Classifications

• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B23/00—Testing or monitoring of control systems or parts thereof
  • G05B23/02—Electric testing or monitoring
  • G05B23/0205—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults
  • G05B23/0218—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults characterised by the fault detection method dealing with either existing or incipient faults
  • G05B23/0243—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults characterised by the fault detection method dealing with either existing or incipient faults model based detection method, e.g. first-principles knowledge model
  • G05B23/0254—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults characterised by the fault detection method dealing with either existing or incipient faults model based detection method, e.g. first-principles knowledge model based on a quantitative model, e.g. mathematical relationships between inputs and outputs; functions: observer, Kalman filter, residual calculation, Neural Networks

Definitions

• the present invention relates to the diagnosis of the operation of a control system of at least one driving parameter of a motor vehicle using a dynamic model.
• driver assistance devices such as anti - skid systems, automatic braking systems, wheel steering systems, etc.
• driver assistance devices such as anti - skid systems, automatic braking systems, wheel steering systems, etc.
• Such systems are controlled by control laws activated by a supervisor according to operations corresponding to a certain number of conditions.
• the control laws are implemented in a computer embedded in the vehicle and generate periodically, at a certain sampling frequency, control signals that are called requests, for actuators acting on certain parts of the vehicle.
• the computer will issue steering requests of the rear wheel steering system.
• Japanese patent application JP 2000/181742 discloses a device for performing a fault diagnosis online in a redundant system. A data reconstruction is performed according to the result of the diagnosis.
• Patent Application US 2004/122 639 describes a method of acquiring driving parameters of a motor vehicle using a three-dimensional model of the kinematics of the vehicle, so as to subsequently reconstruct the movement of the vehicle from the signals. representative of lateral and longitudinal dynamics.
• the model used is a kinematic model.
• a method for diagnosing the operation of a control system of a driving parameter of a motor vehicle, using a dynamic model, the diagnosis being made from input data and from system output that were recorded during operation at a certain sample rate includes the steps of: recording system input and output data at a sampling rate lower than the system sampling rate; stimulating the dynamic model with the recorded input data to determine reconstructed output data; comparing the reconstructed output data with the output data recorded for consistency diagnosis.
• the method preferably comprises a preliminary step of interpolating the data recorded at the sampling rate of the system.
• a step of reconstituting the static correction parameters and coefficients is then carried out on the basis of recorded input data.
• the comparison step is made for example by comparing the difference between the reconstructed data and the recorded data with a threshold value for each data item. An alert information is deduced therefrom if said deviation is greater than the threshold value.
• the method preferably comprises, prior to the step of stimulating the dynamic model, a step of reconstructing the initial state vector from recorded input and output data.
• the dynamic model uses, for each sampling step, discretized dynamic equations involving state variables of the model.
• the step of reconstructing the initial state vector is then performed by inverting a system of equations comprising stored initial data and aforementioned dynamic equations corresponding to a minimum number of sampling steps, starting from the state. initial.
• a system for diagnosing the operation of a control system of a driving parameter of a motor vehicle, using a dynamic model comprising means for recording on a non-volatile memory, system input and output data during operation.
• the recording means is adapted to record said data with a sampling frequency lower than the sampling frequency of the system.
• the system includes a dynamic model capable of being stimulated with the recorded input data to determine reconstructed output data. Comparison means are also provided for comparing reconstructed output data with the output data recorded for consistency diagnostics.
• the dynamic model comprises discretized dynamic equations involving, for each sampling step, state variables of the model.
• the system includes means for reconstructing the initial state vector by inverting a system of equations comprising stored initial data and the aforementioned dynamic equations corresponding to a minimum number of sampling steps from the initial state.
• the input vector can be defined as:
• Each of the components of this input vector from 1 to j corresponds to a sampling instant noted k during the sampling period T e during which the recording is activated.
• the m output data to which the diagnosis is to be related can be expressed by an output vector Y in the form:
• the dynamic model uses, for each sampling step, discretized dynamic equations, in the form: where k is positive or zero, and where Ak and Bk are parameters expressed in matrix form.
