# US 11,994,582 B2 · Inverse radar sensor model and evidential grid mapping processors

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- Number: US 11,994,582 B2
- Document ID: US11994582B2
- Status: Granted
- Kind: B2
- Application number: 17/472,809
- Filed: 2021-09-13
- Published: 2023-03-23
- Granted: 2024-05-28
- Earliest claimed: 2021-09-13
- Assignees: Texas Instruments Incorporated
- Applicants: Texas Instruments Incorporated
- Inventors: Gunawath Dilshan Godaliyadda; June Chul Roh
- Web page: https://patentgrep.com/patent/US11994582B2

## CPC

- G01S 13/931: of land vehicles
- G01S 7/354: {Extracting wanted echo-signals (Doppler systems G01S13/50)}
- G01S 13/726: {Multiple target tracking}
- G01S 13/449: {Combined with MTI or Doppler processing circuits}
- G01S 13/589: {measuring the velocity vector}
- G01S 13/865: {Combination of radar systems with lidar systems}
- G01S 13/867: {Combination of radar systems with cameras}
- G01S 13/89: for mapping or imaging
- G01S 2013/93274: {on the side of the vehicles}
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

An apparatus includes an inverse radar sensor model processor and a grid mapping processor. The inverse radar sensor model processor receives radar sensor data for a time k from a radar sensor, generates object data based on the radar sensor data, and calculates instantaneous masses at the time k for each cell in a field of view (FOV) of the radar sensor based on the object data and a sensor characteristic. The inverse radar sensor model processor outputs the calculated instantaneous masses to the grid mapping processor, which also receives accumulated masses for each cell in the FOV for a time period 0:k−1. An accumulated mass represents a combination of instantaneous masses for the cell at each time increment in the time period 0:k−1. The grid mapping processor generates updated accumulated masses for a time period 0:k.

## Claims

### Claim 1

An apparatus, comprising:
an inverse radar sensor model processor configured to:
receive radar sensor data for a time k from a radar sensor;
generate object data for the time k based on the radar sensor data;
calculate instantaneous masses at the time k for each cell in a field of view (FOV) of the radar sensor based on the object data for the time k and a sensor characteristic; and
output the calculated instantaneous masses for each cell in the FOV at the time k; and
a grid mapping processor configured to:
receive the calculated instantaneous masses for each cell in the FOV at the time k and accumulated masses for each cell in the FOV for a time period 0:k−1 prior to the time k, wherein an accumulated mass for a cell in the FOV for the time period 0:k−1 represents a combination of instantaneous masses for the cell at each time increment in the time period 0:k−1; and
generate, for each cell in the FOV, updated accumulated masses for a time period 0:k based on the calculated instantaneous masses for the time k and the accumulated masses for the time period 0:k−1.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the radar sensor data for the time k comprises point cloud data, wherein each data point in the point cloud data comprises a range with respect to the radar sensor, an azimuth angle with respect to the radar sensor, and a radial velocity with respect to the radar sensor.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein the apparatus further comprises:
a motion sensor configured to output motion data for the apparatus at the time k;
a motion calculator configured to:
receive the motion data; and
determine calculated motion data based on the motion data; and
a motion compensator configured to:
receive the calculated motion data and the radar sensor data for the time k; and
adjust, for each data point in the point cloud data, the radial velocity based on the calculated motion data.

### Claim 4 (depends on 3)

The apparatus of claim 3, wherein the inverse radar sensor model processor comprises:
an object level data calculator configured to:
receive the radar sensor data for the time k and the adjusted radial velocity data; and
generate the object data for the time k based on the radar sensor data for the time k and the adjusted radial velocity data; and
an instantaneous mass calculator configured to:
receive the object data for the time k;
calculate the instantaneous masses at the time k for each cell in the FOV based on the object data for the time k, the adjusted radial velocity data, and the sensor characteristic; and
output the calculated instantaneous masses at the time k.

### Claim 5 (depends on 4)

The apparatus of claim 4, wherein the sensor characteristic comprises at least one of:
an antenna gain as a function of angle with respect to the radar sensor, an antenna gain as a function of range with respect to the radar sensor, a signal-to-noise ratio as a function of angle with respect to the radar sensor, and a signal-to-noise ratio as a function of range with respect to the radar sensor.

