EP1480846A1

EP1480846A1 - Method and means for measuring the interaction between driver and vehicle

Info

Publication number: EP1480846A1
Application number: EP03703605A
Authority: EP
Inventors: Mats BJÖRKMAN
Original assignee: Cesium AB
Current assignee: Cesium AB
Priority date: 2002-02-04
Filing date: 2003-02-04
Publication date: 2004-12-01
Also published as: JP2005517582A; WO2003070504A1; KR20040083496A; AU2003206315A1; CN1625494A

Abstract

The present invention relates to a method to measure the interaction driver/vehicle or vice versa during use of a CPU with appropriate software. The invention is characterised in that the torque/force on the steering device is recorded by a first sensor and that the lateral forces acting on the vehicle on that occasion are recorded by other sensors, or vice versa, that the recorded values are continuously calculated, filtered and arranged to decide one or several of the following parameters or parameter constellations; coupling grade, means values of reaction times, reaction spectra, inquire frequency, fault frequency and variations of amplitudes.

Description

Method and means for measuring the ktβraetipn between driver and vehicle.

The present invention relates to a method and means at vehicles, more precisely a measuring and parameter managing method and a computing unit to extract indicators of various security critical interactions (parameter constellations) over the interface driver/vehicle, the purpose of which is to quality grade said communication over said interface. By the invention a picture is created of the transmission capacity of each part of the system and how these separate parts are working dynamically.

In the quality consolidation is also steps to influence a driver lacking in the micro control over the vehicle by using suitable measures to put the driver's attention to said lack in micro control so she or he hardly will continue to drive the vehicle uninfluenced. If this happens in spite of measures taken it must take place with a conscious and preferably experienced effort. There are always drivers who for some reasons lack in attention. The reasons can be many, e.g. tiredness, drunkenness, sickness, talking in the cellular phone, etc. The driver, the vehicle and the surroundings must work together. This goes on over the interface driver/vehicle and vehicle/road. It is not about how well the parts are by themselves, but how well they work together. The quality of the joint over the interfaces is of vital importance for the total safety. Alert and experienced drivers do seldom cause accidents and fatal material failure is very rare. Often, Accidents are caused by "incompablities" over the interfaces and which the driver cannot handle. An example of incompatibility can be an unfavourable relation between the driver's experience, the characteristics and speed resources of the car, the state of the roads and existing speed limit. The major problem is that the driver's ability to safely handle the vehicle is not static.

A safe driving with a vehicle takes for granted that the driver all the time adaptively adapts himself to a dynamic process and has enough of decision- making inputs to control the vehicle. The senses of sight, balance and equilibrium do hereby have a vital importance in the collecting of information, or in reality a flow of information being managed and evaluated continuously, principally on a not conscious level. Tiredness, stress, influence of drugs and medicine and maybe talking in the cellular phone may affect the driver negatively both concerning the receptivity, and possibility to make the right decisions. In the sentence "to make the right decisions" is also simple reflex behaviours being trigged by the driver in a not conscious manner. You can also mention "micro decisions, i.e. small reflex like corrections, mostly by the steering wheel having their origin in the unconscious way to make check-up questions to the surroundings in connection to an ongoing activity to have this turned out in as wanted. Feed forward and feed back are terms for sensations often used in this context? The human being has an excellent ability to train sensitivity to small alterations in the inertia force pattern, e.g. caused by turning the steering wheel.

One example of a very clear check-up question (one of several) is when a man is making his way on a slippery surface. One check-up question asked is in the form of a small twist of the forward foot during load whereby an earlier made experience is compared regarding the easiness by which the foot is twisted, i.e. how slippery it is and from that how long steps to be taken without giving rise to too big lateral forces to loose the grip both when putting the foot down and pushing it backwards (when walking).

