Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization — Part 1: Rules for the structure and drafting of standardizing documents.
This document has been redrafted and modified in relation to ISO 15037-1:2019 Road vehicles—Vehicle dynamics test methods—Part 1: General conditions for passenger cars.
This document is changed largely from ISO 15037-1:2019 in structure; the correspondence between this document and ISO 15037-1:2019 in clause number is listed in Annex A.
The main technical differences with respect to ISO 15037-1:2019 and their reasons are as follows:
——The application scope was changed from "passenger cars and light trucks" to "vehicles of category M1, M2 and N1 having a design total mass not exceeding 3.5t" (see Clause 1), which is consistent with the current standard.
——ISO 8855:2011 was replaced by GB/T 12549-2013 (see 4.1), the former not equivalent to the latter. GB/T 12549-2013 has been revised and adjusted based on ISO 8855:2011 according to the standards in China.
——In Table 1, the typical operating ranges of steering wheel angle was changed from "-360°to 360°" to "-1,080°to 1,080°" (see 5.1.1), which is consistent with the commonly used steering wheel angle transducers.
——With regard to the analog signal debugging, "In order to preserve low-frequency signals, the signals shall be DC coupled." (see 5.3.2.2) was added. In order to ensure the integrity of low-frequency information in analog signals, analog signal processing is uniformly standardized.
——In Annex C, "the way to measure the longitudinal velocity is by Global Positioning System (GPS)" in C.3 was changed to "GNSS"; in C.11, "the vehicle trajectory can be measured by a Global Positioning System (GPS)" was changed to "GNSS" (see C.3 and C.11). The longitudinal velocity and trajectory measurement system is not only GPS, but also GNSS such as BeiDou Navigation Satellite System (BDS).
The following editorial changes have been made in this document:
——In order to coordinate with the existing standards, the name of the standard was changed to "General condition of vehicle dynamics test for passenger cars".
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This standard was proposed by the Ministry of Industry and Information Technology of the People's Republic of China.
This document is under the jurisdiction of the National Technical Committee of Auto Standardization (SAC/TC 114).
General condition of vehicle dynamics test for passenger cars
1 Scope
This standard specifies the general condition of vehicle dynamics test for passenger cars.
This standard is applicable to vehicles of category M1, M2 and N1 having a design total mass not exceeding 3.5t.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 12549-2013 Terms and definitions for vehicle controllability and stability (ISO 8855:2011, NEQ)
3 Terms and definitions
None
4 Variables
4.1 Reference system
The variables of motion recorded in the test shall meet the coordinate system definition in GB/T 12549-2013. The location of the origin of the coordinate is usually the centroid of the vehicle, and other positions are allowed, which shall be recorded in the test report, see Annex B.
4.2 Variables to be measured
To describe of driver input and vehicle response related to vehicle dynamics, the main variables are as follows:
——steering wheel angle, δH;
——steering wheel torque, MH;
——longitudinal velocity, vX;
——sideslip angle of complete vehicle, β; or lateral velocity, vY;
——longitudinal acceleration, aX;
——lateral acceleration, aY;
——yaw velocity, dΨ/dt;
——roll velocity, dφ/dt;
——pitch velocity, dθ/dt;
——roll angle, φ;
——pitch angle, θ.
All tests that make reference to this standard shall specify which variables apply. The tests are carried out according to specific standards, and other variables can be added or recommended accordingly. These variables can be measured directly or calculated from the measured values.
5 Measurement
5.1 Requirements for measuring equipment
5.1.1 Measurement range and error requirements of equipment
Multi-channel acquisition systems and transducers are used in the tests. The operating ranges and the recommended maximum errors of the transducer and recording system are given in Table 1. Both measured and calculated variables should be up to the specified accuracy, which shall be improved in order to calculate some characteristic values.
