System and method of load sharing control for automobile

A system and method for load sharing processing operations between a vehicle mounted station (105) and a stationary base station (25) having a large capacity host computer is described. The vehicle mounted station has detectors for determining operating conditions of a vehicle and controllers (3, 4, 501) for varying the operating conditions. The controllers are connected to a transmitter-receiver (5) which is arranged to communicate over a path (10) with a transmitter-receiver (11) of the base station. The base station has a host computer (18) having a large memory capacity. At predetermined intervals, for example, distance of travel or at engine stop, the vehicle transmitter (5) transmits operating conditions to the base receiver (11) for data processing and the base transmitter (11) then transmits processed data back to the vehicle receiver (5), whereupon the controllers (3, 4, 501) modify the vehicle operating conditions. The vehicle operating conditions may be an indication of life expectancy of fuel injectors or sensors, updating data processing maps. The presence of abnormal operating conditions may be detected by the vehicle mounted station, evaluated by the base station and an emergency warning indication provided back to the vehicle mounted station, or if the abnormal condition is not of an emergency nature then counter measures are transmitted from the base station to the vehicle mounted station.

BACKGROUND OF INVENTION 
1) Field of Invention 
This invention relates to a system and method for load sharing processing 
operations between a vehicle mounted station and a stationary base station 
and in particular for controlling various items of equipment mounted on an 
automobile using a large-capacity host computer installed at a stationary 
base station, e.g. on the ground. 
2) Description of Related Art 
The number of electrically controlled items used in an automobile, 
particularly an internal combustion engine, are increasing and control 
systems therefor are becoming ever more complicated. Several different 
systems have been attempted to collectively control the various items by 
time sharing interruptable arithmetic processing using a processor mounted 
on the automobile. 
Such examples include Japanese Patent Publication No. 63-15469 (1988), 
"Electronic Engine Controller" and Japanese Patent Publication No. 
62-18921 (1987), "Computer for Vehicle Control", and controls using a 
computer are now common. 
A central control method using a LSI microprocessor responds to many 
requirements, such as responding to hazardous components located in the 
exhaust gas of the internal combustion engine and for reducing fuel 
consumption. In addition, microprocessors have been utilized in areas 
extending to attitude control, i.e. levelling control, steering 
performance and driving stability with regard to a vehicle body suspension 
control. 
Regarding transmission of programs between a base station and the vehicle, 
for example, there is Japanese Patent Application Laid-Open No. 62-38624 
(1987), "Radiocommunication Unit". However, this publication relates to 
revision of an operational control program for a vehicle mounted 
processor, and does not teach load sharing under predetermined driving 
conditions. In addition, regarding mutual communications, there is 
Japanese Patent Application Laid-Open No. 62-245341 (1987), "Engine 
Controller", but this describes only installation of a means to load 
failure diagnosis is programs and does not mention any relationship with 
the driving conditions of the vehicle. 
A full dependence upon a vehicle-mounted processor to process all that is 
included in the above mentioned conventional technologies and control 
systems to be newly installed will not only make the system complex but 
also necessitate a large-capacity processor. Computer control has been 
used to exploit such advantages as high processing speed and accuracy, 
easy modification of control characteristics and low cost. However, there 
are numerous control items, including fuel supply control and ignition 
control, for which real-time processing is required and implementing all 
of these together is difficult. 
That is, processing all control parameters including the initial setting 
correction of set values caused by ageing (wear) changes of various 
characteristics, for example, an engine, transmission, steering, 
suspension, within a control system having only a vehicle-mounted computer 
makes the processing program increasingly large. 
However, the conventional technologies are neither concerned with this 
difficulty nor even indicate that there is such a problem. 
SUMMARY OF THE INVENTION 
An object of this invention is to provide a new computer control method for 
vehicles which at least partially mitigates the above mentioned problems. 
According to one aspect of this invention there is provided a method of 
load sharing processing operations between a vehicle mounted station and a 
stationary base station including the steps of said vehicle mounted 
station detecting operating conditions of the vehicle, transmitting data 
representative of the detected operating conditions to the base station, 
said base station receiving data from the vehicle mounted station, 
processing said data in accordance with data stored by said base station, 
said base station transmitting processed data to a receiver at said 
vehicle mounted station and control means at said vehicle mounted station 
connected to the vehicle mounted receiver and being arranged to perform at 
least one of revising or displaying the vehicle operating conditions in 
dependence upon the processed data. 
