Patent Publication Number: US-10787185-B2

Title: Method for controlling the height of a transport vehicle and related transport vehicle

Description:
The present invention relates to a method for controlling the position of a floor of a carriage of a railway vehicle running on rails, relatively to a platform, the carriage comprising a body and at least a bogie, the bogie including an axle, a bogie chassis, at least one primary suspension interposed between the axle and the bogie chassis, and at least one secondary suspension interposed between the primary suspension and the floor, the axle comprising wheels connected through a shaft, the method including the following steps: 
     measurement of the height of the secondary suspension defined from the top of the bogie chassis, and 
     adjustment of the height of the secondary suspension, according to the height of the platform defined from the top of the rails in order to position the floor at the height of the platform. 
     BACKGROUND OF THE INVENTION 
     In the sector of railway transport of travelers, a vehicle is caused to perform several stops in stations, or railway stations, in order to allow the exit or the entry of travelers. 
     The access of the travelers to a carriage operates at the level of the flooring of the carriage which is found globally positioned facing the platform of the station. 
     However, the difference in heights, which may exist between the floor and the platform may prove to be unacceptable for certain users, notably those said to be with reduced mobility. In particular, the ADA standard, for American Disability Act, imposes a height difference between the platform and the lower floor of 16 mm. The problem of adapting the height of the floor to platform heights is further posed, which may vary from one station to another. 
     Document DE 10 236 246 B4 proposes a solution for adjusting the height of the floor, so that it is found at the same height as that of the platform. 
     This solution is however unsatisfactory. Indeed, the height of the access floor is subject to notable variations, under the effect of various parameters. Mention may notably be made of the value of the load of the corresponding carriage notably to the mass of the passengers and of the luggage occupying the carriage, the distribution of this load, or further the wear of the wheels. In particular, such a solution does not give the possibility of observing the ADA standard. 
     SUMMARY OF THE INVENTION 
     An object of the invention is therefore to propose a method allowing simple modifications of the height of a transport vehicle, notably for ensuring easy access to the users of this vehicle, during its different stops in stations. 
     For this purpose, the object of the invention is a method for controlling the height of a transport vehicle of the aforementioned type, comprising a step for estimating the height of the top of the bogie chassis defined from the shaft of the axle, the adjustment of the height of the secondary suspension being achieved depending on the estimated height of the top of the bogie chassis defined from the shaft. 
     According to particular embodiments, the method includes one or several of the following features: 
     the step for estimating the height of the top of the bogie chassis comprises a step for estimating the height of the primary suspension defined from de the shaft of the axle; 
     the step for estimating the height of the primary suspension comprises the following steps: calculating the flexure under load of the primary suspension, and calculation of the height of the primary suspension defined from the shaft of the axle, this calculation comprises the subtraction of a characteristic parameter of the primary suspension bye the flexure under load calculated from the primary suspension; 
     the characteristic parameter of the primary suspension is equal to the height defined from the shaft of the primary suspension for a reference load on the body; 
     the step for estimating the height of the primary suspension defined from the shaft of the axle comprises a step for measuring a load exerted by the body on the bogie, the flexure under load of the primary suspension being equal to the ratio of the sum of the load exerted by the body, measured on the bogie and with a predetermined mass between the primary and secondary suspensions, over the stiffness of the primary suspension; 
     the secondary suspension comprises at least one pneumatic cushion and a load sensor able to apply the step for measuring the load, the load sensor being able to measure the pressure of each pneumatic cushion of the secondary suspension; 
     the method comprises a step for estimating the height of the shaft of the axle defined from the top of the rails, the adjustment of the height of the secondary suspension being achieved according of the estimated height of the shaft defined from the top of the rails; 
     the step for estimating the height of the shaft of the axle defined from the top of the rails comprises the following steps: estimation of the theoretical wear of the wheels, and calculation of the height of the shaft defined from the top of the rails, this calculation comprising the subtraction of a characteristic parameter of the axle by a theoretical decrease in the height of the shaft associated with the theoretical wear of the wheels; and 
     the vehicle has received at least one control operation, the characteristic parameter of the axle being equal to the height of the shaft defined from the top of the rails measured at the end of this control operation. 
