GB2171547A - Detecting drowsy or incapacitated drivers - Google Patents

Abstract

Means for detecting an anomaly in the grip on a steering wheel generates a warning and/or stops the vehicle. A number of sensors such as SE1 are spaced at intervals around the steering wheel. Each sensor comprises a diode LES surrounded by a number of phototransistors PHS. Electronic circuits are provided for determining an anomaly. As described, the driver's grip may be sensed by photoelectric means SE1 comprising an I.R. photoemitter LES and at least one photodetector PHS adjacent thereto so as to receive light reflected by the driver's hand. A plurality of spaced apart sensing means SE1-SEn may be used. A signal processing means CPU1 analyses the sensor output(s) and may, in succession, emit a warning and (i) cause a constant speed controller SPC of the vehicle to reduce speed; and if not sufficient then (ii) apply the brakes via circuit BKC; and if not sufficient then (iii) switch of the engine ignition via RLY. Additionally the steering wheel may be locked, and a mechanical linkage between the accelerator pedal and the throttle valve may be disconnected (lest the driver has become incapacitated while depressing the accelerator). The constant speed vehicle controller is described with reference to Figs 3 and 4. <IMAGE>

Description

SPECIFICATION Safety apparatus for a road vehicle The invention relates to safety apparatus for a road vehicle.

Apparatus according to the invention comprises meansfordetecting an anomaly in the grip on the steering wheel of a hand of a driver, and means for generating a warning and/orstoppingthevehicleon the detection of the anomaly.

Such a warning alerts the driver or passengers to the possibility of an accident due to a health condition orthe fatigue of the driver. A heart attack or a doze due to accumulated fatigue greatly increased the possibility of an accident, while an accumulation of fatigue reduces efficiency and impairs health.

The detecting means may be on the vehicle steering wheel, on a steering wheel cover or on a band for securingtothewristorarm of the driver. It may comprise light emitting means and light receiving means, the former being preferably surrounded by the latter.

A numberofdetecting means may be spaced at intervals, and means provided for comparing their output and selecting those for use. An oscillator may be provided for producing an electric wave, and a modulatorfor modulating the wave with the hearbeat.

Means for lowering the vehicle speed may be included.

A number of detecting means may be spaced along the grip of the steering wheel to allow detection when the steering wheel is gripped at any position. If a number of detecting means are connected in parallel to obtain a signal, the level background "noise" is raised by light coming from the outside because there are less detecting means which actually produce the desired signal. The S/N (signal/noise) ratio may be too low, so output levels ofthe individual detecting means may besequentialy monitored to find those which produce a signal indicating an anomaly, and such detecting means may be selectively connected to a measuring section. As selection ofthe detecting means is automatic, operation is simple.As the detecting means are selected by monitoring outputs, there occurs no selection error. If the detecting means are optical sensors, the output of each sensor exhibits a level corresponding to the sum of a desired signal and extraneous light, and the intensity of extraneous light is different depending on its position on the steering wheel. Accordingly, when making a decision upon comparison ofthe detected signal level with a given threshold value, erroneous detection may result if setting ofthe threshold value is not appropriate.

Thus levels of adjacent detecting means are compared to find the beginning and end detecting means to be used. Those in the range are all selected. As the extraneous light acts upon the adjacent detecting means in a similar manner, the above arrangement can offset such influence.

If the detecting means is to be buried in a steering wheel, the steering wheel has to be specially made and attached, but otherwise the appartus is easily attached and detached.

If the detecting means is fitted on the steering wheel coverandconnectedtotheremainderoftheapparatus by wires, this interferes with the driving. Thus, there are preferred signal transmitting means from the detecting means utilizing an electric wave, and signal receiving means for demodulatingthe signal.

This permits dispensation with wires. The signal transmitting means may be releasable attached to a spoke ofthe steering wheel.

As drivers often wear gloves, and since the steering wheel is differently gripped by individual drivers, optical reflection sensors are preferred. The anomaly determination level is adjusted in accordance with conditions such as whether the driver's hands are placed on the steering wheel, orwhetherthe steering wheel is gripped with forces greaterthan a predetermined value.

