JPS60135330A - Detector of holding state of steering wheel - Google Patents

Abstract

PURPOSE:To automatically alarm for preventing accidents when any trouble occurs with a driver, by providing a steering wheel with means such as a reflection-type optical sensor capable of detecting whether the steering wheel is duly held or not. CONSTITUTION:When a driver is holding a steering wheel, at least one of optical sensors SE1-SEn is faced to his hands so that a square-wave signal of 1kHz having large amplitude is obtained at the input terminal of an amplifier AM1. If some trouble occurs with the driver, causing him to release his hold from the steering wheel, the amplitude of the signal to the input terminal of the amplifier AM becomes small. The signal from the output terminal of the amplifier AM1 is sent via an AD converter ADC to a microcomputer CPU1 where it is sampled to determine the amplitude of the 1kHz signal, whereby any trouble occurred with the driver can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a steering wheel grip detection device for detecting an abnormality in the operating condition of a vehicle, a ship, etc.

[Prior Art] If a driver suffers from, for example, a heart attack while driving a vehicle, the driver will be unable to drive, which is likely to lead to a traffic accident.

In such cases, if it is possible to detect that something is wrong with the driver, it is possible to take measures such as issuing a warning to notify passengers or automatically stopping the vehicle, thereby minimizing traffic accidents. .

[Purpose] The first purpose of the present invention is to detect whether the driver is able to drive normally, and to take measures to automatically issue a warning or prevent an accident when an abnormality occurs with the driver. The second purpose is to obtain the following.

[Configuration] If a driver suffers a heart attack while driving, or if the driver begins to fall asleep, the driver generally loses or weakens his/her grip on the steering wheel. Therefore, by detecting the grip state of the steering wheel, it is possible to detect an abnormality of the driver. Therefore, in the present invention, a means for detecting the grip state of the steering wheel is provided on the steering wheel, such as a reflective optical sensor, a pressure sensor, a temperature sensor, a potential sensor, and a capacitance sensor.

Drivers often wear gloves on their hands when driving, and the way each driver grips the steering wheel differs greatly, so depending on the type of sensor and the conditions at the time, it may not be possible to detect the grip state. sell. Therefore, in one preferred embodiment of the present invention, the means for detecting the grip state is a reflective optical sensor. In the case of a reflective optical sensor, the determination level can be easily adjusted depending on detection conditions such as whether a hand is on the steering wheel or whether the steering wheel is being gripped with more than a predetermined force. In addition, in the case of a reflective optical sensor, a heartbeat signal can be obtained by processing the signal it outputs, so this sensor can be used for other purposes such as an on-board heartbeat needle.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the vicinity of the driver's seat of a vehicle equipped with an on-vehicle heart rate monitor according to an embodiment. Referring to FIG. 1, the center of the steering wheel 4 is provided with a cancel switch SWI for instructing the start of heart rate measurement.

Details of the steering wheel 4 are shown in FIG. 2a.

Shown in Figures 2b and 2c. Referring to these drawings, the upper surface of the steering wheel 4 includes reflective optical sensors SEI, SE2. ...SEn are distributed and arranged at predetermined intervals (at least an interval tJs smaller than the width of a hand). Each optical sensor consists of a light emitting diode LES and a phototransistor PTS arranged near the light emitting diode LES. The light emitting diode provided in each optical sensor is an infrared light emitting diode that emits light in the infrared region. The light emitting diode LES and phototransistor PTS of each optical sensor have their optical axes oriented in the same direction (above the steering wheel 4). The steering wheel 4 consists of an iron core 4b and a resin 4a covering it.
Each optical sensor is made of resin 4a except for the light emitting part and the light receiving part.
It is embedded and fixed in the part. Electric wires drawn out from each optical sensor pass through the resin 4a and are connected to an electronic circuit in a panel at the center of the steering wheel 4.

FIG. 3 shows the configuration of the steering wheel grip detection device mounted on the vehicle shown in FIG. 1. This will be explained with reference to FIG. A microcomputer CPUI controls the entire device. Microcomputer CPUI
Includes an analog/digital converter ADC and a cancel switch SWI.

Frequency/voltage converter FVC, vehicle speed control device spc.

Brake control device BKC, relay R'LY, buzzer BZ, etc. are connected.

