Method and apparatus for determining latency

Abstract

A method for determining a delay between a first temporal reference frame of a system under test in a host vehicle and a second temporal reference frame of a reference system in the host vehicle. The system under test includes at least one sensor for acquiring sensor data around the host vehicle. The reference system includes an inertial measurement unit (IMU). A time-dependent first speed of the host vehicle in a first temporal reference frame is determined with the system under test. A time-dependent second speed of the host vehicle in a second temporal reference frame is determined with the reference system. A delay between the first time reference frame and the second time reference frame is calculated using the first speed and the second speed.

Description

Technical Field

[0001] The invention relates to a method and a device for determining a delay between a first time reference frame of a system under test in a host vehicle and a second time reference frame of a reference system in the host vehicle. Background Art

[0002] Advanced Driver Assistance Systems (ADAS) provide functions that help the driver with driving and parking maneuvers.

[0003] The perception system is a subsystem within ADAS that processes and compresses sensor data into a low-dimensional representation of the host vehicle's surroundings. Tracked traffic participants can be selected as targets for specific functions, such as automatic emergency braking or adaptive cruise control.

[0004] System-level performance can be measured at the functional level. However, the top-level performance reflects the sum of the defects of all lower-level system components, which makes the identification of root causes a lengthy process and reduces the modularity of subsystems. To address this issue, some form of perception-assessment framework can be implemented.

[0005] Measuring tracking accuracy also requires some form of reference data, which can be provided by dual vehicle dynamic motion analyzers (ADMA) or differential GPS (dGPS) devices. Another approach involves advanced reference systems such as the LiDAR automatic annotator pipeline.

[0006] DE 10 2021 212 632 A1 relates to the testing of environmental sensors and environmental perception systems of a vehicle, in particular for the purpose of driver assistance systems. Summary of the invention

[0007] The present invention provides a method and apparatus for determining a delay between a first time reference frame of a system under test in a host vehicle and a second time reference frame of a reference system in the host vehicle.

[0008] Preferred embodiments are stated in the dependent claims.

[0009] According to a first aspect, the present invention provides a method for determining a delay between a first time reference frame of a system under test in a host vehicle and a second time reference frame of a reference system in the host vehicle. The system under test includes at least one sensor for acquiring sensor data about the host vehicle. The reference system includes an inertial measurement unit (IMU). A time-dependent first velocity of the host vehicle in the first time reference frame is determined using the system under test. A time-dependent second velocity of the host vehicle in the second time reference frame is determined using the reference system. A delay between the first time reference frame and the second time reference frame is calculated using the first velocity and the second velocity.

[0010] According to a first aspect, the present invention provides a device for determining a delay between a first time reference frame of a system under test in a host vehicle and a second time reference frame of a reference system in the host vehicle. The system under test includes at least one sensor for acquiring sensor data around the host vehicle. The reference system includes an inertial measurement unit (IMU). The device includes an interface configured to receive a time-dependent first speed of the host vehicle in the first time reference frame determined by the system under test. The interface is also configured to receive a time-dependent second speed of the host vehicle in the second time reference frame determined by the reference system. The device also includes a calculation unit configured to calculate the delay between the first time reference frame and the second time reference frame using the first speed and the second speed.

[0011] Advantageous Effects of the Invention

[0012] In order to get a proper evaluation, it is crucial to ensure that the reference data object state obtained by the reference system is compared to the state of the object obtained by the system under test at the same timestamp. In certain cases, there is no common time basis between the reference system and the system under test, which can introduce additional errors into the evaluation. This can be interpreted as a delay, which can offset the reference data state from the measured state.

[0013] The invention allows the delay to be determined and can therefore contribute to a more reliable perceptual assessment. According to the invention, the delay can be determined based on a first speed acquired by the system under test and a second speed acquired by a reference system. By comparing or matching these speeds, the delay can be determined.

[0014] In one embodiment of the method, calculating the delay between the first time reference frame and the second time reference frame comprises minimizing the difference between a first speed in the first time reference frame and a second speed in the second time reference frame shifted by the delay. If the correct delay is used, the difference will be minimized because the speed data from the two systems are substantially consistent.

[0015] In one embodiment of the method, linear regression is used to minimize the difference between the first speed and the second speed. This is a computationally efficient method of determining the delay.

[0016] In one embodiment of the method, a time-dependent acceleration of the host vehicle in a second time reference frame is determined using the reference system. The delay between the first time reference frame and the second time reference frame is also calculated using the acceleration of the host vehicle. The acceleration can be used in a linear regression method.

[0017] In one embodiment of the method, a first speed is determined using a first sampling rate. A second speed is determined using a second sampling rate. The second speed is resampled to the first sampling rate. By resampling, the first speed and the second speed can be compared.

