details of the seatbelt storing control will be described hereinafter with reference to Fig. 12.

Then, the MPU 14 executes seatbelt retraction failure detecting control at a step S409, followed by the processing returning to the step S401. The seatbelt 30 retraction failure detecting control is carried out when the tongue of the seatbelt is disconnected from the buckle and retracted, as described hereinafter with reference to Fig. 13. In this connection, when the seatbelt retraction failure detecting control has been 35 started, the built-in timer of the MPU 14 starts

measuring time t elapsed after the start of the control.

Fig. 5 is a flowchart showing the seatbelt protraction control executed at the S401.

First, it is determined at a step S501 whether 5 attaching of the tongue of the seatbelt to the buckle has been detected by the buckle connection detector 16.

If attaching of the seatbelt has been detected, the MPU 14 judges that protraction of the seatbelt has been completed, and'delivers a control signal commanding to 10 stop the rotation of the reel shaft 13 to the DC motor driver 11 at a step S509, followed by terminating the present processing. On the other hand, if attaching of the seatbelt has not been detected, the MPU 14 delivers a control signal commanding to temporarily stop the 15 rotation of the reel shaft 3 to the DC motor driver 11 in order to assist protraction of the seatbelt at a step S502. Then, the terminal voltage across the DC motor 10 and the sign thereof are measured by the circuit C2 of 20 the DC motor driver 11 at a step S503. It is determined whether the measured terminal voltage exceeds 0.3 volts and at the same time the sign of the terminal voltage corresponds to the direction of protracting the seatbelt at a step S504. The answer to this question becomes 25 affirmative (YES) if the occupant lightly protracts the seatbelt. If it is determined at the step S504 that the terminal voltage does not exceed 0.3 volts or the sign does not correspond to the direction of protracting the 30 seatbelt, the processing returns to the step S503, whereas if the terminal voltage exceeds 0.3 volts and at the same time the sign of the terminal voltage corresponds to the direction of protracting the -

seatbelt, the MPU 14 delivers a control signal 35 commanding to rotate the reel shaft 3 in the seatbelt

a) protracting direction, to the DC motor driver 11 at a step S505, whereby the seatbelt can be easily protracted. According to the control of the steps S501 to 5 S505 described above, when the measured terminal voltage exceeds 0.3 volts and at the same time the sign of the terminal voltage corresponds to the direction of protracting the seatbelt, the seatbelt can be brought into a state where it can be easily protracted. As a result, a large force as required in the conventional apparatus is not needed, and therefore even a weak occupant who has degraded physical ability such as an advanced-age occupant can easily mount the seatbelt onto his body.

15 Then, it is determined at a step S506 whether attaching of the tongue of the seatbelt has been detected by the buckle connection detector 16 If attaching of the seatbelt has been detected, the processing proceeds to the step S509, On the other 20 hand, if attaching of the seatbelt has not been detected, it is determined at a step S507 whether a predetermined time period (e.g. 7 see) has elapsed after the control signal commanding to rotate the reel shaft 3 was delivered to the DC motor driver 11.

25 If the predetermined time period has not elapsed, the processing returns to the step S505, whereas if it has elapsed, which means that the seatbelt has been protracted but the tongue of the seatbelt has not been connected to the buckle such that the seatbelt is in a 30 slackened state, a control signal commanding to stop the rotation of the reel shaft 3 is delivered to the DC motor driver 11 at a step S508, and then the processing proceeds to the step S408 to carry out the seatbelt storing control.! 35 Fig. 6 is a flowchart showing the buckle attaching

(: control executed at the step S402, which is executed after attaching of the tongue of the seatbelt to the buckle. First, the MPU 14 waits for a predetermined time 5 period (e.g 2 see) at a step S601, to give the occupant a time period for the occupant to correct torsion of the seatbelt or the like after the attaching of the tongue to the buckle. Upon the lapse of the predetermined time period, the MPU 14 delivers a control signal commanding 10 to rotate the reel shaft 3 in the seatbelt retracting direction to the DC motor driver 11 at a step S602, whereby the seatbelt is retracted. Then, current flowing to the DC motor is measured by the circuit C1 of the DC motor driver 11 at a step S603. It is determined 15 at a step S604 whether the measured current exceeds a predetermined value (e.g. 1.4 amperes).