Table 1 Variables, typical operating ranges and recommended maximum errors
Variable Typical operating range Recommended maximum error
Steering wheel angle -1,080°~1,080° ±1°, for |δH|≤50°
±2°, for 50°<|δH|≤180°
±4°, for |δH|>180°
Steering wheel torque -30 N·m to 30 N·m ±0.1 N·m, |MH|≤10 N·m
±0.3 N·m, |MH|>10 N·m
Longitudinal velocity 0 km/h to 180 km/h ±1 km/h, vX≤100 km/h
±2 km/h, vX>100 km/h
Lateral velocity -36 km/h to 36 km/h ±0.72 km/h
Sideslip angle -20° to 20° ±0.3°
Longitudinal acceleration -15 m/s2 to 15 m/s2 ±0.15 m/s2
Lateral acceleration -15 m/s2 to 15 m/s2 ±0.15 m/s2
Yaw velocity -50°/s to 50°/s ±0.3°/s for dΨ/dt≤20°/s
±1°/s for dΨ/dt>20°/s
Pitch velocity -50°/s to 50°/s ±0.3°/s for dθ/dt≤20°/s
±1°/s for dθ/dt>20°/s
Roll velocity -50°/s to 50°/s ±0.3°/s for dφ/dt≤20°/s
±1°/s for dφ/dt>20°/s
Roll angle -15° to 15° ±0.15°
Pitch angle -15° to 15° ±0.15°
5.1.2 Treatment of unsatisfied equipment errors
If the error of the adopted system exceeds the recommended value but meet the test requirements, the error and the actual maximum error shall be recorded in the test report, as shown in Annex B.
5.2 Transducer installation
The installation position of the transducer in the reference coordinate system shall be accurately recorded for appropriate data transformation in data processing. See Annex C for transducer installation.
5.3 Data processing
5.3.1 General
The frequency range relevant on test and evaluation of dynamics of passenger cars is between 0 Hz and 5 Hz.
5.3.2 Analog signal debugging
5.3.2.1 The bandwidth of the transducer and the acquisition system shall not be less than 8 Hz.
5.3.2.2 In order to execute the necessary filtering of signals, low-pass filters shall be employed. The width of the passband (from 0 Hz to frequency f0 at -3 dB) shall not be less than 9 Hz. Amplitude errors shall be less than ±0.5% in the relevant frequency range of 0 Hz to 5 Hz. All analog signals shall be processed with filters having phase characteristics sufficiently similar to ensure the same time delay due to filtering.
Note: In order to preserve low-frequency signals, the signals shall be DC coupled. During analog filtering of signals with different frequency contents, phase shifts can occur. Because of this, a digital data processing method such as that given in 5.3.3 is preferable.
5.3.3 Aliasing error and anti-alias filter
5.3.3.1 Preparation of analog signal processing includes consideration of sampling rate and filter amplitude attenuation, and filter phase lags and time delays to avoid aliasing errors.
5.3.3.2 Considerations for sampling and digitization:
a) a pre-sampling magnification ensuring the minimum digitization error;
b) the number of bits for each sampling;
c) the number of samples per cycle;
d) sample and hold amplifier;
e) sample space;
f) for other phaseless digital filters, consideration shall be given to the selection of passband, stop band, attenuation, allowable ripple, and the correction of filter phase lag.
5.3.3.3 In order to achieve the acquisition accuracy of ±0.5% for the overall data, the above influencing factors shall be taken into comprehensive consideration.
5.3.3.4 See Annex D for attenuation and phase shift of Butterworth filter. In order to avoid aliasing errors that cannot be corrected, the analog signals shall be appropriately filtered before sampling and digitizing. The order of the filters used and their passband shall be chosen according to both the required flatness in the relevant frequency range and the sampling rate. The minimum filter characteristics and sampling rate shall be such that:
a) within the relevant frequency range of 0 Hz to fmax(fmax-5 Hz), the maximum attenuation of analog signal shall be less than the resolution of the signal digitization, and
b) at one-half the sampling rate (i.e. the Nyquist or “folding” frequency), the magnitudes of all frequency components of signal and noise shall be reduced to less than the digital resolution.
Example: For a resolution of 0.05 %, the filter (within 5 Hz) attenuation shall be less than 0.05 % and the attenuation shall be greater than 99.95 % at all frequencies greater than one-half the sampling rate.
5.3.3.5 Recommended anti-alias filters are four-order or higher, see Annex D.
5.3.3.6 Anti-alias filtering shall be performed and excessive analog signal filtering shall be avoided. In addition, all filters shall have sufficiently similar phase characteristics such that time delay differences lie within the required accuracy for the time measurement.
Note: Phase shifts are especially significant when measured variables are multiplied together to form new variables. This is because while amplitudes multiply, phase shifts and associated time delays add. Phase shifts and time delays are reduced by increasing f0, the cut-off frequency of filter.