[0018] In one embodiment of the method, the IMU measures the speed, acceleration and position of the host vehicle. In an embodiment, a Kalman filter is used to measure the speed, acceleration and position of the host vehicle.

[0019] In one embodiment of the present method, the IMU includes three orthogonally placed gyroscopes for measuring rotational motion of the host vehicle and / or three accelerometers for measuring linear movement of the host vehicle.

[0020] In one embodiment of the method, sensor drifts of the reference system are compensated by using a Global Navigation Satellite System GNSS.Based on the GNSS, the absolute position of the host vehicle is determined.

[0021] In one embodiment of the method, the system under test includes at least one of a radar sensor, a laser radar sensor, an infrared sensor, and a camera sensor. Each sensor can acquire sensor data around the host vehicle.

[0022] In one embodiment of the method, the delay is used to bring the first data obtained by the system under test and the second data obtained by the reference system into a common time reference frame. Therefore, the delay can be used to match the data obtained by the system under test and the reference system.

[0023] Other advantages, features and details of the present invention will become apparent from the following description, in which various embodiments are described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic block diagram of an apparatus for determining delay is shown.

[0025] Figure 2 A schematic diagram of a first speed of a host vehicle as a function of time and a second speed of the host vehicle as a function of time is shown.

[0026] Figure 3 A schematic flow chart of a method for determining a delay is shown.

[0027] The numbering of the process steps is for the sake of clarity only and does not generally imply any particular chronological order. In particular, some process steps may also be performed simultaneously. DETAILED DESCRIPTION

[0028] Figure 1A schematic block diagram of an apparatus 1 for determining a delay between a first time reference frame (eg a temporal time reference frame) of a system under test 4 in a host vehicle and a second time reference frame of a reference system 5 in the host vehicle is shown.

[0029] The system under test 4 includes at least one sensor for acquiring sensor data around the host vehicle. The system under test 4 may include at least one of a radar sensor, a lidar sensor, an infrared sensor, and a camera sensor.

[0030] The reference system 5 includes an inertial measurement unit IMU. The IMU measures the speed, acceleration and position of the host vehicle using, for example, a Kalman filter. The IMU may include three orthogonally placed gyroscopes for measuring rotational motion. The IMU may also include three accelerometers for measuring the linear movement of the host vehicle.

[0031] The reference system 5 may include a vehicle dynamic motion analyzer (ADMA).

[0032] The device 1 comprises an interface 2 configured to receive a time-dependent first speed of a host vehicle in a first time reference frame determined by a system under test 4. The interface 2 is also configured to receive a time-dependent second speed of the host vehicle in a second time reference frame determined by a reference system 5. The interface 2 may comprise any wired or wireless connection for receiving data, for example, via a CAN bus.

[0033] The device 1 further comprises a computing unit 3. The computing unit 3 may comprise at least one of a microprocessor, an integrated circuit, an image processing unit and the like. The computing unit 3 may further comprise at least one storage device for storing data and computing instructions.

[0034] The first speed is determined using the first sampling rate. The second speed is determined using the second sampling rate. The calculation unit 3 may first resample the second speed to the first sampling rate.

[0035] The calculation unit 3 may further calculate the delay between the first time reference frame and the second time reference frame using the first speed and the second speed.

[0036] The calculation unit 3 can minimize the first speed v of the host vehicle (HV) in the first time reference frame (obtained by the system under test 4) HV (t) TEST The second velocity v in the second time reference frame shifted by a delay δ HV (t) ADMA The delay (eg, relative time shift) between the first time reference frame and the second time reference frame is calculated by using the difference between the first time reference frame and the second time reference frame.

[0037] In other words, the delay δ aims to minimize the following expression (where the double brackets denote the L2 norm):

[0038] ||v HV (t) TEST -v HV (t+δ) ADMA ||

[0039] At t, v HV (t+δ) ADMA Perform a first-order Taylor expansion:

[0040]

[0041] This equation has simple physical meaning, namely that the delay causes a difference in the velocities, and this difference is proportional to the acceleration.

[0042]

[0043] The difference between this first speed and the second speed can be minimized using linear regression. The signal can be treated as a time vector to formulate the minimization problem as a linear regression task. The calculation unit 3 can assume that there is no systematic error in the speed, so the first coefficient α in the following calculation can not be used as a free parameter, as it is assumed to be close to 1:

[0044]

[0045] Here, a HV_ADMA It may be related to the time-dependent acceleration of the host vehicle in a second time reference frame (eg, determined by reference system 5). The delay between the first time reference frame and the second time reference frame may be calculated using the acceleration of the host vehicle.

[0046] The calculation unit 3 can calculate the pseudo-inverse by singular value decomposition and multiply the pseudo-inverse at both ends of the equation to complete the linear regression task. The goodness of fit can be calculated, such as a determined R2 coefficient.