     The invention relates, according to a second aspect, to a transport vehicle comprising at least one carriage comprising a floor, a body and at least one bogie, the bogie including an axle, a bogie chassis, at least one primary suspension interposed between the axle and the bogie chassis, and at least one secondary suspension interposed between the primary suspension and the floor, the axle comprising wheels connected through a shaft, the vehicle being able to control the position, relatively to a platform, of the floor of the carriage, according to a method as defined above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood upon reading the description which follows, given as an example and made with reference to the appended drawings, wherein: 
         FIG. 1  is a simplified view, a sectional view, of a vehicle carriage according to the invention; 
         FIG. 2  is a partial schematic view of a vehicle, and; 
         FIG. 3  is a flow chart of a method for controlling the height of a vehicle according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A carriage  10  of a transport vehicle for travelers is illustrated, as a section, in a simplified way in  FIG. 1 . A partial diagram of the carriage  10  is illustrated in  FIG. 2 . 
     Such a transport vehicle is for example, a bus, a trolleybus, a tramway, a metro, a train or any other type of railway vehicle. The vehicle is able to stop at a station including a platform  12 . The platform  12  has a height H pla , defined from the top of the rails  11  on which circulates the vehicle. 
     The carriage  10  comprises a floor  14  for access of the travelers to a body  16  and at least one bogie  18 . Advantageously, the vehicle includes several carriages  10  and several bogies  18  distributed along the vehicle. For example, each carriage  10  comprises two bogies  18 . 
     The bogie  18  comprises an axle  20 , a bogie chassis  21 , at least one primary suspension  22  interposed between the axle  20  and the bogie chassis  21 , and at least one secondary suspension  24  interposed between the primary suspension  22  and the floor  14 . For example and as illustrated in  FIG. 1 , the bogie  18  comprises two primary suspensions  22  and two secondary suspensions  24 . 
     The axle  20  is movable in rotation relatively to the bogie chassis  21  along an axis substantially parallel to the ground, the axis being transverse to the rails  11 . The axle  20  includes two wheels  26  and a shaft  28  connecting the wheels  26 . 
     The wheels  26  are for example solid wheels intended to cooperate with rails  11 , or wheels equipped with tires. In the embodiment of the figures, the wheels  26  of the vehicle are solid wheels. 
     The shaft  28  of the axle  20  has a height R defined from of the rails  11 . More specifically, the relevant height is for example the height of the upper portion of the shaft  28  defined from the top of the rails  11 . This height R depends on the characteristics of the wheels  26 . 
     Indeed, the wheels  26  exhibit wear which depends on the number of kilometers covered by the vehicle. This wear deforms the wheels  26  in a non-uniform way which reduces the adherence and therefore the safety of the passengers. In order to find a remedy to this problem, from a given mileage, the vehicle is usually conducted into a maintenance center where control operations are conducted on the vehicle. These control operations are for example maintenance operations. The vehicle is advantageously caused to receive several times these control operations during its lifetime. It should be noted that the components of the vehicle have received a first control operation during their building. 
     In the case when the wheels  26  are equipped with tires, depending on the state of degradation of the tires, these control operations may comprise the replacement of the tires. 
     In the case when the wheels  26  are solid wheels intended to cooperate with rails  11 , these control operations for example, comprise an operation for re-profiling the wheels  26 , during which the wheels  26  are machined in order to give them back a standardized shape. 
     During this re-profiling operation, each wheel has a material removal with a predetermined thickness. This material removal thickness is optionally different for each wheel of the vehicle, in order to guarantee perfect symmetry between the wheels of a same axle and between the different axles of the vehicle. 
     At each re-profiling operation, the shaft  28  of the axle  20  thus looses height. The total height lost by the shaft  28  during all the re-profiling operations conducted on the wheels  26  since the building of the wheels  26  is noted as Δ repro . 
     The wear of the wheels  26  since the last re-profiling operation also involves an actual decrease Δ wear  of the height of the shaft  28 . 
