TEST BED FOR TESTING A REAL TEST OBJECT IN DRIVING OPERATION

Abstract

The invention relates to a test bed and a method for testing a real test object in driving operation, wherein the test object has at least one real component of a vehicle which is capable of applying torque to a wheel hub. The test bed comprises a load machine configured to be connected to the wheel hub so as to transmit torque, an actuator configured to generate a relative movement between the wheel hub on the one hand and a vehicle frame supporting the wheel hub on the other, simulation means for simulating the driving operation, wherein the simulation means is configured to simulate a virtual wheel and dynamics of the virtual wheel as if it were arranged on the wheel hub, and control means configured to operate the real test object in consideration of the simulated dynamics of the virtual wheel on the test bed.

Claims

1.-15. (canceled)

16. A test bed for testing a real test object in driving operation, wherein the real test object has at least one real component of a vehicle which is capable of applying torque to a wheel hub, and wherein the test bed comprises: a load machine which is configured to be connected to the wheel hub so as to transmit torque; an actuator which is configured to generate a relative movement between the wheel hub on the one hand and a vehicle frame supporting the wheel hub on the other; simulation means for simulating the driving operation, wherein the simulation means is configured to simulate a virtual wheel and dynamics of the virtual wheel, characterized by torsional vibration frequencies, vibrational frequencies in the vehicle's transverse and longitudinal direction, tire deformation and/or tire curvature, as if it were arranged on the wheel hub; and control means configured to operate the real test object in consideration of the simulated dynamics of the virtual wheel on the test bed.

17. The test bed according to claim 16, wherein the test bed comprises fixing means in order to fix the real test object such that the relative movement results exclusively from a movement of the wheel hub.

18. The test bed according to claim 16, wherein the simulation means is further configured to simulate a movement of the vehicle frame relative to a roadway, wherein the control means is further configured to factor in the simulated movement of the vehicle frame when controlling the actuator such that the relative movement at least substantially corresponds to a relative movement between the wheel hub and the vehicle frame on the roadway.

19. The test bed according to claim 16, wherein the simulation means comprises a tire model in order to take properties of a tire of the virtual wheel into account during simulation, wherein preferably the tire model characterizes a change in the tire, particularly due to the active tire geometry and/or the active tire temperature and/or active tire wear.

20. The test bed according to claim 16, wherein the simulation means is further configured to adapt simulation parameters on the basis of measurement data recorded on the test bed using a self-learning algorithm.

21. The test bed according to claim 16, wherein the actuator acts at least substantially in the vertical direction and/or acts in, particularly on, the region of the wheel hub.

22. The test bed according to claim 16 having a plurality of load machines and/or actuators, wherein preferably the number of load machines corresponds to the number of wheel hubs to which a torque can be applied via a real component of the real test object, and/or preferably the number of actuators corresponds to the number of wheel hubs.

23. A measuring arrangement comprising a test bed according to claim 16 and the real test object which is installed on the test bed and which at the least comprises the real component of the vehicle capable of applying torque to a wheel hub.

24. A method for testing a real test object having a real component of a vehicle capable of applying torque to a wheel hub on a test bed comprising a load machine and an actuator, wherein the method comprises the following work steps: simulating travel of the vehicle on a virtual test track via a vehicle model which maps a virtual wheel, in particular its dynamics, and other components of the vehicle which are not actually physically present, wherein at least target values for a torque (M.sub.Soll(t) or an engine speed (N.sub.Soll(t)) of the load machine and target values for a, particularly vertical, force (F.sub.z_Soll(t)) or position (Z.sub.Soll(t)) of the actuator are determined; providing a torque or engine speed to the wheel hub via the load machine and a, particularly vertical, force or position to the wheel hub via the actuator as a function of the respective simulated target values (M.sub.Soll(t); N.sub.Soll(t), F.sub.z_Soll(t); Z.sub.Soll(t)); operating the real test object, in particular the real component able to apply torque to a wheel hub, on the test bed such that the vehicle travels along the virtual test track; and measuring actual values of the engine speed (N.sub.lst(t)) and/or the torque (M.sub.lst(t)) at the wheel hub and/or measuring actual values of the, in particular vertical, force (F.sub.z_lst(t)) and/or position (Z.sub.lst(t)) of the wheel hub, wherein at least those parameters of the parameter pair of engine speed and torque (N.sub.lst(t); M.sub.lst(t)) or the parameter pair of force and position (Z.sub.lst(t); F.sub.z_lst(t)) for which no target values were determined are measured in each respective case.

25. The method according to claim 24, wherein target values for a braking force (F.sub.B(t)) and/or a vehicle acceleration (a(t)) are furthermore determined via the vehicle model during the simulating of the vehicle's travel, wherein the real test object, in particular the real component of the vehicle capable of applying a torque to the wheel hub, is operated subject to these respective target values.