5.3.4 Sampling and digitization
5.3.4.1 To limit dynamic errors caused by changing analog inputs to 0.1 %, the sampling or digitizing time shall be less than 32 μs. All pairs or sets of data samples to be compared shall be taken simultaneously or over a sufficiently short time period.
5.3.4.2 The digitizing system shall have a minimum resolution of 12 bits (±0.05 %) and an accuracy of 2LSB(±0.1 %). Amplification of the analog signal before digitization shall be such that during the digitization process, the composite error shall be less than 0.2 % due to limited resolution and inaccurate digitization.
5.3.5 Phaseless digital filters
For filtering in data evaluation, phaseless (zero-phase-shift) digital filters incorporating the following characteristics shall be used (see Figure 1):
——passband range of from 0 Hz to 5 Hz;
——stopband beginning at 10 Hz to 15 Hz;
——filter gain in passband of 1±0.005;
——filter gain in stopband of ±0.01.
Key:
X——frequency, f(Hz);
Y——filter gain;
a——passband;
b——stopband.
Figure 1 Required characteristics of phaseless digital filters
6 Test conditions
6.1 General
Requirements for ambient conditions and vehicle test conditions are established in the following subclauses; these requirements shall be maintained throughout the specific test. Any deviations shall be shown in the test report (see Annexes B and E) including the individual diagrams of the presentation of results. For each test procedure, the test-specific conditions and those which cannot be kept constant (e.g. tread depths) shall be recorded in a separate test report in accordance with Annex E.
6.2 Test track
All tests shall be carried out on a smooth, clean, dry and uniform paved road surface. The gradient of this surface to be used shall not exceed 2 % (1.5 % recommended) in any direction. For each test, the road surface conditions and paving material shall be recorded in the test report (see Annex E).
6.3 Wind velocity
The ambient wind velocity shall not exceed 5 m/s during a test. For each test, the climate conditions shall be recorded in the test report (see Annex E).
6.4 Test vehicle
6.4.1 General data of the test vehicle shall be presented in the test report in accordance with Annex B. The general data shall be recorded again for any change of parameters (such as load) of vehicles.
6.4.2 Wheel alignment parameters shall meet the product design requirements.
6.5 Tyre
6.5.1 New tyres shall be fitted on the test vehicle according to the vehicle manufacturer's specifications. lf not specified by the tyre manufacturer, they shall be run in for at least 150 km the test vehicle or an equivalent vehicle without excessively harsh use (severe braking, acceleration, cornering, hitting the kerb, etc.). After run-in, the tyres shall be maintained at the same position on the vehicle for the tests.
6.5.2 Tyres shall have a tread depth (including the width of the tyre contacting the ground and the whole tyre surface) of at least 90 % of the original values.
6.5.3 The date of production of the tyre shall be recorded in the test conditions, as shown in Annex E, and the test tyre shall not exceed one year from the date of production.
6.5.4 Tyres shall be inflated to the pressure specified by the vehicle manufacturer for the test ambient temperature. For tyre pressure less than or equal to 250 kPa, the error of cold inflation pressure is ±5 kPa; when the tyre pressure exceeds 250 kPa, the error does not exceed 2%.
6.5.5 The inflation pressure and tread depth of the tyres determined before tyre warm-up shall be recorded in the test report (see Annex E).
6.5.6 Tests may also be performed under conditions other than general tyre conditions. The details shall be noted in the test report (see Annex E).
6.5.7 As the tread depth or uneven tread wear can have a significant influence on test results, it is recommended that they be taken into account when making comparisons between vehicles or between tyres.
6.6 Critical components
Models and types of critical components likely to influence the complete vehicle performance tests and design parameters likely to influences the tests (e.g. shock absorber, suspension geometry) shall be as specified by the manufacturer. Any deviations from manufacturer specification shall be noted in the presentation of general data (see Annex B).
6.7 Loading conditions
6.7.1 The total test mass shall be between the complete vehicle kerb mass and the maximum authorized total mass. The maximum authorized axle loads shall not be exceeded.
6.7.2 Care shall be taken to generate a minimum deviation in the location of the centre of gravity and in the moments of inertia as compared to the loading conditions of the vehicle in normal use. The resulting wheel loads shall be determined and recorded in the test report, as shown in Annex B.
6.8 Drivetrain conditions of the vehicle
For vehicles with regenerative braking capabilities, the specific vehicle configuration can alter the dynamic vehicle behaviour while releasing the accelerator pedal and/or while pressing the brake pedal. For these vehicles, the different dynamic vehicle behaviour with or without active regenerative braking shall be considered while performing the tests. The selected level of regenerative braking capability and the transmission lever position shall be documented in the test report.