DRAWINGS Figure 1 is a block diagram of apparatus according to the invention; Figure 2 is a flow chart of a microcomputerCPUl in Figure 1; Figure 3 is an electronic circuit diagram of a vehicle speed controller SPC in Figure 1; Figure 4 is a longitudinal section through a negative pressure actuator orthrottle controller connected to thecontrollershown in Figure 20; and Figures 5a, 5b, 5c, 5d and Se are flow charts of a microcomputerCPU2 in Figure 4.

Figure 1 is a block diagram for detecting whetherthe driverfirmly grips the steering wheel, or his grip weakens during driving. Connected to a microcomputer CPU 1 are an analog/digital converter ADC, cancel switch SW1, frequency/voltage converter FVC, vehicle speed controller SPC, brake controller BKC, relay RLY, buzzer BZ etc. Output terminals of the optical sensors SE1 to SEn are connected in parallel through respec tivecapacitorsandtoan inputterminal of the amplifier Ambi.

Most of the light emitted from the diodes LES will not reach the photo transistors PHS unless there is an obstacle crossing their optical axes. The 1 KHz signal component produced at an output terminal ofthe photo transistor PHS has a low level. If the driver's hand crosses the optical axis, most of the light emitted from the diode LES is reflected by the hand, and part of the reflected light reaches the photo transistor PHS.

The output terminal of the photo transistor PHS produces the 1 KHz signal component at a relatively high level.

The output terminals of photo transistors PHS of the optical sensors SE1 to SEn are connected through capacitors for interrupting DC components, and then to the input terminal ofthe amplifierAMi. A signal level resulting from addition of output signals from the respective optical sensors is amplified by the amplifierAM1. In otherwords, when the driverfirmly gripsthesteering wheel,the driver's hand is positioned opposite at least one optical sensor, and a square 1 KHzsignal of a relatively large amplitude is appliedtotheinputterminal oftheamplifierAMl. If the driver's hands are released from the steering wheel 4the amplitude ofthe 1 KHz signal component appliedtotheinputterminal ofthe amplifier becomes small.

An outputterminal of the amplifierAM1 is con nected to one input terminal of the analog/digital converterADC. The microcomputerCPU1 detects the presence or absence of an anomoly in the driver's condition by sampling the signal produced from the am plifier AM 1 and then determining the level ofthe sampled signal, i.e. the amplitude ofthe 1 KHz signal.

A reed switch SW7 connected to an input terminal of the frequency/voltage converter FVC is connected near a permanent magnet rotating with the vehicle speed meter cable, and so applies a square signal of frequency corresponding to the vehicle speed to the frequency/voltage converter FVC. An output terminal ofthefrequency/voltage converter FVC is connected to another input terminal ofthe analog/digital converterADC.

The vehicle speed controller SPC makes for con stant speed, so that the vehicle speed can be maintained at a preset constant level without any need for the driverto push the accelerator. The micro computer CPU 1 applies a signal for releasong the constant-speed running control to the vehicle speed controller SPC. The brake controller BKC actuates a brake so as to stop the vehicle. The microcomputer CPU1 instructs the brake controller BKC to effect braking when desired. A contact of the relay RLY is connected to an ignition circuit of an engine and, when this is disconnected, the engine stops. Thus, the engine brake is applied upon disconnection of the contactofthe relay RLY.

The flowchart of Figure 2 is as follows: When power is on, the CPU 1 first sets the states of the output ports to initial levels and clears the memories. The contact of the relay RLY is interconnected and the engine is readyfor starting. The value of O is set in a registerT as an initial value.

An input channel of the analog/digital converter ADC is first selected to the outputterminal side of the amplifier AM 1, and A/D conversion is performed several times to obtain a level change with a period of 1 msec.i.e.,anamplitudeLofthel KHzsignal component. The amplitude L is compared with a preset reference value Lref and, unless L < Lref, the registerT is set again to zero and the above operation is repeated. If L < Lret the content ofthe register is incremented by +1 and the resultant value is compared with the preset reference value Tref.