If the measured current does not exceed the predetermined value, the processing returns to the step S603, whereas if the former exceeds the latter, the MPU 20 14 judges that the retraction of the seatbelt has almost reached its limit, and then waits for a predetermined time period (e.g. 2 see) to allow the occupant to fit the seatbelt to his body at a step S605. Upon the lapse of the predetermined time period, the MPU 14 delivers to 25 the DC motor driver 11 a control signal commanding to stop the rotation of the reel shaft 3 after the retraction of the seatbelt has reached its limit, at a step S606.

Then, the MPU 14 delivers a control signal 30 commanding to rotate the reel shaft 3 in the seatbelt protracting direction to the DC motor driver 11 at a step S607. Accordingly, the seatbelt starts to be protracted, and after the lapse of predetermined time period (e.g. 1 see) (step S608) when the seatbelt should 35 be already given a predetermined amount of looseness,

the MPU 14 delivers a control signal commanding to stop the rotation of the reel shaft 3 to the DC motor driver 11 at a step S609.

Then, it is determined at a step S610 whether 5 attaching of the tongue of the seatbelt to the buckle has been detected by the buckle connection detector 16.

If attaching of the seatbelt has been detected, the present processing is terminated, whereas if attaching of the seatbelt has not been detected, the processing 0 proceeds to the step S408 to carry out the seatbelt storing control.

According to the seatbelt attaching control described above, after the attaching of the seatbelt tongue to the buckle, the seatbelt is retracted,and 15 after the retraction of the seatbelt has reached its limit, the seatbelt starts to be protracted to be given a predetermined amount of looseness. As a result, the inconvenience with the conventional automotive passenger restraint and protection apparatus can be eliminated 20 that the seatbelt mounted on the occupants body always gives the occupant a feeling of oppression owing to the bias force of the bias force-imparting means and makes him uncomfortable.

Fig. 7 is a flowchart showing the collision 25 warning, collision unavoidableness and doze warning control executed at the step S403 in Fig. 4.

First, it is determined at a step S701 whether any one of a first signal giving warning of danger of collision, a second signal indicative of unavoidableness 30 of collision, and a third signal giving warning against dozing has been received. If none of the signals has been received, the present processing is immediately terminated, whereas if any one of the signals has been received, the kind of the received signal is determined 35 at a step S702.

c) If it is determined that the received signal is the second signal indicative of unavoidableness of collision, the MPU 14 delivers a control signal commanding to rotate the reel shaft 3 in the seatbelt 5 retracting direction to the DC motor driver 11 at a step S703. Thus, the seatbelt is retracted. Then, the MPU 14 waits for a predetermined time period (e.g. 5 see) within which the restraint of the occupant immediately after collision should become unnecessary after the 10 determination that a collision is unavoidable, at a step S704. Upon the lapse of the predetermined time period, the MPU 14 delivers a control signal commanding to stop the rotation of the reel shaft 3 to the DC motor driver 11 at a step S707 15 On the other hand, if it is determined at the step S702 that the received signal is the first signal giving warning of danger of collision or the third signal giving warning against dozing, the MPU 14 delivers a control signal having a frequency of 20 Hz 20 and commanding to rotate the reel shaft 3 alternately in the seatbelt retracting direction and in the seatbelt protracting direction at a step S705. Accordingly, the retraction of the seatbelt and the protraction of the same start to be alternately carried out, and then the 25 MPU 14 waits for a predetermined time period (e.g. 2 see) as a warning time during which the alternate retraction and protraction is continued, at a step S706, followed by the program proceeding to the step S707.

Then, the MPU 14 delivers a control signal 30 commanding to rotate the reel shaft 3 in the seatbelt protracting direction to the DC motor driver 11 at a step S708, and then waits for a predetermined time period (e.g. 1 see) at a step S709. Upon the lapse of the predetermined time period when the seatbelt should 35 be already given a predetermined amount of looseness,

the MPU 14 delivers a control signal commanding to stop the rotation of the reel shaft 3 to the DC motor driver 11 at a step S710, followed by terminating the present processing 5 According to the collision warning, collision unavoidableness and doze warning control described above, when the received signal is a signal indicative of unavoidableness of a collision, the seatbelt is retracted, to thereby positively protect the occupant 10 upon a collision of the vehicle, and on the other hand, when the received signal is a signal giving warning of danger of collision or a signal giving warning the occupant against dozing, the seatbelt is alternately retracted and protracted, to thereby enable warning the 15 occupant of danger of collision or against dozing.