• the output vector Y linearly depends on the state X and optionally, nonlinearly, the input data U according to the relation:
• the input data U [O] and the output data Y [O] are known because they have been recorded in the nonvolatile memory of the system .
• Equation (4) has n unknowns (X (O)) and m equations in the form:
• I is the unit matrix
• the driving parameter which is the object of the diagnosis may be a steering request of a rear wheel of a vehicle comprising at least three steered wheels.
• the initial recorded data used in the above system of equations may then include the longitudinal vehicle speed, the steering angle of the front wheels, the dynamic part of the rear wheel steering angle, the static part of the angle. rear wheel steering and the set point of the rear wheel steering angle.
• the aforementioned dynamic equations include, as unknowns, the modeled value of the rear wheel steering angle, the yaw rate, the lateral drift and an intermediate positive feedback value of the rear wheel steering angle. If we add the set value of the rear wheel steering angle, we are in the presence of four states. The set value of the rear wheel steering angle is, however, entirely determined by the knowledge of the input and the output at time k.
• the initial state vector for initializing the dynamic model has not been registered.
• the reconstructed data used in the comparison step is then data reconstructed from a reconstructed initial state.
• the initial state vector allowing the initialization of the dynamic model has instead been recorded.
• the method then comprises an additional step of prior checking of coherence between the registered initial state vector and the reconstructed initial state vector by comparison with threshold values, differences between the components of the registered initial state vector and the components of the reconstructed initial state vector.
• the step of stimulating the dynamic model with the recorded input data, in order to determine reconstructed output data is performed from the registered initial state vector.
• a first stimulation of the dynamic model is carried out with the recorded input data to determine first reconstituted output data and then, starting from reconstructed initial state vector, at a second dynamic pattern stimulation with the recorded input data for determining second reconstructed output data and comparing the reconstructed first output data, the reconstructed second output data, and the output data. recorded for the purpose of the final consistency diagnosis.
• FIG. 1 illustrates by way of example the instants of recording data in a report versus sampling dynamic model calculations used in a rear wheel steering control system of a vehicle with at least three steered wheels
• FIG. 2 schematically illustrates the main elements included in a computer comprising a dynamic model for the steering control of a motor vehicle rear wheel according to a first variant
• FIG. 3 illustrates the main elements of a diagnostic system for verifying the operation of the control system comprising the dynamic model illustrated in FIG. 2
• FIG. 4 illustrates the different steps of a diagnostic method according to the invention implemented with a system as illustrated in FIG. 3;
• FIG. 1 illustrates by way of example the instants of recording data in a report versus sampling dynamic model calculations used in a rear wheel steering control system of a vehicle with at least three steered wheels
• FIG. 2 schematically illustrates the main elements included in a computer comprising a dynamic model for the steering control of a motor vehicle rear wheel according to a first variant
• FIG. 3 illustrates the main elements of a diagnostic system
• FIG. 5 illustrates a second on-board computer variant comprising a dynamic model for determining control requests for the steering of a motor vehicle rear wheel, this time with the recording of a larger number of data; and
• FIG. 6 illustrates the different steps of a diagnostic method implemented using a system as illustrated in FIG. 3, associated with a computer as illustrated in FIG. 5.
• Such a control system makes it possible to generate, by means of a dynamic model, steering angle request values of at least one rear wheel, these requests being supplied to an actuator device capable of performing the required steering of the rear wheels.
• the system comprises a dynamic model making it possible, in particular, to model the lateral dynamics of the vehicle by the evolution of a certain number of step sizes that characterize the movement. of the vehicle in space.
• the system further comprises a positive feedback module capable of developing a rear wheel steering angle setpoint value from a control and acting on the transient response dynamics. The module also builds a static control value.
• the method for implementing such a system as described in this patent application furthermore comprises the selective activation or deactivation of the various modules of the system so as to take account of the different situations with which the vehicle is confronted in order to to obtain, in certain situations, a setpoint value of rear wheel steering angle improving the behavior of the vehicle and the driving comfort.