     Thus, the height R of the shaft  28  from the top of the rails  11  depends, between other factors: 
     on the rated construction height R n  of the shaft  28  defined from the top of the rails  11 , 
     on the decrease in height Δ wear/total  associated with the wear between the date of building of the wheels  26  and the date of the last re-profiling operation, 
     on the lost height Δ repro  during all the re-profiling operations conducted on the wheels  26 , and 
     on the actual decrease in height Δ wear  associated with wear since the last re-profiling operation conducted on the wheels  26 . In the case when the wheels  26  have not been subject to any re-profiling operation, this actual decrease Δ wear  is associated with wear since the building of the wheels  26 . 
     For example, the height R of the shaft  28  defined from the top of the rails  11  is equal to R=R 0 −Δ wear , wherein R 0  is a characteristic parameter of the axle. The characteristic parameter R 0  is for example equal to the height of the shaft  28  defined from the top of the rails  11  measured at the end of the last control operation. This height is advantageously measured by an operator at the end of each control operation. 
     Alternatively, the vehicle comprises a specific traction/braking piece of software, when it is executed, for calculating the diameter of the wheels of each axle from of the measured speed of this axle and thus calculating the height R. 
     In the case when the wheels  26  have not yet been subject to a re-profiling operation, the parameter R 0  is therefore for example equal to R 0 =R n . 
     In the case when the wheels  26  have been subject to re-profiling operations, the parameter R 0  is for example equal to R 0 =R n −Δ repro −Δ wear/total . 
     For a same axle  20  and after each re-profiling operation, the material removals are optionally compensated by adding shims for compensating for the re-profiling  29 A of thickness Δ shims/repro . Advantageously, these shims for compensating for the re-profiling  29 A also compensate for the wear of the wheels  26  ascertained between two re-profiling operations. 
     The thickness of the shims for compensating for re-profiling  29 A Δ shim/repro  is for example equal to the sum of the total height lost by the shaft  28  during all the re-profiling operations undergone by the wheels  26 , and the lost height by the shaft  28  associated with the wear of the wheels  26  ascertained between each re-profiling operation since the building of the wheels  26 . 
     The shims for compensating for the re-profiling  29 A are placed, for example under the secondary suspension  24  and on the bogie chassis  21 . The bogie chassis  21  then comprises the shims for compensating for the re-profiling  29 A. 
     The control operations also comprise for example an estimation of the creep Δ creep  of the primary suspension  22 . This is notably the case when the primary suspension  22  comprises elements in an elastomeric material. 
     The creep is then evaluated by an operator and optionally compensated by adding shims for compensating for the creep  29 B with thickness Δ shims/creep . 
     Advantageously, the thickness Δ shims/creep  of the shims for compensating for the creep  29 B is equal to the creep Δ creep . 
     The shims for compensating for the creep  29 B are placed for example under the secondary suspension  24  and on the bogie chassis  21 . The bogie chassis  21  then comprises the shims for compensating for the creep  29 B. 
     The bogie chassis  21  comprises a crossbar  21 A which lies on the primary suspension  22 . The top of the bogie chassis  21  is defined as the upper wall of the crossbar  21 A at right angles to the primary suspension  22 . 
     At right angles to the primary suspension  22 , the bogie chassis  21  has a thickness H c . This thickness H c  is for example equal to the rated construction thickness H cn , of the bogie chassis  21  measured at right angles to the primary suspension  22 . 
     The bogie chassis  21  includes for example, other components like tearing shims (not shown). The thickness of these components, in particular of these tearing shims, is then added to the rated building thickness H cn  in the value of the height H c  of the bogie chassis  21 . 
     The primary suspension  22  includes dampers not shown and springs  30  to be selected from the group comprising: pneumatic springs or metal springs. Advantageously, the springs  30  have the same stiffness K and are placed between the axle  20  and the bogie  18 . Through the springs  30 , the primary suspension  22  then has a stiffness K. 
     As illustrated in  FIG. 1 , the secondary suspension  24  extends from the top of the bogie chassis  21 . 
     The secondary suspension  24  for example includes at least one, or even several pneumatic cushion(s)  36 , a device  38  for actuating the secondary suspension  14 , a compressed air tank  40  and a height sensor  42 . 
     The actuation device  38  is able to control the adjustment of the height of the secondary suspension  24 . More specifically, the actuation device  38  is configured for increasing or decreasing the pressure in the pneumatic cushion(s)  36 , by controlling the arrival of compressed air from the tank  40 . The pressure variation in the pneumatic cushion(s)  36  modifies the height of the secondary suspension  24 . 