26. The method according to claim 24, wherein a test driver presets target values for a braking force (F.sub.B(t)) and/or a vehicle acceleration (a(t)) when operating the real test object, wherein the real test object, in particular the real component of the vehicle capable of applying a torque to the at least one wheel hub, is operated subject to these respective target values.

27. The method according to claim 24 performed iteratively, in particular in real time, wherein during each increment of time while simulating the travel, the measured actual values (N.sub.lst(t); M.sub.lst(t), Z.sub.lst(t); F.sub.z_lst(t)) from the preceding increment of time are taken into account.

28. The method according to claim 24 further comprising the following work step: adapting simulation parameters on the basis of measurement data recorded on the test bed, in particular the measured actual values (N.sub.lst(t); M.sub.lst(t), Z.sub.lst(t); F.sub.z_lst(t)), using a self-learning algorithm.

29. A computer program comprising instructions which, when executed by a computer, prompt it to execute the steps of a method according to claim 24.

30. A computer-readable medium on which a computer program according to claim 29 is stored.

Description

[0071] Further features and advantages are yielded by the following description referencing the figures. Shown therein at least partly schematically:

[0072] FIG. 1 a perspective plan view of an exemplary embodiment of a measuring arrangement having a test bed and a real test object;

[0073] FIG. 2 a side plan view of the exemplary embodiment of a measuring arrangement according to FIG. 1; and

[0074] FIG. 3 an exemplary embodiment of a method for testing a real test object.

[0075] FIG. 1 shows a perspective plan view of a measuring arrangement 13. The measuring arrangement comprises a test bed 1 as well as a real test object 2.

[0076] The elements of the test bed 1 are preferably all arranged on a common base 17 which is further preferably formed by a base plate.

[0077] Four load machines 5a, 5b, 5c, 5d are supported on the base 17 by means of bearings 22a, 22b, 22c, 22d. Each dynamometer 5a, 5b, 5c, 5d exhibits shafts 23a, 23b, 23c, 23dwhich connect the dynamometers 5a, 5b, 5c, 5d to preferably existing flanges 18a, 18b, 18c, 18d. The preferably present flanges 18a, 18b, 18c, 18d serve in the rotationally fixed connection to the wheel hubs 4a, 4b, 4c, 4d of the real test object 2.

[0078] The shafts 23a, 23b, 23c, 23d are further supported by the actuators 6a, 6b, 6c, 6d.

[0079] The base 17 thereby extends in the xy-plane of the plotted xyz-coordinate system.

[0080] The bearings 22a, 22b, 22c, 22d extend upward in the vertical z-direction.

[0081] The actuators 6a, 6b, 6c, 6d, which support the shafts 23a, 23b, 23c, 23d via bearings, also extend in the z-direction. Via the actuators 6a, 6b, 6c, 6d, a force can be exerted in the vertical z-direction on the shafts 23a, 23b, 23c, 23d, which are preferably flexibly connected both to the dynamometers 5a, 5b, 5c, 5d as well as to the flanges 18a, 18b, 18c, 18d.

[0082] The test bed 1 further exhibits an electronic control unit 16 which preferably comprises simulation means 8 and control means 10. Further preferably, the simulation means 8 and the control means 10 can also be arranged in separate electronic control units. Preferably, the control unit 16 or the control units is/are designed as a computer.

[0083] As FIG. 1 shows, the electronic control unit 16 is signal-connected to the dynamometers 5a, 5b, 5c, 5d as well as to the actuators 6a, 6b, 6c, 6d of the test bed 1 for signal transmission. Preferably, these elements of the test bed 1 are controlled by the electronic control unit 16. Furthermore, the electronic control unit 16 and the test bed 1 are configured to measure measurement signals on the torque-transmitting unit generated in each case by the shafts 23a, 23b, 23c, 23d, and in their extension, by the respective flanges 18a, 18b, 18c, 18d, wheel hubs 4a, 4b, 4c, 4d and drive shafts 3d. These elements are preferably connected together in rotationally fixed manner. A corresponding measurement signal could for example be transmitted to the electronic control unit 16 via the respective signal connection to the dynamometers 5a, 5b, 5c, 5d.

[0084] As previously stated, the control means 10 serves in the controlling of the test bed 1. In addition, the controller 10 can also control unit 3a.

[0085] The simulation means 8 preferably comprises a vehicle model 14. In addition, further preferably stored in the simulation means 8 is a tire model 11, which is further preferably part of the vehicle model 14. The simulation means preferably simulates all the components of the vehicle which are not actually physically present on the test bed. In particular, a so-called virtual test object can be simulated by the simulation model.

