Patent Publication Number: US-2023150504-A1

Title: Automatic test subject driving device, automatic test subject driving method, and test subject testing system

Description:
TECHNICAL FIELD 
     The present invention relates to an automatic test object driving device and an automatic test object driving method for automatically driving a test object that is a test vehicle or a part of the test vehicle on the basis of a command vehicle speed, and a test object testing system in which the automatic test object driving device is used. 
     BACKGROUND ART 
     Conventionally, for example, when a vehicle is automatically driven on a chassis dynamometer, the vehicle is caused to run in a predetermined running pattern by using an automatic driving robot for operating an accelerator, a brake, and the like of the vehicle, and a test of the vehicle is performed. 
     The automatic driving robot receives input of a command vehicle speed on the basis of a running pattern defined by a legal regulation or a user. Examples of legal regulations in respective countries include JC08 (Japan), NEDC (Europe), WLTP (mainly in Japan, Europe, etc.), FTP75 (the United States (US)), US06 (US), HWFET (US), and SC03 (US). 
     The automatic driving robot needs to drive various vehicles according to predetermined running patterns. Thus, the automatic driving robot uses a running performance map indicating a relationship among a vehicle speed, an acceleration, and a throttle opening degree obtained for each test vehicle to calculate a throttle opening degree command value. On the basis of this command value, the automatic driving robot operates an accelerator or a brake to cause an actual vehicle speed of a vehicle to follow a command vehicle speed. 
     The running performance map, however, needs to be obtained for each test vehicle. Thus, pre-learning is performed for obtaining the running performance map before the running test is performed. The pre-learning requires about 20 to 40 minutes per one time, and thus this hinders improvement in test efficiency. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 08-035913 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     The present invention has been made in view of the above problem, and it is a main object of the present invention to make it possible to automatically drive a test object without performing pre-learning for a running performance map for each vehicle. 
     Solutions to Problem 
     That is, an automatic test object driving device according to the present invention is an automatic test object driving device configured to automatically drive a test object that is a test vehicle or a part of the test vehicle based on a command vehicle speed, and includes a driving control unit configured to control the test object based on the command vehicle speed. The driving control unit includes a first accelerator map and a second accelerator map each of which indicates a relationship among a vehicle-speed-related value, an acceleration-related value, and an accelerator-depression-amount-related value. The driving control unit is configured to use the first accelerator map to determine an accelerator-depression-amount-related value corresponding to the command vehicle speed, and to use the second accelerator map to correct the accelerator-depression-amount-related value by feeding back a vehicle-speed-related value or an acceleration-related value of the test object. 
     With such a configuration, in the first accelerator map and the second accelerator map each of which indicates the relationship among the vehicle-speed-related value, the acceleration-related value, and the accelerator-depression-amount-related value, the first accelerator map is used to determine the accelerator-depression-amount-related value corresponding to the command vehicle speed, and the second accelerator map is used to correct the accelerator depression amount by feeding back the vehicle-speed-related value or the acceleration-related value of the test object. Therefore, it is possible to automatically drive the test object without performing pre-learning for a running performance map for each vehicle. As a result, it is possible to efficiently perform a running test of the test object. 
     Here, the vehicle-speed-related value may be a value indicating a vehicle speed in addition to the vehicle speed itself. The acceleration-related value may be a value indicating an acceleration in addition to the acceleration itself. The accelerator-depression-amount-related value may be a value indicating an accelerator depression amount in addition to the accelerator depression amount itself. 
     Specifically, the driving control unit is preferably configured to determine the accelerator-depression-amount-related value corresponding to the command vehicle speed through feedforward control in which the first accelerator map is used, and to correct the accelerator-depression-amount-related value corresponding to the command vehicle speed through feedback control in which the second accelerator map is used. 
     Here, the first accelerator map is preferably a standard map that is common to vehicle models, and the second accelerator map is preferably a standard map that is common to vehicle models in an initial state. It is conceivable that the standard map is, for example, a map created by averaging existing pieces of accelerator map data of a plurality of vehicle models, or a map restored by performing principal component analysis on existing pieces of accelerator map data of a plurality of vehicle models. 