If the amplitude L becomes large orthe cancel switch SW1 is turned on beforeT > Tref,the registerT is set again to zero. On the other hand, if a predetermined time Tref has lapsed while keeping L < Lref, it is decided that any anomaly has occured in the driver's condition. If the driver's hands are released from the steering wheel 4 and a reduction in amplitude ofthe 1 KHz signal has been detected continuously over a predetermined time Tref, it is decidedthatthe driver has lost his ability to grip the steering wheel.

The buzzer BZ is actuated and a stop control subroutine is executed. This operation will be repeated until the vehicle speed becomes zero orthe cancel switch SW1 is turned on.

In the stop control subroutine, first an input channel ofthe analog/oig ital converter ADC is set to the side of the frequency/voltage converter FVC and the vehicle speed is read. Then, a stop instruction signal is applied to the vehicle speed controller SPC. The CPU1 waits foragiven time and checks during thattimewhethera vehicle speed change (vehicle speed reduction) larger than a predetermined amount hac iccured. It is monitored whetherthe vehicle speed is normally lowered, because the vehicle speed cannot be lowered even with the vehicle speed controller SPC receiving an instruction to release the constant-speed control, if the driver's foot is on the accelrator pedal in the state where the vehicle speed controller SPC is free of constant-speed control.

If the vehicle speed is not normally lowered, the contact of the relay RLY isturned off, the power to the ignition system is interrupted, and the engine brake is forcible applied. If the change in-vehicle speed is smallerthan a predetermined amount, the brake controller BKC is instructed to actuate the braking mechanism. When the cancel switch SW1 is turned on during the stop control, the stop control operation is released.

The vehicle speed controller SPC circuit in Figure 3 comprises an electronic controller 10 mainly com- posed of a single-chip microcomputer CPU2. A runaway detector circuit 20 is connected to a reset port RESETofthe CPU2 and a vehicle speed detecting reed switch SW7, clutch switch SW3, stop switch SW4, set switch SWS and a resume switch SW6 are connected to an external interruption input port IRQ and inputs ports K2, K3, KO and K1 through interface circuits IFI, IF2, IF3, IF4 and IFS, respectively. Asignal line led from the output port of the microcomputer CPU 1 forthe unitfordetecting grasp ofthe steering wheel is connected in parallel to the clutch switch SW3 through a diode.

When the contact of the vehicle speed detecting reed switch SW7 isturnedfrom a closed state to an open state, an output level ofthe interface circuit IF1 becomes a low level L,thus applying an interrupt request to the microcomputer CPU. The clutch switch SW3 is opened and closed in an interlock relation with a clutch pedal of the road-vehicle, and the stop switch SW4 is opened and closed in an interlock relation with a brake pedal of the road-vehicle. Connected to the stop switch SW4 is a stop lamp, which is lit up upon turning-on (closing) ofthe SW4.

Both the set switch SW5 and the resume switch SW6 are push button switches disposed on an instrument panel to allowthe driver easy operation.

An output port Oo of the microcomputerCPU2 is connected to the runaway detecting circuit 20, while drivers DV1 and DV2 are connected to output ports 02 and 03, respectively. Connected to an output of the driver DV1 is a control solenoid SL1 for controlling a negative pressure actuator later described, and connected to an output of the driver DV2 is a release solenoid SL2.

Voltage from a battery loaded on the road-vehicle is appliedthroug an ignition switch SWO to the control solenoid SL1, release solenoid SL2 and a constantvoltage power supply circuit 30 for generating con stantvoltage Vcc. A circuit 40 is provided to deenergist the release solenoid SL2 independently of operation ofthe CPU2, when a brake is applied.

Figure 4 shows the negative pressure actuator 100 controlled by the electric circuit shown in Figure 3. A housing 101 is composed oftwo halves 101 a and 101 b. Adiaphragm 102 is held between the flanged portions ofthosetwo halves 101 a and 101 b. Aspace defined bythediaphragm 1O2andthe M and the housing half 1 ops serves as a negative pressure chamber, while a space defined bythe diaphragm 102 and the housing half 101 b is communicated with the atmosphere. A compression coil spring 103 interposed between the housing half 101 a, which spring pushes the diaphragm 102 back to such a position as shown by phantom lines, when the pressure in the negative pressure chamber is nearly equal to the atmospheric pressure.A projection 104fixed near the centre of the diaphragm 102 is connected to a linkofathrottle valve 105. The housing half 101 a has a negative pressure intake port 107 in communication with an intake manifold 106, and atmosphere intake ports 108 and 109.