A movement in the room is an example of an activity with feedback and with check-up questions. During training a skill and in different forms of disabilities, tiredness, brain diseases, unawareness, and sickness the feed-back of the system and the ability to ask check-up question may be not be fully requisitioned or fully developed, or it is disturbed with changes in reaction time and/or reaction pattern as a consequence. Compared to a normally performed activity a disturbed feedback will often result in negative effects on the performing of the activity. Here it is possible to tell the difference between two different kind of documented movement and reflex patterns in connection to an activity; one being a destruction of a previously learnt and working reflex pattern and one showing an incomplete reflex pattern under construction. In the latter case it is possible to follow a positive development of the interaction/reflex pattern as the myelination or re-myelination, e.g. after a stroke, of the nerve net used for that activity is taking place. In the case the activity is a basic skill training, e.g. to drive a vehicle, it is important to exercise in a neuro pedagogic correct way, i.e. e without any mentally restricting elements as an excessive focusing on risk and consequence which will obstruct the learning process, which assumes to take place in fully safe and confident forms. A f ightened and anxious man has drastically deteriorated his capacity to an effective training by adventure and experience - the man simply does not dare to try out - and in stead of experiences and observations of limits for what is possible the man run the risk of being too careful, i.e. insecure in performing the present activity.

To drive a car in a safe way is based upon a complex interaction between the driver and the vehicle. Continuously there is big flow of dynamically variable information and all the time decisions of decisive importance have to be made. All the things happening during a ride cannot be considered and dealt with in a logical mental activity but must take place in an automatic way. The driver has to trust his reflexes and intuition. It is also possible to express as the driver performs will-powered (pyramidalic) commands, which are embedded in unconscious (extra-pyramidalic) minor position commands safely steering the vehicle. The torque acting on the steering wheel is a representation of the driver's influence on the vehicle by the steering wheel. This torque signal is more important than the angle deflection of the steering wheel because it exists in chronological order ahead and a change of the torque must not necessarily result in a change of angle deflection of the steering wheel. Compared with the reasoning about exertion-relaxation it seems plausibly that most of the manoeuvres are not perceptible as angle deflections at all, but just as a "counteraction". It is possible to see the micro control as an inquiry, a reply and compensation. The driver seeks information, deciphers said information instinctively and reacts and the car responds. The response from the car is at the same time an inquire back to the driver and the drivers response is again a new inquire to the car, i.e. a continuous dynamic interaction is in progress. The commands from the driver have to be distinct as well as the responding of the vehicle to these commands must be consistent, clear and logical. The tires, the wheel suspension and the steering must bring about information from the road and give signals about the behaviour of the vehicle; i.e. as a response to executed motions to the steering wheel. It may also be expressed such that the vehicle ought to supply the driver with small but clear signals confirming and supporting the driver in his further control of the vehicle. This clear signalling is achieved first after filtering and removal of noise and unnecessary disturbances. Different signals initiated from the vehicle may be of different strength at different speeds and at different states of the road. However the behaviour characterisation of the vehicle should not be changed in view of different external conditions, as state of the road, load distribution, choice of tires, etc.

US-A-5 821 860 disclose a technique to supervise the condition or fitness of a driver to drive a vehicle. This technique confirms the "normality" of a driver's behaviour during a ride and compares using neural network technique with different ride critical parameters to warn when a risky behaviour exists.

The main object of the present invention is to obtain a technique being active much earlier compared to driver supervising technique of the prior art and to react on enhanced risks for wrong decisions and misbehaviour of the driver prior to there might have been a serious accident. This is accomplished by a continuous supervision of the interaction between driver/vehicle/road over the interface driver/vehicle. By a very early establishment of the conditions for the driver to really be able to drive his vehicle in a safe way, or establishment of the capability of the vehicle to react on the actions from the driver, the incompatibility between the driver and the vehicle, and to some extend also between the driver and road by way of the vehicle in the interface driver/vehicle is disclosed. In this lies also to identify such shortages in the communication (interaction) which are considered to increase the risks for misjudgement and near-accidents/accidents. It is here also possible to get an understanding about how the driver's prospective memory, working storage and semantic memory, respectively are active and involved during the different cognitive stress. To some extend it is also possible to perceive the legibility and the reaction time for separate perceptions, e.g. the interaction of the sight in a driving sequence.