[0086] The real test object 2 preferably comprises a vehicle frame 7, which is further preferably formed as a chassis. Unit 3a, in particular a combustion engine or electric motor, is preferably connected in torque-transmitting manner to a transmission and/or differential 3c via a cardan shaft 3b. The transmission and/or differential 3c is in turn rotationally fixed to wheel hubs 4a, 4b on which wheels 9a, 9b can be mounted via drive shafts 3d.

[0087] In the depicted example, the wheel flanges 4a, 4b form the rear axle of a vehicle constituting the real test object 2. All the aforementioned elements which transmit torque to the wheel hubs 4a, 4b are preferably mounted on the vehicle frame 2. Preferably, the unit 3a is thus part of the real test object 2. In principle, however, depending on which components are to be tested, the unit can also be part of the test bed 1 and likewise designed for example as a dynamometer.

[0088] The front axle is formed by two pivotable shaft sections 3d which support the wheel hubs 4c, 4d preferably on the chassis 7. The shaft sections 3d are each braked by brakes 3e, in particular disc brakes with brake shoes. The disk brakes 3e can also apply a torque to the wheel hubs 4c, 4d, in this case a braking torque.

[0089] The wheel hubs 4a, 4b, 4c, 4d are, as depicted, rotationally fixed to the flanges 18a, 18b, 18c, 18d of the test bed 1. However, it is also alternatively possible for the shafts 23a, 23b, 23c, 23d to act directly on the wheel flanges 4a, 4b, 4c, 4d.

[0090] Further preferably, it is possible for the wheel flanges 4a, 4b, 4c, 4d to be part of the real test object 2 or the test bed 1. Additionally or alternatively, the vehicle frame 7 can also be part of the test bed. In that case, the real components 3a, 3b, 3c, 3e, 3d are mounted on the vehicle frame 7 of the test bed 1.

[0091] The vehicle frame 7 is preferably likewise securely fixed to the base 17 via fixing means 21. In particular, the fixing means 21 are configured such that the vehicle frame or chassis 7 respectively is at least substantially unable to move relative to the base 17.

[0092] As previously stated, the simulation means 8 preferably comprises a tire model 11 and a vehicle model 14. The simulation means 8 serves in particular in simulating those components of the vehicle not physically present on the test bed, in particular a so-called virtual test object.

[0093] At least wheels 9a, 9b, 9c, 9d are simulated in the depicted exemplary embodiment. Preferably, the wheels thereby comprise a wheel rim 15a, 15b, 15c, 15d, which is generally rigid, and the tire 12a, 12b, 12c, 12d. The dynamics of the wheels 9a, 9b, 9c, 9d are thereby simulated in the simulation means 8 by means of virtual wheels as if they were affixed to the edge flanges 4a, 4b, 4c, 4d of the real test object 2.

[0094] FIG. 2 shows a side view of the exemplary embodiment of the measuring arrangement 13 from FIG. 1 in a plan view in the y-direction of the depicted coordinate system.

[0095] Reference is made to FIG. 1 with respect to the description of the individual elements shown in FIG. 2.

[0096] Dotted lines are used to depict the actuators 6b, 6c as well as the shafts 23b, 23c of the test bed 1 since they are technically hidden behind the bearings 22b, 22c and the dynamometers 5b, 5c in the FIG. 2 view.

[0097] The double arrows shown in FIG. 2 indicate that the depicted actuators 6b, 6c can exert a force on the shafts 23b, 23c of the test bed 1 in the z-direction in order to induce a relative movement of the virtual wheels 9b, 9c (not shown) relative to the vehicle frame or chassis respectively.

[0098] FIG. 3 shows an exemplary embodiment of the inventive method 100 for testing a real test object 2.

[0099] In a first work step 101, the travel of the vehicle 19 on a virtual test track 20 is simulated.

[0100] The vehicle model 14, in particular utilizing a tire model 11, models the virtual components of the vehicle 19, in particular the dynamics of the virtual wheels 9a, 9b, 9c, 9d (not shown). Target values are thereby calculated for a torque M.sub.Soll(t) or an engine speed N.sub.Soll(t) for the dynamometers 5a, 5b, 5c, 5d (not shown). Furthermore, target values for a braking force F.sub.B(t) and/or a vehicle acceleration a(t) are preferably determined during the simulation via the vehicle model 14.

[0101] In a second work step 102, the test bed 1, in particular its dynamometers 5a, 5b, 5c, 5d and actuators 6a, 6b, 6c, 6d (neither shown), is controlled on the basis of the simulation such that the dynamometers 5a, 5b, 5c, 5d provide a torque subject to the target value of the torque M.sub.Soll(t) or an engine speed subject to the target value of the engine speed N.sub.Soll(t). The same applies to the actuators 6a, 6b, 6c, 6d (not shown) which provide a force based on the target value F.sub.Z_Soll(t) or set the wheel hubs 5a, 5b, 5c, 5d (not shown) and/or the shafts 23a, 23b, 23c, 23d (not shown) to a defined position subject to the target value Z.sub.Soll(t).