A negative pressure control valve 110 and a negative pressure release valve 111 are both fixed to the housing half 101 a. A movable piece 112 of the negative pressure control valve 110 is capable of tilting aboutAas afulcrum. It has one end connected to a tension coil spring 113 and the other end opposite to the control solenoid SL1. Both ends of the movable piece 112 function as valve bodies, causing the negative pressure intake port 107to open and the atmosphere intake port 108 to close (the state shown) orcausingthe negative pressure intake port 107 to close and the atmosphere intake port 108 to open in accordance with energization of deenergization ofthe solenoid SL1.

The negative pressure release valve 111 also has a movable piece 114,tension coil spring 115 and the solenoidSL2similarlytothevalve 1 10, but the movable piece 1 l4functions to close or open the atmosphere intake port 109 (the state shown). An accelerator pedal 116 and a tension soil spring 117 are provided.

Operation ofthe microcomputerCPU2 shown in Figure 3 will now be described with reference to Figures Sa, Sb, Sc, Sd and 5e. While the vehicle is running, the reed switch SW7 is repeatedlyturned on/off at all times and the microcomputer CPU2 implements the external interrupt processing shown in Figure 5d whenever the switch SW2 is turned off.

When the power is on, the CPU2 first makes an initial setting: it sets the respective output ports to initial levels and clears the content of each memory.

Then, the level of the output port Oo is inverted. If the output port Oo had been set to a high level H, the level is now setto a low level L, and if it has been set to a low level Lit is now set to a high level H. The above processing is always carried out at least once within a predetermined period oftime in which the CPU2 is under normal operation. As a result, a pulse signal with an almost constant period is applied to the runaway detecting circuit 20 from the CPU2.When the pulse signal is applied to the runaway detecting circuit 20, an output level of a comparator CP is set to H and a transistor Qi is turned on, thereby maintaining the RESETterminal of the CPU2 at a high level H. lfthere is no pulse at the output port Oo from runaway of the CPU2 or other reasons, the output level of the comparator CP is inverted to Land the transistor Q1 is turned off, thereby applying a low level Lto the RESET terminal ofthe CPU2. The CPU2 performs the same operation as that effected at the time of power-on when the RESETterminal is set to L, so that runaway is stopped.

In normal operation,the CPU2 reads levels at the input ports K0, K1, K2 and K3, and it discriminates operations of the switches and then proceeds in accordance with the discriminated switch as follows: When there is no change in inputs (exceptforthe case that the timer, flag, etc, is set), the CPU2 implements a processing loop in which it passes through steps S2-S3S4-S42-S43, executes a plural-storage routine shown in Figure 5c and then returns again to the step S2. At this time, the contents ofthe vehicle speed memory, target value register, flags, etc. remain unchanged.

If the clutch switch SW3 orthestop switch SW4 is turned on, that the vehicle speed is less than a given level (e.g., Km/h), orthat a stop signal is applied from the CPU 1, the levels atthe output ports are set to not energize the solenoids and the content of the targetvalue register R0 is cleared to release the constant-speed control. At the same time, flags orso are all cleared. This clears a constant-speed running mode when it has been set. Further, the release solenoid SL2 is deenergized to operate the negative pressure actuator 100 in such a direction that the throttle valve is closed quickly. Next, the CPU2 proceeds to step S61 and then returns back to step S2 after passing the plural-storage routine.

When the set switch SW5 is tu rned on; the CPU2 proceeds through steps S9-S17-S18-S19-S20, sets a set-on flag SET-ON to "1 ", and then sets the control solenoid controlling duty to 5%. Atthe control solenoid controlling duty of 5%, the proportion of time in which negative pressure control valve 110 connects the inside of the negative pressure actuator 100 to atmosphere is increased. The negative pressure actuator 110 is moved so thatthethrottle valve closes and the vehicle speed lowers after a lapse oftinie.