Figs. 8 and 9 are flowcharts showing the movement control executed at the step S404 in Fig. 4.

First, the terminal voltage across the DC motor 10 and the sign of the same are measured by the circuit 20 C2 of the DC motor driver 11 at a step S801. It is determined at a step S802 whether the measured terminal voltage exceeds a predetermined value (e.g. 0.3 volts) and at the same time the sign corresponds to the direction of protracting the seatbelt. The answer to 25 this question is affirmative (YES) if the seatbelt is protracted due to a motion of the occupant with the seatbelt mounted on his body, for example.

If the terminal voltage does not exceed the predetermined value or the sign of the terminal voltage 30 does not correspond to the seatbelt protracting direction, the present processing is immediately terminated, whereas if the terminal voltage exceeds the predetermined value and at the same time the sign corresponds to the seatbelt protracting direction, the 35 MPU 14 delivers a control signal commanding to rotate

the reel shaft 3 in the seatbelt protracting direction to the DC motor driver 11 at a step S803. By this control, the seatbelt can be made easy to protract.

Then, the MPU 14 waits for a predetermined time 5 period (e.g. 2 see) within which the occupant should stop moving after starting moving, at a step S804, and upon the lapse of the predetermined time period, the MPU 14 delivers a control signal commanding to stop the rotation of the reel shaft 3 to the DC motor driver 11 10 at a step S805.

Then, the terminal voltage across the DC motor 10 and the sign of the same are measured by the circuit C2 of the DC motor driver 11 are at a step S806, and it is determined at a step S807 whether the measured terminal 15 voltage exceeds a predetermined value (e.g. 0.1 volts) and the sign corresponds to the direction of retracting the seatbelt. The answer to this question is affirmative (YES) if the occupant has returned to his original position after moving and accordingly the 20 seatbelt has been retracted by the bias force-imparting means formed of a spiral spring or the like.

If the answer to the question of the step S807 is affirmative (YES), the MPU 14 delivers a control signal commanding to rotate the reel shaft 3 in the seatbelt 25 retracting direction to the DC motor driver 1 at a step S810). Thus, the seatbelt is retracted.

Then, the current flowing to the DC motor 10 is measured by the circuit C1 of the DC motor driver at a step S811, and then it is determined at a step S812 30 whether the measured current exceeds a predetermined value (e.g. 1.4 amperes).

If the measured current does not exceed the predetermined value, the processing.returns to the step S811, whereas if the former exceeds the latter, the MPU 35 14 judges that the retraction of the seatbelt has almost

Hi: reached its limit, and then waits for a predetermined time period (e g. 2 see) to allow the occupant to fit the seatbelt to his body. Upon the lapse of the predetermined time period after the retraction has 5 reached its limit, the MPU 14 delivers a control signal commanding to stop the rotation of the reel shaft 3 at a step S814 Then, the MPU 14 delivers a control signal commanding to Notate the reel shaft 3 in the seatbelt 0 protracting direction to the DC motor driver 11 at a step S815. The MPU 14 then waits for a predetermined time period (e.g. 1 see) after the seatbelt starts to be protracted, and upon the lapse of the same when the seatbelt should be already given a predetermined amount 15 of looseness, the MPU 14 delivers a control signal commanding to stop the rotation of the reel shaft 3 to the DC motor driver 11 at a step S817, followed by terminating the present processing.

If it is determined at the step S807 that the 20 terminal voltage does not exceed the predetermined value or the sign of the same does not correspond to the seatbelt retracting direction, it is determined at a step S808 whether the terminal voltage exceeds a second predetermined value (e.g. 0.3 volts) and at the same 2S time the sign corresponds to the seatbelt protracting direction. The answer to this question is affirmative (YES) if the occupant again starts to move so that the seatbelt is protracted, for example.

If it is determined at the step S808 that the 30 terminal voltage exceeds the second predetermined value and at the same time the sign corresponds to the seatbelt protracting direction, the processing returns to the step S803, whereas if the terminal voltage does not exceed the second predetermined value or if the sign 3S does not correspond to the seatbelt protracting

- direction, which means that the occupant remains stationary without moving again, it is determined at a step S809 whether a predetermined time period (e.g. 7 see) has elapsed after the control signal commanding to 5 stop the reel shaft 3 started to be delivered to the DC motor driver 11 If the predetermined time period has not elapsed, the processing returns to the step S806, whereas if the same has elapsed, the MPU 14 judges that the occupant 10 remains stationary without moving, that is, the occupant stays in the proper position, and then the processing proceeds to the step S810.

