A bench test system and method for WLTC cycle conditions

Abstract

The present invention relates to a bench test system and method for WLTC cycle conditions, which adopts a throttle brake robot to be fixed on a vehicle to be tested through a robot clamping mechanism, and is connected to the vehicle pedal through a connecting rod; a central controller is electrically connected to the throttle brake robot for adjusting the pedal stroke; a vehicle chassis dynamometer is connected to the central controller through a data acquisition module, and is used to send the vehicle's test parameters to the central controller. The control of the WLTC cycle condition test is standardized to improve the test consistency; in multiple tests on the same vehicle, the unmanned test system of the present invention has higher speed following repeatability and reduces randomness compared to manual tests; and can meet the WLTC cycle condition test under high and low temperature environments. In multiple groups of tests under high and low temperature environments, the unmanned test system of the present invention has higher consistency in speed and vehicle economy than manual tests.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle testing, and in particular relates to a bench testing system and method for WLTC cycle conditions. Background Art

[0002] Before a car is put on the market, it needs to be tested for fuel economy according to a standard procedure. Usually, the fuel consumption of the car is measured on a laboratory rotating hub test bench to simulate a series of driving conditions. Because the NEDC standard test is too idealized, such as in a 195-second urban driving cycle, mechanically repeating several stages such as starting, acceleration, constant speed, deceleration and stopping, and then repeating this cycle again 3 times; for example, in a 400-second suburban driving condition, continuous highway driving is not included; therefore, there is always a large difference between the NEDC standard test and the actual situation. It is precisely because of this limitation of NEDC that WLTC is used as a European vehicle certification procedure. Compared with NEDC, this standard better represents actual and modern driving conditions and has also been accepted.

[0003] WLTC simulates four different operating conditions: city (low speed), suburban (medium speed), rural (high speed) and highway (superhigh speed), each with a different maximum vehicle speed. The ratio between urban sections and non-urban sections is basically the same, 52% and 48% respectively. The total duration of the WLTC Category 3 test cycle is 1,800 seconds. Over a cumulative mileage of 23.3 kilometers, the maximum speed reaches 131.3km / h, the average non-stop speed is 53.5km / h, and the average parking speed is 46.5km / h. Because WLTC simulates a more dynamic route, a wider range of driving conditions, and optional configurations can be added separately, it is more in line with actual driving conditions. Compared with NEDC, WLTC often reflects higher fuel consumption and lower mileage of electric vehicles.

[0004] It is precisely because WLTC is more complex in testing specifications and vehicle control than NEDC, and has higher requirements for manual driving, and how to achieve data consistency, better fuel consumption quality, and reduce manual random errors have become technical issues that need to be solved urgently. Summary of the invention

[0005] In order to solve the problems of large errors and poor data consistency in the prior art, the present invention provides a bench test system and method for WLTC cycle conditions, which has the characteristics of replacing manual labor to achieve unmanned and standardized, and improve test consistency.

[0006] A bench test system for WLTC cycle conditions according to a specific embodiment of the present invention includes: a throttle brake robot, a robot clamping mechanism, a central controller, a data acquisition module and a vehicle chassis dynamometer;

[0007] The throttle brake robot is fixed on the vehicle to be tested through a robot clamping mechanism and connected to the vehicle pedal through a connecting rod;

[0008] The central controller is electrically connected to the throttle brake robot for adjusting the pedal stroke;

[0009] The vehicle chassis dynamometer is connected to the central controller via the data acquisition module and is used to send the test parameters of the vehicle to the central controller.

[0010] Furthermore, the bench test system for the WLTC cycle condition also includes a power module, which is used to provide required power for the throttle brake robot, the central controller and the data acquisition module.

[0011] Furthermore, the throttle brake robot is connected to the pedal via a rocker arm connecting rod mechanism.

[0012] Furthermore, the throttle brake robot includes a pedal clamping mechanism, which is used to connect the automobile pedal and the rocker arm connecting rod mechanism.

[0013] Furthermore, the bench test system for the WLTC cycle condition also includes a control handle, which is connected to the vehicle chassis dynamometer and the central controller respectively, and is used to trigger the start of the WLTC cycle condition signal and synchronize the clocks of the vehicle chassis dynamometer and the central controller.

