Method for monitoring an egomotion state estimation of a vehicle

1 . A method for monitoring an egomotion state estimation of a motor vehicle, comprising the following steps:

receiving, by a processor system that has access to a memory of the vehicle, inertial measurement data output by at least one inertial measurement unit (IMU) of the vehicle, the inertial measurement unit including at least one accelerometer and at least one gyroscopic sensor;

storing, by the processor system, the inertial measurement data of the inertial measurement unit in the memory of the vehicle;

receiving, by the processor system, velocity data of an absolute-velocity measurement sensor of at least one wheel sensor of the vehicle, the velocity data identifying a current velocity of the vehicle at a current time;

determining, by the processor system and as a first current egomotion state of the vehicle at the current time, a first estimate that is obtained by propagating a first base state, which is an immediately preceding egomotion state, forward to the current time by fusing the inertial measurement data received at the current time with the identified current velocity;

determining, by the processor system and as a second current egomotion state of the vehicle at the same current time, a second estimate obtained by:

(a) retrieving from the memory (i) as a second base state, a prior egomotion state estimated as having been present at a defined past time point preceding the current time and (ii) a set of the stored inertial measurement data that was stored in the memory since the defined past time point; and

(b) integrating the retrieved inertial measurement data forward in time from the second base state to the current time, thereby reconstructing the egomotion of the vehicle without using any determined velocity measurement that is used in determining the first current egomotion state, such that the determination of the second current egomotion state is independent of the absolute-velocity measurement sensor on which the determination of the first current egomotion state is dependent;

comparing, by the processor system, the first and second current egomotion states, each representing the vehicle's egomotion at the same current time but derived from different base states and data sets, by computing a difference between corresponding motion parameters of the two states;

evaluating, by the processor system, the difference against at least one threshold corresponding to a fault of at least one of the IMU and the velocity sensor; and

controlling, by the processor system, a drive operation of the vehicle in response to the evaluation indicating that the difference exceeds the threshold.

2 . The method according to claim 1 , wherein the first current egomotion state is estimated using an estimation method including using a Kalman filter and/or a particle filter, which takes into account both movement dynamics of the vehicle and a correction using the current output data of the absolute-velocity measurement sensor.

3 . The method according to claim 1 , wherein the first current egomotion state of the vehicle and/or the second current egomotion state of the vehicle are each estimated using an egomotion dynamics equation including a strapdown algorithm.

4 . The method according to claim 1 , wherein output data of a further absolute-velocity measurement sensor including a further wheel sensor of the vehicle are received, wherein a further current velocity of the vehicle is determined based on the output data of the further absolute-velocity measurement sensor of the vehicle, wherein the first current egomotion state of the vehicle is estimated based on the further current velocity determination.

5 . The method according to claim 1 , further comprising the following steps:

receiving current output data of a further inertial measurement unit of the vehicle, the further inertial measurement unit including at least one further accelerometer and at least one further gyroscopic sensor;

storing the current output data of the further inertial measurement unit of the vehicle in the memory, in which older output data of the further inertial measurement unit are stored up to the defined past;

estimating a third current egomotion state of the vehicle based on a last estimated third egomotion state of the vehicle, the current output data of the further inertial measurement unit of the vehicle, and the current velocity determination;

estimating a fourth current egomotion state of the vehicle based on a third egomotion state that is in the defined past and older than the last estimated third egomotion state, based on the output data of the further inertial measurement unit that are stored in the memory and are within a time period from the defined past to the current time, and based on the current output data of the further inertial measurement unit; and

monitoring the egomotion state estimation based on the estimated third current egomotion state and the estimated fourth current egomotion state.

6 . The method according to claim 1 , wherein, (i) based on the ascertained difference, an at least partially automated function including a driving function of the vehicle provided by a first vehicle system is limited, or (ii) based on the ascertained difference, a change is made to an alternative vehicle system which can provide the same function.