According to the movement control described above, in the event that the occupant starts to move 15 after the seatbelt has been attached to his body to cause the seatbelt to be protracted, the protracting motion is assisted to facilitate the occupant's movement. Further, when the occupant remains stationary for a predetermined time period (e.g. 7 see) or longer 20 after he moved, it is judged that the occupant stays in the proper position, and then retraction of the seatbelt is carried out. Still further, when the occupant starts to return to his original position after he moved, retraction of the seatbelt is carried out. Thus, the 25 occupant can be always protected with reliability.

Fig. 10 is a flowchart showing the mode selecting control executed at the step S405 in Fig. 4.

First, it is determined at a step S1001 whether the mode selector 18 has been caused by the occupant to 30 select the doze preventing function adding mode. If this mode has been selected, the MPU 14 continuously delivers a control signal having a frequency of 20 Hz commanding to rotate the reel shaft 3 alternately in the seatbelt retracting direction and in the seatbelt 35 protracting direction at random time intervals of 30 to

300 sec to the DC motor driver 11 for a predetermined time period (e.g. 2 see) at a step S1002. Thus, retraction and protraction of the seatbelt are carried out alternately at irregular time intervals.

5 Then, a flag S. which, when set to '1', indicates that the doze preventing function adding mode or the rough road traveling function adding mode has been selected, is set to "1" at a step S1005, followed by terminating the present processing. In this connection, 10 if the doze preventing function adding mode is selected, the timer 21 is started to measure the above random time intervals of 30 to 300 seconds. So long as the doze preventing function adding mode is not selected, the timer is cleared.

15 On the other hand, if it is determined at the step S1001 that the doze preventing function adding mode has not been selected, it is determined at a step S1003 whether the occupant has caused the mode selector 18 to select the rough road traveling function adding mode.

20 If this mode has been selected, the MPU 14 delivers a control signal commanding to rotate the reel shaft 3 in the seatbelt retracting direction to the DC motor driver at a step S1004. Thus, the seatbelt is retracted to fixedly hold the occupant to his seat.

25 Then, the flag S is set to "1" at a step S1006, followed by terminating the present processing.

If it is determined at the step S1003 that the rough road traveling function adding mode has not been selected, the MPU 14 delivers a control signal 30 commanding to stop the rotation of the reel shaft 3 to the DC motor driver 11 at a step S1001, and then determines at a step S1008 whether the doze preventing function adding mode or the rough road traveling function adding mode was selected in the last time of 35 mode selecting control, that is, whether the flag S was

- set to "1" in the last time of mode selecting control.

If it is determined at the step S1008 that the flag S was not set to "1", the default mode continues to be selected, followed by terminating the program. On 5 the other hand, if the flag S was set to "1", the flag S is reset to "0" at a step Step 1009, and the MPU 14 delivers a control signal commanding to rotate the reel shaft 3 in the seatbelt retracting direction to the DC motor driver 11 at a step S1010. Thus, the seatbelt is 10 retracted.

Then, the current flowing to the DC motor 10 is measured by the circuit C1 of the DC motor driver 11 at a step S1011, and it is determined at a step S1012 whether the measured current exceeds a predetermined 15 value (e.g 1.4 amperes).

If the measured current does not exceed the predetermined value, the processing returns to the step S1011, whereas if the former exceeds the latter, the MPU 14 judges that the retraction of the seatbelt has 20 reached its limit, and waits for a predetermined time period (e.g. 2 see) within which the occupant should fit the seatbelt to his body, at a step S1013, and upon the lapse of the predetermined time period, delivers a control signal commanding to stop the rotation of the 25 reel shaft 3 to the DC motor driver 11 at a step S1014.

Then, the MPU 14 delivers a control signal commanding to rotate the reel shaft 3 in the seatbelt - protracting direction to the DC motor driver 11 at a step S1015. Thus, upon the lapse of the predetermined 30 time period (step S1016) when a predetermined amount of looseness should be already given to the seatbelt after the seatbelt starts to be protracted, the MPU 14 delivers a control signal to the DC motor driver 11 to stop the rotation of the reel shaft 3 (step S1017), 35 followed by termination of the program

According to the mode selecting control described above, when the doze preventing function adding mode is selected, the retraction and protraction of the seatbelt are alternately carried out at irregular time intervals, 5 to thereby enable preventing the occupant from dozing while driving the vehicle. Further, when the rough road traveling function adding mode is selected, the seatbelt is retracted to fix the occupant to his seat to thereby enable preventing the occupant from shaking even in traveling on a rough road and provide a safe driving condition. Fig. 11 is a flowchart showing the retraction stopping control executed at the step S406 in Fig. 4.