Advantageously the vehicle mounted station detected operating conditions 
are performed by a detecting means adapted to detect at least one of water 
temperature, air flow ratio air fuel quantity, battery voltage, throttle 
valve opening angle, engine speed, transmission gear position and 
suspension setting. In a feature of this invention the vehicle mounted 
station includes a control means adapted to control at least one of a fuel 
injector, a transmission gear change means, and a suspension setting 
actuator. 
Conveniently the data transmitted from the vehicle mounted station to the 
base station is performed at times of occurrence of predetermined 
conditions including at least one of the vehicle covering a predetermined 
distance, detection of the engine ceasing rotation and low fuel tank 
condition, and advantageously data transmitted between the vehicle mounted 
station and the base station includes header bits, vehicle identification 
bits, data control bits, data array bits, check symbol bits and end of 
transmission bits. 
Preferably the vehicle mounted station transmits a request to transmit to 
the base station, said base station transmits a permission to transmit for 
the vehicle mounted station, said vehicle transmits data including header 
bits, vehicle identification bits, data control bits, data array bits and 
check symbol bits, said base station transmits a receipt acknowledgement 
and said stationary base station transmits end of transmission bits. In 
one preferred embodiment the vehicle mounted station contains at least one 
map indicative of vehicle operating conditions including an indication of 
ageing in at least one of vehicle injectors and sensors, said map being 
transmitted by said vehicle mounted station to said base station, said 
base station comparing transmitted map values with previously transmitted 
map values and estimating the amount of deterioration in said injectors 
and sensors, said base station being arranged to estimate the life 
expectancy of said injectors and sensors and to transmit data indicative 
thereof to said vehicle mounted station whereby said vehicle mounted 
station stores said updated information and indicates the life expectancy 
by visual or aural means. In such an embodiment corrected map values are 
transmitted from the base station to the vehicle mounted station when 
engine rotation has ceased for subsequent real time processing and 
conveniently the vehicle mounted station updates corrected map values in a 
series of steps during vehicle running and uses said corrected map values 
for real time control. 
Advantageously a life predicting diagnosis of the vehicle is carried out by 
the base station by using current operating condition signals received 
from the vehicle mounted station, said predicting diagnosis being carried 
out at predetermined intervals of time or distance travelled. In a feature 
of the invention the vehicle mounted station is arranged to detect an 
abnormality and to transmit data indicative thereof to said base station, 
said base station evaluates said abnormality and determines whether an 
emergency retransmission to said vehicle mounted station is necessary to 
provide an indicative warning by one of a display means or an aural means, 
and in such feature if the abnormality is not of an emergency nature the 
data is stored in a failure chart prior to transmitting counter measures 
from the base station to said vehicle mounted station. 
The vehicle-mounted station may transmit an abnormal condition signal to 
the base station, the base station transmits a request for data to be 
analysed, the vehicle mounted station transmits data for analysis, the 
base station diagnoses a failure and if an emergency is determined by said 
base station then said base station immediately transmits a warning for 
indication by said vehicle mounted station but if said base station 
determines there to be no emergency then said base station stores data 
indicative of the abnormality and subsequently transmits counter measures 
to said vehicle mounted station whereupon said vehicle mounted station 
takes appropriate action in dependence thereof. 
According to another aspect of this invention there is provided a system 
for load sharing processing operations between a vehicle mounted station 
and a stationary base station, said vehicle mounted station including 
detecting means for detecting operating conditions of the vehicle, 
first transmitting means for transmitting data representative of the 
detected operating conditions to the base station, 
first receiving means for receiving data from the base station, 
and control means for controlling vehicle operating conditions, said 
control means being connected to said first receiving means, 
and said base station comprising second receiver means for receiving data 
from the vehicle mounted station, 
processing means and storage means for processing the data received from 
the vehicle mounted station based upon information held in said storage 
means, 
and second transmitting means for transmitting the processed data to the 
first receiving means whereupon the control means is arranged to perform 
at least one of revise or display the vehicle operating conditions in 
dependence upon the processed data. 