     The actuation device  38  is advantageously a solenoid valve. 
     The secondary suspension  24  advantageously comprises a load sensor  32 . The load sensor  32  is able to measure the load, noted as P, exerted by the body  16  on the bogie  18 . The load P notably depends on the mass of the passengers and of the luggage occupying the body  16 . 
     The load sensor  32  is for example able to measure the pressure of the pneumatic cushions  36 . 
     From these measurements, the load sensor  32  is able to infer therefrom a measurement of the load P exerted by the body  16  on the bogie  18 . 
     The secondary suspension  24  advantageously includes an average vane valve intended to control the braking force of the vehicle. Advantageously, this average vane valve is then the load sensor  32 . 
     The primary suspension  22  exhibits a flexure under load equal to the ratio of the load Q on the primary suspension by the stiffness K of the springs  30 . The load Q on the primary suspension is equal to the sum of the measured load P and of the suspended mass between the primary and secondary suspension stages. The suspended mass between the primary and secondary suspension stages has a predetermined value which depends on the configuration of the bogie. 
     The primary suspension  22  thus has a height H p  defined from the shaft  28  of the axle  20 . 
     For example, the height H p  of the primary suspension  22  defined from of the shaft  28  is equal to H p =H p0 −Q/K, wherein H p0  is a characteristic parameter of the primary suspension  22 . 
     The characteristic parameter H o  depends on the rated building height H pn , of the primary suspension  22  defined from of the shaft  28 , from the load P exerted by the body  16  on the bogie  18 , from the stiffness K of the primary suspension  22  and from the creep Δ creep  of the suspension. 
     In particular, the characteristic parameter H p0  is for example equal to the height of the primary suspension  22  defined from the shaft  28  for a reference load on the body  16 , for example, when the body  16  is without any passengers, i.e. when the body  16  is with zero load. This height is advantageously measured by an operator at the end of each control operation. 
     Thus, the characteristic parameter H p0  is for example equal to H p0 =H pn −Δ creep . 
     The primary suspension  22  for example includes other components like tearing shims (not shown) intended to compensate for the manufacturing tolerances in the elements of the vehicle. The thickness of these components, in particular these tearing shims, is then added in the expression of the parameter H p0 . 
     The height of the top of the bogie chassis  21  is designated by H cb  defined from the shaft  28 . This height H cb  then depends on the height H c  of the bogie chassis  21  measured at right angles of the primary suspension  22 , of the height H p  of the primary suspension  22  defined from of the shaft  28 , and optionally from the thickness Δ shims/repro  of the shims for compensating for the re-profiling  29 A and/or of the thickness Δ shims/creep  of the shims for compensating for creep  29 B. 
     In the case when the wheels  26  have not undergone any re-profiling operation, and the primary suspension  22  has not undergone any operation for estimating creep, the height H cb  is for example equal to H cb =H c +H p . 
     In the case when the wheels  26  have undergone re-profiling operations, but the primary suspension  22  has not undergone any creep estimation operation, the height H cb  is for example equal to H cb =H c +H p +Δ shims/repro . 
     In the case when the wheels  26  have not undergone any re-profiling operation, but the primary suspension  22  has undergone creep estimation operations, the height H cb  is for example equal to H cb =H c +H p +Δ shims/creep . 
     Finally, in the general case when the wheels  26  have undergone re-profiling operations, and the primary suspension  22  has undergone creep estimation operations, the height H cb  is for example equal to H cb =H c +H p +Δ shims/repro +Δ shims/creep . 
     The secondary suspension  24  has a height H s  defined from the top of the bogie chassis  21 . The height sensor  42  is specific for measurement of this height H s . 
     The floor  14  has, at the bogie  18 , a height H f  defined from the top of the rails  11 . 
     The height H f  of the floor  14  depends on the height R of the shaft  28  of the axle  20  defined from the top of the rails  11 , on the height H cb  of the top of the bogie chassis  21  defined from the shaft  28 , and on the height H s  of the secondary suspension  24  defined from the top of the bogie chassis  21 . 