First, the MPU 14 delivers a control signal 15 commanding to rotate the reel shaft 3 in the seatbelt protracting direction to the DC motor driver 11 at a step S1101. Thus, the seatbelt is protracted to be slackened. Then, the current flowing to the DC motor 10 is 20 measured by the circuit C1 of the DC motor driver 11 at a step S1102, and it is determined at a step S1103 whether the measured current is not smaller than a predetermined amount (e.g. 0.24 amperes).

If the measured current is smaller than the 25 predetermined amount, the processing returns to the step S1102, whereas if the former is not smaller than the latter, the MPU 14 delivers a control signal commanding to stop the rotation of the reel shaft 3 to the DC motor driver 11 at a step S1104, to thereby secure loosening 30 of the seatbelt and inhibit retraction of the seatbelt due to the bias force of the bias forceimparting means.

Then, the program is terminated.

According to the retraction stopping control, when the current flowing to the DC motor 10 is not 35 smaller than the predetermined amount, the rotation of

ail the reel shaft 3 is stopped, to thereby secure loosening of the seatbelt and inhibit retraction of the seatbelt due to the bias force of the bias force-imparting means.

Fig. 12 is a flowchart showing the seatbelt 5 storing control executed at the step S408 in Fig. 4.

First, when the occupant has disconnected the tongue of the seatbelt from the buckle, the terminal voltage across the DC motor 10 and the sign of the same are measured by the circuit 2 of the DC motor driver 11 10 at a step S2101, and it is determined at a step S1202 whether the measured terminal voltage exceeds a predetermined value (e.g. 0.3.volts) and at the same time the sign corresponds to the seatbelt retracting direction. The answer to this question is affirmative 15 (YES) if the seatbelt has been retracted due to the bias force of the bias force-imparting means, and therefore retraction of the seatbelt through driving by the DC motor 10 is not needed.

If the measured terminal voltage exceeds the 20 predetermined value and at the same time the sign corresponds to the seatbelt retracting direction, the i processing returns to the step S1201, whereas if the measured terminal voltage does not exceed the predetermined value or if the sign does not correspond 25 to the seatbelt retracting direction, that is, if the seatbelt is no longer retracted due to the bias force of the bias force-imparting means but retraction of the seatbelt by the driving force of the DC motor 10 is needed, it is determined at a step S1203 whether 30 attaching of the tongue of the seatbelt to the buckle has been detected by the buckle connection detector 16.

If attaching of the seatbelt has been detected, it is judged that although the tongue was once disconnected from the buckle, the tongue has again been 35 mounted onto the buckle, and then the above described

(! buckle attaching control (step S402) is carried out, whereas if attaching of the seatbelt has not been detected, the MPU 14 delivers a control signal commanding to rotate the reel shaft 3 in the seatbelt 5 retracting direction to the DC motor driver 11 at a step S1204. Thus, the seatbelt is retracted.

Then, the current flowing to the DC motor 10 is measured by the circuit C2 of the DC motor driver 11 at a step S1205, and it is determined at a step S1206 10 whether the measured current exceeds a predetermined amount (e.g. 1.4 amperes).

If the measured current does not exceed the predetermined amount, the processing returns to the step S1205, whereas if the former exceeds the latter, the MPU 15 14 judges that the retraction of the seatbelt has reached its limit, and delivers a control signal commanding to stop the rotation of the reel shaft 3 to the DC motor driver 11 at a step S1207.

According to the seatbelt storing control 20 described above, when the seatbelt is no longer retracted by the bias force of the bias forceimparting means but retraction of the seatbelt by the driving - force of the DC motor 10 is needed (the answer is NO at the step S1202), and at the same time the attaching of 25 the seatbelt tongue to the buckle has not been detected (the answer is NO at the step S1203), the seatbelt is retracted by the driving force of the DC motor 10.

Therefore, after the seatbelt tongue has been disconnected from the buckle, the seatbelt can be 30 retracted without fail. As a result, it can be avoided that the seatbelt tongue is caught in the door.

