|Title of Invention||
A CONTROL SYSTEM FOR VEHICLES
|Abstract||A control system is specified for vehicles, in particular rail-bound vehicles, having a plurality of computers and at least one bus manager. The bus manager coordinates the transmission of data protocols between the computers via a common bus. All the computers and bus managers operate asynchronously with a separate clock. The bus manager provides data protocols which are important for the operation of the vehicle with a chronological offset. As a result of the chronological pairing of the data protocols dead times during the processing of the data protocols are avoided. (Figure 1)|
|Full Text||The invention relates to the field of control and instrumentation technology. It is based on a control system for vehicles in accordance with the preamble of the first claim. Such a control system can be used in particular for controlling and regulating rail-bound vehicles, in particular for locomotives.
Discussion of Background
A control system of the generic type is described in the third part ("Multifunction Vehicle Bus") of the Standardization Proposal lEC 9 332 for a train data network, Version 1.8, October 1994. The control system here is one which exchanges data between various computers via a so-called multifunction vehicle bus. The exchange of data on the bus is coordinated by one or more bus managers. The transmission of data takes place asynchronously, that is to say each computer or bus manager has a separate clock. As a result of this asynchronism, at the time when new data arrives, a computer may not actually be ready to receive and process this data. The bus manager transmits a series of data protocols during a so-called bus cycle. The transmission sequence of the data protocols is determined by the bus manager. As a result, the sequence of for example two data protocols may be interchanged and the computers in question may only be able to extract the data from the next bus cycle. Owing to these two circumstances caused by the asynchronism, dead times in the processing arise. In a normal case, this is not particularly disruptive since in most cases it is only necessary to process control tasks for which it is not significant whether the data
is processed immediately or not. However, in the case of data which is important for the operation of the vehicle, the dead times may have disadvantageous consequences. Thus, for example the power converter control unit (SLG) and the drive power converter controller (ASC) of a locomotive are also connected to one another via this bus, and the data for the regulation of adhesion is transmitted from the ASC via the bus to the SLG and processed there. With a computing time of several milliseconds and a bus cycle of for example 16 ms, dead times and fluctuations up to 30 ms may arise owing to the asynchronism of the two devices during the calculation of the adhesion regulation data. As a result, under certain circumstances, the regulation means reacts to modified adhesion conditions too late. This has a negative effect on the quality of the ride and the efficiency of the locomotive. On a wet rail on an incline with a heavy load the vehicle may even fail to move off.
SUMMARY OF THE INVENTION
Accordingly one object of the invention is to provide a novel control system in which such dead times, and thus also the negative influences on the operation of a vehicle, can be avoided.
This object is achieved with a control system of the type mentioned at the beginning by means of the features of the first claim.
The essential idea of the invention is therefore that those data protocols which are significant for the operation of the vehicle are provided with a defined chronological offset with respect to one another and that these specific data protocols trigger an interrupt in the computer for which they are determined.
As a result of the interrupt it becomes possible for the data protocols to be processed immediately. The chronological offset permits
synchronization between the computers involved and ensures that the necessary data protocols occur in the correct sequence. In this way, the disruptive dead times are effectively avoided.
In a realized exemplary embodiment, the specific data protocols constitute a desired value which is transmitted from a first computer to a second computer, and an actual value which is transmitted from the first computer to the second computer. The invention is used to particular advantage for regulating the adhesion of a locomotive. In this case, for example a drive control unit specifies a desired traction force value or braking force value which is set in a drive supervision unit. As a result, an actual" traction force value or braking force value is set. The said value is transmitted to the drive control unit where it serves for the calculation of a new desired value. This value is subsequently fed in turn to the drive supervision unit and the process described above starts again. With the system according to the invention it has been possible to improve drastically the adhesion properties of an electric locomotive.
Further exemplary embodiments result from the corresponding dependent claims.
Accordingly, the present invention provides a control system for vehicles, in particular for rail-bound vehicles, in particular locomotives, comprising a bus to which at least two computers and at least one bus manager are connected, each computer and each bus manager operating asynchronously from one another and each bus manager coordinating the transmission of data protocols which circulate on the bus between the computers, wherein the bus manager is provided for providing specific data protocols, which are important for the operation of the vehicle and are required by at least two computers, with a chronological offset tl which can be prescribed from the outside, and wherein these specific data protocols are provided for triggering an interrupt in the computers for which they are intended.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
Fig. 1 shows a schematic view of a control system according to the invention;
Fig. 2 shows a portion of the control system according to the invention with two computers which communicate with one another;
Fig. 3 shows a time diagram with two different data protocols.
The reference symbols used in the drawings and their meanings have been listed compiled in the reference list.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, in Figure 1 an outline of a control system according to the invention is shown. 1 designates a bus to which a number of computers 2 and at least one bus manager 3 are connected. The computers 2 exchange data and addresses via the bus. The exchange of data is coordinated here by the bus manager or managers 3.
The data protocols are transmitted cyclically with a bus cycle time TB. The sequence or the chronological order of various data protocols can be freely selected by the bus manager so that the sequence of the data protocols has, under certain circumstances, just been interchanged or the chronological interval between the data protocols is too small or too large. Further information on the definition of the data protocols etc. can be found in the standardization proposal mentioned at the beginning. Therefore, the contents of this document are to be expressly included in the description.