Each light emitting diode LE of optical sensors SEI to SEn
S are connected in series, one end of which is connected to the oscillation circuit 08C1, and the other end of which is grounded. The oscillation circuit osct oscillates at a frequency of 1 KHz in this example and generates a square wave voltage.

However, the low voltage level is not a cloud, so the intensity of light emitted by the light emitting diode LES of each optical sensor changes binary with a period of 1 m5ec. The output terminals of the optical sensors SEI to SEn are connected in parallel to each other via capacitors, and are connected to the input terminal of the amplifier AMI.

The light emitting diode LES and phototransistor PH8 of each optical sensor have their optical axes oriented in the same direction, so if there is no obstacle in the direction of the optical axis, most of the light emitted from the light emitting diode LES will be directed toward the phototransistor. transistor PH8
, and the level of the II (Hz signal component obtained at the output terminal of phototransistor PH3 is small. However, if a hand is present in the optical axis direction of the optical sensor, most of the light emitted from the light emitting diode LES is reflected by the hand, and part of the reflected light reaches the phototransistor PH3, so that a relatively high-level 1 KHz signal component is obtained at the output terminal of the phototransistor PHS.

The output terminals of the phototransistors PH8 of the optical sensors SEI to SEn are commonly connected to each other via a DC blocking capacitor, and are connected to the input terminal of the amplifier AM1. Therefore, the level obtained by adding the output signals of each optical sensor is amplified by the amplifier AMI. In other words, when the driver is holding the steering wheel, the driver's hand is facing at least one optical sensor, so the input terminal of the amplifier AMI receives a relatively large amplitude square wave IK)Iz. I get a signal.

However, if an abnormality occurs in the driver and the driver's hands move away from the steering wheel 4, the amplitude of the 1 KHz signal component obtained at the input terminal of the amplifier AMl becomes small.

The output terminal of the amplifier AMI is connected to one input terminal of the analog/digital converter ADC.

Therefore, the microcomputer CPUI can detect whether there is an abnormality in the driver by sampling the signal obtained from the amplifier AMI and determining the signal level, that is, the amplitude of the 1 KHz signal.

The reed switch SW7 connected to the input terminal of the frequency/voltage converter FVC is placed near a permanent magnet that is connected to the speedometer cable of the vehicle and rotates as the cable rotates, and changes the frequency according to the vehicle speed. A square wave signal of F V C&: is applied to the frequency/voltage converter. The output terminal of the frequency/voltage converter FVC is connected to one input terminal of the analog/digital converter ADC.

The vehicle speed control device SPC is a device that performs constant speed control so that a predetermined vehicle speed can be maintained without the driver stepping on the accelerator. In this example, the microcomputer CPUI applies a signal to the vehicle speed control device spc to cancel constant speed cruise control. Brake control device B
KC is a device that biases the braking mechanism so that the vehicle stops.

When the microcomputer CPUI reaches a predetermined state, it instructs the brake control device BKC to perform braking. Relay R
, LY are connected to the engine's ignition system, and when these contacts are separated, the ignition circuit is interrupted and the engine is stopped. Therefore, when the contacts of relay RLY are separated, engine braking is applied.

FIG. 4 shows the microcomputer CPU1 shown in FIG.
The outline of the operation is shown below. This will be explained with reference to FIG. When the power is turned on, that is, when the ignition switch is turned on, the state of the output port is first set to the initial level and the memory is cleared. As a result, the contacts of relay RL'Y are connected, making it possible to start the engine. Register T is set to 0 as an initial value.

First, select the input channel of the analog/digital converter ADC to the output terminal side of the amplifier AMI, and perform multiple A/D conversions.
The conversion is performed to calculate the level change of 1 m5 ec period, that is, the amplitude of the 1 K, Hz signal component. The amplitude is compared with a predetermined reference value Lref, and if it is not L(Lref), the register T is reset to 0 and this operation is repeated.

When L<Lref, the contents of the register T are modified and the result is compared with a predetermined reference value T ref.

T ) Does the amplitude increase before reaching T ref?
Alternatively, if the cancel switch SWl is turned on, the register T is set to 0 again, but if the predetermined time Tref continues with L < T-ref, it is determined that an abnormality has occurred in the driver. That is, if the driver's hands are removed from the steering wheel 4 and the amplitude of the IKI (z signal becomes small) is detected for a predetermined period of time Tref or more, it is determined that the driver is no longer able to grip the steering wheel. When detected, the buzzer BZ is first set to energized, a stop control subroutine is executed, and this operation is repeated until the vehicle speed becomes 0 or the cancel switch SWI is turned on.