     To correct response characteristics of the test object and thus improve performance of following the command vehicle speed, the driving control unit preferably includes a map update section that is configured to update the second accelerator map based on the command vehicle speed, the corrected accelerator-depression-amount-related value, and the vehicle-speed-related value or the acceleration-related value of the test object. 
     To allow adjustment of a driving mode (roughness or smoothness of driving) of the test object, the driving control unit preferably includes a feedforward control section that is configured to perform differentiation of a command vehicle speed after a predetermined look-ahead time, and that is configured to input an acceleration-related value obtained by the differentiation to the first accelerator map. 
     To correct the response characteristics of the test object and thus perform a running test with high accuracy, the feedforward control section is preferably configured to change the look-ahead time based on the command vehicle speed, the corrected accelerator-depression-amount-related value, and the vehicle-speed-related value or the acceleration-related value of the test object. 
     The driving control unit preferably includes a first brake map and a second brake map each of which indicates a relationship between a deceleration-related value and a brake-depression-amount-related value. The driving control unit is preferably configured to use the first brake map to determine a brake-depression-amount-related value corresponding to the command vehicle speed, and to use the second brake map to correct the brake-depression-amount-related value by feeding back the vehicle-speed-related value or the acceleration-related value of the test object. Here, the deceleration-related value may be a value indicating a deceleration in addition to the deceleration itself. The brake-depression-amount-related value may be a value indicating a brake depression amount in addition to the brake depression amount itself. 
     A test object testing system according to the present invention preferably further includes a driving actuator that is configured to perform driving operation of the test object. The driving control unit is preferably configured to control the test object by controlling the driving actuator. 
     The test object testing system according to the present invention includes a chassis dynamometer that is configured to perform a running test of a test object that is a test vehicle or a part of the test vehicle, and the above-described automatic test object driving device. 
     An automatic test object driving method according to the present invention is an automatic test object driving method of automatically driving a test object that is a test vehicle or a part of the test vehicle based on a command vehicle speed. The method includes using a first accelerator map and a second accelerator map each of which indicates a relationship among a vehicle-speed-related value, an acceleration-related value, and an accelerator-depression-related-value amount. The using includes using the first accelerator map to determine an accelerator-depression-amount-related value corresponding to the command vehicle speed, and using the second accelerator map to correct the accelerator-depression-related-value amount by feeding back a vehicle-speed-related value and an acceleration-related value of the test object. The method further includes controlling a driving actuator that is configured to perform driving operation of the test object, based on the corrected accelerator-depression-amount-related value. 
     Advantageous Effects of Invention 
     According to the present invention described above, it is possible to automatically drive a test object without performing pre-learning for a running performance map for each vehicle. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is an overall schematic diagram of an automatic test object driving device according to an embodiment of the present invention. 
         FIG.  2    is a functional block diagram of a driving control unit according to the embodiment. 
         FIG.  3    is a schematic diagram illustrating a method of creating a standard map in an accelerator map. 
         FIG.  4    is a schematic diagram illustrating a method of creating a standard map in a brake map. 
         FIG.  5    is a schematic diagram illustrating a method of correcting a standard map in an accelerator map. 
         FIG.  6    is a schematic diagram illustrating a method of updating a standard map in an accelerator map. 
         FIG.  7    is a functional block diagram of a driving control unit according to a modified embodiment. 
         FIG.  8    is a functional block diagram of a driving control unit according to another modified embodiment. 
     
    
    
     REFERENCE SIGNS LIST 
     
         
         
           
               100  automatic driving device 
               200  chassis dynamometer 
             V test vehicle (test object) 
               2  driving operation unit 
               21  driving actuator 
               10 A first map 
               10 B second map 
               3  driving control unit 
               31  feedforward control section 
               32  feedback control section 
               33  adder 
               34  map update section 
           
         
       
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an automatic test object driving device according to an embodiment of the present invention will be described with reference to the drawings. 