Although in the above seatbelt storing control, if retraction of the seatbelt has reached its limit such that the current flowing to the DC motor 10 exceeds the

A - predetermined value (step S1204), the control signal is delivered to the DC motor driver 11 to stop the rotation of the seatbelt (step S1207), alternatively the seatbelt may be protracted by the driving force of the DC motor 5 for a predetermined time period so as to give a predetermined amount of slackness to the occupant, and irrespective of whether the occupant thereafter protracts the seatbelt, the seatbelt is again retracted to its limit and then protracted by the motor driving 10 force so as to give a predetermined amount of slackness to the occupant, to thereby eliminate an extra amount of looseness of the seatbelt and hence properly protect the occupant. Fig. 13 is a flowchart showing the seatbelt 15 retraction failure detecting control executed at the step S4098 in Fig. 4.

First, the current i flowing to the DC motor 10 is detected by the circuit C1 at a step S1301, and it is determined at a step S1302 whether the detected current 20 i exceeds a predetermined amount (e.g. 1.4 amperes).

If the detected current i does not exceed the predetermined amount, it is judged that the retraction of the seatbelt is being carried out normally, and a time t elapsed after the start of the present control is 25 reset to "0" at a step S1304, followed by terminating the present processing. On the other hand, if the detected current i exceeds the predetermined amount, the elapsed time t is incremented by 1 at a step S1303.

Then, it is determined at a step S1305 whether 30 the elapsed time t exceeds a predetermined time period (e.g. 60 see).

If the elapsed time t does not exceed the predetermined time period, it is judged that the retraction of the seatbelt is being carried out 35 normally, followed by terminating the present

/ processing, whereas if the former exceeds the latter, it is judged that the retraction of the seatbelt is being carried out abnormally, and the supply of supply voltage to the DC motor from the battery Vb is stopped at a step 5 S1200, to stop the retraction of the seatbelt, followed by terminating the present processing According to the seatbelt retraction failure detecting control described above, when the current i flowing to tine' DC motor 10 continuously exceeds the 10 predetermined amount over the predetermined time period (the answers are YES at the steps S1302 and S1305), it is judged that the retraction of the seatbelt is being carried out abnormally, and then the supply of supply voltage to the DC motor 10 is stopped (step S1306) to 15 stop the.retraction of the seatbelt, whereby the occurrence of a fault due to the retraction of the seatbelt can be prevented.

As described above, according to the first embodiment, the MPU 14 carries out the seatbelt 20 protraction control, buckle attaching control, collision warning, collision unavoidableness and doze warning control, movement control, mode selecting control, retraction stopping control, seatbelt storing control, and seatbelt retraction failure control. As a result, a 25 comfortable seatbelt attaching environment can be provided, and the occupant can be warned of danger to thereby positively protect the occupant.

The above kinds of control carried out by the MPU 14 are executed at least one time after the occupant 30 mounts the seatbelt onto his body and until he dismounts the seatbelt from his body.

The automotive passenger restraint and protection apparatus according to the present embodiment may be provided at any of the driving seat, the assistant 35 driving seat, and the back seats.

- '/ The values of the waiting time by the MPU 14, terminal voltage across the DC motor 10 and curcrent flowing to the DC motor 10 used in the present emobodiment as described above are given by way of 5 example and not limitative.

A second embodiment of the invention will be described hereinbelow In the description of

this embodiment, elements and parts as well as steps corresponding to those in the first embodiment described 10 above are designated by identical reference numerals, detailed description of which is omitted In the

following, only those which differ from the first embodiment will be described.

Second Embodiment 1S The second embodiment is distinguished from the above described first embodiment only in that it is provided with a mechanism for stopping the retraction of the seatbelt (304, 308, 309 and 317).

Fig. 14 is a block diagram showing the 20 arrangement of an automotive passenger restraint and protection apparatus according to the second embodiment.

The apparatus according to the present embodiment is provided with a seatbelt retractor 300.

The reel shaft 3 has a central shaft 3a coupled 25 to a central shaft of a retraction stopping gear 304, which is rotatable in the same direction as the reel -shaft 3, and has an outer periphery thereof formed with a predetermined number of outer teeth. The gear 304 has a teeth surface facing in the seatbelt retracting 30 direction which extends almost normally to the seat belt, and a teeth surface facing in the seatbelt protracting direction which extends- at a gentle -

inclination relative to the seatbelt.