Advantageously the detecting means isadapted to detect at least one of 
water temperature, air/fuel ratio, air flow quantity, battery voltage, 
throttle valve opening angle, engine speed, transmission gear position and 
suspension setting. Preferably the control means is arranged to control at 
least one of a fuel injector, a transmission gear change means, and a 
suspension setting actuator. 
Conveniently the first transmitting means is adapted to transmit data 
comprising a header, a vehicle identification, data control bits, a data 
array, a check symbol and an end of transmission indicator. 
In a feature of this invention a vehicle-mounted station includes detecting 
means for detecting operating conditions of a vehicle, 
transmitting/receiving means for transmitting data representative of the 
detected operating conditions to a base station capable of evaluating said 
data, said transmitting/receiving means being adapted to receive evaluated 
signals from the base station and to apply signals representative of said 
evaluated signals to a control means adapted to perform at least one of 
vary or display said operating conditions in dependence upon said received 
evaluated signals. 
In another feature of this invention there is provided a stationary base 
station adapted to receive data from a vehicle mounted station, said base 
station including processing means and storage means for processing the 
data received from the vehicle mounted station based upon information held 
in said storage means, the base station being adapted to perform at least 
one of updating/correcting maps carried by a vehicle located processor 
indicative of ageing in at least one of vehicle located sensors and 
injectors, establish the expected life expectancy of said sensors and 
injectors and further including transmitting means for transmitting 
processed data to a vehicle. 
Thus, the above mentioned object is principally realized by controlling 
load sharing between computers. A study of computer control for vehicles 
indicates that data processing is roughly divided into data requiring 
high-speed real-time processing and data which may be processed in a 
comparatively long period. For example, ignition timing control and fuel 
injection control are control subjects that require processing in 
synchronism with engine rotation so that high-speed processing is required 
in response to high speed engine rotation. On the other hand, modification 
of initial settings because of ageing changes such as those in an engine 
transmission and suspension, may be computed over a relatively long time 
cycle. Also, controls which have to be computed with a high accuracy take 
time when processed by a vehicle-mounted computer and only increase the 
load on the computer. 
Also, with regard to failure diagnosis or failure prediction processing 
when status data is obtained, arithmetic processing itself may be 
separated from the real-time processing without difficulty. Of course, 
there may be some diagnoses which require emergency processing and a 
feature of this invention is to discriminate and act upon abnormal 
conditions that require urgent actions and diagnoses. 
In consideration of the increasing complexity of the control system and the 
necessity for higher speed processing accompanied by the increasing r.p.m. 
of modern engines, this invention carries out load sharing between a 
vehicle-mounted computer and a stationary host computer. 
More specifically a feature of this invention resides in predetermining the 
processing sharing conditions when specific operating conditions of the 
engine or specific conditions of the vehicle-mounted computer are 
detected, transmitting information to and from the host computer and 
sharing the processing. 
The load sharing between the vehicle-mounted computer and the stationary 
host computer is achieved through the following operations. When the 
operating conditions for the engine are detected, the subsequent 
processing thereon is shifted to the host computer to be shared thereby. 
Thus, increases in load on the vehicle-mounted computer are prevented. 
The above operating conditions are detected, for example, at predetermined 
distance of travel, when cumulative driving time reaches a predetermined 
time and/or when a predetermined condition is met such as engine stopped 
or fuel tank low.

DESCRIPTION OF PREFERRED EMBODIMENTS 
In the drawings, FIG. 1 shows one embodiment of the overall system where 
information is transmitted between a vehicle and a host computer located, 
for example, at a stationary, ground based dealership location through a 
telecommunications network. 
An engine 2 in the vehicle is connected with a vehicle mounted computer 105 
including an engine controller 3, a transmission 400 controller 4 and 
suspension 500 controller 501. In the currently described embodiment only 
three controllers are shown, but usually a number of these types of 
controllers are mounted on the vehicle. A transmitter-receiver 5 for 
transmitting and/or receiving information to and from the host computer 18 
is provided within processor 105. 