### Claim 6 (depends on 5)

The apparatus of claim 5, wherein the object data for the time k comprises locations at which radar reflections are centered at the time k, wherein the instantaneous mass calculator is configured to calculate the instantaneous masses at the time k for each cell in the FOV by being further configured to, for each cell (i,j) in the FOV:
determine a probability of occupancy Pocc(i,j;k) at the time k based on a range of the cell (i,j) from the locations at which the radar reflections are centered;
determine a position of the cell (i,j) with respect to a position of the radar sensor;
update the Pocc(i,j;k) based on an ambiguity of the radar sensor data associated with the position of the cell (i,j);
determine whether the Pocc(i,j;k) satisfies an occupancy criterion ∈occ;
in response to the Pocc(i,j;k) not satisfying the ∈occ, perform a first set of operations;
in response to the Pocc(i,j;k) satisfying the ∈occ, perform a second set of operations.

### Claim 7 (depends on 6)

The apparatus of claim 6, wherein the instantaneous mass calculator is configured to perform the first set of operations by being configured to:
determine whether the position of the cell (i,j) is between the position of the radar sensor and a position of a cell (a,b) with a corresponding Pocc(a,b;k) that satisfies the ∈occ;
in response to the position of the cell (i,j) not being between the radar sensor and the position of the cell (a,b):
calculate an instantaneous mass for a free state with low confidence;
set an instantaneous mass for a static-dynamic state to zero; and
set an instantaneous mass for a dynamic state to zero;
in response to the position of the cell (i,j) being between the radar sensor and the position of the cell (a,b):
calculate the instantaneous mass for the free state with high confidence;
set the instantaneous mass for the static-dynamic state to zero; and
set the instantaneous mass for the dynamic state to zero.

### Claim 8 (depends on 7)

The apparatus of claim 7, wherein the instantaneous mass m(i,j;k)(F) for the free state of a cell (i,j) at the time k with low confidence is represented as:
m(i,j;k)(F)=pƒ,1*wƒ,1(θi,j)*wƒ,1(ri,j)
where θi,j represents an angle of the position of the cell (i,j) with respect to the position of the radar sensor, ri,j represents a range of the position of the cell (i,j) with respect to the position of the radar sensor, pƒ,1 represents a constant, wƒ,1(θi,j) represents a first weight based on the sensor characteristic associated with the angle θi,j, and wƒ,1(ri,j) represents a second weight based on the sensor characteristic associated with the range ri,j.

### Claim 9 (depends on 7)

The apparatus of claim 7, wherein the instantaneous mass m(i,j;k)(F) for the free state of a cell (i,j) at the time k with high confidence is represented as:
m(i,j;k)(F)=pƒ,2*wƒ,2(θi,j)*wƒ,2(ri,j)
where θi,j represents an angle of the cell position with respect to the position of the radar sensor, ri,j represents a range of the cell position with respect to the position of the radar sensor, pƒ,2 represents a constant, wƒ,2(θi,j) represents a first weight based on the sensor characteristic associated with the angle θi,j and wƒ,2(ri,j) represents a second weight based on the sensor characteristic associated with the range ri,j.

### Claim 10 (depends on 6)

The apparatus of claim 6, wherein the instantaneous mass calculator is configured to perform the second set of operations by being configured to:
determine whether an adjusted radial velocity associated with the cell (i,j) satisfies a velocity criterion ∈ν;
in response to the adjusted radial velocity not satisfying the ∈ν:
calculate an instantaneous mass for a static-dynamic state;
set an instantaneous mass for a free state to zero; and
set an instantaneous mass for a dynamic state to zero;
in response to the radial velocity satisfying the ∈ν:
calculate the instantaneous mass for the dynamic state;
set the instantaneous mass for the free state to zero; and
set the instantaneous mass for the static-dynamic state to zero.

### Claim 11 (depends on 10)

The apparatus of claim 10, wherein the instantaneous mass m(i,j;k)(SD) for the static-dynamic state of a cell (i,j) at the time k is represented as:
m(i,j;k)(SD)=Pocc(i,j;k)*ρocc(radar)
where ρocc(radar) represents a weight based on the sensor characteristic.

### Claim 12 (depends on 10)

The apparatus of claim 10, wherein the instantaneous mass m(i,j;k)(D) for the dynamic state of a cell (i,j) at the time k is represented as:
m(i,j;k)(D)=Pocc(i,j;k)*ρocc(radar)
where ρocc(radar) represents a weight based on the sensor characteristic.