The gear 304 has a stopper arm 308 for stopping

of' retraction of the seatbelt, which is normally biased by a coiled spring or the like in such a direction that retraction of the seatbelt cannot be stopped by the stopper arm 308, and lifted by the action of a stopper 5 arm driving solenoid 309 when retraction of the seatbelt is to be stopped. In the lifted position, the stopper arm 308 is in mesh with the outer teeth of the gear 304 to stop the retraction of the seatbelt.

When the gear 304 is rotated in the seatbelt 10 protracting direction, the seatbelt can be protracted by virtue of the above-mentioned teeth profile of the gear 304 even when the gear 304 is in mesh with the stopper arm 308.

The solenoid driver 317 actuates the stopper arm 15 driving solenoid 309 in response to a control signal from the MPU 14 to lift up the stopper arm 308 into mesh with the outer teeth of the retraction stopping gear 304 to thereby stop the retraction stopping gear 304.

The mode selector 18 delivers an output signal 20 corresponding to the selected mode to the MPU 14, which in turn delivers a control signal corresponding to the selected mode to the DC motor driver 11 and the solenoid driver 317 to control the seatbelt retractor 300.

In the present embodiment, the MPU 14 controls 25 the electric retractor 300 based upon a main control program which is basically identical with the control program of Fig. 4 employed the first embodiment, except for the buckle attaching control, collision warning, collision unavoidableness and doze warning control, 30 movement control, mode selecting control, and seatbelt storing control. In the following description, only

different points of these controls from the first embodiment will be described..

Fig. 15 is a flowchart of buckle attaching 35 control according to the present embodiment executed at

/ ) the step S402 in Fig. 4. The buckle attaching control according to the present embodiment is distinguished from the one (Fig. 6) according to the first embodiment only in that a step S1511 is added.

5 After waiting for the predetermined time period (e.g. 1 see) at the step S608, the MPU 14 delivers a control signal commanding to drive the stopper arm driving solenoid 309 to the solenoid driver 317 to thereby stop the rotation of the gear 304 at the step S1511, followed by the program proceeding to the step S609. Even by the above described buckle attaching control according to the present invention, similar results to those obtained by the buckle attaching 15 control of Fig. 6 according to the first embodiment can be obtained.

Fig 16 is a flowchart showing the collision warning, collision unavoidableness and doze warning control according to the present embodiment executed at 20 the step S403 in Fig. 4. This control is distinguished from the above described control of Fig. 7 only in that steps S1611 to S1613 are added.

If it is determined at the step S702 that the received signal is the second signal indicative of a 25 collision being unavoidable, the MPU 14 delivers to the solenoid driver 317 a control signal commanding to reenergize the stopper arm driving solenoid 309 so as not to lift up the stopper arm 308 and hence allow the retraction stopping gear 304 to be relatively driven at 30 the step S1612, followed by the program proceeding to the step S703.

On the other hand, if it is determined at the step S702 that the received signal is the first signal giving warning of danger of collision or the third 35 signal giving warning against doze, the MPU 14 delivers

( to the solenoid driver 317 a control signal commanding to Reenergize the stopper arm driving solenoid 309 so as not to lift up the stopper arm 308 and hence allow the retraction stopping gear 304 to be rotatively driven at 5 the step S1611, followed by the program proceeding to the step S705.

After waiting for the predetermined time period (e.g. 1 see) at the stepS709, the MPU 14 delivers a control signal commanding to energize the stopper arm 10 driving solenoid 309 to the solenoid driver 307 to thereby stop the rotation of the retraction stopping gear 304 at the step S1613, followed by the program proceeding to the step S710.

Even by the above described collision warning, 15 collision unavoidableness and doze warning control according to the present embodiment, similar results to those obtained by the control of Fig. 7 according to the first embodiment can be obtained.

Figs. 17 and 18 are flowcharts showing the 20 movement control according to the present invention executed at the step S404 in Fig. 4. The movement control according to the present embodiment is distinguished from the movement control of Figs. 8 and 9 according to the first embodiment only in that steps 25 S1720 and S1721 are added.

After executing the step S803, the MPU 14 delivers to the solenoid driver 317 a control signal commanding to Reenergize the stopper arm driving solenoid 309 so as not to lift up the stopper arm 308 30 and hence allow the retraction stopping gear 304 to be rotatively driven at the step S1720, followed by the program proceeding to the step S804.