Another object of the invention is to disclose a method to train and confirm the ability of the driver to both register and "understand" the behaviour of the vehicle caused by the manoeuvring and by outer influences. What is important in this respect is not to understand in a conscious way, but to make it easy and possible to train a sensation of where the limits are both considering the road grip and the behaviour of the vehicle, i.e. also over the interface vehicle/road. This sensation is necessary in the achievement of a healthy confidence in the role as a driver.

Yet another object of the invention is to quality assure the communication between driver/vehicle/road by exercising a sensitive for small variations in the pattern of gravitational pull caused by steering deflections. Here the presence of mind is supervised, the motoric quickness and behaviour in the interaction with the vehicle and according to performed measurements a basis is formed to calculate and decide what type of driver assistance (ABS, traction control, etc) the car and driver have use for, but which can also warn the driver against lack of engagement and communication (interaction) with the vehicle, and/or between vehicle/road.

By the invention a technique is disclosed registering the lack of interaction between driver and vehicle and thereby, in a first stage make the information from the vehicle clear in such a way that the comfort is decreased, e.g. by letting the throttle pedal have an increasing resistance against being pressed down, i.e. the driver will to some extend in an unconscious way strive to achieve a high comfort, which will cause him or her to instinctively put a bigger intensity and engagement in the drive of the vehicle to thereby get a "reward" in an increased comfort. By connecting the system for quality insurance of the communication over the interface to a throttle pedal increasing the resistance against being pressed down in dependence of the driver's increasing incapacity for microcontroU, the driver will be aware of said shortage and will at the same time experience a physically increasing resistance, which in most of the cases will make the driver realise that it is time for a break, e.g. In case of severe lack of micro control, e.g. caused by drug use, it is possible to also activate hazard warning flasher, etc.

The technique to supervise the interface communication driver/vehicle/road is disclosed in our PCT applications nos. SE01/00334 and SE01/01697 to which we hereby refer. Most of the human activities are working as feed back systems, where impressions from our senses are processed in the brain and result in a certain wanted movement of the body, which in turn has an influence on the activity and this is again fed back by our senses in sensoric activity to the brain. We strive to obtain a balance and a correspondence between a wanted condition and the actual condition. Generally speaking the communication hereby obtained can be said to take place in the one hand of our free will to control or direct the activity (macro) and on the other hand in a more intuitively (micro) way where the balance is achieved. To decide about a specific situation the brain has often to create a small movement, i.e. ask a control inquire to the body and to the surroundings to form a true picture of the situation. Learning and experience is a matter of decisive importance. Often the driver follows the road and places the vehicle on the road within the zone he thinks to be safe. With reference to neurology and research about how the brain, and especially the cerebellum in an intuitive way controls the body/vehicle, it is stated that the muscle system is active as long as the person is awake and it is about a continuous dynamic interplay to obtain a balance between muscles and groups of muscles and that this is dependent upon a continuous feed back. To obtain a controlled movement or to just keep the body/vehicle in a certain position a very complicated interaction between tension and relaxation is necessary. When holding the hand immovably in front of oneself the hand seems to be inactive. The underlying interaction is not visible. This can be called microcontroU and it is most likely that this also goes for the driver's way of controlling the vehicle as an extension of his own body. The underlying interaction is mostly not visible to the naked eye.

Another object of the present invention is to detect is to detect an existing incompatibility between driver and vehicle, i.e. when the driver and the vehicle do not "speak the same language". Hereby increased risks for defective behaviours from the driver are quickly detected, i.e. already prior to they necessarily has come into existence. Especially this applies to older drivers and the object will then be to try to reshape a compatibility between the driver and the vehicle by intensify the response of a steering deflection, i.e. the resulting lateral inertia forces as far as possible, e.g. with sound and/or light signals.

The above-mentioned objects with the present invention will be achieved by giving the method and the device the characterising clauses mentioned in the claims.

When several of the calculated parameters and constellations of parameters will be within approved reference values the conclusion of "good total security" for the system, including driver, vehicle and environment (road) is trustworthy. The same goes for the contrary, i.e. when several parameters are to be found near or outside approves reference values the conclusion of "poor total security" is likewise trustworthy.

