METHOD AND APPARATUS FOR READING TACHOGRAPH CHARTS

Abstract: Method and apparatus for reading tachograph discs employs a document scanner feeding data to a personal computer and associated printer. Analysis of electronic data from the scanner enables first the establishment of the disc type and orientation, followed by identification of the data traces and analysis of these by reference to concentric bands of the disc which are converted from circular to linear form, and by a line-following process, as part of the data-processing method. Activities and violations of international vehicle regulations can be identified by counting the crossing points of the graphic trace with respect to predetermined traces representing vehicle use parameters such as speed. The computer produces a graphic display or printed summary of the data or image from the disc.

Description: METHOD AND APPARATUS FOR READING TACHOGRAPH CHARTS This invention relates to a method and apparatus for reading the recorded graphic data on tachograph charts, for example tachograph discs. By the term "chart" as used in this context it is intended to refer to not only discs but also charts which may be used for a similar purpose in any other suitable shape or form. Legal requirements relating to the enforced use of tachograph apparatus for recording data relating to vehicle use have been in force in at least many European countries for many years. The regulations relating to the use of -tachographs are modified from time to time, and also vary from country to country. The legislation and regulations require the fitment and use of tachographs on most goods vehicles and passenger vehicles, including coaches and long distance buses. Tachographs • record the times and dates of all vehicle movements, together with details of speed and hence distance travelled, driver particulars, vehicle particulars, and journeys undertaken. As a result of legislation and regulations relating to vehicle drivers and their periods of work, and vehicle milage and history and use, employers must organise drivers' work in such a way that these requirements are complied with. Tachograph charts represents a way of monitoring compliance in this regard. It will be understood that the regulations relating to tachographs require that the charts be monitored and interpreted at regular intervals. Accordingly, in view of the very high numbers of vehicles in daily use in industrialised countries, the number of tachograph discs requiring reading and interpretation every day is extremely large. Presently used methods of reading and interpreting tachograph discs are, to the best of the applicants' knowledge, all based on human visual interpretation of the discs in association with various visual and data-recording aids. Thus, for example, a typical tachograph disc reader comprises a manually operated disc table with cursor, an illuminated magnifying lens for visually inspecting the disc, a small keyboard for the operator to key-in data read from the tachograph disc, and various colour-coded light-emitting diodes which serve as visual aids for the user of the apparatus and to serve as reminders of functions of the apparatus which have been used or are in use. Thus, existing systems forreading tachograph charts rely entirely upon human effort and visual inspection of the disc itself, coupled with a requirement for accuracy in keying-in the information visually read. Obviously, such a system is - somewhat time-consuming to use and is extremely subject to the inherent inaccuracies of a visual inspection and keying-in procedure, due to factors such as fatigue and interpretation errors. Other shortcomings include the likewise inherent difficulties in such an inspection process for detecting cleverly concealed falsification of the graphic record such as, for example, the forcible manipulation of the tracing element so that it indicates a vehicle speed which is significantly lower than the actual speed. An object of the present invention is to provide a method and apparatus for electronically reading the recorded graphic data on tachograph charts offering improvements in relation to the speed and/or accuracy and/or efficiency of reading the data and/or converting same into text and/or numerals, without requiring human visual interpretation of the data as a step in the production of said text and/or numerals, and/or any one or more improvements in relation to other matters discussed or disclosed herein, or generally. According to the invention there is provided a method of reading the recorded graphic data on a tachograph chart, and apparatus for such reading, as defined in the accompanying claims. In an embodiment described below, a method and apparatus for reading the recorded graphic data on a tachograph disc employs electronic scanning apparatus on which a tachograph chart is located, in use. The chart is electronically scanned by the scanner so as to produce electronic data representative of the data recorded on the chart. The scanner also produces data relating to the disc itself enabling the dimensions and orientation of the disc to be used in computing and analysing the recorded graphic data on the disc. In the embodiment, the electronic data produced by the scanner is fed to a computer in which the data is processed so as to modify the form of the graphic data so that it can be visually presented in the form of text, charts, graphic display and/or numerals. Thus, for example, the scanner/computer combination can be linked to a printer in order to generate printed paper copies (hard copies) of numerical and textual data and images corresponding to the