6.9 Active systems
For vehicles with active systems influencing the test results, such as active steering, electronic stability control or active suspensions, the different dynamic vehicle behaviours possible with different settings of the systems shall be considered while performing the tests. If the driver can choose between different settings of the system, e.g. by a “sport/comfort” switch, the settings chosen for the test shall be documented in the test report.
7 Test preparation
7.1 Warm-up
All relevant vehicle components shall be warmed up prior to the tests in order to achieve a temperature representative of normal driving conditions. Tyres shall also be warmed up to achieve an equilibrium temperature and pressure representative of normal driving conditions. A procedure equivalent to driving at the test speed for a distance of 10 km or 500 m at a lateral acceleration of 3 m/s2 (both left and right turn each) may be appropriate for warming up the tyres.
7.2 Initial conditions
7.2.1 General
7.2.1.1 The initial driving condition is specified in each vehicle dynamics test procedure. It may be either as steady-state, straight-ahead or steady-state circular run.
7.2.1.2 If there is no specific requirement in the test standard, during the test, for manual transmission, the high gear shall be selected from the multiple gears applicable, and for automatic transmission, the D gear shall be adopted. The position of the transmission lever and the selected driving program shall be recorded in the test report (see Annex E).
7.2.1.3 The position of the steering wheel and the accelerator pedal shall be kept as constant as possible during the initial driving condition. The moment of observation, tss, used to evaluate steady state conditions, is defined as the point in time which is usually between 0.5 s and 0.8 s before the reference point in time, t0, of the specific test procedure. The initial condition is considered to be sufficiently constant if, for the moment of observation, tss, the requirements of 7.2.2 and 7.2.3 are fulfilled (see Figure 2, defined t1 and t2).
Note: For test procedures used to determine only steady-state values, the moment of observation tss and the reference point t0 will be identical.
Key:
X——time (s);
Y——test variable;
t0——moment in the test;
t1——measuring time 1;
t2——measuring time 2;
tss——moment of observation for evaluating steady-state conditions.
Figure 2 Definition of times for observation in test
7.2.2 Steady-state straight-ahead run
7.2.2.1 The longitudinal velocity in the initial driving condition shall not deviate by more than ±1 km/h (±2 km/h for velocities above 100 km/h) from the nominal value during the time interval from t1 to t2 and the mean value of lateral acceleration shall be within a range from -0.3 m/s2 to 0.3 m/s2. The standard deviation of the lateral acceleration shall not exceed 0.3 m/s2. As an alternative to the limits of lateral acceleration, the mean value of the yaw velocity shall be within a range from -0.5°/s to 0.5°/s, and the standard deviation of the yaw velocity shall not exceed 0.5°/s.
7.2.2.2 The difference between the mean values of the longitudinal velocity during the time intervals t1 to ts and tss to t2 shall not exceed ±1 km/h (±2 km/h for velocities above 100 km/h).
7.2.3 Steady-state circular run
7.2.3.1 The initial radius, R0, may be calculated using equation (1) or (2):
(1)
(2)
where,
vX0——the initial longitudinal velocity;
dΨ/dt——the yaw velocity;
aY0——the initial lateral acceleration.
7.2.3.2 The radius in the initial driving condition shall not deviate by more than 2 % or ±2 m from the nominal value during the time interval from t1 to t2.
7.2.3.3 For the time interval t1 to t2, the standard deviation of the lateral acceleration shall not exceed 5 % of its mean value and the standard deviation of the longitudinal velocity shall not exceed 3 % of its mean value.
7.2.3.4 The difference between the mean values during the time intervals t1 to tss and tss to t2, shall not exceed the nominal value for the lateral acceleration by more than 5 % and the longitudinal velocity by more than 3 %.
7.2.3.5 For the time interval t1 to t2,the mean value of the lateral acceleration shall not deviate from the nominal value by more than ± 3%.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Variables
5 Measurement
6 Test conditions
7 Test preparation
Annex A (Informative) Structural changes between this document and ISO 15037-1:
Annex B (Normative) Test report — General data
Annex C (Informative) Transducers and their installation
Annex D (Informative) Analog filtering: Butterworth filter
Annex E (Normative) Test condition
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization — Part 1: Rules for the structure and drafting of standardizing documents.