A type of micro communication between driver and vehicle will take place within the frequency range 0, 3 to 10 Hz and mean that a driver's execution of a force onto the steering wheel is timely displaced and proportional to the lateral forces of the vehicle. In this connection the proportional constant is decided by the dynamic of the steering system and of the speed of the vehicle.

The micro communication will take place in a subconscious way and the effect the driver will exert onto the steering wheel is usually less than ± 0,1 % of a full steering deflection. Thus a movement of the vehicle can be initiated by the fact that nerve impulses of the brain are transformed in the muscles to a force acting on the steering wheel. This force is transmitted to the steering connecting rods by the steering system of the vehicle and with a time delay this force is transformed into a lateral force acting on the vehicle.

For a vehicle with a steering wheel the force executed onto the steering wheel is the derivative of the steering angle. Thus the steering angle and the lateral force is not proportional.

In this specification the micro communication is regarded as a flow of nonverbal control inquires and responses between the driver and the vehicle. In the same way as the vehicle reacts on the manoeuvres of the driver the driver also reacts on the movements of the vehicle. . The driver asks and the vehicle responds after a certain time delay. This response is also a new inquire to the driver who reacts and respond after his or hers reaction time. The relationship between the force influence on the steering device and the lateral forces is described in such a way that a movement of the vehicle to the right is attained by applying a force to the right onto the steering device resulting in a lateral force to the left, but a compensation of a movement to the right (with lateral force to the left) is obtained with a force to the left on the steering device.

The experience and the mental condition of the driver are possible to make out in how the driver and vehicle asks and responds. Fatigue can be seen in a disturbed communication where the reaction pattern is changed at the same time, as a poor communication itself will cause fatigue.

Fatigue will cause traffic accidents and micro communication contains several security critical parameters, which can be seen both for the driver and the vehicle. Together they create a representation of how well the driver and the vehicle interacts. By using sound with a progressively increasing power responding to the appearance of lateral forces during the drive the sensitiveness for small deviations in these lateral forces can be increased at an inexperienced driver when training, or at older drivers with a decreased perception. Also an influence from the steering device can generate a sound signal being dependent on the applied force or moment (at a steering wheel).

The parameters defined and the connections established are according to the invention the following:

1. coupling grade seen as the difference between the lateral force of the vehicle and the force exerted on the steering device with a compensation for either the reaction time of the driver or of the vehicle, and within a certain time interval. The coupling grade can be compared to electric conductance and is related to the experience (the skilfulness) of the driver;

2. reaction time being seen as a momentary type value or an average value during a certain time;

3. reaction spectrum which can be seen as the relationship between the presence of different reaction times classified in at least two categories;

4. inquire frequency seen as inquires responded to during a certain period;

5. fault frequency seen as inquires not responded to during a certain period.

The invention will now be described in connection to the figures below, where

Fig. 1 is a flow scheme of the signal reading

Fig. 2a, 2b are graphs of the force applied on the steering device and of the lateral acceleration

Fig. 3 is also a graph of the force applied on the steering device and of the lateral acceleration

Fig. 4 illustrate the coupling grade between the driver and the vehicle with regard to the reactions of the driver Fig. 5 is reaction spectra, and