• the diagnostic system comprises means for recording on a non-volatile memory embedded in the vehicle, a certain number of input and output data of the control system.
• the recording of these data is preferably done at certain specific times for which the recording of the data seems important. This will be the case, for example, when triggering an anti-skid system or a rear wheel steering system, these systems coming into operation in particular driving situations of the vehicle.
• the recorded data will be recorded with a sampling frequency lower than that of the control system.
• FIG. 1 illustrates this feature.
• the activation signal of the recording has been shown.
• the signal changes from value 0 to value 1.
• This rising edge causes activation of the recording.
• the values of the input data which constitutes the steering angle of the front wheels ⁇ av (in radians) are recorded. This angle is measured or estimated for example from the measurement of the rotation angle of the steering wheel of the vehicle.
• the longitudinal speed of the vehicle v x is also recorded in m / s.
• This speed is measured or estimated for example from the knowledge of the rotational speeds of the wheels or from the filtered derivative of the position delivered by a geographical positioning system of the vehicle (GPS, registered trademark).
• GPS geographical positioning system of the vehicle
• two output values namely the static steering motion of the rear wheels has a s "(in radians) and the dynamic steering motion of the rear wheels CLJ d" ( in radians).
• FIG. 2 shows schematically the main bodies of a computer on board a motor vehicle and capable of providing steering control of the rear wheels, as shown for example in the French patent application No. 2,864 002.
• the computer referenced 1 as a whole, comprises an input block 2 which receives at each sampling step, at the sampling frequency T e , the measured values of the steering angle. front wheels ⁇ av and the longitudinal speed of the vehicle v x .
• a static steering calculation block 3 receives on its two inputs, the measured values of the steering angle of the front wheels ⁇ av and the longitudinal velocity of the vehicle v x from the input block 2.
• the block 3 delivers the static gain rate T gs which is a setting parameter depending on the vehicle speed and the steering angle of the front wheels. This parameter is set when the vehicle is in focus.
• the calculator 1 also includes a calculation block 4 which comprises two models which are not identified precisely in the figure and which are, one a model of the lateral dynamics of the vehicle and the other a model of the dynamic of the vehicle. the steering actuator of the rear wheels.
• the model of the lateral dynamics of the vehicle takes into account the evolution of the state variables that are the yaw rate ⁇ and the lateral drift of the vehicle ⁇ .
• ⁇ [k + l] a a c r [k] (15)
• ⁇ is the characteristic time constant of the first order dynamic model
• aZ is the modeled value of the steering angle of the rear wheels
• 0C ⁇ r is the setpoint of the steering angle of the rear wheels.
• the computer 1 further comprises a block 5 for calculating a control law by placing poles as described for example in the French patent application No. 2,864,002.
• This block delivers an intermediate variable CL ⁇ req which corresponds to a positive reaction in the system, as described in the aforementioned French patent application.
• This intermediate variable is obtained by the equation:
• Kik] 1 K I k] + TgSIkU -K 2 [kU + ⁇ 7 ⁇ C_DFF - v x [k]) + K ⁇ [k] ⁇ V * W
• Block 6 illustrated in FIG. 2 and symbolized by the mention 1 / z, causes a delay of one sampling step which results in the following formula: Note that the set value of the steering angle of rear wheels a c ar is initialized at the start of the recording independently and without respecting this equation.
• the block 7 is an addition block which receives on its positive input the set value cC end block 5 and on its negative input, the static steering request a s "end of block 3.
• the adder block 7 therefore delivers the dynamic steering request of the rear wheels according to the formula:
• a non-volatile memory referenced 8 equips the computer 1 and allows the recording, as indicated above, input and output data to the sampling period T r .
• the recording of this information starts as soon as the activation signal goes from 0 to 1.
• the recording stops automatically when the required number of recorded data is reached.
• the input data ⁇ av and v x are fed to the memory 8 via the connections 9 and
• the memory 8 also receives at the beginning of the recording, the distance traveled D p by the connection 1 1.