graphics recorded on the tachograph disc. Thus., for example , the printed textual/numerical/graphical data may include a statement of the sequence of activities carried out by the vehicle concerned, such as rest, driving, and other work, with a list of times from and to, for each type of activity, and a summary of the hours and minutes between these times. There may also be provided an overall summary of the activities carried out by the vehicle. Other options include a presentation of vehicle speed and distance travelled, together with other corresponding summaries and, on demand, a hard copy of the graphic trace area where an infringement of a regulation has occurred. As a result of the ability of the apparatus to read the recorded graphic data in an automatic mode and with automatic and practically simultaneous conversion of the graphic data so that it can be presented in textual and/or numerical form, together with, or alternatively as, a copy of the graphic trace itself, there is provided the ability to analyse and report the content of tachograph discs in a rapid and automatic way and with a very high degree of accuracy and consistency, and without the inherent variability of analyses based upon human observation. In the embodiment the overall processing of the data from the scanner comprises the preliminary step of processing scanned data relating to the tachograph chart itself, that is to say its shape and dimensions, this data being processed to establish the type and orientation of the chart. For this purpose, the chart is scanned to identify its characteristics. These are identified by colour or intensity changes with respect to the background colour or intensity of the support on which the chart is located. In the case where a circular chart or disc is being analysed, the data from the scanner is -processed to identify sufficient edge points on the disc, whereby its centre can be calculated. For example, four edge points may be established, these being obtained by identifying the topmost and bottommost black/white transitions and the leftmost and rightmost black/white transmissions. These transitions between the white of the disc and the black of its backgroundproviding a direct identi ication of the disc edge. In regard to the graphic data recorded on the tachograph chart, analysis of same by the computer comprises identifying the graphic trace by identifying colour or intensity changes on the disc with respect to the basic disc colour/intensity. It is preferred to analyse on the basis of colour ie the black of the trace and printed matter, and the white of the disc background. All other colours are masked out. Having identified the trace itself, the data analysis proceeds by dividing the tachograph chart data into data relating to the concentric bands on the chart, and this data is then transformed by the computer so as to correspond to a linear representation of these concentric bands. This linear representation of the disc is used as a basis for the interpretation of the distance and activity and speed data recorded on the chart. In this way, the graphic data from the tachograph disc itself can be reliably computed to generate text, graphical display, and/or numerical data which is readily understood and read by even a relatively unskilled person. An embodiment of the invention will now be described by way of example with reference to the accompanying drawing which shows a typical tachograph disc. In the embodiment, the apparatus consists of a document scanner coupled to a personal computer incorporating a programme to analyse the scanned tachograph image. ' While a document scanner is currently preferred as the scanning apparatus, it is envisaged that alternative electronic scanning means such as an electronic camera may be substituted. The results generated provide details of driver and vehicle activity, distances covered and vehicle speeds, together with any other trace information recorded by the tachograph on the tachograph disc surface. This data is printed in the form of text, graphs and numerals by means of a standard printer, for example a laser printer. A summary of the steps involved in reading the tachograph disc, analysing the data, and re-presenting same is as follows • 1 Scan the disc image using a document scanner; 2 Filter out colours so that analysis is based upon the black of the graphic trace and the white background; 3 Identify four edge points by noting the limits of the black/white change between the disc and its background, top and bottom and left and right; 4 Identify centre of disc by intersecting two diameter lines based on identified edge locations; 5 Identify "12 o' clock" position on disc by finding disc eccentric cut-out location; 6 Read disc concentric bands and straighten same at known radii for distance and activity and speed analysis; 7 Follow graphic trace lines using specific graphic- following techniques; 8 Interpret trace lines on basis of knowledge of disc layout; and 9 Produce output to meet operator requirements, such as text/numerals/graphic data. In use, the system operates in the following manner. The tachograph chart is first placed on the document scanner. This is a standard document scanner. It scans the tachograph chart and produces a resultant image in the form of electronic data which is fed to the computer and stored therein. The scanned image is analysed in the computer memory, rather than on disc, for rapidity of processing. A facility for storing the image on disc is provided, principally to obviate the need for re-scanning the disc later, if need should arise. The format of the image data is determined by