Fig. 6 is a well-arranged block scheme of the control system driver/vehicle

Thus fig. 1 is a flow scheme of the signal reading and how parameters are extracted from the signals from the sensor for the force acting on the steering device 1 and the sensor for the lateral acceleration 2. The signal from each sensor will pass a phase corrected band pass filter 3 with break frequencies in the magnitude of 0,3 to 5 Hz where also the amplitude is normalised to make the signals comparable. The signal for the lateral acceleration 2 will be delayed in a delay link 6 either with a fixed time corresponding to the median value of the reaction time of the driver, see fig. 4 (17), or with the instantaneous reaction time of the driver. The coupling grade 9 of the reactions of the driver on the movements of the vehicle is calculated 5 as the absolute value of the difference between the absolute values of the integrated signals over a certain time, see fig. 4 - the shady area 16. In the same way the coupling grade 9 for the respond of the vehicle be calculated if now the signal 1 is delayed 4. The variation of the amplitude 10 is calculated 5 as the difference between the top value and the bottom value of a running average value of the absolute amount of the signal amplitude during a certain time, e.g. 10-sec. To be able to make calculations of the reaction times 11, 12, 13 of the driver and of the vehicle said signals flanks 7 are detected by derivate each signal and look for sign changes: zero, plus, zero for a positive flank, fig. 3 (14b) and zero, minus, zero for a negative flank, see fig. 2 (14a) The reaction times 11 are calculated 5 as the time - fig. 2 (15a) and fig. 3 (15b) respectively - between a flank on one of the signals and the next flank on the other signal fig. 2 (14a) and fig. 3 (14b) respectively. The reaction times are divided 8 in at least two categories (12a, 12b, 12c, 12d) where the number of different reaction times is summed up during a certain time. These are brought together to reaction spectra - fig. 5. The inquire frequency 13a is calculated 5 as the accumulated number of flanks on each signal during a certain time. The fault frequency 13b is calculated 5 as the difference between the accumulated number of positive and negative flanks of the signals.

The diagrams according to fig. 2a and 2b show the force exerted on the steering device 1 in relation to the lateral acceleration 2. The X-axis represents time and the diagrams cover 18 sec. The Y-axis represents normalised amplitude. It is clear how the driver's manoeuvring of the steering device is directly connected to the lateral acceleration of the vehicle. Further to a timely displacement 15a, which can be seen as the time between two on each other following flanks 14a, the deviation can also be seen in the shape of the curve. These deviations appear because of the condition of the road and the environment and are dependent of the driver's ability to understand and perceive the movements of the vehicle. Thus the diagram according to fig. 3 shows the applied force on the steering device 1 in relationship to the lateral acceleration 2. The X-axis represents time and the shown diagrams cover 18 sec. The Y-axis represents normalised amplitude. The microcommunication takes place in two directions, thus the same signal contains both inquires and responses. To illustrate the driver's response on the movements of the vehicle signal 1 is in this case inverted in relationship to fig. 2. This is possible thanks to that the direction of that on the steering wheel applied force will go to the opposite direction when the driver initiates a wanted movement and when compensating for a not wanted movement. The reaction time 15a of the driver can be seen in the same way as in fig. 2 - with the difference that the flank on the lateral acceleration 14b is initiating.

Fig. 4 discloses the coupling grade between the driver and the vehicle with regard to the reactions of the driver. The X-axis represents time and the shown diagrams cover 18 sec. The Y-axis represents normalised amplitude. The signal for the lateral acceleration 2 is delayed in relation to the signal 1. By calculating the absolute value of the difference between the absolute values of the integrated signals over a certain time 16 the coupling grade is obtained. The time for the delay is either set as a fixed time corresponding to the median value of the reaction time of the driver, or of the instantaneous reaction time - fig. 3 (15b) of the driver. In the same way it is possible to calculate the coupling grade of the vehicle response on the manoeuvres of the driver by delaying a signal 1 in relation to a signal 2 provided that the signals are oriented as in fig. 2. Thus the delay is set to the reaction time 15a of the vehicle.

Fig. 5 is a reaction spectra or more precisely a diagram where the number of different reaction times are summed up over an estimated time and are grouped into four categories of time 12a, b, c, and d. The X-axis is the categories and the Y-axis is relative amplitude where the sum of the number of reactions over the estimated time is 100 %. The category grouping may be done with the interval 0,3s - 0,5s (12a); 0,5s - 0,8s (12b); 0,8s - 1,5s (12c); 1,5s - 2,5s (12d), or in some other way suitable for the application. An increasing fatigue of a certain driver will be seen as a displacement of the reaction times towards longer times 17. The experience of the driver will in the first place influence the longest reaction times 18 where an experienced driver will use proportionately few long reaction times.