In the stop control subroutine, first, the input channels of the analog/digital converters A and DC are connected to the frequency/voltage converter FVC to read the vehicle speed. Next, a stop instruction signal is output to the vehicle speed control device spc.

Wait for a predetermined period of time, and check whether or not there has been a predetermined or greater (IL speed ratio change speed decrease) during that period. That is, when the vehicle speed control device spc is in a state where constant speed control is canceled,
If the driver's foot is on the accelerator pedal, the vehicle speed cannot be reduced even if the vehicle speed control device spc is instructed to cancel constant speed control, so whether or not the vehicle speed is reduced normally is monitored.

If the vehicle speed has not decreased normally, relay RL
Turn off the Y contact to cut off the power to the ignition system and forcefully apply engine braking.

Furthermore, if the change in vehicle speed is smaller than a predetermined value, the controller instructs the brake control device BKC to energize the braking mechanism. When the cancel switch SWI is turned on during stop control, the stop control operation is canceled.

5 shows the configuration of the electric circuit of the vehicle speed control device spc shown in FIG. 3, FIG. 6 shows the configuration of the throttle drive system, and FIGS. 7a, 7b, and 7c.

7d and 7e show a schematic operation of the microcomputer CPU2 of FIG. 5. First, the circuit configuration of the vehicle speed control device spc will be explained with reference to FIG.

In this example, the electronic control device 10 is mainly composed of a single-chip microcomputer CPU2. CPU
A runaway detection circuit 20 is connected to the reset port RESET 2, and the external interrupt input port 1-IRQ and the input port 2. 3. KO and K1 have interface circuits IF1, IF2 . IF3. Vehicle speed detection reed switch SW7 via IF4 and IF5
．． Clutch switch SW3. Stop switch SW4.
Set switch SW5 and resume switch SW6
Connect it. Further, a signal line drawn out from the output port of the microcomputer CPU2 of the steering wheel grip detection device is connected in parallel with the clutch switch SW3 via a diode.

In this example, when the contact of the vehicle speed detection reed switch SW7 changes from idle to open, the output level of the interface circuit IFI becomes low level L, and the microcomputer CP
An interrupt request is sent to U2.

Clutch switch SW3 opens and closes in conjunction with the vehicle's clutch pedal, and stop switch SW4 opens and closes in conjunction with the vehicle's brake pedal. Stop switch SW4
A stop lamp is connected to , and when SW4 is turned on (
(closed), the stop lamp lights up.

Set switch SW5 and resume switch SW6
is a push button switch, which is placed on the instrument panel at a position that is easy for the driver to operate.

The output port ○0 of the microcomputer CPU2 is connected to the runaway detection circuit 20, and the output port ○0 of the microcomputer CPU2 is connected to the runaway detection circuit 20.
3 are connected to drivers DVI and DV2, respectively. The output of the driver DVI includes a control solenoid SL that controls a negative pressure actuator, which will be described later.
A release solenoid SL2 is connected to the output of the driver DV2.

Control solenoids SL, I, release solenoid SL2, and constant voltage power supply port N! that generates constant voltage Vcc! A voltage from the vehicle battery is applied to r30 via the ignition key switch SWO. The circuit 4o is for deenergizing the release solenoid sL2 separately from the operation of the CPU 2 when the brake is applied.

FIG. 6 shows the configuration of the negative pressure actuator 100 controlled by the electric circuit shown in FIG. 5. This will be explained with reference to FIG. The housing 101 consists of two parts 101a and 101b. Diaphragm 102 has two parts 101
It is held between the flange portions a and 101b. A space surrounded by the diaphragm 102 and the housing 1018 is a negative pressure chamber, and the diaphragm 102 and the housing 101b
The space surrounded by is in communication with the atmosphere. A compression coil spring 103 is inserted between the housing 101a and the diaphragm 102, and pushes the diaphragm 102 back to the imaginary line position when the pressure in the negative pressure chamber is close to atmospheric pressure. A protrusion 104 fixed near the center of the diaphragm 102 is connected to a link of a throttle valve 105. The housing 101a is provided with a negative pressure intake port 107 communicating with the intake manifold 106 and atmospheric intake ports 108 and 109.