the manufacturer of the scanner. The data from the scanner, if storage of the image is required, is stored in an industry standard format, for example that known as PYX. The image data is then converted into a different format, known as bitmap or BMP which is more easily interpreted by the computer programme. In order to analyse and reproduce the stored image data, the system operator selects an appropriate menu option from the visual display unit of the computer of the system, in the usual way, and activates the computer to commence data processing. As a preliminary to analysis of the recorded graphic data on the tachograph chart, the computer first processes data relating to the chart or disc itself in order to establish the disc size, disc type, disc centre and disc orientation. These factors are needed in order to properly relate the graphic data represented by the tachograph trace. Thus, the geometrical techniques adopted by the computer in analysing the data relating to the tachograph disc itself are as follows. Firstly, to identify the disc edges, and hence the disc size, four points on the disc edge are identified, at the top, the bottom, the left and the right sides. This is achieved by colour analysis as between the disc and its support. The process is carried out in a single pass on the data relating to each line of the scanned image, for reasons of efficiency. The disc centre is established by taking two diametral lines based on the topmost/bottommost/leftmost/rightmost edge points located, and by finding their point of intersection. The diameters also provide, of course, a measure of the disc radius. With regard to orientation of the disc, and the determination of its 12 o 1 clock position, the characteristically shaped central cutout on all presently available tachograph discs can be read by the system from the image data produced by the scanner. The technique for this is as follows. As shown in the drawing, disc 10 comprises a central cut¬ out 12 which is generally pear-shaped. Such a shape is provided on.Lucas-Kienzle discs. Other manufacturers' discs have alternative orientation means such as a central circular aperture and two marker holes. In the case of the disc 10, the orientation of the disc is identified as follows. Firstly, the circumference of a circle with a radius slightly larger than that of the circular part of the pear- shaped opening is searched for black sections ie sections which are not white, the dominant colour of the disc. The largest black section found is deduced to be the open-ended part of the pear. A point halfway between the ends of this section is deduced, and the 12 o'clock position is therefore on the radius line that runs from the disc centre through this point. Of course, for discs having different formations identifying disc orientation, modified analysis to establish orientation is needed. In a modification, the orientation of the disc is established by use of mechanical means, such as a lug, provided on the scanner and cooperating mechanically with the disc to physically ensure that it is mounted in a predetermined orientation for scanning purposes. After establishing the geometry of the disc, the analysis of the data by the computer can then proceed by a series of steps, as follows. Firstly, the data from the disc is divided into data relating to concentric bands of defined radii. Then, the data relating to each band is transformed so as to represent the band in linear rather than circular form. This is achieved by taking each radius line from the centre of the disc and treating it as a pixel-wide slice from a rectangle. In this way, the computer has produced a linear representation of the ' graphic data recorded on the tachograph disc. This linear representation is then interpreted in accordance with the following procedure. The image of the graphic trace that is obtained from the scanner is not necessarily complete, and may contain a large amount of extraneous information, this usually taking the form of islands of black, which is a result of the effect of printing onto sensitive paper, and scratches caused by disc handling. Therefore, the following process is employed to identify the graphic trace and to eliminate matter which is to be ignored. Firstly, a pixel-wide slice of the (straightened) band under consideration is examined. Secondly, each band of black in that slice is given a weighting, initially zero. The weighting indicates how long the particular line has been followed, and determines whether the line is to be followed or not, as indicated below. Thirdly, the band with the highest weighting is considered to be the trace line unless there are bands with equal weightings, in which case the widest is considered to be the trace. Overlap of bands is handled as follows. Where bands in the preceding slice split, the weighting of each band in the new slice is given the same weighting ie the previous weighting plus one. Where bands in the preceding slice merge, the weighting of the band in the new slice is given the same weighting as one and only one of the preceding bands plus 1. Bands that are not considered significant in accordance with these rules are discarded. The above process is applied to each of the three trace lines on disc 10. That is to say, distance trace 14, activity trace 16 and speed trace 18 are analysed in the above- indicated way. This has the effect of picking out continuous data lines and discarding spurious data. As a refinement of the above process, in order to deduce the presence of a line where the actual scanned image simply does not contain any data (such as can occur when the trace line under