     The height H f  also depends on a geometrical constant H f0  depending on the geometry and on the dimensions of the carriage  10 . The constant H f0  is thus for example equal to the height of the floor  14  measured at right angles to the secondary suspension  24 . 
     More specifically, the height H f  is equal to H f =R+H cb +H s +H f0 . 
     The vehicle comprises a processing unit  44  and an odometer  46 . 
     The odometer  46  is able to calculate the number of covered kilometers by the vehicle between two predetermined dates. The predetermined dates are for example the date of the last control operation and the current date. 
     For this, the odometer  46  for example comprises a processor  48  able to handle the operation of the odometer  46 , a memory  50  able to store the number of covered kilometers between both predetermined dates, and a geolocalization system  52 , for example of the GPS (Global Positioning System) type. The processor  48  is then connected to the memory  50  and to the geolocalization system  52 . 
     The processing unit  44  is connected to the odometer  46 , to the load sensor  32 , to the displacement sensor  42  and to the actuation device  38  of the secondary suspension  24  of each bogie  18  of each carriage  10  of the vehicle. 
     The processing unit  44  includes a processor  54  connected to a memory  56  and to a graphic interface  58 . 
     The memory  56  is able to store the known values of the characteristics of the platform  12  and of the vehicle. In a non-exhaustive way, these characteristics are for example: 
     the height H pla  of the platform  12  defined from the top of the rails  11 , 
     the characteristic parameter R 0 , i.e. the height of the shaft  28  defined from the top of the rails  11  measured at the end of the last control operation, for each bogie  18  of each carriage  10 , 
     the rated building height R n  of the shaft  28  of the axle  20  defined from the top of the rails  11 , for each bogie  18  of each carriage  10 , 
     the height Δ repro  lost by the axle  20  during all the re-profiling operations, for each bogie  18  of each carriage  10 , if the vehicle  10  has undergone such operations, 
     the decrease in height Δ wear/total  associated with wear between the building date of the wheels  26  and the date of the last re-profiling operation, for each bogie  18  of each carriage  10 , 
     the characteristic parameter H p0 , i.e. the height of the primary suspension  22  defined from the shaft  28  when the body  16  is without any travelers, for each bogie  18  of each carriage  10 , 
     the rated building height H pn , of each primary suspension  22  defined from the shaft  28 , for each bogie  18  of each carriage  10 , 
     the height H c  of the bogie chassis  21  measured at right angles to each primary suspension  22 , for each bogie  18  of each carriage  10 , 
     the thickness Δ shims/repro  of the shims for compensating for the re-profiling  29 A, for each bogie  18  of each carriage  10 , if the vehicle  10  has undergone a re-profiling operation, 
     the creep Δ creep  of the primary suspension  22 , for each bogie  18  of each carriage  10 , if the vehicle  10  has undergone a creep estimation operation, 
     the thickness Δ shims/creep  of the shims for compensating for the creep  29 B, for each bogie  18  of each carriage  10 , if the vehicle  10  has undergone a creep estimation operation, 
     the stiffness K of each primary suspension  22 , for each bogie  18  of each carriage  10 , 
     the suspended mass between the primary and secondary suspension stages, 
     the thickness of optional tearing shims of the bogie chassis  21  and/or of each primary suspension  22 , for each bogie  18  of each carriage  10 , and 
     the geometrical constant H f0 , at each bogie  18  of each carriage  10 . 
     The memory  56  is also able to store the number of kilometres covered by the vehicle between both predetermined dates. 
     For example, the graphic interface  58  is configured for allowing an operator to store in the memory  56  the known values of the preceding characteristics. 
     The memory  56  comprises a program  60 . The program  60  is able to handle the steps of the method for controlling the position of the floor  14  of the carriage  10  of the vehicle, the processor  54  being able to perform the calculations. 
     The processor  54  is able to estimate the height R of the shaft  28  defined from the top of the rails  11 . 
     Advantageously, the processor  54  is able to take into account the wear of the wheels  26  in its calculation of the height R of the shaft  28  defined from the top of the rails  11 . 
     For this, the processor  54  is able to calculate, from data from the odometer  46 , theoretical wear of the wheels according to the number of kilometres covered by the vehicle. 