     As illustrated in  FIG.  1   , the automatic test object driving device  100  according to the present embodiment includes a driving operation unit  2  and a driving control unit  3 . The driving operation unit  2  is provided for automatically driving a test vehicle V, which is a test object placed on rotation rollers  201  of a chassis dynamometer  200 . The driving control unit  3  controls the driving operation unit  2 . The automatic test object driving device  100  is, together with the chassis dynamometer  200 , included in a test object testing system. 
     The driving operation unit  2  is placed on a seat surface of a driver&#39;s seat V 1  in the test vehicle V, and includes driving actuators  21  each of which operates a corresponding one of an accelerator pedal, a brake pedal, a shift lever, or an ignition switch, or the like of the test vehicle V. 
     Specifically, the driving operation unit  2  includes an accelerator actuator that performs depression operation of the accelerator pedal, a brake actuator that performs depression operation of the brake pedal, a shift lever actuator that operates the shift lever, or a switch actuator that operates the ignition switch, each of which serves as the driving actuator  21 . Besides, the driving operation unit  2  may, as necessary, include a clutch actuator that performs depression operation of a clutch pedal, or the like. 
     The driving control unit  3  controls each actuator  21  of the driving operation unit  2  using an input command vehicle speed as a target value to cause an actual vehicle speed of the test vehicle V to follow the command vehicle speed. The command vehicle speed r(t) is, for example, a vehicle speed that is determined by a running pattern defined by each legal regulation such as JC08 (Japan), NEDC (Europe), WLTP (mainly in Japan, Europe, etc.), FTP75 (US), US06 (US), HWFET (US), or SC03 (US), or a vehicle speed that is determined by a running pattern defined by a user. 
     Specifically, as illustrated in  FIG.  2   , the driving control unit  3  controls each actuator  21  (particularly, the accelerator actuator or the brake actuator) of the driving operation unit  2  by using two running performance maps  10 A and  10 B. The driving control unit  3  is a computer including a central processing unit (CPU), an internal memory, an input/output interface, an analog-to-digital (AD) converter, and the like. The driving control unit  3  controls each actuator  21  on the basis of a driving control program stored in the internal memory. 
     The two running performance maps  10 A and  10 B include accelerator maps  10 A- 1  and  10 B- 1 , respectively, and include brake maps  10 A- 2  and  10 B- 2 , respectively. As illustrated in  FIG.  3   , each of the accelerator maps  10 A- 1  and  10 B- 1  is a three-dimensional standard map that is common to vehicle models, and is data with which an accelerator depression amount can be obtained from a speed and an acceleration. As illustrated in  FIG.  4   , each of the brake maps  10 A- 2  and  10 B- 2  is a two-dimensional standard map that is common to vehicle models, and is data with which a brake depression amount can be obtained from a deceleration. 
     Hereinafter, when the two running performance maps  10 A and  10 B are distinguished, the one of them is referred to as a “first map  10 A” or the like, and the other is referred to as a “second map  10 B” or the like. The two running performance maps  10 A and  10 B are stored in a map storage section  30  provided in the driving control unit  3 . 
     As illustrated in  FIGS.  3  and  4   , it is conceivable that each of the running performance maps  10 A and  10 B is, for example, a map created by averaging existing running performance maps of a plurality of vehicle models, or a map restored by performing principal component analysis on existing running performance maps of a plurality of vehicle models. In the case where creation is made through the restoration by performing the principal component analysis, the principal component analysis is performed on the existing pieces of map data of the plurality of vehicle models, and then, for example, scores up to the seventh principal component are averaged to achieve the restoration. As illustrated in  FIG.  5   , as necessary, fully-closed deceleration data of the test vehicle V may be obtained, then a standard map may be corrected using the fully-closed deceleration data, and this corrected standard map may be used. 
     Here, each of the existing running performance maps is, for example, a map that has been created in the past. 
     A past accelerator map is created by the following procedures (1) to (3). (1) Learning running of a test vehicle is performed to obtain respective speeds and respective accelerations at various different accelerator depression amounts. (2) Then, data in which the accelerator depression amounts, the respective speeds, and the respective accelerations are related to one another is obtained. (3) Subsequently, on the basis of the data in which the accelerator depression amounts, the respective speed, and the respective accelerations are related to one another, plotting is performed on data (an accelerator map) with which an accelerator depression amount can be obtained from a speed and an acceleration. 