consideration is thin enough to fall between adjacent scan lines used by the scanner) , the following modification is adopted. (We observe first, that this problem is reduced with higher resolution in the scanner, but higher resolution causes certain problems, particularly with regard to speed and the memory required for analysis.) The refinement involves reducing the band weightings in adjacent slices, rather than discarding the band completely, when it is not present in a slice. This amounts to a "join the dots" enhancement, because parts of the trace can be reduced to a set of disjointed dots which clearly should be joined, but are not. With regard to analysis of the distance portion 14 of the tachograph disc 10, analysis is made of the number of times that the trace line passes through the edges of the band being analysed. In this embodiment, each such passage corresponds to 5 kilometres of distance travelled for every two peaks of the waveform, and hence the vehicle distance travelled can be calculated. With regard to the activity portion 16 of the disc, an analysis of the data is made with respect to the thickness of the trace line, that is to say whether the trace line is thick or thin, and also of its distance from the disc centre. This analysis establishes periods of vehicle movement and periods when the vehicle was stationery. Also, the analysis shows the 10 position of the activity selection switch of the tachograph instrument itself. The tachograph activity switch is a driver-operated control which is manipulated by the driver to indicate to the tachograph the type of activity undertaken by the vehicle at any given time. As shown in the drawing, the activity trace 16 indicates the activity type by means of the radial position of the trace, working outwards from the centre of the disc. Thus, the innermost position indicated at 16A indicates rest, there is shown at 16B "other work" ie a subsequent inactive period, and at 16C is shown driving activity. With respect to the speed portion 18 of the tachograph disc, the electronic data produced from the graphic image is checked for the passage of the trace line through the disc radius corresponding to a menu-selectable speed. Where the trace line passes through the radius, the trace around the speed violation is checked in order to see if this is the start or the end of an over-limit event. The starts and ends of these events are accumulated to produce a speeding offence summary. Finally, the data produced as described above is passed to a visual display unit and/or a printer for study by the operator. The output from the computer can alternatively be passed, via a serial data link, for use in the same manner and in the same format as that currently produced by manual tachograph readers. As a result, the computer output can be plugged directly into higher level vehicle fleet management systems and, for example, the data can also be used in association with the UK Department of Transport's Hours Law software package. This is a user-selectable option, and the data can be formatted to correspond to that of known manual readers eg that known as Veeder Root. It will be understood that the data derived from tachograph charts and disc is stored in the computer and can be accessed, sorted and displayed in accordance with a variety of criteria. For example, by virtue of the fact that the system permits rapid and automatic analysis of discs, the processing of these can be on an every disc basis rather than merely on the basis of occasional analysis of discs from time to time. As a result, it becomes feasible to analyse the total activities of a given vehicle or a given driver over a period, and to print out a summary of these. Such an approach enables, for example, unauthorised use of vehicles to be monitored, and the total recorded tachodisc milage can be compared to the vehicle odometer. In the above embodiment, the analysis and identification of the graphic trace on the tachograph chart or disc depends, amongst other things, upon an ability of the computer to identify and distinguish the trace from standard printing on the disc, irregular black or other colour marks on it, and from scratches etc. Such distinguishing of the trace is achieved, as described, by steps in the analysis programme whereby certain data transmitted by the scanner is ignored. Likewise, as a result of the calculation of the disc orientation, the location of the trace on the disc is known, whereby data from elsewhere on the disc can be ignored. Also, the location of the printed matter on the disc is also known and instructions can be included in the programme to ignore (so far as identification of the graphic traces is concerned) such printed matter. Amongst other advantages provided by the above embodiment is the high speed and accuracy of the analysis of the graphic data. This can be read to acceptable standards in a period of, for example, approximately 2 minutes, compared with the 20 to 30 minutes per card required for previous systems reliant upon human visual interpretation of the card, the exact time required for the latter depending on the standard of accuracy required and the operator's experience and expertise. Likewise, it will be appreciated that when vehicle use regulations change, or regulations relating to another country are to be applied, data relating to the modified regulations can be provided for the computer so that violations of these modified regulations are automatically produced, without the need for training of operators and the inevitable learning curve which would apply in the case of visual interpretation of the graphic data.