This document has been redrafted and modified in relation to ISO 15037-1:2019 Road vehicles—Vehicle dynamics test methods—Part 1: General conditions for passenger cars.
This document is changed largely from ISO 15037-1:2019 in structure; the correspondence between this document and ISO 15037-1:2019 in clause number is listed in Annex A.
The main technical differences with respect to ISO 15037-1:2019 and their reasons are as follows:
——The application scope was changed from "passenger cars and light trucks" to "vehicles of category M1, M2 and N1 having a design total mass not exceeding 3.5t" (see Clause 1), which is consistent with the current standard.
——ISO 8855:2011 was replaced by GB/T 12549-2013 (see 4.1), the former not equivalent to the latter. GB/T 12549-2013 has been revised and adjusted based on ISO 8855:2011 according to the standards in China.
——In Table 1, the typical operating ranges of steering wheel angle was changed from "-360°to 360°" to "-1,080°to 1,080°" (see 5.1.1), which is consistent with the commonly used steering wheel angle transducers.
——With regard to the analog signal debugging, "In order to preserve low-frequency signals, the signals shall be DC coupled." (see 5.3.2.2) was added. In order to ensure the integrity of low-frequency information in analog signals, analog signal processing is uniformly standardized.
——In Annex C, "the way to measure the longitudinal velocity is by Global Positioning System (GPS)" in C.3 was changed to "GNSS"; in C.11, "the vehicle trajectory can be measured by a Global Positioning System (GPS)" was changed to "GNSS" (see C.3 and C.11). The longitudinal velocity and trajectory measurement system is not only GPS, but also GNSS such as BeiDou Navigation Satellite System (BDS).
The following editorial changes have been made in this document:
——In order to coordinate with the existing standards, the name of the standard was changed to "General condition of vehicle dynamics test for passenger cars".
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This standard was proposed by the Ministry of Industry and Information Technology of the People's Republic of China.
This document is under the jurisdiction of the National Technical Committee of Auto Standardization (SAC/TC 114).
General condition of vehicle dynamics test for passenger cars
1 Scope
This standard specifies the general condition of vehicle dynamics test for passenger cars.
This standard is applicable to vehicles of category M1, M2 and N1 having a design total mass not exceeding 3.5t.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 12549-2013 Terms and definitions for vehicle controllability and stability (ISO 8855:2011, NEQ)
3 Terms and definitions
None
4 Variables
4.1 Reference system
The variables of motion recorded in the test shall meet the coordinate system definition in GB/T 12549-2013. The location of the origin of the coordinate is usually the centroid of the vehicle, and other positions are allowed, which shall be recorded in the test report, see Annex B.
4.2 Variables to be measured
To describe of driver input and vehicle response related to vehicle dynamics, the main variables are as follows:
——steering wheel angle, δH;
——steering wheel torque, MH;
——longitudinal velocity, vX;
——sideslip angle of complete vehicle, β; or lateral velocity, vY;
——longitudinal acceleration, aX;
——lateral acceleration, aY;
——yaw velocity, dΨ/dt;
——roll velocity, dφ/dt;
——pitch velocity, dθ/dt;
——roll angle, φ;
——pitch angle, θ.
All tests that make reference to this standard shall specify which variables apply. The tests are carried out according to specific standards, and other variables can be added or recommended accordingly. These variables can be measured directly or calculated from the measured values.
5 Measurement
5.1 Requirements for measuring equipment
5.1.1 Measurement range and error requirements of equipment
Multi-channel acquisition systems and transducers are used in the tests. The operating ranges and the recommended maximum errors of the transducer and recording system are given in Table 1. Both measured and calculated variables should be up to the specified accuracy, which shall be improved in order to calculate some characteristic values.