Fig. 6 is a well-arranged block scheme of the control system, which involves the driver 33 and the vehicle 34. The electric nerve impulses of the brain 19 will be transformed in the muscle motors of the arms and will be transmitted to the steering device 21 by the hands 20. The steering system 22 of the vehicle will transmit the power, maybe over a steer servo 23 to the steering wheel/tires 24. The seat 25 transfers the movements of the vehicle and the driver is sensible of the movement by the tactile sense 26 and the sense of balance and equilibrium 31. At the same time the driver registers the movement 28 of the vehicle by the eyesight 29. The tactile and balance 27 feed back will be in the frequency register 0,3 to 4 Hz. The eyesight 30 feed back will be in the frequency register 0 - 1 Hz. Often the driver feels some of the movement of the vehicle in the steering device by forces from the steering front wheel are fed back directly by the steering system. For that reason the double directed arrows 21, 22, 23. The surroundings and the road 32 will influence the system from the outside. The signal for the driver's influence on the steering system 1 will be a read off by a power sensor, e.g. strain-gauge sensor on the steering column. A sensor for inertia forces e.g. arranged low and forward in the vehicle reads the signal for lateral acceleration 2.

The invention is not restricted to the examples stated above, but modifications can be made within the scoop of the claims states below.

Claims

A method to measure the interaction driver/vehicle or vice versa during use of a CPU with appropriate software, characterised in that the torque/force on the steering device is recorded by a first sensor and that the lateral forces acting on the vehicle on that occasion are recorded by other sensors, or vice versa, that the recorded values are continuously calculated, filtered and arranged to decide one or several of the following parameters or parameter constellations; the coupling grade, mean values of reaction times, reaction spectra, inquire frequency, fault frequency and variations of amplitudes.

A method according to claim 1, characterised in that the signal (1; 2) from each sensor is passing a phase corrected band pass filter (3) with break frequencies in the magnitude of 0,3 Hz to 5 Hz where also the amplitude is normalised in such a way that the signals are comparable, that the signal for lateral acceleration (2) is delayed in a delay link (6) either with a fixed time corresponding to the median value of the reaction time (17) of the driver, or with the instantaneous reaction time of the driver, that the coupling grade (9) for the reaction of the driver on the movements of the vehicle is calculated (5) as the absolute value of the difference between the integrated signals over a certain time (16), and/or that the coupling grade (9) for the response of the vehicle is calculated if (instead) the signal (1) is delayed (4).

A method according to claim 1, characterised in that the variation (10) of the amplitude is calculated as the difference between the top value and the bottom value of a running mean value of the absolute value of the amplitude during a certain time, e.g. 10 sec.

A method according to claim 1, characterised in that the flank (7) of each signal are detected by derivating each signal and look for the change of sign: zero, plus, zero for a positive flank (14b), and zero, minus, zero for a negative flank (14a), whereby the reaction times (11) are calculated (5) as the time (15a) and (15b) respectively - between a flank on the one signal and next flank on the other signal (14a) and (14b) respectively, and that the reaction times are divided (8) in at least two categories (12a, 12b, 12c, 12d) where the number of different reaction times are summed up for a certain time. A method according to claim 4, characterised in that the reaction times are brought together to a reaction spectra (fig. 5).

A method according to claim 4 or 5, characterised in that the inquire frequency (13a) is calculated (5) as the accumulated number of flanks on each signal for a certain time.

A method according to claim 4 or 5, characterised in that the fault frequency (13b) is calculated (5) as the difference between the accumulated number of positive and/or negative flanks of the signals.

A method according to any of the preceding claims, characterised in that appeared increasing lateral forces are followed of a sound, the strength or frequency of which will increase progressively.

A method according to any of the preceding claims, characterised in that the comfort in the vehicle is proportional against the coupling grade between driver and vehicle.

A device to measure the interaction driver/vehicle, or vice versa, including a CPU with appropriate software, and to perform the method according to claim 1, characterised by a sensor registering the parameter torque/force on the steering device and at least one sensor registering the parameter corresponding to the lateral forces acting on the vehicle, whereby the recorded parameter values are handled by e.g. a band pass filter and delay means, wherein one or more of the parameters or parameter constellations coupling grade, mean value of reaction time, reaction spectra, inquire frequency, fault frequency and variation of the amplitude are arranged and are show and/or may perform an action on the controls of the vehicle and/or on its reckless driving.