Claims: CLAIMS : - 1 A method of reading the recorded graphic data on a tachograph chart, the method being characterised by :- a) providing scanning apparatus and locating a chart to be read in operative relationship to said apparatus, for reading; b) providing electronic scanning means to scan the chart to produce electronic data representative of the data recorded on said chart; c) feeding said electronic data to a computer and causing said computer to process same so as to modify the form of said graphic data for visual presentation of said graphic data in the form of text and/or numerals. 2 A method of reading recorded data on a chart, the method comprising using electronic scanning means to produce electronic data representative of the recorded data on the chart and feeding same to a computer and causing the computer to process same to reproduce the data in the form of text and/or numerals. 3 A method according to claim 1 or claim 2 characterised by the step of causing said computer to process said electronic data comprising the step of providing said computer with data relating to the chart itself and processing same to establish the orientation of the chart. 4 A method according to claim 3 characterised by said step of processing said data relating to the chart itself to establish the orientation of the chart comprises scanning the chart to identify the edges of the chart. 5 A method according to claim 4 characterised by the step of identifying the edges of the chart by identifying colour or intensity changes with respect to the background colour or intensity of the support on which the chart is located. 6 A method according to claim 4 or claim 5 characterised by said chart being circular and said method comprising identifying sufficient edge points of the chart and thereby enabling the centre thereof to be calculated. 7 A method according to any one of the preceding claims characterised by said step of causing said computer to process said electronic data comprises analysis of said graphic data by identifying the graphic trace representing said data by identifying colour or intensity changes with respect to the basic colour or intensity of the chart. 8 A method according to claim 7 characterised by the step of dividing said chart into concentric bands and converting the data representing same into data representing 'the bands in linear form so as to produce a linear data representation of the data on the chart. 9 A method according to claim 7 or claim 8 characterised by said analysis of said electronic data comprising the step of taking data relating to a slice of a band of the chart, giving a weighting to each band of black in the slice, the weighting depending on the length of the band or line, and identifying the graphic trace as the line with the highest weighting, or if there are -two or more with the same weighting, the line with the highest weighting and the greatest width. 10 A method according to claim 7 or claim 8 characterised by the step of analysing the contents of said linear bands by the steps of, in a portion of the chart corresponding to the distance or travel of a vehicle or machine recorded on the chart, counting the number of times the graphic trace line passes through the edges of the band. 11 A method according to claim 7 or claim 8 characterised by analysis of the data of said linear bands by, in the portion of the chart corresponding to the activity of the vehicle or machine recorded, measuring the thickness of the trace line and its distance from the centre of the chart. 12 A method according to any one of claims 7 to 11 characterised by analysis of the data of said linear bands by, in the portion of the chart corresponding to the speed of the vehicle or machine, monitoring the passage of the trace passing through a radius corresponding to a selectable speed of the vehicle, thereby to enable instances of vehicle speed above the selected speed to be identified. 13 A method according to any one of claims 1 to 12 characterised by the step of comparing or relating the data produced by the computer from the graphic data of the tachograph chart to standard data relating to legal or other requirments concerning the driver and vehicle activities or like requirements in order to produce an indication of compliance with said regulations. 14 Apparatus for reading the recorded graphic data on a tachograph chart, the apparatus being characterised by :- a) scanning apparatus on which can be placed a chart to be read, in operative relationship thereto, said scanning apparatus being operable to scan a chart to produce electronic data representative of the graphic data recorded on the chart; b) a computer and means for feeding said electronic data from said scanning means to said computer, said computer being able to process same so as to modify the form of said graphic data for visual presentation thereof in the form of text and/or numerals. 15 Apparatus for reading recorded graphic data on a chart characterised by scanning apparatus connected to computer means whereby electronic data produced by said scanning apparatus and representative of said graphic data can be processed by said computer to produce said data in the form of text and/or numerals. 16 Apparatus according to claim 14 or claim 15 characterised by said scanning means being adapted to scan said chart itself and produce data relating to the chart and said computer being adapted to process said data relating to the chart itself to establish the orientation of the chart. 17 Apparatus according to any one of claims 14 to 16 characterised by data printing apparatus to present said text and/or numerals in printed form. 18 A method of reading the recorded graphic data on a tachograph chart substantially as described herein. 19 Apparatus for reading the recorded graphic data on a tachograph chart substantially as described herein.

Inventors: WEST DAVID SIDNEY, WEST PHILIP CYRIL, WEST, DAVID, SIDNEY, WEST, PHILIP, CYRIL
Applicants: TRUTAC LIMITED
Application year: 1992
Main classification: G06K11
IPC codes: G07C5