Table 1 Variables, typical operating ranges and recommended maximum errors
Variable Typical operating range Recommended maximum error
Steering wheel angle -1,080°~1,080° ±1°, for |δH|≤50°
±2°, for 50°<|δH|≤180°
±4°, for |δH|>180°
Steering wheel torque -30 N·m to 30 N·m ±0.1 N·m, |MH|≤10 N·m
±0.3 N·m, |MH|>10 N·m
Longitudinal velocity 0 km/h to 180 km/h ±1 km/h, vX≤100 km/h
±2 km/h, vX>100 km/h
Lateral velocity -36 km/h to 36 km/h ±0.72 km/h
Sideslip angle -20° to 20° ±0.3°
Longitudinal acceleration -15 m/s2 to 15 m/s2 ±0.15 m/s2
Lateral acceleration -15 m/s2 to 15 m/s2 ±0.15 m/s2
Yaw velocity -50°/s to 50°/s ±0.3°/s for dΨ/dt≤20°/s
±1°/s for dΨ/dt>20°/s
Pitch velocity -50°/s to 50°/s ±0.3°/s for dθ/dt≤20°/s
±1°/s for dθ/dt>20°/s
Roll velocity -50°/s to 50°/s ±0.3°/s for dφ/dt≤20°/s
±1°/s for dφ/dt>20°/s
Roll angle -15° to 15° ±0.15°
Pitch angle -15° to 15° ±0.15°
5.1.2 Treatment of unsatisfied equipment errors
If the error of the adopted system exceeds the recommended value but meet the test requirements, the error and the actual maximum error shall be recorded in the test report, as shown in Annex B.
5.2 Transducer installation
The installation position of the transducer in the reference coordinate system shall be accurately recorded for appropriate data transformation in data processing. See Annex C for transducer installation.
5.3 Data processing
5.3.1 General
The frequency range relevant on test and evaluation of dynamics of passenger cars is between 0 Hz and 5 Hz.
5.3.2 Analog signal debugging
5.3.2.1 The bandwidth of the transducer and the acquisition system shall not be less than 8 Hz.
5.3.2.2 In order to execute the necessary filtering of signals, low-pass filters shall be employed. The width of the passband (from 0 Hz to frequency f0 at -3 dB) shall not be less than 9 Hz. Amplitude errors shall be less than ±0.5% in the relevant frequency range of 0 Hz to 5 Hz. All analog signals shall be processed with filters having phase characteristics sufficiently similar to ensure the same time delay due to filtering.
Note: In order to preserve low-frequency signals, the signals shall be DC coupled. During analog filtering of signals with different frequency contents, phase shifts can occur. Because of this, a digital data processing method such as that given in 5.3.3 is preferable.
5.3.3 Aliasing error and anti-alias filter
5.3.3.1 Preparation of analog signal processing includes consideration of sampling rate and filter amplitude attenuation, and filter phase lags and time delays to avoid aliasing errors.
5.3.3.2 Considerations for sampling and digitization:
a) a pre-sampling magnification ensuring the minimum digitization error;
b) the number of bits for each sampling;
c) the number of samples per cycle;
d) sample and hold amplifier;
e) sample space;
f) for other phaseless digital filters, consideration shall be given to the selection of passband, stop band, attenuation, allowable ripple, and the correction of filter phase lag.
5.3.3.3 In order to achieve the acquisition accuracy of ±0.5% for the overall data, the above influencing factors shall be taken into comprehensive consideration.
5.3.3.4 See Annex D for attenuation and phase shift of Butterworth filter. In order to avoid aliasing errors that cannot be corrected, the analog signals shall be appropriately filtered before sampling and digitizing. The order of the filters used and their passband shall be chosen according to both the required flatness in the relevant frequency range and the sampling rate. The minimum filter characteristics and sampling rate shall be such that:
a) within the relevant frequency range of 0 Hz to fmax(fmax-5 Hz), the maximum attenuation of analog signal shall be less than the resolution of the signal digitization, and
b) at one-half the sampling rate (i.e. the Nyquist or “folding” frequency), the magnitudes of all frequency components of signal and noise shall be reduced to less than the digital resolution.
Example: For a resolution of 0.05 %, the filter (within 5 Hz) attenuation shall be less than 0.05 % and the attenuation shall be greater than 99.95 % at all frequencies greater than one-half the sampling rate.
5.3.3.5 Recommended anti-alias filters are four-order or higher, see Annex D.
5.3.3.6 Anti-alias filtering shall be performed and excessive analog signal filtering shall be avoided. In addition, all filters shall have sufficiently similar phase characteristics such that time delay differences lie within the required accuracy for the time measurement.
Note: Phase shifts are especially significant when measured variables are multiplied together to form new variables. This is because while amplitudes multiply, phase shifts and associated time delays add. Phase shifts and time delays are reduced by increasing f0, the cut-off frequency of filter.