Actual driving ofthe control solenoid is made in step 543 in accordance with the preset duty. Where the set switch SWS is depressed, the CPU2 proceeds through steps S61 - S62 - S81....while passing the plural- storage routine, and then again proceeds through steps S2-S3...S9-S17-S18-S61.

When the set switch SWS is turned off, the CPU2 proceedsthrough steps S9-S10-S1 -S12-S13- S14, clears the set-on flag SET-ON (to "0") and then sets a set-offflag SET-OFF to 1. Subsequently, it proceeds to step S61, passesthrough steps S67-S68 - S69-S70-S81... becausetheset-offflag SET-OFFis set to 1, increments the content of a counter (pointer) RAforspecifying the vehicle speed memory (within a range not exceeding 3), and then clears and starts a one-second timerfor setting. After completion of this processing, the set-offflag SET-OFF is cleared to "0".

In other words, steps S67,S68,S69 and S70 are implemented only in the first time processing after the setswitch SW5 has been turned off. From the subsequenttime, it proceedsthrough steps S61-S62 -S63...

If the set switch SW5 is not turned on in one second after it has been turned off, it is checked in step S63 thatthe preset time is over and, if so, the CPU2 proceeds through steps S64- S65- S66. This causes the content of the target value register RDlo be stored in the vehicle speed memory disignated by the content of the counter RA and, after implementing a throttle initializing routine described below, the opera tion mode is set to a constant-speed control mode.

Since the target value register RD stores the vehicle speed at the time when step 14 was implemented, i.e., at the moment when the set switch SW5 was turned off, the vehicle speed at that time is loaded into given memory. If the set switch SWS is turned on/offtwo times, for example, and finally turned off (for one second), the processing step of S67- 588-S69-S70 is implemented two times and hence the content of the counter RA becomes 2, and the content of the target value register R0 is stored in the vehicle speed memory 2. Since there are three speed vehicle memories, step 67 is provided to prevent the value of the counter RA from exceeding three.Accordingly, even if the set switch SW5 is turned on/off cnntinuous- ly three or more times, the vehicle speed memory 3 is selected. Coming into a constant-speed control mode, the CPU2 proceeds through steps S4D- S40-S41 - S42 and, whenever implementing this process, the control solenoid duty is so reset that the content ofthe target value register RO, i.e., the stored vehicle speed, becomes equal to the current vehicle speed. If the set switch SW5 remains depressed, the vehicle speed is gradually lowered, because the control duty is still set at S$o instep S20.

When the resume switch SW6 is turned on, the CPU proceeds through steps 581 - S44- S45-S46- 547- S48-S43, sets a resume-on flag RESUME-ON to and and then clears and starts a 0.9 timerfor resuming. Next, it implements a processing loop passing through S61 - S81 - S82 - S2. If the resume switch SW6 continuously remains depressed (on) for 0.9 second, it is detected in step S48 that the preset time is over, and the CPU2 proceeds to S49 where the control solenoid cotrolling duty is set to 90%.Where the control solenoid controlling duty is 90%, a proportion of time in which the negative pressure control valve 110 communicates the inside of the negative pressure actuator 100 with a negative pressure source (or intake manifold). As a result, the negative pressure actuator 110 is moved in such a direction thatthethrottle valve opens, so that the vehicle speed is increased with a lapse oftime.

When the resume switch SW6 is turned off, the CPU2 first proceeds through steps S31~S32~S33~ S34 - 535- 546..., clears the resume-on flag RESUME ON to "0", and then sets a resume-offflag RESUME OFFto "1". If the resume switch SW6 is turned on for a long time and the 0.9 second timer is up, the CPU2 proceeds through steps S36-S37-S38-S39. In a similarwaywhen the set switch SW5 is turned on/off, it loads the current vehicle speed in the target value register RO, and the content of the target value register is stored in the vehicle speed memory designated by the content of the register R0.The resume-off flag RESUME-OFF is cleared to "0" so as to avoid the normal resuming not being run in the plural-storage routine.