[0014] A bench test method for a WLTC cycle condition provided according to a specific embodiment of the present invention, applied to the bench test system for the WLTC cycle condition described above, comprises:

[0015] The speed and voltage of the vehicle chassis dynamometer are collected based on the 16-bit analog channel, and the instantaneous vehicle speed and acceleration data are obtained through the easily preset conversion formula;

[0016] Calibrate the speed of the test vehicle according to the WLTC cycle to generate a vehicle calibration table;

[0017] The accelerator brake robot is controlled to control the accelerator pedal based on the instantaneous motion stroke of the brake pedal robot.

[0018] Further, the performing of vehicle speed calibration on the test vehicle according to the WLTC cycle condition to generate a vehicle calibration table includes:

[0019] The vehicle acceleration and speed are mapped to the throttle or brake travel, and an initial calibration table is generated for each vehicle based on the vehicle speed calibration algorithm.

[0020] Furthermore, the step of calibrating the vehicle speed of the test vehicle according to the WLTC cycle condition to generate a vehicle calibration table also includes: segmenting the vehicle speed according to the WLTC cycle condition data, calibrating the PID in different vehicle speed segments, and generating an initial PID calibration table.

[0021] The beneficial effects of the present invention are as follows: the throttle brake robot is fixed on the vehicle to be tested through a robot clamping mechanism and connected to the vehicle pedal through a connecting rod; the central controller is electrically connected to the throttle brake robot for adjusting the pedal stroke; the vehicle chassis dynamometer is connected to the central controller through a data acquisition module for sending the vehicle's test parameters to the central controller. The control of the WLTC cycle condition test is standardized and the test consistency is improved; in multiple tests on the same vehicle, the unmanned test system of the present invention has higher speed following repeatability and reduces randomness compared to manual tests; and it can meet the WLTC cycle condition test under high and low temperature environments. In multiple groups of tests under high and low temperature environments, the unmanned test system of the present invention has higher consistency in speed and vehicle economy than manual tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 is a schematic diagram of a bench test system for WLTC cycle conditions provided according to an exemplary embodiment;

[0024] Figure 2 is a scatter diagram of vehicle speed and instantaneous acceleration under WLTC condition provided according to an exemplary embodiment;

[0025] Figure 3 The present invention is a flow chart of generating a vehicle calibration preprocessing speed calibration table for a bench test method for a WLTC cycle condition according to an exemplary embodiment. DETAILED DESCRIPTION

[0026] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0027] Reference Figure 1As shown, an embodiment of the present invention provides a bench test system for WLTC cycle conditions, including: a throttle brake robot, a robot clamping mechanism, a central controller, a data acquisition module and a vehicle chassis dynamometer;

[0028] The accelerator brake robot is fixed on the vehicle to be tested through a robot clamping mechanism and connected to the vehicle pedal through a connecting rod;

[0029] The central controller is electrically connected to the accelerator brake robot for adjusting the pedal stroke;

[0030] The vehicle chassis dynamometer is connected to the central controller via a data acquisition module, which is used to send the vehicle's test parameters to the central controller.

[0031] Specifically, the accelerator brake robot can control the vehicle's accelerator pedal according to the control signal of the central controller to achieve the functions of refueling and reducing oil. Then the vehicle chassis dynamometer tests the vehicle's power, chassis output power, multi-condition emission indicators and fuel consumption, thereby replacing manual testing, reducing test labor costs and improving test efficiency; achieving standardization of control of WLTC cycle test conditions and improving test consistency; in multiple tests on the same vehicle, the unmanned test system provides a higher speed follow-up repeatability compared to manual testing, reducing randomness; meeting the WLTC cycle test conditions under high and low temperature environments, in multiple groups of tests under high and low temperature environments, the vehicle speed and vehicle economy are more consistent than those of manual testing.

[0032] In another specific embodiment of the present invention, a power module is also included, and the power module is used to provide the required power for the throttle brake robot, the central controller and the data acquisition module.

[0033] The throttle brake robot is connected to the pedal via a rocker arm connecting rod mechanism. The throttle brake robot includes a pedal clamping mechanism, which is used to connect the vehicle pedal and the rocker arm connecting rod mechanism. The specific implementation forms of the rocker arm connecting rod mechanism and the pedal clamping mechanism can be selected by those skilled in the art according to actual conditions, and the present invention does not limit this.