### Claim 13

A non-transitory computer readable medium (CRM), comprising computer executable code to:
receive radar sensor data for a time k from a radar sensor;
generate object data based on the radar sensor data, wherein the object data comprises locations at which radar reflections are centered;
calculate, for each cell in a field of view (FOV) of the radar sensor, an instantaneous mass m(i,j;k) based on the object data and a radar sensor characteristic, wherein (i,j) represents a cell position; and
accumulate, for each cell in the FOV, the calculated instantaneous mass m(i,j;k) and a prior accumulated mass m(i,j;0:k−1), wherein the prior accumulated mass m(i,j;0:k−1) represents an accumulation of instantaneous masses for (i,j) from a time 0 to a time k−1.

### Claim 14 (depends on 13)

The non-transitory CRM of claim 13, wherein the computer executable code to calculate, for each cell in the FOV, an instantaneous mass m(i,j;k) further comprises computer executable code to:
determine a probability of occupancy Pocc(i,j) based on a range of the cell (i,j) from the locations at which the radar reflections are centered;
determine a position of the cell (i,j) with respect to a position of the radar sensor;
update the Pocc(i,j) based on an ambiguity of the radar sensor data associated with the cell position;
determine whether the Pocc(i,j) satisfies an occupancy criterion ∈occ;
in response to the Pocc(i,j) not satisfying the ∈occ, perform a first set of operations; and
in response to the Pocc(i,j) satisfying the ∈occ, perform a second set of operations.

### Claim 15 (depends on 14)

The non-transitory CRM of claim 14, wherein the computer executable code to perform the first set of operations further comprises computer executable code to:
determine whether the cell position is between the position of the radar sensor and a position of a cell (a,b) with a corresponding Pocc(a,b) that satisfies the ∈occ;
in response to the cell position not being between the position of the radar sensor and the cell position of the cell (a,b):
calculate an instantaneous mass m(i,j;k)(F) for a free state with low confidence;
set an instantaneous mass m(i,j;k)(SD) for a static-dynamic state to zero; and
set an instantaneous mass m(i,j;k)(D) for a dynamic state to zero; and
in response to the cell position being between the position of the radar sensor and the cell position of the cell (a,b):
calculate the instantaneous mass m(i,j;k)(F) for the free state with high confidence;
set the instantaneous mass m(i,j;k)(SD) for the static-dynamic state to zero; and
set the instantaneous mass m(i,j;k)(D) for the dynamic state to zero.

### Claim 16 (depends on 15)

The non-transitory CRM of claim 15, wherein the instantaneous mass m(i,j;k)(F) of the cell (i,j) with low confidence is represented as:
m(i,j;k)(F)=pƒ,1*wƒ,1(θi,j)*wƒ,1(ri,j)
where θi,j represents an angle of the cell position with respect to the position of the radar sensor, ri,j represents a range of the cell position with respect to the position of the radar sensor, pƒ,1 represents a constant, wƒ,1(θi,j) represents a first weight based on the radar sensor characteristic associated with θi,j, and wƒ,1(ri,j) represents a second weight based on the radar sensor characteristic associated with range ri,j.

### Claim 17 (depends on 16)

The non-transitory CRM of claim 16, wherein the second weight wƒ,1(ri,j) is a function in which the second weight wƒ,1 decreases monotonically with range.

### Claim 18 (depends on 16)

The non-transitory CRM of claim 16, wherein the radar sensor characteristic is a radar sensor gain, wherein the first weight wƒ,1(θi,j) represents the radar sensor gain as a function of angle normalized to a first number between zero and one, and wherein the second weight wƒ,1(ri,j) represents the radar sensor gain as a function of range normalized to a second number between zero and one.

### Claim 19 (depends on 18)

The non-transitory CRM of claim 18, wherein the first weight wƒ,1(θi,j) is represented as:
w
f
,
1
(
θ
i
,
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)
=
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cos
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*
9
⁢
0
θ
max
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if
⁢
θ
i
,
j
≤
θ
max
0
otherwise
where θmax represents an angle of edges of the FOV, wherein the second weight wƒ,1(ri,j) is represented as:
w
f
,
1
(
r
i
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j
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=
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if
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r
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if
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otherwise
where r1 represents a range of an object, rmax represents a maximum range for the radar sensor, and b represents a constant chosen based on the radar sensor characteristic.

### Claim 20 (depends on 16)

The non-transitory CRM of claim 16, wherein pƒ,1 represents a first constant, and wherein the instantaneous mass m(i,j;k)(F) of the cell (i,j) with high confidence is represented as:
m(i,j;k)(F)=pƒ,2*wƒ,2(θi,j)*wƒ,2(ri,j)
where pƒ,2 represents a second constant, wƒ,2(θi,j) represents a third weight based on the radar sensor characteristic associated with θi,j, and wƒ,2(ri,j) represents a fourth weight based on the radar sensor characteristic associated with ri,j.