A telecommunication path 10 which may be wired or wireless, e.g. a radio 
link interconnects the vehicle side located processor 105 with a 
stationary host computer station 25 including a transmitter-receiver 11 on 
the host computer station side of the path. There is provided I/O 
(input/output units) for data analysis 12, I/O for maintenance arithmetic 
processing 13, I/O for failure analysis computation 14 and I/O for vehicle 
information 15 over a 2-way bus to the transmitter-receiver 11 and to the 
host computer 18. The I/O's are also linked to a data base 16 such as a 
memory store. The host computer side apparatus may be installed at the 
vehicle dealership or at a vehicle information service center. Although in 
this exemplary embodiment only 4 I/O's are shown, other I/O's for many 
other controllers may exist. The host computer 18 may have a capacity of 
several mega bytes. Also, here a radio communications link connecting the 
vehicle side and the host side is shown; radio links are preferred as 
being more practical because the vehicle side is normally moving. Of 
course, when occasion demands, information can be transmitted or received 
by wire communication lines from the host computer to a beacon by the 
roadside for subsequent wireless transmission/reception to the 
vehicle-mounted computer. 
Also, in some cases the engine controller 3 or the transmission controller 
4 as shown in FIG. 1 has its own built-in processor and carries out 
respective processings or a vehicle-mounted processor 7 is provided as 
indicated in broken lines. Hereinafter engine controls are described 
wherein a processor for engine control is built in. 
FIG. 2 shows the computer 105 on the vehicle side with the suspension 
controller 501 omitted. ROM 21, RAM 22 and CPU 7 are connected by a bus 
line 30 for I/O processing. The bus line consists of a data bus, a control 
bus, and an address bus. 
Other sensors (of which only two are shown) sense the engine operating 
conditions, inter alia, the engine cooling water temperature (TWS) 32 and 
the air/fuel ratio (O.sub.2 S) 34. Battery voltage and throttle valve 
opening and rotation speed also correspond to operating condition signals, 
but here they are omitted. A multiplexer 36 inputs the operating condition 
signals into an A/D conversion circuit 38. A register 40 sets A/D 
converted values. 
An inlet pipe air flow sensor (AFS) 51 has its value set in a register 54 
after conversion in an A/D converter 52. An engine angle sensor (AS) 56 
provides reference signals REF and angle position signals POS to an angle 
signal processing circuit 58. The processed signals are used to control 
synchronizing signals and timing signals. 
Engine operating condition ON/OFF switches (SWI-SWi) 59-61 indicate 
parameters such as start engine and engine idle. These signals are input 
into an ON-OFF switch-condition signal-processing circuit 60 and are used 
independently or in combination with other signals forming logic signals 
to determine controls or controlling methods known per se. 
The CPU 7 carries out computations based on the above mentioned operating 
condition signals in accordance with multiple programs stored in ROM 21 
and outputs its computation results into respective control circuits 
through the bus lines 30. Here the engine control circuit 3 and the 
transmission control circuit 4 have been shown, but numerous other control 
circuits such as an idle speed control circuit and exhaust gas 
recirculation (EGR) control circuit are possible. 
The engine control circuit 3 has a fuel controller for controlling air/fuel 
ratios and increases or decreases the amount of fuel supplied by 
controlling an injector 44. 42 is a logic circuit for these controls. The 
transmission controller 4 carries out a transmission shift 48 in the 
transmission 400 through a logic circuit 46 based on the computation 
results of the driving conditions. A control mode register 62 presents 
timing signals for various control outputs. 
Timing circuits 64-70 control transmitting and receiving operations. For 
example, circuit 64 outputs a trigger signal into the transmitter-receiver 
whenever a predetermined distance is travelled and transmits a 
corresponding engine operation condition signal through the 
transmitter-receiver to the stationary host computer. A display 90 is used 
to display instructions to the driver. 
Circuit 66 is used to detect an engine stopped and to trigger an output 
signal thereupon. Circuit 68 is used to detect a low fuel tank condition 
and trigger an output signal thereupon. Circuit 70 is used to check 
whether predetermined conditions are met and when satisfactory, generate a 
trigger output signal. FIG. 3 shows symbol illustrations of these 
circuits. 