Each computer 2 and each bus manager 3 operate asynchronously, i.e. they have their own clock. Figure 2 shows, by way of example, two computers 2 which are connected via the bus 1. The said computers are, on the one hand, a drive control unit 4 and a drive supervision unit 5, for example of an electrical locomotive. An adhesion regulator II is provided in the drive control unit 4 and a drive regulator 16 is provided in the drive supervision unit 5. The drive regulator of is connected to a drive power converter 6
and actuates it. The power converter 6 drives a motor 7. Furthermore, a rotational speed detection means 12 is provided which measures an actual rotational speed value of the wheels of the vehicle. This can be carried out for example by means of a known Wigand sensor. The actual rotational speed value and an actual traction force value or actual braking force value are now transmitted from the drive supervision unit 5 via the bus 1 to the drive control unit 4. A new desired traction force value or desired braking force value is calculated there from this data in the adhesion regulator 11. The said desired traction force value or desired braking force value is subsequently transmitted to the drive supervision unit 5 and set. A new actual value is set and the control loop is run through again.
In a system according to the prior art, it may be the case that, for example the drive control unit 4 is not ready to receive the data at the moment when the data arrives from the drive supervision unit 5. This is insignificant when there is less relevant data since the bus manager transmits the data periodically with a bus cycle time TB. The drive control unit 4 can therefore retrieve the data at the next bus cycle. However, this results in the dead times mentioned at the beginning which do not have any large influence on data which serve for example exclusively for control and therefore do not have critical timing. The dead times can also arise within a bus cycle as a result of the optional sequence of the data protocols which is determined autonomously by the bus manager alone. Thus, for example the sequence of the desired values and actual values can be interchanged.
However, desired and actual values of the traction force and/or braking force are fundamentally important for the operation of the locomotive and also for the adhesion regulation which depends thereon. Therefore, these dead times should be as far as possible avoided. This is also particularly the case
because the adhesion regulation is very intensive in terms of computation.
The dead times are avoided according to the invention in that the data protocols which are important for the operation of the vehicle - for example actual rotational speed value and desired and actual values of the traction force or braking force -are provided with a prescribable chronological offset Tl with respect to one another (see Fig. 3). This determines the sequence and the chronological order of the data protocols in question. Dead times as a result of interchanging the sequence or as a result of unnecessary waiting for the necessary data can thus be avoided. In Figure 3, two different data protocols, whose chronological offset within one bus period TB is tl are illustrated by way of example. The chronological offset tl can be for example precisely half of one bus period; other values are of course also conceivable. In the realized exemplary embodiment, the bus period TB was 16 ms while 8 ms was selected for the chronological offset.
Furthermore, an immediate evaluation of the data protocols is achieved in that the data protocols trigger an interrupt in the computers in question. As a result, undelayed processing of the data protocols is ensured, and dead times resulting from busy computers can be avoided. For this purpose, the computers comprise a buffer 8 in which the data can be buffered after arrival (see Fig. 2). At the same time, an interrupt 9 is triggered and the data is loaded into the corresponding regulator 10 or 11 and subsequently processed.
With the system according to the invention it has been possible to set the reaction time of the adhesion regulation constantly to less than 20 ms. In the prior art, the reaction time fluctuated between 63 ms and approximately 21 ms. As a result of this constant reaction time, which is also reduced in comparison with the prior art, it has been possible to
achieve a considerable improvement in the adhesion behavior of an electric locomotive.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
LIST OF DESIGNATIONS
3 Bus manager
4 Drive control unit
5 Drive supervision unit
6 Drive power converter
10 Drive regulator
11 Adhesion regulator
12 Rotational speed detection means
1. A control system for vehicles, in particular for rail-bound vehicles, in particular locomotives, comprising a bus (1) to which at least two computers (2) and at least one bus manager (3) are connected each computer (2) and each bus manager (3) operating asynchronously from one another and each bus manager (3) coordinating the transmission of data protocols which circulate on the bus (1) between the computers (2) wherein the bus manager (3) provides specific data protocols, which are important for the operation of the vehicle and are required by at least two computers (2) , with a chronological offset tl which can be prescribed from the outside, and wherein these specific data protocols trigger an interrupt (9) in the computers (2) for which they are intended.
2. The control system as claimed in claim 1, wherein the specific data protocols comprise a desired value, which is transmitted from a first computer (2) to a second computer (2), and an actual value, which is transmitted from the second computer to the first.
3. The control system as claimed in claim 2, wherein the desired value and actual value are traction force values and/or braking force values and the first computer is a of a drive control unit (4) and the second computer is a component of a drive supervision unit (5).
4. The control system as claimed in claim 3, wherein the drive control unit (4) prescribes a desired traction force value or desired braking force value which is set in the drive supervision unit (5), and as a result of which an actual traction
force value or actual braking force value is set, and wherein this actual traction force value or actual braking force value is passed on from the drive supervision unit (4) to the drive control unit (5) by means of which a new desired traction force value or desired braking force value is calculated in the drive control unit (5).
5. The control system as claimed in claim 4, wherein
the chronological offset tl is selected to be less
than or equal to a first time period which is
required to set the desired traction force value
or desired braking force value and is selected to
be less than or equal to a second time period
which is required to calculate new desired
traction force values or desired braking force
6. The control system as claimed in one of claims 1
to 5, wherein the bus manager (3), or each bus
manager (3) transmits the data protocols
cyclically with a time period TB, and the
chronological offset tl corresponds to half a time
7. A control system for vehicles, in particular for rail-bound
vehicles substantially as herein described with reference
to the accompanying drawing.
95/075 LIST OF DESIGNATIONS
3 Bus manager
4 Drive control unit
5 Drive supervision unit
6 Drive power converter
10 Drive regulator
11 Adhesion regulator
12 Rotational speed detection means
|Indian Patent Application Number||989/MAS/1996|
|PG Journal Number||20/2006|
|Date of Filing||07-Jun-1996|
|Name of Patentee||DAIMLERCHRYSLER RAIL SYSTEMS GMBH|
|Applicant Address||SAATWINKLER DAMM 43, 13627 BERLIN|
|PCT International Classification Number||B61C15/08|
|PCT International Application Number||N/A|
|PCT International Filing date|