[0047] And in Figure 1 In the embodiment, the system under test 4 and the reference system 5 are shown as external units. In other embodiments, the device 1 may also include the system under test 4 and the reference system 5.

[0048] The calculation unit 3 may further be configured to compensate for sensor drift of the reference system using data from a global navigation system GNSS (eg obtained via the interface 2 ).

[0049] The calculation unit 3 can also use the delay to bring the first data obtained by the system under test 4 and the second data obtained by the reference system 5 into a common time reference frame. For example, the time stamp of the second data can be shifted by the delay.

[0050] The calculation unit 3 may filter out all cycles of the second speed whose quality is unacceptable, such as cycles indicated by the specified signal. Furthermore, the delay may be calculated only for non-constant speed scenarios.

[0051] Figure 2 shows the time-dependent first speed v of the host vehicle as a function of time t HV (t) TEST and the time-dependent second velocity v of the host vehicle HV (t) ADMA It can be observed that even though it has been recorded in the host vehicle, in both signals v HV (t) ADMA With v HV (t) TEST There is also a noticeable offset between the two, which corresponds to the delay (or related time shift).

[0052] Figure 3 A schematic flow chart of a method for determining a delay between a first time reference frame of a system under test 4 in a host vehicle and a second time reference frame of a reference system 5 in the host vehicle is shown.

[0053] The system under test 4 comprises at least one sensor for acquiring sensor data around the host vehicle. The reference system 5 comprises an inertial measurement unit IMU.

[0054] In step S1 , a first time-dependent speed of a host vehicle in a first time reference frame is determined using the system under test 4 .

[0055] In step S2 , a second time-dependent speed of the host vehicle in a second time reference frame is determined using the reference system 5 .

[0056] In step 3, a delay between the first time reference frame and the second time reference frame is calculated using the first speed and the second speed. The delay between the first time reference frame and the second time reference frame can be calculated by minimizing the difference between the first speed in the first time reference frame and the second speed in the second time reference frame shifted by the delay.

[0057] In step 4, the delay may be used to bring the first data obtained by the system under test 4 and the second data obtained by the reference system 5 into a common time reference frame.

Claims

1. A method for determining a delay between a first time reference frame of a system under test (4) in a host vehicle and a second time reference frame of a reference system (5) in the host vehicle, wherein: The system under test (4) comprises at least one sensor for acquiring sensor data around the host vehicle, and wherein the reference system (5) comprises an inertial measurement unit (IMU), wherein the method comprises the following steps: Determining (S1) a first time-dependent speed of the host vehicle in the first time reference frame using the system under test (4); determining (S2) a time-dependent second speed of the host vehicle in the second time reference frame using the reference system (5); and A delay between the first time reference frame and the second time reference frame is calculated (S3) using the first speed and the second speed.

2. The method according to claim 1, wherein: Calculating the delay between the first time reference frame and the second time reference frame includes: A difference between the first speed in the first time reference frame and the second speed in the second time reference frame shifted by the delay is minimized.

3. The method according to claim 2, wherein: Linear regression is used to minimize the difference between the first speed and the second speed.

4. The method according to any one of the preceding claims, further comprising the step of determining, using a reference system (5), a time-dependent acceleration of the host vehicle in the second time reference frame; in, A delay between the first time reference frame and the second time reference frame is also calculated using the acceleration of the host vehicle.

5. A method according to any one of the preceding claims, wherein: determining the first speed using a first sampling rate; wherein the second speed is determined using a second sampling rate; and The second speed is resampled to the first sampling rate.

6. A method according to any one of the preceding claims, wherein: The IMU includes three orthogonally placed gyroscopes for measuring rotational motion of the host vehicle and / or three accelerometers for measuring linear movement of the host vehicle.

7. A method according to any one of the preceding claims, wherein: The sensor drift of the reference system (5) is compensated by using data from the Global Navigation Satellite System GNSS.

8. A method according to any one of the preceding claims, wherein: The system under test (4) includes at least one of a radar sensor, a laser radar sensor, an infrared sensor and a camera sensor.

9. The method according to any of the preceding claims, further comprising the step of bringing (S4) first data obtained by the system under test (4) and second data obtained by the reference system (5) into a common time reference frame using said delay.

10. A device (1) for determining a delay between a first time reference frame of a system under test (4) in a host vehicle and a second time reference frame of a reference system (5) in the host vehicle, wherein: The system under test (4) comprises at least one sensor for acquiring sensor data around the host vehicle, and wherein the reference system (5) comprises an inertial measurement unit (IMU), wherein the device comprises: an interface (2) configured to receive a time-dependent first speed of the host vehicle in the first time reference frame determined by the system under test (4), and configured to receive a time-dependent second speed of the host vehicle in the second time reference frame determined by the reference system (5); and A calculation unit (3), wherein the calculation unit (3) is configured to calculate a delay between the first time reference frame and the second time reference frame using the first speed and the second speed.

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