110 is a negative pressure control valve, and 111 is a negative pressure release valve, both of which are fixed to the housing 101a. The movable piece 112 of the negative pressure control valve 110 is tiltable about P as a fulcrum, and has one end connected to a tension coil spring 113, and the other end facing the control solenoid SL1. Both ends of the movable piece 112 function as valve bodies, and they open the negative pressure intake port 107, close the atmospheric air intake port 108 (the state shown in the figure), or close the negative pressure intake port 107 in response to the energization/deenergization of the solenoid SL1. , the air intake port 108 is opened.

Similarly to the negative pressure release valve 110, the negative pressure release valve 111 has a movable piece 114, a tension coil spring 115, and a solenoid SL2, but the movable piece 114 closes (the illustrated state) or opens the atmospheric air intake port 109. Note that 116 is an accelerator pedal, and 117 is a tension coil spring.

Figures 7a, 7b, 7c, 7d and 7e
Referring to the figure, the microcomputer CPU2 in FIG.
Explain the operation. Note that when the vehicle moves, the reed switch SW7 is constantly turned on and off, and each time SW2 is turned off, the microcomputer CPTJ
Execute the external interrupt processing shown in the figure.

First, when the power is turned on, initial settings are performed. That is, the output port is set to the initial level and the contents of the memory are cleared.

Inverts the level of output port O0. That is, if this boat Oo is set to a high level H, that level is set to a low level L, and if it is set to a low level L, it is set to a high level T. This process is always executed once within a predetermined period of time if the CPU is operating normally.

As a result, the runaway detection circuit 20 receives a substantially constant periodic pulse (fJ No. J CPU is applied. Runaway detection port w!
20 sets the output level of comparator CP to H when a pulse signal is applied, turns on transistor Q1, and turns on CP.
The RESET end of U is set to high level H.

However, the CPU went out of control and the boat went out of order.

When the pulse is no longer generated, the output level of the comparator CP is inverted to L, the transistor Ql is turned off, and a low level L is applied to the reset terminal RESET of the CPU. When the reset terminal RESET becomes L, the CPU performs the same operation as when the power is turned on, so the runaway stops.

If the operation is proceeding normally, the CPU is connected to input port K.
O, Kl, 2. It reads level 3, etc., determines the operation of the switches as follows, and performs processing according to the determined switch.

If there is no change in the input (unless a timer, flag, etc. is set), step 52-83-5
4-842-843, executes the multiple storage routine of FIG. 7c, and then executes a processing loop that returns to step S2 again. In this case, the contents of the vehicle speed memory, target value register, flag, etc. do not change.

When clutch switch SW3 or stop switch SW4 is on, the vehicle speed is below a predetermined value (for example, 30 km/h
In the following cases) or when a stop signal is applied from the CPU, the level of the output port is set in a direction that does not energize the solenoid, and the contents of the target value register RO are cleared in order to cancel constant speed control. Also clear all flags. As a result, if the constant speed driving mode is set, it is canceled. Further, the release solenoid sL2 is deenergized so that the negative pressure actuator I0O quickly operates in the direction of closing the throttle valve. Next, the process advances to step S61, passes through the multiple storage routine, and returns to step s2.

When the center switch SW5 is turned on, the process proceeds to steps S9-817-818-819 to S20 for the first time, and sets the set-on flag 5ET-ON to "1" to the cellar 1.
Set the controller 1 to roll solenoid control duty to 5%. When the control solenoid control setting is 5%, the proportion of time that the negative pressure control valve 110 communicates the inside of the negative pressure actuator 100 with the atmosphere increases, so the negative pressure actuator 110 moves in the direction of closing the throttle valve, and the vehicle speed decreases with time. do. Actual driving of the control solenoid is performed in step 843 according to the set duty. When the set switch SW5 is pressed, the process proceeds to steps 561-862-88, exits the multiple storage routine, and steps 52-33-----8.
Proceed to 9-S17-S18-861.