     A past brake map is created by the following procedures (1) to (3). (1) Learning running of a test vehicle is performed to obtain respective decelerations at various different brake depression amounts. (2) Then, data in which the brake depression amounts and the respective decelerations are related to each other is obtained. (3) Subsequently, on the basis of the data in which the brake depression amounts and the respective decelerations are related to each other, plotting is performed on data (a brake map) with which a brake depression amount can be obtained from a deceleration. 
     Then, the driving control unit  3  controls the driving actuator  21  such as the accelerator actuator or the brake actuator of the driving operation unit  2  by using a control algorithm of a two-degree-of-freedom control system. Here, the accelerator control and the brake control performed by the driving control unit  3  are switched such that the accelerator control is turned off and the brake control is turned on when a value in the accelerator map (the standard map) after correction becomes zero. 
     Specifically, the driving control unit  3  includes a feedforward control section  31  and a feedback control section  32 . The feedforward control section  31  uses the first map  10 A to determine an accelerator depression amount Acc FF (t) corresponding to the command vehicle speed r(t) or a brake depression amount Brk FF (t) corresponding to the command vehicle speed r(t). The feedback control section  32  uses the second map  10 B to correct the accelerator depression amount Acc FF (t) or the brake depression amount Brk FF (t) by feeding back an actual vehicle speed and an actual acceleration of the test vehicle V. 
     The feedforward control section  31  differentiates a future command vehicle speed r(t) after a certain period of time (a predetermined look-ahead time) from the present time, and inputs a differential value (an acceleration) obtained by the differentiation to the first map  10 A to obtain the accelerator depression amount Acc FF (t) or the brake depression amount Brk FF (t) of the feedforward control system. 
     The feedback control section  32  inputs a deviation between the command vehicle speed r(t) and the actual vehicle speed v(t) at the present time to a controller (for example, proportional-integral-derivative (PID) control). Then, the feedback control section  32  inputs an output value of the controller to the second map  10 B to obtain an accelerator depression amount Acc FB (t) or a brake depression amount Brk FB (t) of the feedback control system. 
     The driving control unit  3  adds the accelerator depression amount Acc FF (t) of the feedforward control system and the accelerator depression amount Acc FB (t) of the feedback control system at an adder  33 , and thus corrects (complements) the accelerator depression amount Acc FF (t) of the feedforward control system by using the accelerator depression amount Acc FB (t) of the feedback control system. Then, the driving control unit  3  controls the accelerator actuator using an accelerator depression amount command value indicating the corrected accelerator depression amount (Acc(t)=Acc FF (t)+Acc FB (t)). The driving control unit  3  also adds the brake depression amount Brk FF (t) of the feedforward control system and the brake depression amount Brk FB (t) of the feedback control system at the adder  33 , and thus corrects (complements) the brake depression amount Brk FF (t) of the feedforward control system by using the brake depression amount Brk FB (t) of the feedback control system. Then, the driving control unit  3  controls the brake actuator using a brake depression amount command value indicating the corrected brake depression amount (Brk(t)=Brk FF (t)+Brk FB (t)). 
     Here, the driving control unit  3  includes a map update section  34  that updates the second accelerator map  10 B- 1  in the second map  10 B on the basis of the command vehicle speed r(t), the corrected accelerator depression amount Acc(t), and the actual vehicle speed v(t) and the actual acceleration a(t) of the test vehicle V. The map update section  34  updates the second accelerator map  10 B- 1  in the second map  10 B using a predetermined map updating rule. The second brake map  10 B- 2  in the second map  10 B is similarly updated by the map update section  34 . 