To sum up, circuits 66 to 70 produce signals which decide timing to 
transmit operating condition data to the stationary host computer. For 
example, from the circuit 64 which generates a signal whenever a 
predetermined distance has been travelled, it is possible to diagnose the 
operating condition per the predetermined travel distance. When only 
condition signals are transmitted, the host side computer makes a 
diagnosis based on deviations from the previous values or past condition 
signal data and conveys instructions based on its results to the 
vehicle-mounted computer. The vehicle-mounted computer gives driver 
instructions through a display or alarm in dependence upon the severity or 
grade of those instructions or modifies processing programs or sets 
parameter values. 
FIG. 4(A) shows an example of a data array and FIG. 4(B) shows a data 
transmitting and receiving sequence during data communications between the 
vehicle-mounted computer and the stationary, e.g. ground, host computer 
(here a dealer located computer). A subject vehicle is specified by a 
header and a vehicle number (a number that is unique to the vehicle such 
as the engine number or the car body number). 
FIG. 5 shows a processing example when correction items in the map matching 
are checked (data analysis), the transmitter-receiver 11 at the dealer 
side being omitted for clarity. When controlling an engine via a 
microcomputer, control data is computed based on output conditions of each 
sensor. In addition, a system is used for subsequent engine control by 
responding to various engine conditions and by storing control data 
computed as a learning map. FIG. 5 shows an example of using other control 
data values after corrections by analysing such control data stored in the 
so-called learning map or data to be changed together with other engine 
controls. 
The program processing on the vehicle side is assumed in this example to be 
to check a map (step 5a). This satisfies conditions by the circuits 64 to 
70 as described previously and the checking program of the map starts. 
Although this is simply called map matching, there is a learning map for 
ignition timing based on the output of a knock sensor or a learning map 
for defining an injection pulse width of the fuel injector based on the 
fuel/air (O.sub.2 feedback) from an exhaust to an inlet fuel injector, 
i.e. an O.sub.2 detector detects if exhaust gas mixture is lean or rich 
and sends a pulse in dependence thereon to the fuel injector. Map revision 
is described later in detail with reference to FIG. 8. Now, the flow of 
the transmission processing at the time of map matching is generally 
explained. 
In step 5a, the vehicle-mounted computer checks data in the map by using 
various methods. For example, when data values contained in the learning 
map for defining the injection pulse width of the injector using 
parameters of number of revolutions of the engine N and engine load Qa/N 
(where Qa is quantity of air) during O.sub.2 feedback are analysed, the 
corresponding map of the output of the inlet pipe air flow sensor and the 
air flow quantity is revised by comparing actual data values with previous 
data values and if the comparison result exceeds a predetermined value 
then the actual value is used to reset the map, thus effecting a 
"learning" process. The injector factor is also revised when the injection 
pulse width of the injector is determined in relation to the engine load 
Qa/N. Based on checking of the map, engine control data revisions are 
determined. In step 5b, the vehicle-mounted computer selects necessary 
data values in the map under check to be used to newly correct engine 
control data or computes data to be transmitted to the host computer by 
processing data values stored in the map and stores them in RAM as a map. 
When data to be transmitted is determined such is rendered as a trigger 
signal, the map arithmetically processed in the vehicle-mounted computer 
and contained in RAM is transmitted through the transmitter-receiver 5. 
The dealer side (host computer), having received this, executes its 
program based on received signals. In step 5c, data signal reception from 
the vehicle-mounted computer is started. However, in step 5d, if the 
dealer-side is already receiving data from another vehicle, a wait 
instruction is issued in step 5e. When not receiving data from another 
vehicle, the received data is stored in the memory of the host computer in 
step 5f. In step 5g, present memory values are compared with past values 
previously transmitted to the host computer. In step 5h, the amount of 
deterioration in actuators, such as injectors, and sensors such as inlet 
air quantity (Qa) sensors, is estimated based on the compared results. 