     Alternatively, the memory  56  comprises a specific traction/braking piece of software able to calculate the diameter of the wheels of each axle from the measured speed of this axle. 
     The processor  54  is then able to infer therefrom a theoretical reduction Δ wear/theo  of the height of the shaft  28  associated with the wear. Advantageously, this theoretical reduction Δ wear/theo  is equal to the actual reduction Δ wear . 
     The processor  54  is also able to calculate the heights H p , H cb , H s  and H f  from the preceding formulae, and to estimate the difference between the height H pla  of the platform  12  and the height H f  of the floor  14 . 
     For the calculation of the height H p , in the case when the primary suspension  22  has undergone a creep estimation operation, the processor  54  is able to calculate the height H p  by assigning to the creep Δ creep , the estimated value at the creep estimation operation. More specifically, the characteristic parameter H p0  is then for example considered to be equal to H p0 =H pn −Δ creep . 
     In the case when the primary suspension  22  has not undergone a creep estimation operation, the processor  54  is configured for assigning the creep a zero value. More specifically, the characteristic parameter H p0  is then for example considered as equal to H p0 =H pn . 
     The processor  54  is then able to control the device  38  for actuating the secondary suspension  24 , so that the difference between the height H pla  of the platform  12  and the height H f  of the floor  14  is comprised between −16 mm and 16 mm, advantageously so as to cancel out this difference. 
     A method for controlling the position of the floor of a carriage of a vehicle will now be described with reference to  FIG. 3 . 
     The method is applied for each bogie of each carriage of the vehicle. 
     The method includes a step  100  for parameterizing the processing unit  44 , a step  102  for estimating the height of the top of the bogie chassis  21  followed by a step  104  for estimating the height of the shaft  28  of the axle  20 , a step  106  for measuring the height of the secondary suspension  24  and a step  108  for adjusting the height of the secondary suspension  24  according to the height of the platform  12  for positioning the floor at the height of the platform  12 . 
     During the preliminary step  100  for parameterization, an operator measures and stores the known values of the preceding characteristics of the platform  12  and of the vehicle, in the memory  56  of the processing unit  44 . 
     The step  102  for estimating the height of the top of the bogie chassis  21  comprises a step  110  for estimating the height of the primary suspension  22 . 
     The step  110  for estimating the height of the primary suspension  22  comprises a step  120  for measuring the load of the body  16  on the bogie  18 , during which the load sensor  32  measures the load P of the body  16  on the bogie  18 . 
     The load sensor  32  for example measures the pressure of the pneumatic cushions  36  and infers therefrom a measurement of the load P. 
     The step  110  for estimating the height of the primary suspension  22  then includes a step  122  for calculating the flexure under load of the primary suspension  22 . 
     During this step  122  for calculating the flexure under load of the primary suspension  22 , the processor  54  calculates the flexure under load of the primary suspension  22 , from the measurement of the load P carried out in step  120  for measuring the load, of the mass between the primary and secondary suspension stage and of the stiffness stored in memory by the memory  56 . More specifically, the processor  54  performs the sum of the measured load P and of the mass between the primary and secondary suspension stages and divides this sum by the stiffness K of the primary suspension  22 . The stiffness K is for example equal to the stiffness of the springs  30 . 
     The step  110  for estimating the height of the primary suspension  22  then comprises a step  124  for calculating the height H p  of the primary suspension  22  defined from the shaft  28 . 
     During this step  124  for calculating the height of the primary suspension  22 , the processor  54  uses the calculation carried out in step  122  for calculating the flexure under load of the preceding primary suspension  22  for inferring therefrom the height H p  of the primary suspension  22  defined from the shaft  28 . More specifically, the processor  54  subtracts the characteristic parameter H p0  of the primary suspension  22  from the flexure calculated in step  122  for calculating the flexure under load of the primary suspension  22 . 
     The step  102  or estimating the height the top of the bogie chassis  21 , comprises a step  125  for calculating the height of the bogie chassis  21 . 
     During this step  125  for calculating the height of the bogie chassis  21 , the processor  54  assigns to the height H cb  of the top of the bogie chassis  21  defined from the shaft  28 , the sum of the height H p  of the primary suspension  22 , of the thickness H c  of the bogie chassis  21 , and optionally the thickness Δ shims/repro  of the shims for compensating for the re-profiling  29 A and/or of the thickness Δ shims/creep  of the shims for compensating for creep  29 B. The thicknesses of the shims are added if the shims are present in the bogie  18 . 
