LOCATION OF A TARGET BY A TRACKING VEHICLE
Some embodiments relate to a method for locating a mobile target for a tracking vehicle, including a first communication module in a first location on the tracking vehicle in order to determine a first distance measurement between the first location and the mobile target at a first time, and a second communication module at a second location on the tracking vehicle in order to determine a second distance measurement between the second location and the mobile target at a second time, and a processing module for determining a forecast of the movement of the tracking vehicle between the first and second times, and for determining a location of the mobile target relative to the tracking vehicle from the first and second distance measurements, taking into account the forecast, so as to compensate for the movement, between the first and second times.
1 . A method for locating a mobile target by a tracking vehicle, comprising:
determining a first measurement of distance between the mobile target and a first location on the tracking vehicle, taken at a first time;
determining a second measurement of distance between the mobile target and a second location on the tracking vehicle, taken at a second time;
predicting movement of the tracking vehicle between the first and second times; and
determining a location of the mobile target with respect to the tracking vehicle based on the first and second measurements of distance, taking into account the prediction, in such a manner as to compensate for the movement between the first and second times.
2 . The method according to claim 1 , wherein the prediction and the location are determined by a Kalman filter.
3 . The method according to claim 2 , wherein the prediction of the movement is determined based on a linear speed measurement and on the orientation of a steering carriage of the tracking vehicle.
4 . The method according to claim 3 , wherein prediction equations of the Kalman filter, between a time k and a time k−1 are
X
k
/
k
-
1
=
R
(
Δ
θ
)
T
(
X
k
-
1
/
k
-
1
-
(
-
Δ
D
sin
(
Δ
θ
/
2
)
Δ
D
cos
(
Δ
θ
/
2
)
)
)
P k/k−1 =R (Δ θ ) T ( P k−1/k−1 +G k Q u G k T ) R (Δ θ )+ Q xy
wherein Q u is a covariance matrix associated with uncertainties in the proprioceptive information coming from the tracking vehicle, such that:
Q
u
=
(
σ
v
r
2
0
0
σ
δ
r
2
)
and
G
k
=
(
-
Δ
T
sin
(
Δ
θ
/
2
)
-
0.5
Δ
D
cos
(
Δ
θ
/
2
)
Δ
T
cos
(
Δ
θ
/
2
)
-
0.5
Δ
D
sin
(
Δ
θ
/
2
)
)
with
Δ
D
=
v
r
,
k
Δ
T
,
and
Δ
θ
=
v
r
,
k
Δ
T
tan
δ
r
,
k
L
.
Δ T is the period of time between the times k and k−1;
v r,k is the linear speed of the tracking vehicle at the time k;
δ r,k is the orientation of the steering carriage of the tracking vehicle at the time k, and,
L is the track-width of the tracking vehicle.
5 . The method according to claim 1 , further comprising determining a control command aimed at adapting the speed and the steering of the tracking vehicle in order to direct it as a function of the location of the target while keeping at a setpoint distance.
6 . A device for locating a mobile target for a tracking vehicle, comprising:
a first communications module at a first location on the tracking vehicle for determining a first measurement of distance between the first location and the mobile target at a first time;
a second communications module at a second location on the tracking vehicle for determining a second measurement of distance between the second location and the mobile target at a second time; and a processing module for determining a prediction of movement of the tracking vehicle between the first and second times, and determining a location of the mobile target with respect to the tracking vehicle based on the first and second measurements of distance, taking into account the prediction in such a manner as to compensate for the movement between the first and second times.
7 . The locating device according to claim 6 , wherein the processing module determines the prediction of the movement of the tracking robot and the location of the target by a Kalman filter.
8 . The locating device according to claim 7 , wherein the processing module determines the prediction of the movement based on proprioceptive measurements of the tracking vehicle.
9 . A tracking vehicle, comprising:
the device according to claim 6 .
10 . A system, comprising:
the tracking vehicle according to claim 9 ; and a communications module equipping the mobile target.