Next, in step 5i, the remaining life is estimated from the deterioration 
amount. In step 5j, data transmitted from the vehicle-mounted computer is 
computed in accordance with a predetermined program to determine data to 
be corrected at the vehicle computer. In step 5k, this data is transmitted 
through the transmitter-receivers 11 and 5. When it receives a 
transmission signal from the host computer, the vehicle-mounted computer 
starts the arithmetic processing. When in step 51 receiving the corrected 
map transmitted from the host computer commences, it is stored in RAM in 
step 5m. In step 5n, the corrected map is re-written when the engine 
restarts after stoppage. In step 5p, notification is made to the driver 
visually, through the display or audibly that the map has been re-written. 
This is an example of notifying the driver for caution's sake, because 
correction items of the map may influence driving characteristics of the 
vehicle and even whether the vehicle should be driven. However, for cases 
that do not specifically require this, notification can be omitted. Also, 
in step 5p, it is possible to display the deterioration amount and 
remaining life of the injector or sensor. Alternatively, re-writing the 
map at the time of re-starting the engine for example and/or shifting to 
the corrected map during travel can be made. However, at this time a 
method to enable a smooth transition is preferred. For example, methods as 
follows may be carried out, in that, when the deviation before correction 
is smaller than a predetermined value, a sequential transition is made and 
when the deviation is larger than the predetermined value, its 
intermediate value (in some cases, plural intermediate values) is 
established and shifted step by step to a corrected map. In addition, 
re-writing the map may also be carried out in a predetermined period after 
the power key switch is turned off, i.e. power is supplied for a 
predetermined period after the power key switch is turned off to enable 
the map to be re-written or memorised. 
FIG. 6 shows an example of a failure diagnosis, the transmitter-receiver 11 
again being omitted for clarity. The vehicle-mounted computer carries out 
time-sharing computations of the injection pulse width for the injector 
and ignition timing in real time. For this, computations for a failure 
diagnosis are made in the intervals of these computations and only a basic 
diagnosis are made. This embodiment is based on the concept of having the 
vehicle-mounted computer make a basic abnormal diagnosis and transmit the 
data to the host computer. The host computer then makes more advanced, 
comprehensive and appropriate diagnosis using data indicative of the 
condition of other control subjects. 
In step 6a, the diagnostic mode starts. This is carried out in parallel 
with the general program and for example, is repetitive at predetermined 
intervals of about 60 ms. In step 6b, a decision on whether any 
abnormality exists is made based on the diagnosis results. When no 
abnormality exists, the process ends. When an abnormality exists, the 
abnormal code is transmitted to the host computer on the dealer side 
through the transmitter-receivers 5 and 11. The host computer is triggered 
by the transmitted signal and executes a more detailed failure diagnosis 
program. Having received the abnormal code in step 6c, in step 6d, the 
host computer selects comprehensive control data necessary for failure 
diagnosis based on the abnormal code and asks the vehicle-mounted computer 
to transmit data for decision. Upon receipt of the request for 
transmission, the vehicle-mounted computer transmits the data for decision 
in step 6e. In step 6f, the host computer diagnoses comprehensively the 
failure using the data for decision transmitted from the vehicle-mounted 
computer. In this case, because the host computer is not carrying out the 
real-time arithmetic processing such as computation of the injector's 
injection pulse width, if the results of the failure diagnosis in step 6f 
in which an overall diagnosis is possible based on the data transmitted 
from the vehicle-mounted computer indicate an emergency, the host computer 
immediately transmits emergency measures to the vehicle-mounted computer. 
If an emergency treatment is not specifically diagnosed, the host computer 
stores the received data in a failure chart in step 6i and subsequently 
transmits countermeasures to the vehicle-mounted computer in step 6j and 
completes the diagnostic flow in step 6l. In step 6k, the vehicle-mounted 
computer takes actions based on the countermeasure signals from the host 
computer and ends the diagnostic mode process at step 6m. 