     The step  104  for estimating the height of the shaft  28  of the axle  20  advantageously includes a step  126  for estimating the theoretical wear of the wheels  26  according to the mileage. 
     During this step  126  for estimating the theoretical wear, the processor  54  collects the number of kilometers covered by the vehicle since the last control operation, from the odometer  46  or from the memory  56 . The processor  54  then calculates the theoretical reduction Δ wear/theo  of the height of the shaft  28  associated with wear. Alternatively, the processor  54  recovers the diameter of the wheel from the data transmitted by the traction/braking piece of software and infers therefrom the theoretical reduction Δ wear/theo  of the height of the shaft  28 . 
     The step  104  for estimating the height of the shaft  28  then includes a step  128  for calculating the height of the shaft  28 , during which the processor  54  calculates the height R of the shaft  28  defined from the top of the rails  11 . For example, if the bogie  18  of the carriage  10  has at least undergone one re-profiling operation, the processor  54  assigns to the height R, the result of the following calculation: R=R 0 −Δ wear/theo . 
     During the step  106  for measuring the height of the secondary suspension  24 , the height sensor  42  measures the height H s  of the secondary suspension  24  defined from the top of the bogie chassis  21 . 
     The step  108  for adjusting the height of the secondary suspension  24  comprises a first step  130  for calculating the height of the floor  14 . 
     During this step  130  for calculating the height of the floor  14 , the processor  54  collects the height H s  of the secondary suspension  24  from the height sensor  42 . The processor  54  then calculates the height H f  of the floor  14  defined from the top of the rails  11 . More specifically, the processor  54  assigns to the height H f , the result of the following calculation: H f =R+H cb +H s +H f0 . 
     The step  108  for adjusting the height of the secondary suspension  24  then comprises a step  132  for adjusting the height of the secondary suspension  24 . 
     During this step  132  for adjusting the height of the secondary suspension  24 , the processor  54  calculates the difference between the height H f  of the floor  14  defined from the top of the rails  11  and the height H pla  of the platform  12  defined from the top of the rails  11 . 
     The processor  54  determines in this way, the height modification which the secondary suspension  24  has to undergo so that the difference is comprised between −16 mm and 16 mm, advantageously so that it is canceled out. 
     In a station, the processor  54  then elaborates a command and sends it to the actuation device  38 . Depending on this command, the device  38  controls the arrival of compressed air from the tank  40  to the pneumatic cushion(s)  36 , and thus varies the volume of the pneumatic cushion(s)  36  and therefore the height of the secondary suspension  24 . 
     While rolling, the processor  54  elaborates a command and sends it to the actuation device  38  only when the height of the secondary suspension varies, for example by more than 50 mm based on a reference height of the secondary suspension. The purpose here is to minimize the consumption of air under dynamic conditions. 
     At the end of stopping (closing of the doors), the secondary suspension is re-shifted towards the reference height in order to be re-centered before the rolling phase. 
     Thus, the adjustment of the height of the secondary suspension  24  is achieved according to the height of the primary suspension  22  and to the height of the shaft  28  of the axle  20  from the top of the rails  11 . 
     Alternatively, the step  104  for estimating the height of the shaft  28  of the axle  20  is applied before the step  102  for estimating the height of the top of the bogie chassis  21 . 
     According to another alternative, the method does not include any step  104  for estimating the height of the shaft  28  of the axle  20 . For the step  130  for calculating the height of the floor  14 , the processor  54  then assigns a constant value to the height R of the shaft  28  of the axle  20  defined from the top of the rails  11 . This value is advantageously the height R 0  of the shaft  28  defined from the top of the rails  11  measured by an operator during the last control operation. 
     The method described provides a solution for adjusting the height of the floor by taking into account the value of parameters like the load of the vehicle or further the wear of the wheels. 
     The method thereby allows simple modification of the height of the transport vehicle in order to facilitate access of all the travelers to the body of the vehicle. In particular, the method gives the possibility of observing the ADA standard.