### Claim 21 (depends on 20)

The non-transitory CRM of claim 20, wherein the third weight wƒ,2(θi,j) and the fourth weight wƒ,2(ri,j) are normalized to a third, larger number between zero and one than the first weight wƒ,1(θi,j) and the second weight wƒ,1(ri,j).

### Claim 22 (depends on 14)

The non-transitory CRM of claim 14, wherein the computer executable code to perform the second set of operations further comprises computer executable code to:
determine whether a radial velocity associated with the cell (i,j) satisfies a velocity criterion ∈ν;
in response to the radial velocity not satisfying the ∈ν:
calculate an instantaneous mass m(i,j;k)(SD) for a static-dynamic state;
set an instantaneous mass m(i,j;k)(F) for a free state to zero; and
set an instantaneous mass m(i,j;k)(D) for a dynamic state to zero; and
in response to the radial velocity satisfying the ∈ν:
calculate the instantaneous mass m(i,j;k)(D) for the dynamic state;
set the instantaneous mass m(i,j;k)(F) for the free state to zero; and
set the instantaneous mass m(i,j;k)(SD) for the static-dynamic state to zero.

### Claim 23 (depends on 22)

The non-transitory CRM of claim 22, wherein the instantaneous mass m(i,j;k)(SD) of the cell (i,j) is represented as:
m(i,j;k)(SD)=Pocc(i,j;k)*ρocc(radar)
where ρocc(radar) represents a weight based on the radar sensor characteristic.

### Claim 24 (depends on 22)

The non-transitory CRM of claim 22, wherein the instantaneous mass m(i,j;k)(D) of the cell (i,j) is represented as:
m(i,j;k)(D)=Pocc(i,j;k)*ρocc(radar)
where ρocc(radar) represents a weight based on the radar sensor characteristic.

### Claim 25

A method, comprising:
receiving radar sensor data for a time k from a radar sensor;
generating object data based on the radar sensor data, wherein the object data comprises locations at which radar reflections are centered;
calculating, for each cell in a field of view (FOV) of the radar sensor, an instantaneous mass m(i,j;k) based on the object data and a radar sensor characteristic, wherein (i,j) represents a cell position, wherein calculating the instantaneous mass m(i,j;k) comprises:
determining a probability of occupancy Pocc(i,j) based on a range of the cell (i,j) from the locations at which the radar reflections are centered;
determining a position of the cell (i,j) with respect to a position of the radar sensor;
updating the Pocc(i,j) based on an ambiguity of the radar sensor data associated with the cell position;
determining whether the Pocc(i,j) satisfies an occupancy criterion ∈occ;
in response to the Pocc(i,j) not satisfying the ∈occ:
determine whether the cell position is between the position of the radar sensor and a position of a cell (a, b) with a corresponding Pocc(a,b) that satisfies the ∈occ;
in response to the cell position not being between the position of the radar sensor and the cell position of the cell (a,b):
calculate an instantaneous mass m(i,j;k)(F) for a free state with low confidence;
set an instantaneous mass m(i,j;k)(SD) for a static-dynamic state to zero; and
set an instantaneous mass m(i,j;k)(D) for a dynamic state to zero; and in response to the cell position being between the position of the radar sensor
and the cell position of the cell (a,b):
calculate the instantaneous mass m(i,j;k)(F) for the free state with high confidence;
set the instantaneous mass m(i,j;k)(SD) for the static-dynamic state to zero; and
set the instantaneous mass m(i,j;k)(D) for the dynamic state to zero; and
in response to the Pocc(i,j) satisfying the ∈occ:
determine whether a radial velocity associated with the cell (i,j) satisfies a velocity criterion ∈ν;
in response to the radial velocity not satisfying the ∈ν:
calculate an instantaneous mass m(i,j;k)(SD) for a static-dynamic state;
set an instantaneous mass m(i,j;k)(F) for a free state to zero; and
set an instantaneous mass m(i,j;k)(D) for a dynamic state to zero; and
in response to the radial velocity satisfying the ∈ν:
calculate the instantaneous mass m(i,j;k)(D) for the dynamic state;
set the instantaneous mass m(i,j;k)(F) for the free state to zero; and
set the instantaneous mass m(i,j;k)(SD) for the static-dynamic state to zero; and
accumulating, for each cell in the FOV, the calculated instantaneous mass m(i,j;k) and a prior accumulated mass m(i,j;0:k−1), wherein the prior accumulated mass m(i,j;0:k−1) represents an accumulation of instantaneous masses for (i,j) from a time 0 to a time k−1.