When the set switch SW5 is turned off, step 59-
810-811-311-313-314, the set-on flag 5ET-ON is cleared (to 0), and the set-off flag 5ET-OFF is set to 1. Next, the process advances to step S61, and the Sera 1-Otsu flag 5ET-OF
Since F is 1, 567-868-36.9-370-S8
1- ・---, and the counter (
(pointer) Increments the contents of RA (but does not exceed 3), clears and starts the 1-second timer for set/use. When this process is finished, the setoff flag S
ET-OF is cleared to "o". That is, S67, S68. Steps S69 and 570(7) are executed only at the first processing timing when the set switch SW5 is turned off. From the next time onwards, the process will proceed to steps S61-862-863...

If the set switch SW 5 remains off but does not turn on even after one second has elapsed, a time-over is detected in step s63, and the process proceeds to 564-S65-866.

This causes the contents of the target value register R0 to be transferred to the counter RA.
After executing a throttle initialization routine to be described later, the operation mode is set to constant speed control mode.

Since the target value register R0 stores the vehicle speed at the moment when step S14 is executed, that is, the set switch SW5 is turned off, the vehicle speed at that time is stored in a predetermined memory. For example, if the ON/OFF state of the Sera 1 switch SW5 is turned on and off twice before the set switch SW5 is finally turned off (off for 1 second), the processing steps 867-868-869-870 are executed during that time. Since the process is executed twice, the content of the counter RA is 2, and the content of the target value register R0 is stored in 2 of the vehicle speed memory.

In this embodiment, since there are three vehicle speed memories, step S67 is provided to prevent the value of RA from exceeding three. Therefore, even if the set switch SW5 is turned on and off three or more times in succession, the vehicle speed memory 3 is selected.

When the constant speed control mode is entered, steps 840-841-8
42, and each time this process is executed, the target value register R is
The control solenoid control duty is reset so that the contents of 0, that is, the memory delivery and the current vehicle speed are equal. If the set switch SW5 is held down, the control duty remains set at 5% in step 820, so the vehicle speed gradually decreases.

When the resume switch SW6 is turned on, the initial value is 53.
1-844-345-846=S47-84, 8-S
43 and resume on flag RESUME-O
Set N to rr 1 rr, clear and start the 0.9 second timer for resume. Then 861...
- Execute the processing loop continuing 581-882-82.

When the resume switch SW 6 remains pressed (on) for 0.9 seconds, a time-over is detected in step S48, and the process proceeds to S49, where the control solenoid control duty is set to 90%. At control solenoid control duty 90%, negative pressure control well 1
10 communicates with the negative pressure source (intake manifold) inside the negative pressure actuator 100 increases, so the negative pressure actuator 110 moves in the direction of opening the throttle valve over time, and the vehicle speed increases.

When the resume switch SW6 is turned off, first step S31-832-533-834-335-836.
...and the resume-on flag RESUME-O
Clear N to '0'' and resume off flag RESU
Set ME-OFF to +r I n. If the on time of the resume switch SW6 is long and the 0.9 second timer has timed out, 536-837-838-
839, the current vehicle speed is stored in the target value register RO, and the R
The contents of the target value register are stored in the vehicle speed memory indicated by the contents of o. In addition, the resume-off flag RESUME-OFF is cleared to ``0'' so that the resume operation of 9;( is not performed in the multiple storage routine).

If the resume switch SW6 turns off before the 0.9 second timer expires, the resume off flag RE
Since SUME-OFF is II 1 II.

Proceed to S81-587-888-889-890, increment the contents of counter RA, and set 1 for resume.
Clear and start the second timer, and clear the resume-off flag RESUME-OFF to II OII. 5
The processing step of 81-887-888-889-890 is performed when the resume-off flag RESUME-OFF is "1".
"(7), ie, once every time the resume switch is turned from on to off. Therefore, the counter RA stores the number of times the resume switch SW6 is turned from on to off.

When one second has passed since the resume switch SW6 was turned off, the one second timer for resume has timed out.
Therefore, S81-382-883-884-885-8
86, the contents of the vehicle speed memory 3 are stored in the target value register RO when the vehicle speed memory specified by the contents of the counter RA, for example, the three-turn zoom switch SW6 is turned on/off. Then, a throttle initialization routine 886 is executed to set the constant speed control mode. When the constant speed control mode is entered, steps 840-841-842-
Step 843, the control solenoid control duty is updated so that the current vehicle speed approaches the contents of the target value register.