FIG. 7 shows an example regarding life prediction or failure prediction in 
accordance with data collected through sampling over a long period of time 
in which the transmitter/receiver 11 is again omitted for clarity. In step 
7a, the vehicle-mounted computer carries out data sampling at every 
predetermined interval to detect abnormalities. Detection of abnormalities 
in this case is a very simple detection of abnormalities and a high-level 
failure diagnosis is carried out by the host computer. In step 7b, an 
existence of abnormalities is confirmed and in step 7c, the 
vehicle-mounted computer transmits the necessary data including sampling 
values to the host computer through the transmitter-receivers 5, 11 and 
completes the flow process. If there is no abnormality, the flow process 
is completed. In addition, in view of the long-term data sampling, 
high-level failure diagnoses by the host computer may be made at every 
predetermined distance of travel as shown in FIG. 3 or by the circuit 64 
in FIG. 2. Upon receipt of the data transmission signal from the 
vehicle-mounted computer, the host computer starts the failure diagnosis 
program in step 7d. In step 7e, control data accumulated in the memory of 
the host computer is analyzed to predict life expectancy. In step 7f, 
defective parts are specified from data analysis results. In step 7g, the 
degree of emergency is determined. If there is an emergency, the host 
computer transmits a signal to that effect to the vehicle-mounted computer 
through the transmitter-receivers 11, 5 in step 7h. The host computer 
makes life expectancy predictions based on the analysis results and stores 
the predictions in the failure chart at step 7i. At step 7j, 
countermeasure signals are transmitted to the vehicle-mounted computer to 
complete the flow process in step 7l. The vehicle mounted computer, in 
step 7k, takes action in accordance with the signal transmitted from the 
host computer and completes the process. 
Thus, this invention has shared processing where items are divided into 
those requiring processing by a vehicle-mounted processor and those 
requiring long-term or highly accurate computations by a stationary larger 
computer. Having a vehicle-mounted processor execute all processings, as 
has been performed in the prior art, only makes a vehicle-mounted 
processor larger in capacity and physical size. 
With regard to checking of the matching map as well as checking of revision 
items in the map, as performed in steps 5a and 5b of FIG. 5, a detailed 
explanation will now be made by taking map revisions based on the 0.sub.2 
feedback map as an example. Although there is a prior application 
(Japanese Patent Application No. 63-283886 (1988)) by the same applicant 
as this invention regarding 0.sub.2 feedback and learning based thereon, 
its basic methods and concepts are described as follows. The injection 
time of the injector is determined by the equations (1) and (2) below. 
EQU Ti=.alpha..multidot.Tp.multidot.(Ke+Kt-Ks).multidot.(1+.SIGMA.Ki)+Ts(1) 
EQU Tp=Kconst.multidot.Qa/N (2) 
where 
Kconst: injector factor 
Tp: basic injection time 
.alpha.: correction factor for air/fuel ratio 
Ts: delayed injection time of injector due to mechanical and electrical 
propogation lag 
Ke: steady-state learning factor 
Kt: transient learning factor 
Ki: a correction factor 
Ks: shift factor 
Qa: sucked air flow amount 
N: number of engine revolutions 
That is, a basic fuel injection time Tp is determined through a sucked air 
flow amount of Qa of the engine and the rotational speed N from equation 
(2) and the correction factor .alpha. is changed and corrected so that a 
stoichiometric air/fuel ratio is obtained based on the output of the 
air/fuel (0.sub.2) sensor. Here, the correction factor .alpha. largely 
deviates from 1.0 because of "ageing" changes in actuators such as the 
injectors and of sensors. Therefore, supplementary corrections are 
performed by means of the steady-state learning factor Ke and the 
transient learning factor Kt to make the correction factor .alpha. be 
nearer to 1.0 and determine the fuel injection time Ti. 
FIG. 8 shows a flow chart for preparing correction maps. In step 8a, the 
0.sub.2 feedback learning map is checked to decide whether there are maps 
requiring corrections. Based on the check results, a decision is made in 
step 8b whether there are maps requiring re-matching. If not, the process 
ends. In this embodiment, a Ts map, a Kconst map and a Qs table are 
illustrated as maps requiring re-matching. Maps requiring re-matching are 
specified in steps 8c, 8e and 8h and in each of steps 8d, 8f and 8i, 
control data to be transmitted to the host computer is selected or 
computed if necessary and is stored in the RAM address of the 
vehicle-mounted computer to prepare the maps. In step 8j, header data of 
revision items corresponding to the map to be corrected is prepared, the 
corrected map is read out from RAM to write in the transmission area in 
preparation for transmission to the host computer in step 8k and the flow 
is completed. 