After waiting for the predetermined time period (e.g. 1 see) at the step S816, the MPU 14 delivers a 35 control signal commanding to energize the stopper arm

c driving solenoid 309 to the solenoid driver 307 to thereby stop the rotation of the retraction stopping gear 304 at the step S1721, followed by the program proceeding to the step S817.

5 Even by the movement control according to the present embodiment, similar results to those obtained by the above described movement control (Figs. 8 and 9) according to the first embodiment can be obtained.

Fig. 19 is a flowchart showing the mode selecting 0 control according to the present embodiment executed at the step S405 in Fig. 4. This control is distinguished from the mode selecting control of Fig. 10 according to the first embodiment only in that steps S1018 and S1019 are added.

15 If it is determined at the step S1003 that the rough road traveling function adding mode has been selected, the MPU 14 delivers to the solenoid driver 317 a control signal commanding to deenergize the stopper arm driving solenoid 309 so as not to lift up the 20 stopper arm 308 and hence allow the retraction stopping gear 304 to be rotatively driven at the step S1018, followed by the program proceeding to the step S1004.

After waiting for the predetermined time period (e.g. 1 see) at the step S1016, the MPU 14 delivers a 25 control signal commanding to energize the stopper arm driving solenoid 309 to the solenoid driver 307 to thereby stop the rotation of the retraction stopping gear 304 at the step S1019, followed by the program proceeding to the step S1017.

30 Even by the mode selecting control according to the present invention, results similar to those obtained by the mode selecting control (Fig. 10) according to the first embodiment can be obtained.

Fig. 20 is a flowchart showing the seatbelt 35 storing control according to the present embodiment

I executed at the step S408 in Fig. 4. This control is distinguished from the seatbelt storing control of Fig. 12 according to the first embodiment only in that a step S1208 is added and the step S1203 in Fig. 12 is replaced 5 by a step S1209 First, after the seatbelt tongue has been disconnected from the buckle, the MPU 14 delivers to the solenoid driver 317 a control signal commanding to reenergize the stopper arm driving solenoid 309 so as 10 not to lift up the stopper arm 308 and hence allow the retraction stopping gear 304 to be rotatively driven at the step S1208, followed by the program proceeding to the step S1201.

If it is determined at the step S1202 that the 15 measured terminal voltage exceeds the predetermined value and at the same time the sign corresponds to the seatbelt retracting direction, it is determined at the step S1209 whether attaching of the the seatbelt tongue to the buckle has been detected by the buckle connection 20 detector 16 within a predetermined time period (e.g. 2 see) after the MPU 14 delivered to the solenoid driver 317 the control signal commanding to deenergize the stopper arm driving solenoid 309 so as not to lift up the stopper arm 308 and hence allow the retraction 25 stopping gear 304 to be rotatively driven at the step S1208.

If it is determined that the attaching has been detected, the aforedescribed buckle attaching control (step S402) is executed, whereas if attaching of the 30 seatbelt has not been detected, the processing proceeds to the step S1204.

Even by the seatbelt storing control according to the present embodiment, similar results to those obtained by the seatbelt storing control (Fig. 12) 35 according to the first embodiment can be obtained.

ó As described above, according to the second embodiment, similarly to the first embodiment, the MPU 14 carries out the seatbelt protraction control, buckle attaching control, collision warning, collision 5 unavoidableness and doze warning control, movement control, mode selecting control, retraction stopping control, seatbelt storing control, and seatbelt retraction failure control. As a result, a comfortable seatbelt attaching environment can be provided, and the 10 occupant can be warned of danger to thereby positively protect the occupant.

Claims

69286/009.900

Clanns: 1. An automotive passenger restraint and protection apparatus for an automotive vehicle, having a seatbelt, for restraining an occupant of the automotive vehicle by the seatbelt to protect the occupant, comprising: PWM signal generating means for generating a PWM signal, a motor for retracting and protracting the seatbelt, said motor having operation thereof controlled by said PWM signal generated by said PWM signal generating means; and determining means for detecting at least one of current flowing to said motor and terminal voltage across said motor and for determining a state of the operation of said motor, based upon the detected at least one of the current and the terminal voltage, said determining means having low-pass filter means having a predetermined cutoff frequency lower than a frequency of said PWM signal; wherein said determining means causes said filter means to reduce higher frequency components than said predetermined cutoff frequency, contained in the at least one of the current and the terminal voltage, and determines said state of the operation of said motor, based upon the at least one of the current and the terminal voltage having the higher frequency components reduced.