• the recording in the memory 8 starts when the activation signal Act is received via the connection 12.
• the output data consisting of the static steering request has s '"' supplied through the connection 13 and the turning motion dynamic CLJ d "supplied through the connection 14 are also recorded, as indicated above, according to the recording period T r greater than or equal to the sampling period T e of the rear wheel steering control strategy to limit the number of recorded data.
• FIG. 3 illustrates the main components of a diagnostic system making it possible to establish a coherence diagnosis of the data recorded by the computer 1 during the operation of the rear wheel steering system illustrated in FIG. 2.
• the computer 1 comprising the non-volatile memory 8.
• the data stored in the memory 8 can be retrieved in a simulator referenced 18 as a whole, by transmission means 19 of conventional type and not described here.
• the retrieval of the recorded data which makes it possible to read the contents of the nonvolatile memory 8, includes various treatments not illustrated here, necessary to render the data readable by the simulator and which may include, for example, decoding steps.
• the data stored in the memory 8 are therefore found in an input block 20 inside the simulator 18. These data have been recorded as indicated above, with a sampling frequency T r .
• the state variables of the dynamic model namely yaw rate ⁇ , lateral drift ⁇ and the modeled value of the steering angle of rear wheels CC ⁇ . have unknown values that are not necessarily null.
• the block 25 also receives on its input the set value of the rear wheel steering angle ⁇ a c r which is calculated by a block 26 corresponding to the block 5 of the computer 1 and which contains the same control law by placement of poles.
• the block 26 receives on its various inputs the values determined by the dynamic model of the block 25 that constitute the yaw rate ⁇ , the lateral drift ⁇ and the modeled value of the rear wheel steering request CC ⁇ . .
• the block 26 also receives via the connection 48 the interpolated value of the front wheel steering angle ⁇ av .
• the block 26 delivers at its output the intermediate positive reaction variable ⁇ ff ⁇ for the request for a rear wheel steering angle that is subject, by the block 27, to a delay of one sampling step so to produce the angle setpoint of rear wheel steering CL a c r which is reacted by the connection 29 to the input of the block 25.
• This value is also brought to the positive input of the adder block 28, which also receives on its negative input, by the connection 30, an interpolated value for the static steering motion of the rear wheels ( ⁇ ⁇ s' - the mlerP ° _
• the first step 33 which is upstream of the block 20 illustrated in Figure 3, allows the recovery of the recorded data. It consists of reading the contents of the non-volatile memory 8 of the calculator
• the second step 34 which takes place in the block 21 allows the interpolation of the data recorded at the sampling step of the system T e .
• the next step consists in calculating the value of the parameter constituted by the static gain rate Tgs as well as the coefficients of the correctors for each sampling step.
• This step is noted in FIG. 4 and is implemented by the block 22 illustrated in FIG. 3.
• the reconstructed values of the corrector coefficients and for Tgs are obtained from the steering data of the front wheels and the speed of the wheel. vehicle, interpolated in the previous step.
• step 36 the calculation of the initial state of the dynamic model is performed from the sole knowledge of the entries and the recorded outputs that were the subject of the interpolation. Since there is a restricted number of recorded values with respect to the model outputs, ie in the example illustrated, the static and dynamic values of the steering angle request. rear wheel, it is important to use the minimum number of points to restore the initial state. If too many points are used, the final diagnosis may be distorted. Indeed, the diagnosis is based on the interpretation of the differences observed between the simulated outputs reconstructed on the basis of the initial state also reconstructed, and the outputs recorded.
• Equations (13), (14), (15), (17) and (19) provide five new equations with four new unknowns, namely a cumulative total of six equations for eight unknowns, which remains insufficient to determine the initial state because it constitutes an indeterminate system of equations.
• the matrix M contains the interpolated data at each sampling step T e and writes:
• the coefficients b ⁇ are defined with the same expressions as ⁇ 1 ⁇ but with V x [l] instead of V x [ ⁇ ]. If we denote by Kini the 9x9 matrix of equation (23), where M is a line vector, ie a 9x1 matrix, the resulting line vector has a dimension 3x1.