[0102] In a third work step 103, the real test object 2, in particular the real component 3 capable of applying a torque to the wheel hubs 4a, 4b, 4c, 4d (neither shown), is operated such that a simulated vehicle 19 drives along a virtual test track 20. Preferably, the target values for the braking force F.sub.B(t) and/or the target value for the vehicle acceleration a(t) preferably likewise calculated in the simulation are thereby used in order to control a drive motor 3a and/or one or more braking devices 3e of the real test object 2.

[0103] The second and third work steps 102, 103 preferably run simultaneously.

[0104] Alternatively, the target values for the braking force FB(t) and/or vehicle acceleration a(t) can also be preset by a test driver.

[0105] In a fourth work step 104, the actual values of the engine speed N.sub.lst(t) or the torque M.sub.lst(t) are measured in the region of the at least one wheel hub 4a, 4b, 4c, 4d (not shown). The torque can thereby in principle be measured on one of the elements rotationally fixed to the wheel hub 4a, 4b, 4c, 4d, as depicted in FIG. 1.

[0106] Preferably, an actual value of the force on the wheel hub 4a, 4b, 4c, 4d (not shown) in the z-direction F.sub.Z_lst(t) or the position Z.sub.lst(t) of the wheel hub 4a, 4b, 4c, 4d (not shown) in the z-direction is alternatively or additionally also measured.

[0107] Measured from the parameter pair of engine speed and torque N.sub.lst(t), M.sub.lst(t) and the parameter pair of force and position Z.sub.lst(t), F.sub.Z_lst(t) is at least those respective parameters for which no target values were determined in the simulation and which were therefore also not predefined by the test bed or the electronic control unit 16 respectively (neither shown).

[0108] Preferably, simulation parameters are adapted in a further work step 105 on the basis of measurement data recorded on the test bed 1 (not shown) using a self-learning algorithm. In particular, the measured actual values are thereby used.

[0109] Further preferably, the method 100 is performed iteratively, in particular in real time. Preferably, during each increment of time while simulating the travel in work step 101, the measured actual values N.sub.lst(t), M.sub.lst(t), Z.sub.lst(t), F.sub.Z_lst(t) from the preceding increment of time are thus taken into account. Preferably, a closed control loop is formed in which the target values and the actual values have a mutual influence on each other. So doing enables taking into account that parameters which change over time, in particular engine speeds, torques, forces and positions, are relayed to the interfaces between the real components and the virtual components in real time.

[0110] The exemplary embodiments described above are only examples which are in no way intended to limit the scope of protection, application and configuration of the invention. Rather, the foregoing description is to provide the person skilled in the art with a guideline for implementing at least one exemplary embodiment, whereby various modifications can be made, particularly as regards the function and arrangement of the described components, without departing from the scope of protection resulting from the claims and from equivalent combinations of features.

LIST OF REFERENCE NUMERALS

[0111] 1 test bed [0112] 2 real test object [0113] 3a, 3b, 3c, 3d, 3e, 3f real component of a vehicle [0114] 4a, 4b, 4c, 4d wheel hub [0115] 5a, 5b, 5c, 5d load machine [0116] 6a, 6b, 6c, 6d actuator [0117] 7 vehicle frame [0118] 8 simulation means [0119] 9a, 9b, 9c, 9d virtual wheel [0120] 10 control means [0121] 11 tire model [0122] 12a, 12b, 12d, 12c, 12d tire [0123] 13 measuring arrangement [0124] 14 vehicle model [0125] 15a, 15b, 15d wheel rim [0126] 16 electronic control unit [0127] 17 base [0128] 18a, 18b, 18c, 18d flange [0129] 19 vehicle [0130] 20 test track [0131] 21 fixing means [0132] 22a, 22b, 22c, 22d bearing [0133] 23a, 23b, 23c, 23d shaft [0134] M.sub.Soll(t) target torque value [0135] N.sub.Soll(t) target engine speed value [0136] F.sub.Z_Soll(t) target value of a force in the z-direction [0137] Z.sub.Soll(t) target value of the position in the z-direction [0138] F.sub.B(t) target braking force value [0139] a(t) target acceleration value [0140] N.sub.lst(t) actual engine speed value [0141] M.sub.lst(t) actual torque value [0142] Z.sub.lst(t) actual value of the position in the z-direction [0143] F.sub.Z_lst(t) actual value of the force in the z-direction