[0034] In some specific embodiments of the present invention, a control handle is also included, which is connected to the vehicle chassis dynamometer and the central controller respectively, and is used to trigger the start of the WLTC cycle working condition signal and synchronize the vehicle chassis dynamometer and the central controller clock.

[0035] An embodiment of the present invention further provides a bench test method for a WLTC cycle condition, which is applied to the bench test system for a WLTC cycle condition described above, and specifically includes:

[0036] 101. Collect the speed and voltage of the vehicle chassis dynamometer based on the 16-bit analog channel, and obtain the instantaneous vehicle speed and acceleration data through the preset conversion formula;

[0037] 102. Calibrate the speed of the test vehicle according to the WLTC cycle to generate a vehicle calibration table;

[0038] 103. Based on the instantaneous motion stroke of the brake pedal robot, the accelerator brake robot controls the accelerator pedal.

[0039] Specifically, the speed and voltage of the automobile chassis dynamometer are collected through the 16-bit analog channel, and the instantaneous vehicle speed and acceleration data are calculated through the conversion formula; then the vehicle calibration preprocessing is performed, and the speed of the test vehicle is calibrated according to the WLTC cycle condition, and a vehicle calibration table is generated; finally, the WLTC cycle condition control is performed, and the start signal is triggered by the handle. The central controller obtains the collection module data and the WLTC condition data to calculate the instantaneous motion stroke of the accelerator pedal robot and the brake pedal robot; the central controller sends motion instructions to the accelerator pedal robot and the brake pedal robot to control the robots to move.

[0040] As a feasible implementation method of the above embodiment, refer to Figure 2 and Figure 3 As shown, for vehicle speed calibration, the calibration tool software sends the target parameters (speed V, throttle stroke ar, brake stroke br) to the throttle brake robot. First, the throttle robot is controlled to execute the ar value according to the throttle stroke (ar), and the dynamometer vehicle speed value (V1) is obtained in real time through the acquisition module, and the acceleration value (acc1) is calculated; when V1>V, the brake robot is controlled to execute the br value according to the brake stroke (br), and the dynamometer vehicle speed value (V2) is obtained in real time through the acquisition module, and the acceleration value (acc2) is calculated; when V2=0, the vehicle speed calibration of this group is completed; the stroke value, speed and acceleration value in the calibration process are saved; since the calibration process data is naturally noisy and uneven (for example, the speed and acceleration are unevenly distributed during movement), it is necessary to perform several steps to clean the calibration process data (speed, acceleration, stroke value).

[0041] First, it can be expected that there will be a response delay caused by the vehicle actuator (for example, there is a time difference between the completion of the throttle / brake command and the reaching of the corresponding acceleration). Such a delay will inevitably affect the quality of the data. A common and effective practice is to add a reasonable delay estimate when collecting data from the sensor. Then use a Butterworth low-pass filter with an order of 3 and a cutoff frequency of 2Hz to eliminate high-frequency interference. Considering that the data after a certain delay estimate may not always be appropriate, we use Formula 1 to further ensure the consistency of the data. Secondly, use the mean filter in Formula 2 to smooth the data; next, use Formula 3 to filter out outliers; use Formula 4 to ensure the monotonicity of the entire control command sequence:

[0042]

[0043] Where t is the estimated delay duration (200ms);

[0044] cmd ref is the control instruction to be updated, such as the instruction executed t(200)ms ago;

[0045] cmd ref+Δt is the control instruction at time ref+Δt;

[0046] δ cmd gap is the maximum allowed instruction disturbance.

[0047] where cmd ref Only in its neighborhood All elements in will be processed only if they satisfy Formula 1.

[0048]

[0049] Where N represents the mean filter window size, x t-1 , x t-2 , ..., x t-n It is the data corresponding to time t-1 to tN.

[0050]

[0051] Where x is the data to be processed, x mean is the mean value of the data, x std is the standard deviation of the data.

[0052]

[0053] Where T′ represents the updated calibration table; T′[cmd i ][V x ]Indicates acceleration cmd iCorresponding control instructions and speed V x .