• the KiniI matrix is invertible and one can obtain the initial state of the dynamic model by the equation:
• This step is to calculate, for instants k ranging from 0, which corresponds to the initialization until time t reg istrement, the state of the dynamic model and steering requests produced on the basis of equations (13), (14), (15), (16), (17), (18) and (19).
• equations (13), (14), (15), (16), (17), (18) and (19) we finally obtain the value of the dynamic steering request of the rear wheels reconstituted by the equation:
• the last step 38 indicated in FIG. 4 consists in carrying out a diagnosis by checking the consistency of the data recorded with the reconstituted data.
• the values OC * "[/ ' ] and CL ⁇ r " [nk] can preferably be plotted on a single graph, where j and k are positive or zero integers, such that j and nk do not exceed the number of samples available. The comparison of these Values are used to check the consistency of the steering requests at the different recording times, as well as the general trend of evolution during the recording time.
• a diagnostic alert message is provided to warn of inconsistency between the recorded data and the reconstructed data. Such an inconsistency will make it possible to investigate the cause of a malfunction of the on-vehicle rear wheel steering control system.
• FIG. 5 illustrates a second embodiment also applied by way of example to the diagnosis of a rear wheel steering control system.
• step 36 the following is calculated as indicated above. initial state of the dynamic model from the only input and output data recorded and interpolated as before.
• a new step 42 makes it possible to carry out a preliminary diagnosis by first checking the coherence between the initial state rebuilt and the initial state saved for the dynamic model. This comparison is performed on each series of recorded data to be analyzed. To analyze this coherence, we take into account the uncertainty associated with the reconstitution of the initial state of the dynamic model in step 36, on the basis of data presenting certain inaccuracies related to the type of memory used, the precision of the interpolation, etc. Data will be considered consistent if the following three conditions are met:
• the diagnostic step referenced 44 in FIG. 6 is then carried out, in which the values recorded are compared with the reconstituted values. This step is done in the same way as step 38 previously explained for the first embodiment.
• step 45 is first of all performed which consists in reconstructing the rear wheel steering requests from the initial registered state. We obtain a request for rear wheel steering noted
• step 47 in which the values obtained in steps 45 and 46 are compared with the recorded values.
• step 42 results from a problem of recording the initial state of the dynamic model or of a problem concerning the computation of the final queries, while in a third situation it will be possible to note for a moment record at least, denoted by k (positive integer or zero), which is simultaneously:
• ⁇ dyn ⁇ constitutes _X ⁇ . ⁇ j _ ⁇ dyn [". ⁇ ]
• ⁇ J authorizes and u a d r yn restores _ 2 X ⁇ n - - ⁇ r] ⁇ > (x a g r ap allows
• step 42 results from a problem on the first two sets of recorded samples that were used to reconstruct the initial state.
• ki and k 2 which are two positive integers or zero integers, for which we simultaneously have: a a d ⁇ n - recons ⁇ ue - 1 [n - k x ] -ce * "[n - k ⁇ ] ⁇ > cc ⁇ ⁇ ap_author> and allows ar

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• Physics & Mathematics (AREA)
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• Evolutionary Computation (AREA)
• Mathematical Physics (AREA)
• General Physics & Mathematics (AREA)
• Automation & Control Theory (AREA)
• Steering Control In Accordance With Driving Conditions (AREA)
• Testing And Monitoring For Control Systems (AREA)
• Control Of Driving Devices And Active Controlling Of Vehicle (AREA)

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• 2008
  • 2008-02-29 FR FR0851329A patent/FR2928219B1/fr not_active Expired - Fee Related
• 2009
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  • 2009-02-23 JP JP2010548148A patent/JP2011515260A/ja active Pending
  • 2009-02-23 US US12/920,225 patent/US20110087400A1/en not_active Abandoned
  • 2009-02-23 WO PCT/FR2009/050283 patent/WO2009112746A2/fr not_active Ceased

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