5.3.4 Sampling and digitization
5.3.4.1 To limit dynamic errors caused by changing analog inputs to 0.1 %, the sampling or digitizing time shall be less than 32 μs. All pairs or sets of data samples to be compared shall be taken simultaneously or over a sufficiently short time period.
5.3.4.2 The digitizing system shall have a minimum resolution of 12 bits (±0.05 %) and an accuracy of 2LSB(±0.1 %). Amplification of the analog signal before digitization shall be such that during the digitization process, the composite error shall be less than 0.2 % due to limited resolution and inaccurate digitization.
5.3.5 Phaseless digital filters
For filtering in data evaluation, phaseless (zero-phase-shift) digital filters incorporating the following characteristics shall be used (see Figure 1):
——passband range of from 0 Hz to 5 Hz;
——stopband beginning at 10 Hz to 15 Hz;
——filter gain in passband of 1±0.005;
——filter gain in stopband of ±0.01.
Key:
X——frequency, f(Hz);
Y——filter gain;
a——passband;
b——stopband.
Figure 1 Required characteristics of phaseless digital filters
6 Test conditions
6.1 General
Requirements for ambient conditions and vehicle test conditions are established in the following subclauses; these requirements shall be maintained throughout the specific test. Any deviations shall be shown in the test report (see Annexes B and E) including the individual diagrams of the presentation of results. For each test procedure, the test-specific conditions and those which cannot be kept constant (e.g. tread depths) shall be recorded in a separate test report in accordance with Annex E.
6.2 Test track
All tests shall be carried out on a smooth, clean, dry and uniform paved road surface. The gradient of this surface to be used shall not exceed 2 % (1.5 % recommended) in any direction. For each test, the road surface conditions and paving material shall be recorded in the test report (see Annex E).
6.3 Wind velocity
The ambient wind velocity shall not exceed 5 m/s during a test. For each test, the climate conditions shall be recorded in the test report (see Annex E).
6.4 Test vehicle
6.4.1 General data of the test vehicle shall be presented in the test report in accordance with Annex B. The general data shall be recorded again for any change of parameters (such as load) of vehicles.
6.4.2 Wheel alignment parameters shall meet the product design requirements.
6.5 Tyre
6.5.1 New tyres shall be fitted on the test vehicle according to the vehicle manufacturer's specifications. lf not specified by the tyre manufacturer, they shall be run in for at least 150 km the test vehicle or an equivalent vehicle without excessively harsh use (severe braking, acceleration, cornering, hitting the kerb, etc.). After run-in, the tyres shall be maintained at the same position on the vehicle for the tests.
6.5.2 Tyres shall have a tread depth (including the width of the tyre contacting the ground and the whole tyre surface) of at least 90 % of the original values.
6.5.3 The date of production of the tyre shall be recorded in the test conditions, as shown in Annex E, and the test tyre shall not exceed one year from the date of production.
6.5.4 Tyres shall be inflated to the pressure specified by the vehicle manufacturer for the test ambient temperature. For tyre pressure less than or equal to 250 kPa, the error of cold inflation pressure is ±5 kPa; when the tyre pressure exceeds 250 kPa, the error does not exceed 2%.
6.5.5 The inflation pressure and tread depth of the tyres determined before tyre warm-up shall be recorded in the test report (see Annex E).
6.5.6 Tests may also be performed under conditions other than general tyre conditions. The details shall be noted in the test report (see Annex E).
6.5.7 As the tread depth or uneven tread wear can have a significant influence on test results, it is recommended that they be taken into account when making comparisons between vehicles or between tyres.
6.6 Critical components
Models and types of critical components likely to influence the complete vehicle performance tests and design parameters likely to influences the tests (e.g. shock absorber, suspension geometry) shall be as specified by the manufacturer. Any deviations from manufacturer specification shall be noted in the presentation of general data (see Annex B).
6.7 Loading conditions
6.7.1 The total test mass shall be between the complete vehicle kerb mass and the maximum authorized total mass. The maximum authorized axle loads shall not be exceeded.
6.7.2 Care shall be taken to generate a minimum deviation in the location of the centre of gravity and in the moments of inertia as compared to the loading conditions of the vehicle in normal use. The resulting wheel loads shall be determined and recorded in the test report, as shown in Annex B.
6.8 Drivetrain conditions of the vehicle
For vehicles with regenerative braking capabilities, the specific vehicle configuration can alter the dynamic vehicle behaviour while releasing the accelerator pedal and/or while pressing the brake pedal. For these vehicles, the different dynamic vehicle behaviour with or without active regenerative braking shall be considered while performing the tests. The selected level of regenerative braking capability and the transmission lever position shall be documented in the test report.