Criteria to decide whether a revision is required and specific revision 
procedures are made in accordance with, for example, prior Japanese Patent 
Application No. 63-181794 (1988) of the present applicants. 
FIG. 9 shows an example of data transmission and reception when an engine 
stops. The engine is controlled by a microcomputer by computing control 
values to control actuators such as the injector based on outputs of each 
sensor, including the inlet air flow and crank angle sensors. Each datum 
may be required for failure diagnosis and matching by the host computer. 
Necessary data is taken in and stored in the host computer at every 
ignition key turn OFF. 
In step 9a, a decision is made whether the ignition key is turned ON or 
OFF. When turned ON, the engine is running and the flow terminates. In 
step 9b, a decision is made whether the engine is rotating or not. When 
rotating, the flow ends. In steps 9c and 9d, a decision is made whether 
data transmission to the host computer is required or not. In other words, 
when the previous revision request is issued in step 9c and when there are 
revision items of the map to be corrected in step 9d, a decision is made 
that data transmission is required and operation proceeds to step 9e. 
Otherwise, operation proceeds to step 9i. In step 9e, a mask setting for 
transmission/reception is made to prevent interruption, the 
transmission/reception program is executed in step 9f and the mask is 
cleared in step 9h. In step 9h, transmission/reception is carried out 
through the transmitter-receiver 5 if transmission/reception is possible. 
If transmission/reception is not possible, the flow ends. When 
transmission/reception is made, the flow proceeds to step 9i, self-shut 
off and automatically stops the computer after the elapse of a 
predetermined time. 
Next, the execution of data matching in step 5j of FIG. 5 by the host 
computer will be explained by taking FIG. 10 as an example. 
FIG. 10 is an example of obtaining deviations from the previous revision 
data and for evaluating correction values. In step 10a, a decision is made 
whether the revision is the first or not. If it is the first revision, 
basic data is stored in step 10c. If not, the previous data is retrieved. 
In step 10d, a correction value is calculated from the map data 
transmitted from the vehicle-mounted computer, revised (corrected) values 
in each map are calculated in step 10e, the calculated values are stored 
in the memory in step 10f and the process completes. 
FIG. 11 is an exemplary flow diagram of data transmission/reception. The 
vehicle-mounted computer starts a flow process at every predetermined 
interval. In step 11a, a decision is made whether the revision request has 
been completed or not. When completed, the flow proceeds to 11g and moves 
to the data return transmission program. If there is a transmission 
request in step 11b, necessary data is transmitted to the host computer. 
Next, the vehicle-mounted computer awaits until the host computer 
transmits a signal permitting transmission. In step 11l, the host computer 
receives the transmission signal from the vehicle-mounted computer and at 
step 11m determines if it is ready to receive the transmission from the 
vehicle-mounted computer. If it is ready a signal permitting transmission 
is derived in step 11n and if it is not ready then a wait instruction is 
issued in step 11o. The vehicle-mounted computer transmits data in step 
11d if it has received a transmission permit in step 11c, lights up the 
display lamp in step 11e and applies a revision request flag ON in step 
11f . If there is no transmission permit, the flow process ends. The host 
computer, which has received data, processes the data in step 11p and 
then, if the vehicle-mounted computer requires data return transmission in 
step 11g, decides whether return transmission is possible or not in step 
11q. If return transmission is possible, it transmits back the processed 
data in step 11r. If it is not possible to transmit data back, the host 
computer issues a wait instruction in step 11s and transmits back the data 
in step 11t. The vehicle-mounted computer releases the wait condition and 
receives the processed data in step 11h when a signal permitting data 
return transmission is transmitted, re-writes the data in step 11i based 
on the data transmission from the host computer in step 11t, turns OFF the 
display lamp in step 11j, puts OFF the revision request flag in step 11k 
and completes the process. 
Having now fully described the present invention it will be realised that 
processing by a vehicle-mounted computer can be transferred to a 
stationary host computer as the occasion demands and real-time vehicle 
controls are implemented effectively without increasing the workload of 
the vehicle-mounted computer. 
It is to be understood that various modifications may be made and that all 
such modifications falling within the spirit and scope of the appended 
claims are intended to be included in the present invention.