The throttle initialization routine will be described with reference to FIG. 7e. Roughly speaking, this process involves the negative pressure actuator 1
00 to a predetermined position (throttle initial opening position) quickly, anticipatory control (open loop control) is performed. That is, the control solenoid control duty is set to a high value (90%), the time to continue this state is calculated in advance according to the contents of the target value register R0, and this is set in a timer. Continue the 90% duty control until it becomes over. When the time is over, set the constant speed control flag to set the constant speed mode.

External interrupt processing will be explained with reference to FIG. 7d. This process is to adjust the on/off cycle of the vehicle speed detection reed switch SW7. Every time this process is executed, that is, every time SW7 is turned off, the count value of the internal timer is read, and the timer is cleared and started. Also,
When the count value of the timer is greater than or equal to a predetermined value (that is, the vehicle speed is less than or equal to a predetermined value), a low speed flag is set. When the low speed flag is set, steps S8 to S8 of the main routine are executed.
15, the constant speed control mode is canceled in the same way as when the clutch pedal or brake pedal is operated.

In the above embodiment, when it is detected that the driver is no longer holding the steering wheel, the throttle valve, brake, and ignition system are controlled to stop the vehicle. However, if the driver applies the brakes without holding the steering wheel, Depending on the road condition, the driver may take the steering wheel and the direction of the vehicle may suddenly change. In such a case, the steering wheel may be braked or locked to prevent the steering wheel from moving significantly. Further, in the embodiment, the accelerator pedal 116 is always connected to the throttle valve, but the accelerator pedal and the throttle valve are connected so that even if the driver falls down while still pressing the accelerator pedal, the throttle valve can be returned to its original position. A V-magnetic latch may be provided in between, and the V-magnetic latch may be disconnected when the steering wheel grip is no longer detected.

[Effects] As described above, according to the present invention, by detecting the grip of the steering wheel, it is possible to detect whether or not there is an abnormality on the part of the driver, and to automatically take predetermined safety measures.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the vicinity of the driver's seat of an automobile equipped with a steering wheel grip detection device according to an embodiment. FIG. 2a is an enlarged front view showing the steering wheel in FIG. 1, and FIGS. 2b and 2c are cross-sectional views taken from line II b - II b and II c - II c in FIG. 2 a, respectively. . FIG. 13 is a block diagram showing the configuration of the steering wheel grip detection device installed in the automobile of FIG. 1. FIG. 4 is a flowchart showing the general operation of the microcomputer CPU1 of FIG. FIG. 5 is a block diagram showing the electric circuit configuration of the vehicle speed control device spc shown in FIG. 3. FIG. 6 is a block diagram schematically showing the throttle control mechanism. Figures 7a, 7b, 7c, 7d and 7e
The figure is a flowchart showing the general operation of the microcomputer CPU2 of FIG. 4 Steering wheel LES: Light emitting diode (light emitting means) PH8: Phototransistor (light receiving means) S, E 1~
SEn: Optical sensor (grip detection means) cptz: Microcomputer (electronic control means) O3CI: Oscillation circuit (
Light emission energizing means) SPC: Vehicle speed control device (security means) BKC Nibrake control device (security means) RLY: Relay (security means) BZ: Buzzer (security means) ADC: Analog/digital converter FVC: Frequency/voltage converter SLl, Sb2: Solenoid IFI, IF2. IF3. IF4JF5: Interface circuit 1 Figure 7d Figure 7e

Claims (5)

[Claims] (1) A grip detection means that is attached to the steering wheel and outputs an electric signal depending on whether or not the steering wheel is gripped; at least one security means; and when the grip detection means detects that the steering wheel is not gripped, the security means is activated. energize. A steering wheel grip detection device comprising electronic control means; (2) The grip detection means includes a plurality of light emitting means and a plurality of light receiving means disposed near the light emitting means, and the electronic control means includes a light emitting energizing means for energizing the light emitting means. The steering wheel grip detection device according to item (1). (3) The light emission energizing means includes an oscillation circuit that periodically changes the amount of light emission energization, and the electronic control means determines the amplitude of the output signal of the light receiving means. A steering wheel grip detection device according to claim (2). (4) The steering wheel grip detection device according to Claims (1), (2), or (3), wherein the safety means includes an alarm sound generating means. (5) Claim (1) above, wherein the safety means includes speed adjustment means for reducing the speed of the vehicle. The steering wheel grip detection device according to item (2) or item (3).