If the resume switch SW6 is turned off before the 0.9 second timer is up, the CPU2 proceeds through steps #81 - SB7 - 588-589 -s90 bsause-the resume-aff flag RESUME-OFF is set at "1", increments the content of the counter RA, clears and start no 1 second timer for resuming, and then clears the resume-off the resume-offflag RESUME-OFFto "0". The process#ing step of S81 -887 - 588- S89-580 is implemented once during the time when the resume-off flag RESUME-OFF is at "1", i.e., whenever the resume switch is turned from an on-state to an off-state.Accordingly, the counter RA stores therein the number of how much the resume switch has been turned from an on-state to an off-state.

When one second has lapsed after the resume switch S5N6 is turned off, the CPU2 proceeds through steps 581-582-583-584-585-586 because the 1 second timer for resuming is up. Then the content of the vehicle speed memory designated by the content of the counter RA, for example the content of the vehicle speed memory3 if the resume switch SW6 is turned on/offthree times, is stored in the targetvalue register RO. The CPU2 implements a throttle initializing routine 586 and sets a constant-speed control mode. Coming into a constant-speed control mode, it proceeds through steps S40-S41-S42-S43 and updates the control solenoid controlling duty such thatthe current vehicle speed approaches the content offthetargetvalue register.

The throttle initializing routine is shown in Figure 5a.

In short, this process is intended to make anticipatory control (i.e. open loop control) in orderthatthe negative pressure actuator 100 is quickly driven to a given position (i.e. throttle initial opening position).

The control solenoid controlling duty is setto a high value (90%), a period of time in which the above state is to be continued is previously calculated based on the content of the target value register R0 and then set in a timer, and the 90% duty control is continued until the set time is over. When the set time is over, a constant-control flag is set to establish a constantspeed mode.

The external interrupt process is shown in Figure 5d.

This is intended to determine an on/off period of the vehicle speed detecting reed switch SW7. Whenever the processing is implemented orSW7 is turned off, the CPU2 reads the counted value of an internal timer, and then clears and starts the timer. If the counted value of the timer is higherthan a predetermined amount (i.e. if the vehicle speed is less than a given level), a low-speed flag is set. When the low-speed flag is set, it proceeds from step S8 in the main routine to step S15, thereby releasing a constant-speed control mode as when the clutch or brake pedal is operated.

The throttle valve, brake and ignition system stop the road-vehicle upon detecting that the driver's hands are released from the steering wheel. There is a fearthatthe steering wheel may be inaccurately steered or abruptly ly changed in direction if a brake is applied when the steering is not firmly gripped. Thus the steering wheel may be braked or locked to prevent movement to a large extent. The accelerator pedal 116 is always connected to the throttle valve, but an electromagnetic clutch may be provided between the accelerator pedal an the throttle valve to be disconnected if grasping of the steering wheel cannot be detected. The throttle valve will thus be returned even ifthedriverhasfallen over while pressing the accelerator pedal.

Claims (10)

1. Safety apparatus for a road vehicle which comprises means for detecting an anomaly in the grip on the steering wheel of a hand of a driver, and means for generating a warning and/or stopping the vehicle on the detection ofthe anomaly.

2. Safety apparatus according to claim 1 in which the detecting means is on the vehicle steering wheel.

3. Safety apparatus according to claim 1 in which the detecting means is on a steering wheel cover.

4. Safety apparatus according to any proceeding claim in which the detecting means comprises light emitting means and light receiving means.

5. Safety apparatus according to claim 4 in which the light emitting means is surrounded by the light receiving means.

6. Safety apparatus according to any preceding claim which comprises a number of detecting means spaced at intervals.

7. Safety apparatus according to claim 6 which includesmeansforcomparingtheoutputofthe detecting means and selecting those for use.

8. Safety apparatus according to any proceeding claim which comprises an oscillator for producing an electric wave, and a modulatorfor modulating the wave with the heartbeat.

9. Safety apparatus according to any preceeding claim which includes means for lowering the vehicle speed.

10. Safety apparatus for a road vehicle as herein described with reference to the drawings.