7 . The method according to claim 1 , further comprising the following steps:

receiving current output data of a further inertial measurement unit of the vehicle, the further inertial measurement unit including at least one further accelerometer and at least one further gyroscopic sensor;

storing the current output data of the further inertial measurement unit of the vehicle in the memory, in which older output data of the further inertial measurement unit are stored up to the defined past;

estimating a third current egomotion state of the vehicle based on a last estimated third egomotion state of the vehicle, the current output data of the further inertial measurement unit of the vehicle, and the current velocity determination;

estimating a fourth current egomotion state of the vehicle based on a third egomotion state that is in the defined past and older than the last estimated third egomotion state, based on the output data of the further inertial measurement unit that are stored in the memory and are within a time period from the defined past to the current time, and based on the current output data of the further inertial measurement unit; and

monitoring the egomotion state estimation based on the estimated third current egomotion state and the estimated fourth current egomotion state;

wherein the monitoring includes a comparison of the estimated third current egomotion state to the estimated fourth current egomotion state, in order to ascertain a further difference between the estimated third current egomotion state and the estimated fourth current egomotion state, wherein, based on the ascertained differences, a functional capability of the inertial measurement unit, of the further inertial measurement unit, and of the absolute-velocity measurement sensor is ascertained.

8 . A device configured to monitor an egomotion state estimation of a motor vehicle, the device comprising:

a memory of the vehicle; and

a computer of the vehicle, wherein the computer has access to the memory and is configured to:

receive inertial measurement data output by at least one inertial measurement unit (IMU) of the vehicle, the inertial measurement unit including at least one accelerometer and at least one gyroscopic sensor;

store the inertial measurement data of the inertial measurement unit in the memory of the vehicle;

receive velocity data of an absolute-velocity measurement sensor of at least one wheel sensor of the vehicle, the velocity data identifying current velocity of the vehicle at a current time;

determine, as a first current egomotion state of the vehicle at the current time, a first estimate that is obtained by propagating a first base state, which is an immediately preceding egomotion state, forward to the current time by fusing the inertial measurement data received at the current time with the identified current velocity;

determine, as a second current egomotion state of the vehicle at the same current time, a second estimate obtained by:

(a) retrieving from the memory (i) as a second base state, a prior egomotion state estimated as having been present at a defined past time point preceding the current time and (ii) a set of the stored inertial measurement data that was stored in the memory since the defined past time point; and

(b) integrating the retrieved inertial measurement data forward in time from the second base state to the current time, thereby reconstructing the egomotion of the vehicle without using any determined velocity measurement that is used in determining the first current egomotion state, such that the determination of the second current egomotion state is independent of the absolute-velocity measurement sensor on which the determination of the first current egomotion state is dependent;

compare the first and second current egomotion states, each representing the vehicle's egomotion at the same current time but derived from different base states and data sets, by computing a difference between corresponding motion parameters of the two states;

evaluate the difference against at least one threshold corresponding to a fault of at least one of the IMU and the velocity sensor; and

control a drive operation of the vehicle in response to the evaluation indicating that the difference exceeds the threshold.

9 . A non-transitory machine-readable storage medium on which is stored a computer program for monitoring an egomotion state estimation of a motor vehicle, the computer program being executable by a computer that has access to a memory of the vehicle and, when executed by the computer, causing the computer to perform the following steps:

receiving inertial measurement data output by at least one inertial measurement unit (IMU) of the vehicle, the inertial measurement unit including at least one accelerometer and at least one gyroscopic sensor;

storing the inertial measurement data of the inertial measurement unit in the memory of the vehicle;

receiving velocity data of an absolute-velocity measurement sensor of at least one wheel sensor of the vehicle, the velocity data identifying a current velocity of the vehicle at a current time;

determining, as a first current egomotion state of the vehicle at the current time, a first estimate that is obtained by propagating a first base state, which is an immediately preceding egomotion state, forward to the current time by fusing the inertial measurement data received at the current time with the identified current velocity;

determining, as a second current egomotion state of the vehicle at the same current time, a second estimate obtained by:

(a) retrieving from the memory (i) as a second base state, a prior egomotion state estimated as having been present at a defined past time point preceding the current time and (ii) a set of the stored inertial measurement data that was stored in the memory since the defined past time point; and

(b) integrating the retrieved inertial measurement data forward in time from the second base state to the current time, thereby reconstructing the egomotion of the vehicle without using any determined velocity measurement that is used in determining the first current egomotion state, such that the determination of the second current egomotion state is independent of the absolute-velocity measurement sensor on which the determination of the first current egomotion state is dependent;

comparing the first and second current egomotion states, each representing the vehicle's egomotion at the same current time but derived from different base states and data sets, by computing a difference between corresponding motion parameters of the two states;

evaluating the difference against at least one threshold corresponding to a fault of at least one of the IMU and the velocity sensor; and

controlling a drive operation of the vehicle in response to the evaluation indicating that the difference exceeds the threshold.