[0054] Reference Figure 2 The WLTC working condition vehicle speed and instantaneous acceleration scatter plot shows that when the vehicle speed calibration software provided by the present invention is used, the calibration table (vehicle speed, acceleration) discrete point diagram can be visually displayed. In order to achieve optimal control, the calibration table discrete point diagram needs to cover Figure 2 Scatter plot of vehicle speed and instantaneous acceleration under WLTC conditions.

[0055] The vehicle acceleration and speed are mapped to the throttle or brake travel, and an initial calibration table is generated for each vehicle based on the vehicle speed calibration algorithm.

[0056] Vehicle calibration preprocessing also includes PID segment calibration, which segments the vehicle speed according to the WLTC cycle operating data, calibrates the PID under different vehicle speed segments, and generates an initial PID calibration table; the present invention provides a vehicle preprocessing calibration tool software to calibrate the PID segments, and the PID calibration needs to be calibrated after the vehicle speed calibration is completed, relying on the vehicle speed calibration table.

[0057] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0058] In addition, each functional unit in each embodiment of the present invention may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0059] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0060] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0061] The above description includes examples of one or more embodiments. Of course, it is impossible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it should be recognized by those skilled in the art that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", as explained by "including" used as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to mean "non-exclusive or".

[0062] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A bench test system for WLTC cycle conditions, characterized in that: include: Throttle brake robot, robot clamping mechanism, central controller, data acquisition module and automobile chassis dynamometer; The throttle brake robot is fixed on the vehicle to be tested through a robot clamping mechanism and connected to the vehicle pedal through a connecting rod; The central controller is electrically connected to the throttle brake robot for adjusting the pedal stroke; The vehicle chassis dynamometer is connected to the central controller via the data acquisition module, and is used to send the test parameters of the vehicle to the central controller; wherein the central controller obtains the acquisition module data and the WLTC working condition data to calculate the instantaneous motion stroke of the accelerator pedal robot and the brake pedal robot; It also includes a control handle, which is connected to the vehicle chassis dynamometer and the central controller respectively, and is used to trigger the start of the WLTC cycle condition signal and synchronize the vehicle chassis dynamometer and the central controller clock; Among them, the test method applied to the bench test system includes: The speed and voltage of the vehicle chassis dynamometer are collected based on the 16-bit analog channel, and the instantaneous vehicle speed and acceleration data are obtained through the easily preset conversion formula; The vehicle speed of the test vehicle is calibrated according to the WLTC cycle to generate a vehicle calibration table. During the calibration process, the consistency of the data is ensured by formula (1); ； Wherein, t is the estimated delay duration, For control instructions with updates, the For in time The control instructions is the maximum allowed instruction disturbance; The data is smoothed using formula (2); ； Wherein, N is the mean filter window size, The data corresponding to time t-1 to tN; Filter outliers using formula (3); ； Wherein, the x is the data to be processed, is the average value of the data, is the standard deviation of the data; Controlling the accelerator brake robot to control the accelerator pedal based on the instantaneous motion stroke of the brake pedal robot; The step of calibrating the vehicle speed of the test vehicle according to the WLTC cycle to generate a vehicle calibration table includes: mapping the vehicle acceleration and speed to the throttle or brake stroke, and generating an initial calibration table for each vehicle based on a vehicle speed calibration algorithm; The step of calibrating the vehicle speed of the test vehicle according to the WLTC cycle condition to generate a vehicle calibration table further includes: segmenting the vehicle speed according to the WLTC cycle condition data, calibrating the PID in different vehicle speed segments, and generating an initial PID calibration table.

2. The bench test system for WLTC cycle conditions according to claim 1, characterized in that: It also includes a power supply module, which is used to provide the required power for the throttle brake robot, the central controller and the data acquisition module.

3. The bench test system for WLTC cycle conditions according to claim 1, characterized in that: The throttle brake robot is connected with the pedal via a rocker arm connecting rod mechanism.

4. The bench test system for WLTC cycle conditions according to claim 3, characterized in that: The throttle brake robot comprises a pedal clamping mechanism, and the pedal clamping mechanism is used to connect the automobile pedal and the rocker arm connecting rod mechanism.

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