6.9 Active systems
For vehicles with active systems influencing the test results, such as active steering, electronic stability control or active suspensions, the different dynamic vehicle behaviours possible with different settings of the systems shall be considered while performing the tests. If the driver can choose between different settings of the system, e.g. by a “sport/comfort” switch, the settings chosen for the test shall be documented in the test report.
7 Test preparation
7.1 Warm-up
All relevant vehicle components shall be warmed up prior to the tests in order to achieve a temperature representative of normal driving conditions. Tyres shall also be warmed up to achieve an equilibrium temperature and pressure representative of normal driving conditions. A procedure equivalent to driving at the test speed for a distance of 10 km or 500 m at a lateral acceleration of 3 m/s2 (both left and right turn each) may be appropriate for warming up the tyres.
7.2 Initial conditions
7.2.1 General
7.2.1.1 The initial driving condition is specified in each vehicle dynamics test procedure. It may be either as steady-state, straight-ahead or steady-state circular run.
7.2.1.2 If there is no specific requirement in the test standard, during the test, for manual transmission, the high gear shall be selected from the multiple gears applicable, and for automatic transmission, the D gear shall be adopted. The position of the transmission lever and the selected driving program shall be recorded in the test report (see Annex E).
7.2.1.3 The position of the steering wheel and the accelerator pedal shall be kept as constant as possible during the initial driving condition. The moment of observation, tss, used to evaluate steady state conditions, is defined as the point in time which is usually between 0.5 s and 0.8 s before the reference point in time, t0, of the specific test procedure. The initial condition is considered to be sufficiently constant if, for the moment of observation, tss, the requirements of 7.2.2 and 7.2.3 are fulfilled (see Figure 2, defined t1 and t2).
Note: For test procedures used to determine only steady-state values, the moment of observation tss and the reference point t0 will be identical.
Key:
X——time (s);
Y——test variable;
t0——moment in the test;
t1——measuring time 1;
t2——measuring time 2;
tss——moment of observation for evaluating steady-state conditions.
Figure 2 Definition of times for observation in test
7.2.2 Steady-state straight-ahead run
7.2.2.1 The longitudinal velocity in the initial driving condition shall not deviate by more than ±1 km/h (±2 km/h for velocities above 100 km/h) from the nominal value during the time interval from t1 to t2 and the mean value of lateral acceleration shall be within a range from -0.3 m/s2 to 0.3 m/s2. The standard deviation of the lateral acceleration shall not exceed 0.3 m/s2. As an alternative to the limits of lateral acceleration, the mean value of the yaw velocity shall be within a range from -0.5°/s to 0.5°/s, and the standard deviation of the yaw velocity shall not exceed 0.5°/s.
7.2.2.2 The difference between the mean values of the longitudinal velocity during the time intervals t1 to ts and tss to t2 shall not exceed ±1 km/h (±2 km/h for velocities above 100 km/h).
7.2.3 Steady-state circular run
7.2.3.1 The initial radius, R0, may be calculated using equation (1) or (2):
(1)
(2)
where,
vX0——the initial longitudinal velocity;
dΨ/dt——the yaw velocity;
aY0——the initial lateral acceleration.
7.2.3.2 The radius in the initial driving condition shall not deviate by more than 2 % or ±2 m from the nominal value during the time interval from t1 to t2.
7.2.3.3 For the time interval t1 to t2, the standard deviation of the lateral acceleration shall not exceed 5 % of its mean value and the standard deviation of the longitudinal velocity shall not exceed 3 % of its mean value.
7.2.3.4 The difference between the mean values during the time intervals t1 to tss and tss to t2, shall not exceed the nominal value for the lateral acceleration by more than 5 % and the longitudinal velocity by more than 3 %.
7.2.3.5 For the time interval t1 to t2,the mean value of the lateral acceleration shall not deviate from the nominal value by more than ± 3%.
Contents of GB/T 40501-2021
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Variables
5 Measurement
6 Test conditions
7 Test preparation
Annex A (Informative) Structural changes between this document and ISO 15037-1:
Annex B (Normative) Test report — General data
Annex C (Informative) Transducers and their installation
Annex D (Informative) Analog filtering: Butterworth filter
Annex E (Normative) Test condition