       FIG.  6    illustrates a specific example of map updating. In the second map  10 B at the present time point, when a gap exists between an actual acceleration (here, 1.8 [km/h/s]) of the test vehicle V and a command acceleration (here, 1.4 [km/h/s]) on the second map  10 B, at a throttle depression amount (here, 0.08), a map correction point is calculated first. For example, a point (here, a quarter-way point (1.5 [km/h/s])) between the actual acceleration and the command acceleration is set as the map correction point. Then, on the basis of the map correction point, the second accelerator map  10 B- 1  in the second map  10 B is updated, for example, by using an approximation method such as a least-square method. 
     The feedforward control section  31  changes the look-ahead time on the basis of the command vehicle speed r(t), the corrected accelerator depression amount Acc(t), and the actual vehicle speed v(t) and the actual acceleration a(t) of the test vehicle V. Specifically, the feedforward control section  31  changes the look-ahead time in accordance with the type of transmission of the test vehicle V. In a case where the length or the like of a response time of the test vehicle V can be estimated during the test, the look-ahead time is changed on an as-needed basis. 
     Effects of Present Embodiment 
     According to the automatic test object driving device  100  in accordance with the present embodiment configured as described above, in the first map  10 A (the first accelerator map  10 A- 1 ) and the second map  10 B (the second accelerator map  10 B- 1 ) each of which indicates the relationship among the vehicle speed, the acceleration, and the accelerator depression amount, the first accelerator map  10 A- 1  is used to determine the accelerator depression amount corresponding to the command vehicle speed, and the second accelerator map  10 B- 1  is used to correct the accelerator depression amount by feeding back the vehicle speed and the acceleration of the test vehicle V. Therefore, it is possible to automatically drive the test vehicle V without performing pre-learning for a running performance map for each test vehicle V. As a result, it is possible to efficiently perform a running test of the test vehicle V on the chassis dynamometer  200 . 
     Other Embodiments 
     For example, in the above embodiment, the feedforward control section  31  changes the look-ahead time on the basis of the command vehicle speed r(t), the corrected accelerator depression amount Acc(t), and the actual vehicle speed v(t) and the actual acceleration a(t) of the test vehicle V. However, as illustrated in  FIG.  7   , the feedforward control section  31  may not change the look-ahead time. 
     In the above embodiment, the second map  10 B is updated by the map update section  34 . However, the first map  10 A may be updated on the basis of the command vehicle speed r(t), the corrected accelerator depression amount Acc(t), and the actual vehicle speed v(t) and the actual acceleration a(t) of the test vehicle V. 
     The configuration in the above embodiment includes the map update section  34 . However, as illustrated in  FIG.  8   , the configuration may not include the map update section  34 . That is, the configuration may be formed such that the first map  10 A and the second map  10 B are not updated. 
     The first map  10 A and the second map  10 B in the above embodiment are the same before updating (in the initial state). However, the first map  10 A and the second map  10 B may be different from each other before updating. 
     The configuration in the above embodiment is provided with both the accelerator map and the brake map as the running performance maps. However, the configuration may be provided with either one (for example, only the accelerator map or only the brake map). 
     The feedforward control section  31  may differentiate a future command vehicle speed r(t) after a certain period of time (a predetermined look-ahead time) from the present time, and may input, to the first map  10 A, a value calculated by multiplying a differential value (an acceleration) obtained by the differentiation by a predetermined gain value. 
     In the above embodiment, a completed vehicle is tested. However, for example, an engine may be tested by using an engine dynamometer. Alternatively, for example, a powertrain may be tested by using a dynamometer. The vehicle may be a hybrid vehicle, an electric vehicle, or a fuel cell vehicle. 
     The driving control unit according to the above embodiment controls the driving actuator. However, the driving control unit may control a test object by inputting a control signal to the test object, while the driving control unit does not control the driving actuator. In this case, for example, the driving control unit does not input, to the test object, a command value for an accelerator depression amount itself. Instead, the driving control unit inputs, to the test object, an accelerator-depression-amount-related value related to the accelerator depression amount. 
     Further, various modifications and combinations of the embodiments may be made without departing from the gist of the present invention. 
     INDUSTRIAL APPLICABILITY 
     According to the present invention, it is possible to automatically drive a test object without performing pre-learning for a running performance map for each vehicle.